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Some tricyclic antidepressants (TCAs), including amitriptyline (ATL), clomipramine (CLO), and desipramine (DES), are known to be effective for management of neuropathic pain. It was previously determined that ATL, CLO, and DES are capable of voltage-dependent blocking of NMDA receptors of glutamate (NMDAR), which play a key role in pathogenesis of neuropathic pain. Despite the similar structure of ATL, CLO, and DES, efficacy of their interaction with NMDAR varies significantly. In the study presented here, we applied molecular modeling methods to investigate the mechanism of binding of ATL, CLO, and DES to NMDAR and to identify structural features of the drugs that determine their inhibitory activity against NMDAR. Molecular docking of the studied TCAs into the NMDAR channel was performed. Conformational behavior of the obtained complexes in the lipid bilayer was simulated by the method of molecular dynamics (MD). A single binding site (upper) for the tertiary amines ATL and CLO and two binding sites (upper and lower) for the secondary amine DES were identified inside the NMDAR channel. The upper and lower binding sites are located along the channel axis at different distances from the extracellular side of the plasma membrane. MD simulation revealed that the position of DES in the lower site is stabilized only in the presence of sodium cation inside the NMDAR channel. DES binds more strongly to NMDAR compared to ATL and CLO due to simultaneous interaction of two hydrogen atoms of its cationic group with the asparagine residues of the ion pore of the receptor. This feature may be responsible for the stronger side effects of DES. It has been hypothesized that ATL binds to NMDAR less efficiently compared to DES and CLO due to its lower conformational mobility. The identified features of the structure- and cation-dependent mechanism of interaction between TCAs and NMDAR will help in the further development of effective and safe analgesic therapy.

The facilitated activity of N-methyl-D-aspartate receptors (NMDARs) in the central and peripheral nervous systems promotes neuropathic pain. Amitriptyline (ATL) and desipramine (DES) are tricyclic antidepressants (TCAs) whose anti-NMDAR properties contribute to their analgetic effects. At therapeutic concentrations <1 µM, these medicines inhibit NMDARs by enhancing their calcium-dependent desensitization (CDD). Li+, which suppresses the sodium−calcium exchanger (NCX) and enhances NMDAR CDD, also exhibits analgesia. Here, the effects of different [Li+]s on TCA inhibition of currents through native NMDARs in rat cortical neurons recorded by the patch-clamp technique were investigated. We demonstrated that the therapeutic [Li+]s of 0.5−1 mM cause an increase in ATL and DES IC50s of ~10 folds and ~4 folds, respectively, for the Ca2+-dependent NMDAR inhibition. The Ca2+-resistant component of NMDAR inhibition by TCAs, the open-channel block, was not affected by Li+. In agreement, clomipramine providing exclusively the NMDAR open-channel block is not sensitive to Li+. This Ca2+-dependent interplay between Li+, ATL, and DES could be determined by their competition for the same molecular target. Thus, submillimolar [Li+]s may weaken ATL and DES effects during combined therapy. The data suggest that Li+, ATL, and DES can enhance NMDAR CDD through NCX inhibition. This ability implies a drug−drug or ion−drug interaction when these medicines are used together therapeutically.

We describe the effect of a tricyclic antidepressant drug desipramine on voltage-dependent K + (Kv) currents in freshly isolated rabbit coronary arterial smooth muscle cells using a conventional whole-cell patch clamp technique. Application of desipramine rapidly decreased the Kv current amplitude in a concentration-dependent manner, with an IC 50 value of 5.91 ± 0.18 μM and a Hill coefficient of 0.61 ± 0.09. The steady-state inactivation curves of the Kv channels were not affected by desipramine. However, desipramine shifted the steady-state inactivation curves toward a more negative potential. Application of train pulses (1 or 2 Hz) slightly reduced the Kv current amplitude. Such reduction in the Kv current amplitude by train pulses increased in the presence of desipramine. Furthermore, the inactivation recovery time constant was also increased in the presence of desipramine, suggesting that desipramine-induced inhibition of the Kv current was use-dependent. Application of a Kv1.5 inhibitor (DPO-1) and/or a Kv2.1 inhibitor (guangxitoxin) did not change the inhibitory effect of desipramine on Kv currents. Based on these results, we concluded that desipramine directly inhibited the Kv channels in a dose- and state-dependent manner, but the effect was independent of norepinephrine/serotonin reuptake inhibition.

Desipramine, a commonly used antidepressant drug, induced cytosolic vacuolization in L929 cells. The level of LC3-II was elevated and that of p62 was reduced in desipramine-treated L929 cells, indicating the induction of autophagy by desipramine. Surprisingly, massive vacuolization was observed in desipramine-treated L929 cells in the presence of LY294002, an inhibitor of autophagy. On the other hand, bafilomycin A1, an inhibitor of vacuolar type H + ATPase, almost completely inhibited vacuolization in desipramine- or desipramine/LY294002-treated L929 cells. Furthermore, desipramine-induced vacuolization was observed in autophagy-deficient Atg7 -/- mouse embryonic fibroblasts (MEFs) as well as wild-type Atg7 +/+ MEFs. These results demonstrate that desipramine-induced lysosomal vacuolization is independent of autophagy., (© 2017 International Federation for Cell Biology.)

Background: Demand for cholesterol is high in certain cancers making them potentially sensitive to therapeutic strategies targeting cellular cholesterol homoeostasis. A potential approach involves disruption of intracellular cholesterol transport, which occurs in Niemann-Pick disease as a result of acid sphingomyelinase (ASM) deficiency. Hence, a class of lysosomotropic compounds that were identified as functional ASM inhibitors (FIASMAs) might exhibit chemotherapeutic activity by disrupting cancer cell cholesterol homoeostasis., Methods: Here, the chemotherapeutic utility of ASM inhibition was investigated. The effect of FIASMAs on intracellular cholesterol levels, cholesterol homoeostasis, cellular endocytosis and signalling cascades were investigated. The in vivo efficacy of ASM inhibition was demonstrated using melanoma xenografts and a nanoparticle formulation was developed to overcome dose-limiting CNS-associated side effects of certain FIASMAs., Results: Functional ASM inhibitors inhibited intracellular cholesterol transport leading to disruption of autophagic flux, cellular endocytosis and receptor tyrosine kinase signalling. Consequently, major oncogenic signalling cascades on which cancer cells were reliant for survival were inhibited. Two tested ASM inhibitors, perphenazine and fluphenazine that are also clinically used as antipsychotics, were effective in inhibiting xenografted tumour growth. Nanoliposomal encapsulation of the perphenazine enhanced its chemotherapeutic efficacy while decreasing CNS-associated side effects., Conclusions: This study suggests that disruption of intracellular cholesterol transport by targeting ASM could be utilised as a potential chemotherapeutic approach for treating cancer.

Antitumor effects of antidepressants have been reported in many cancer cell lines. However, anti-proliferative effects of desipramine, a tricyclic antidepressant, in hepatocellular carcinoma are currently unknown. In this study, we examined the effects of desipramine in human hepatoma Hep3B cells. To evaluate anti-proliferative effects of desipramine in Hep3B cells, we determined cell viability, reactive oxygen species (ROS) production, mitochondrial membrane potential (MMP), mitogen-activated protein kinase (MAPK) activity, and intracellular Ca2+ levels after desipramine treatment. Desipramine reduced cell viability, increased ROS production, and decreased MMP activity in Hep3B cells. In addition, desipramine activated MAPKs (ERK 1/2, JNK, and p38) and increased intracellular Ca2+ levels. Pro-apoptotic effects of desipramine were abolished after MAPK inhibitors (PD98059, SB203580, and SP600125) or N-acetyl-L-cysteine (NAC), as a ROS scavenger, treatments. These findings suggest that desipramine shows anti-proliferative effects in Hep3B cells mediated by promotion of apoptosis, activation of MAPK signaling, and increase in intracellular Ca2+ levels.

Here we provide evidence that repeated immobilization stress (RIS) in rats induces a persistent increase in noradrenergic activity in the anterior aspects of the anterolateral bed nucleus of the stria terminalis (alBNST). This increase in noradrenergic activity results from both enhanced synthesis and reuptake of norepinephrine (NE). It leads to a decrease in the synaptic availability of NE, which elicits an augmented noradrenergic response to the inhibitors of NE reuptake (NRIs), such as desipramine (DMI), an antidepressant. The enduring depression-like behavior and the augmentation of the climbing behavior seen in repeatedly stressed rats following subchronic administration of DMI in the forced swimming test (FST) might be explained by a dysregulation of noradrenergic transmission observed in alBNST. Taken together, we propose that dysregulation of noradrenergic transmission such as the one described in the present work may represent a mechanism underlying major depressive disorders (MDD) with melancholic features in humans., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Stressful events are associated with increased risk of mood disorders. Volumetric reductions have been reported in brain areas critical for the stress response, such as medial prefrontal cortex (mPFC), and dendritic remodeling has been proposed as an underlying factor. Here, we investigated the time-dependent effects of acute stress on dendritic remodeling within the prelimbic (PL) region of the PFC, and whether treatment with the antidepressant desipramine (DMI) may interfere. Rodents were subjected to foot-shock stress: dendritic length and spine density were analyzed 1 day, 7 days, and 14 days after stress. Acute stress produced increased spine density and decreased cofilin phosphorylation at 1 day, paralleled with dendritic retraction. An overall shift in spine population was observed at 1 day, resulting in a stress-induced increase in small spines. Significant atrophy of apical dendrites was observed at 1 day, which was prevented by chronic DMI, and at 14 days after stress exposure. Chronic DMI resulted in dendritic elaboration at 7 days but did not prevent the effects of FS-stress. Collectively, these data demonstrate that 1) acute stressors may induce rapid and sustained changes of PL neurons; and 2) chronic DMI may protect neurons from rapid stress-induced synaptic changes., (© The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.)

Neuropathic pain impacts approximately 3-4.5% of the global population and remains an unresolved health problem. The management of neuropathic pain has two distinct goals-prevention of development and control of established neuropathic pain. We examined the impact of both prophylactic and therapeutic treatments with the tricyclic antidepressant desipramine on the development and maintenance of toxic neuropathic pain induced by the chemotherapeutic agent paclitaxel. We also investigated the involvement of endogenous analgesic (i.e., endogenous opioid and endocannabinoid) systems in the antinociceptive actions of desipramine in these two distinct phases of neuropathic pain. Chronic subcutaneous infusion of desipramine via osmotic pumps suppressed both the development and maintenance of paclitaxel-induced neuropathic pain. However, only prophylactic desipramine treatment blocked the development of neuropathic pain throughout the three month observation interval; neuropathic pain did not return. The opioid receptor antagonist naloxone blocked the antinociceptive effects of both prophylactic and therapeutic desipramine treatments throughout the entire timecourse of desipramine-induced antinociception. By contrast, cannabinoid CB 1 and CB 2 receptor antagonists partially attenuated the antinociceptive actions of desipramine in a manner that was restricted to the development phase of paclitaxel-induced neuropathic pain only. Paclitaxel decreased cell viability in TMD231 tumor cells in an MTT assay in vitro. Notably, desipramine (1nM-1μM) alone did not alter tumor cell viability and did not prevent the cytotoxic effects of paclitaxel under identical conditions. The highest concentration of desipramine (10μM) reduced tumor cell viability alone and enhanced the cytotoxic effects of paclitaxel. Our study identifies a previously unrecognized preemptive analgesic strategy that prevents development of paclitaxel-induced neuropathic pain, and also dissects receptor mechanisms underlying desipramine-induced antinociceptive effects. This information may be applied to improve current therapeutic strategies with the goal of preventing and managing neuropathic pain induced by chemotherapeutic treatment., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Brain bioenergetic abnormalities in mood disorders were detected by neuroimaging in vivo studies in humans. Because of the increasing importance of mitochondrial pathogenetic hypothesis of Depression, in this study the effects of sub-chronic treatment (21days) with desipramine (15mg/kg) and fluoxetine (10mg/kg) were evaluated on brain energy metabolism. On mitochondria in vivo located in neuronal soma (somatic) and on mitochondria of synapses (synaptic), the catalytic activities of regulatory enzymes of mitochondrial energy-yielding metabolic pathways were assayed. Antidepressants in vivo treatment modified the activities of selected enzymes of different mitochondria, leading to metabolic modifications in the energy metabolism of brain cortex: (a) the enhancement of cytochrome oxidase activity on somatic mitochondria; (b) the decrease of malate, succinate dehydrogenase and glutamate-pyruvate transaminase activities of synaptic mitochondria; (c) the selective effect of fluoxetine on enzymes related to glutamate metabolism. These results overcome the conflicting data so far obtained with antidepressants on brain energy metabolism, because the enzymatic analyses were made on mitochondria with diversified neuronal in vivo localization, i.e. on somatic and synaptic. This research is the first investigation on the pharmacodynamics of antidepressants studied at subcellular level, in the perspective of (i) assessing the role of energy metabolism of cerebral mitochondria in animal models of mood disorders, and (ii) highlighting new therapeutical strategies for antidepressants targeting brain bioenergetics., (Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.)

Aggregation of amyloid [Formula: see text] protein (A[Formula: see text] and progressive loss of memory are the main characteristics of Alzheimer's disease (AD). It is noteworthy that approximately 40% of AD patients have depressive symptom. The close correlation between cognitive deficits and mental depression suggests a possibility that antidepression treatment might be beneficial to cognitive improvement in AD. The present study, by using tail-suspension test (TST), forced swimming, alternative electro-stimulus Y maze test and immunohistochemistry, examined the neuroprotective effects of desipramine, a newer generation tricyclic antidepressants (TCA), and investigated its possible molecular mechanism. The results showed that: (1) intra-hippocampal injection of A[Formula: see text] induced depression-like behavior and associative learning deficits in mice, with an increased mean immobility time in tail-suspension and forced swimming test and an increased mean error times in Y maze test; (2) after treatment with desipramine (10[Formula: see text]mg/kg, i.p.), the average immobility time significantly decreased, from [Formula: see text][Formula: see text]s in A[Formula: see text] group to [Formula: see text][Formula: see text]s in A[Formula: see text] plus desipramine group ([Formula: see text]) in TST and from [Formula: see text][Formula: see text]s to [Formula: see text][Formula: see text]s ([Formula: see text] or 9, [Formula: see text]) in forced swimming test, respectively;the mean error times of mice in Y maze test also significantly decreased, from [Formula: see text] in A[Formula: see text] group to [Formula: see text] in A[Formula: see text] plus desipramine group ([Formula: see text], [Formula: see text]); (3) desipramine administration significantly prevented against A[Formula: see text]-induced down-regulation of phosphorylated cAMP response element binding protein (p-CREB) in the hippocampus. These results indicate that A[Formula: see text] could concurrently mimic the depression-like behavior and working memory disorder in mice, while desipramine could effectively reverse both the deficits induced by A[Formula: see text]. The neuroprotection of desipramine may be involved in the up-regulation of p-CREB level in the hippocampus of mice.

Monoamine uptake inhibitors are common treatments for depression; however, the therapeutic efficacy of these drugs varies widely. Two factors that are commonly linked to clinical outcome are age and serotonin transporter (SERT) genotype. Mouse models provide powerful tools to study consequences of age and genotype on antidepressant-like efficacy; however, to date, systematic studies of this nature are lacking. Here, we used the tail suspension test (TST), a preclinical assay for antidepressant efficacy, to gain insight into age and SERT genotype dependency of immobility time in the TST under control conditions (saline injection) and in response to the tricyclic antidepressant, desipramine (DMI). Immobility after saline injection in juvenile, adolescent, adult, mature adult and middle-aged mice (postnatal days 21, 28, 90, 210 and 300, respectively) significantly increased with age; however, the rate of increase was slower for SERT null (-/-) mice than for wild-type (+/+) or heterozygote (+/-) mice. Desipramine reduced immobility across ages and SERT genotypes. Middle-aged, but not adult, SERT(-/-) mice were significantly more sensitive to DMI than age-matched SERT(+/+) or SERT(+/-) mice. Desipramine was less potent in middle-aged SERT(+/+) and SERT(+/-) mice than in adult SERT(+/+) or SERT(+/-) mice. Regardless of age, DMI's maximal effects were greater in SERT(-/-) mice than in SERT(+/+) or SERT(+/-) mice. These results show that immobility time in the TST varies as a function of age and SERT genotype, underscoring the utility of the TST as a potential model to examine age- and SERT genotype-dependent influences on antidepressant response., (© 2015 John Wiley & Sons Ltd and International Behavioural and Neural Genetics Society.)

Recent studies report that a history of antidepressant use is strongly correlated with the occurrence of Parkinson's disease (PD). However, it remains unclear whether antidepressant use can be a causative factor for PD. In the present study, we examined whether tricyclic antidepressants amitriptyline and desipramine can induce dopaminergic cell damage, both in vitro and in vivo. We found that amitriptyline and desipramine induced mitochondria-mediated neurotoxicity and oxidative stress in SH-SY5Y cells. When injected into mice on a subchronic schedule, amitriptyline induced movement deficits in the pole test, which is known to detect nigrostriatal dysfunction. In addition, the number of tyrosine hydroxylase-positive neurons in the substantia nigra pars compacta was reduced in amitriptyline-injected mice. Our results suggest that amitriptyline and desipramine may induce PD-associated neurotoxicity.

Serotonin (SSRI) and serotonin-norepinephrine (SNRI) reuptake inhibitors (SSRI) are the first-line recommended drug treatments for post-traumatic stress disorder (PTSD); but despite their benefits, much residual pathology remains and no new drugs have yet emerged with a clearly demonstrated benefit for treating the disorder. A case is made that tricyclic drugs deserve a closer look, based on their ability to affect several of the main neurotransmitters that are relevant to PTSD. Their promising efficacy, which was shown 30 years ago, had not been followed up, until a recent trial of desipramine found advantages over a SSRI in PTSD with comorbid alcohol dependence. Opportunities exist for studying newer and purportedly safer tricyclic formulations, as well as further the work with older, established compounds. A reappraisal of their risk:benefit ratio seems in order, when treating PTSD., (© The Author(s) 2015.)

Antidepressant medication constitutes the first line pharmacological treatment for posttraumatic stress disorder (PTSD), however, because many patients display no beneficial drug effects it has been suggested that combinations of antidepressants with additional drugs may be necessary. The defining symptoms of PTSD include re-experiencing, avoidance and hyperarousal. In addition, PTSD patients were shown to become easily distracted and often suffer from poor concentration together with indications of comorbidity with attention-deficit hyperactivity disorder (ADHD). Methylphenidate (MPH) is the most common and effective drug treatment for ADHD, thus we aimed to investigate the effects of MPH treatment, by itself or in combination with the antidepressants fluoxetine (FLU) or desipramine (DES). We modified an animal model of PTSD by exposing rats to chronic stress and evaluating the subsequent development of behavioral PTSD-like symptoms, as well as the effects on proinflammatory cytokines, which were implicated in PTSD. We report that while FLU or DES had a beneficial effect on avoidance and hyperarousal symptoms, MPH improved all three symptoms. Moreover, the combination of MPH with DES produced the most dramatic beneficial effects. Serum levels of interleukin-1β (IL-1β) and IL-6 were elevated in the PTSD-like group compared with the control group, and were decreased by MPH, FLU, DES or the combination drug treatments, with the combination of DES+MPH producing the most complete rescue of the inflammatory response. Considering the versatile symptoms of PTSD, our results suggest a new combined treatment for PTSD comprising the antidepressant DES and the psychostimulant MPH.

Antidepressant mechanisms of action remain shrouded in mystery, greatly hindering our ability to develop therapeutics which can fully treat patients suffering from depressive disorders. In an attempt to shed new light on this topic, we have undertaken a series of studies investigating actions of tricyclic antidepressant drugs (TCAs) at the α2A adrenergic receptor (AR), a centrally important receptor, dysregulation of which has been linked to depression. Our previous work established a particular TCA, desipramine, as an arrestin-biased α2AAR ligand driving receptor endocytosis and downregulation but not canonical heterotrimeric G protein-mediated signaling. The present work is aimed at broadening our understanding of how members of the TCA drug class act at the α2AAR, as we have selected the closely related but subtly different TCAs imipramine and amitriptyline for evaluation. Our data demonstrate that these drugs do also function as direct arrestin-biased α2AAR ligands. However, these data reveal differences in receptor affinity and in the extent/nature of arrestin recruitment to and endocytosis of α2AARs. Specifically, amitriptyline exhibits an approximately 14-fold stronger interaction with the receptor, is a weaker driver of arrestin recruitment, and preferentially recruits a different arrestin subtype. Extent of endocytosis is similar for all TCAs studied so far, and occurs in an arrestin-dependent manner, although imipramine uniquely retains a slight ability to drive α2AAR endocytosis in arrestin-null cells. These findings signify an important expansion of our mechanistic understanding of antidepressant pharmacology, and provide useful insights for future medicinal chemistry efforts., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Kainate (KA), used for modelling neurodegenerative diseases, evokes excitotoxicity. However, the precise mechanism of KA-evoked [Ca(2+)]i increase is unexplored, especially in acute brain slice preparations. We used [Ca(2+)]i imaging and patch clamp electrophysiology to decipher the mechanism of KA-evoked [Ca(2+)]i rise and its inhibition by the tricyclic antidepressant desipramine (DMI) in CA1 pyramidal cells in rat hippocampal slices and in cultured hippocampal cells. The effect of KA was dose-dependent and relied totally on extracellular Ca(2+). The lack of effect of dl-2-amino-5-phosphonopentanoic acid (AP-5) and abolishment of the response by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) suggested the involvement of non-N-methyl-d-aspartate receptors (non-NMDARs). The predominant role of the Ca(2+)-impermeable α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate receptors (AMPARs) in the initiation of the Ca(2+) response was supported by the inhibitory effect of the selective AMPAR antagonist GYKI 53655 and the ineffectiveness of 1-naphthyl acetylspermine (NASPM), an inhibitor of the Ca(2+)-permeable AMPARs. The voltage-gated Ca(2+) channels (VGCC), blocked by ω-Conotoxin MVIIC+nifedipine+NiCl2, contributed to the [Ca(2+)]i rise. VGCCs were also involved, similarly to AMPAR current, in the KA-evoked depolarisation. Inhibition of voltage-gated Na(+) channels (VGSCs; tetrodotoxin, TTX) did not affect the depolarisation of pyramidal cells but blocked the depolarisation-evoked action potential bursts and reduced the Ca(2+) response. The tricyclic antidepressant DMI inhibited the KA-evoked [Ca(2+)]i rise in a dose-dependent manner. It directly attenuated the AMPA-/KAR current, but its more potent inhibition on the Ca(2+) response supports additional effect on VGCCs, VGSCs and Na(+)/Ca(2+) exchangers. The multitarget action on decisive players of excitotoxicity holds out more promise in clinical therapy of neurodegenerative diseases., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Effects of 14 consecutive day exposure to desipramine (10mg/kg i.p.), by itself or following chronic open field (OF) exposure, on subsequent neuroimmunological effects of acute (30 min) OF stress and the involvement of individual differences in response to novelty or social position in the anti-depressive responsiveness were investigated. Chronic desipramine pretreatment did not protect against OF stress-induced suppression of blood anti-tumor natural killer cell activity but increased plasma interleukin-10 and decreased interferon-γ and corticosterone concentration. These effects were particularly dangerous for the animals with increased responsivity to stress (desipramine alone) or with low behavioral activity (desipramine after chronic stress)., (© 2013.)

Antidepressant medication is the standard treatment for major depression disorder (MDD). However, the response to these treatments is often incomplete and many patients remain refractory. In the present study, we show that the glucocorticoid receptor (GR) agonist dexamethasone (DEX) increased MAPK/ERK1/2 signaling in the presence of the noradrenergic antidepressant, desipramine (DMI), while no such effect was induced by DEX or DMI alone in human neuroblastoma SH-SY5Y cells. This enhancement was dependent on the activation of both α(2) adrenergic receptors (AR) and GR. The timing of MAPK/ERK1/2 activation as well as DEX-induced reduction in membranous α(2) AR suggests the involvement of a β-arrestin-dependent mechanism. In line with the latter, DEX increased cytosolic and decreased membranous levels of β-arrestin. Concomitantly, DEX induced a time-dependent increase in cytosolic α(2) AR-β-arrestin interaction and a decrease in β-arrestin interaction with Mdm2 E3 ubiquitin ligase. All of these effects of DEX were prevented by the GR antagonist RU486. Our data suggest an additional intracellular role for DEX, in which activation of GR interferes with the trafficking and degradation of β-arrestin-α2c-AR complex. We suggest that such an interaction in the presence of DMI can enhance MAPK/ERK1/2 signaling, a key player in neural plasticity and neurogenesis processes, which is impaired in MDD, while stimulated by antidepressants.

Emotional stress activates the sympathetic nervous system (SNS) and release of the neurotransmitter norepinephrine to promote breast tumor pathogenesis. We demonstrate here that the metastatic mammary adenocarcinoma cell line 4T1 does not express functional adrenergic receptors (AR), the receptors activated by norepinephrine, yet stimulation of adrenergic receptor in vivo altered 4T1 tumor progression in vivo. Chronic treatment with the antidepressant desipramine (DMI) to inhibit norepinephrine reuptake increased 4T1 tumor growth but not metastasis. Treatment with a highly selective α2-adrenergic receptor agonist, dexmedetomidine (DEX), increased tumor growth and metastasis. Neither isoproterenol (ISO), a β-AR agonist, nor phenylephrine, an α1-AR agonist, altered tumor growth or metastasis. Neither DMI- nor DEX-induced tumor growth was associated with increased angiogenesis. In DMI-treated mice, tumor VEGF, IL-6, and the prometastatic chemokines RANTES, M-CSF, and MIP-2 were reduced. Tumor collagen microstructure was examined using second harmonic generation (SHG), a nonabsorptive optical scattering process to highlight fibrillar collagen. In DMI- and DEX-treated mice, but not ISO-treated mice, tumor SHG was significantly altered without changing fibrillar collagen content, as detected by immunofluorescence. These results demonstrate that α2-AR activation can promote tumor progression in the absence of direct sympathetic input to breast tumor cells. The results also suggest that SNS activation may regulate tumor progression through alterations in the extracellular matrix, with outcome dependent on the combination of adrenergic receptor activated. These results underscore the complexities underlying SNS regulation of breast tumor pathogenesis, and suggest that the therapeutic use of adrenergic receptor blockers, tricyclic antidepressants, and adrenergic receptor agonists must be approached cautiously in patients with breast cancer.

Background: The effects of chronic treatment with tricyclic antidepressant (desipramine, DMI) on the hippocampal transcriptome in mice displaying high and low swim stress-induced analgesia (HA and LA lines) were studied. These mice displayed different depression-like behavioral responses to DMI: stress-sensitive HA animals responded to DMI, while LA animals did not., Results: To investigate the effects of DMI treatment on gene expression profiling, whole-genome Illumina Expression BeadChip arrays and qPCR were used. Total RNA isolated from hippocampi was used. Expression profiling was then performed and data were analyzed bioinformatically to assess the influence of stress susceptibility-specific phenotypes on hippocampal transcriptomic responses to chronic DMI. DMI treatment affected the expression of 71 genes in HA mice and 41 genes in LA mice. We observed the upregulation of Igf2 and the genes involved in neurogenesis (HA: Sema3f, Ntng1, Gbx2, Efna5, and Rora; LA: Otx2, Rarb, and Drd1a) in both mouse lines. In HA mice, we observed the upregulation of genes involved in neurotransmitter transport, the termination of GABA and glycine activity (Slc6a11, Slc6a9), glutamate uptake (Slc17a6), and the downregulation of neuropeptide Y (Npy) and corticotropin releasing hormone-binding protein (Crhbp). In LA mice, we also observed the upregulation of other genes involved in neuroprotection (Ttr, Igfbp2, Prlr) and the downregulation of genes involved in calcium signaling and ion binding (Adcy1, Cckbr, Myl4, Slu7, Scrp1, Zfp330)., Conclusions: Several antidepressant treatment responses are similar in individuals with different sensitivities to stress, including the upregulation of Igf2 and the genes involved in neurogenesis. However, the findings also reveal that many responses to antidepressant treatments, involving the action of individual genes engaged in neurogenesis, neurotransmitter transport and neuroprotection, depend on constitutive hippocampal transcriptomic profiles and might be genotype dependent. The results suggest that, when and if this becomes feasible, antidepressant treatment should take into consideration individual sensitivity to stress.

In the present study, we established a role of individual differences in locomotor response to novelty or social position in modulatory effect of chronic (14 consecutive days) antidepressant drug desipramine pretreatment (10mg/kg i.p.) on acute (30 min), white and illuminated open field (OF)-induced changes in spleen anti-tumor activity of natural killer (NK) cells (chromium release assay) in parallel to the brain anti-inflammatory interleukin 10 (IL-10) and Fos expression (immunohistochemistry), splenocytic pro-inflammatory interferon γ (IFN-γ) and IL-10 production (ELISA), and plasma corticosterone concentration (RIA) in rats. The involvement of individual differences (high (HR) and low (LR) responders to novelty or dominants (D) and subordinates (S)) in the anti-depressive responsiveness, was investigated in the desipramine treated by itself (DES) or following 7 consecutive days of OF exposure (ChS-DES) group. In the desipramine pretreated groups, OF stress decreased spleen NKCC, behavioral activity, the Con A-stimulated splenocyte IFN-γ response and plasma corticosterone concentration whereas it increased the brain and splenocyte IL-10 response. The percentage of OF-induced IL-10/Fos(+) cells was increased in the CA1 and dentate gyrus of the hippocampus and amygdaloid nucleus, particularly in the LR-D (DES) and LR-S (ChS-DES) rats. Moreover, a decreased splenocytic ability to produce IFN-γ and IL-10, particularly in the HR-S (DES) and LR-S (ChS-DES) rats, was noted. There were no significant differences in the OF-induced NKCC suppression between the behavioral groups. These studies emphasize that chronic desipramine pretreatment had anti-inflammatory but not immunoprotective properties against OF stress-induced neuroimmunological effects which depend on the animal's behavioral characteristics and treatment., (Copyright © 2013 Elsevier Inc. All rights reserved.)

This review article systematically and critically summarizes the current evidence regarding desipramine for treating children and adolescents with attention deficit hyperactivity disorder (ADHD). PRISMA guideline was used for gathering the data. The databases of PubMed/Medline and Google scholar were electronically searched. This review included controlled clinical trials investigating the efficacy of desipramine for treating children and adolescents with ADHD. The primary outcome measure was clinical improvement measured by valid and reliable objective instruments in order to assess the severity of ADHD clinical symptoms. Adverse effects were evaluated as well. Out of 267 titles under the study, thirty three articles mentioned desipramine for treating ADHD. Two trials met the inclusion criteria. Desipramine decreases ADHD clinical symptoms. However, there are many concerns about its safety and efficacy. In view of serious concerns about its safety and lack of enough well-controlled trials providing strong evidence about the efficacy of desipraimine, it should be prescribed for treating children with ADHD with a high precaution, and further well-controlled trials should be performed.

Rapid eye movement (REM) sleep enhances hippocampus-dependent associative memory, but REM deprivation has little impact on striatum-dependent procedural learning. Antidepressant medications are known to inhibit REM sleep, but it is not well understood if antidepressant treatments impact learning and memory. We explored antidepressant REM suppression effects on learning by training animals daily on a spatial task under familiar and novel conditions, followed by training on a procedural memory task. Daily treatment with the antidepressant and norepinephrine reuptake inhibitor desipramine (DMI) strongly suppressed REM sleep in rats for several hours, as has been described in humans. We also found that DMI treatment reduced the spindle-rich transition-to-REM sleep state (TR), which has not been previously reported. DMI REM suppression gradually weakened performance on a once familiar hippocampus-dependent maze (reconsolidation error). DMI also impaired learning of the novel maze (consolidation error). Unexpectedly, learning of novel reward positions and memory of familiar positions were equally and oppositely correlated with amounts of TR sleep. Conversely, DMI treatment enhanced performance on a separate striatum-dependent, procedural T-maze task that was positively correlated with the amounts of slow-wave sleep (SWS). Our results suggest that learning strategy switches in patients taking REM sleep-suppressing antidepressants might serve to offset sleep-dependent hippocampal impairments to partially preserve performance. State-performance correlations support a model wherein reconsolidation of hippocampus-dependent familiar memories occurs during REM sleep, novel information is incorporated and consolidated during TR, and dorsal striatum-dependent procedural learning is augmented during SWS.

The analgesic effect of acute i.p. administration of amitriptyline (norepinepherine and serotonin reuptake inhibitor), clomipramine (serotonin reuptake inhibitor) and desipramine (norepinepherine reuptake inhibitor) was studied in chronic constriction injury (CCI) model of sciatic nerve in rats and mRNA and protein expression of inducible nitric oxide synthase (iNOS) were also investigated. Acute treatment with amitriptyline and clomipramine produced antinociceptive effects after sciatic nerve injury and blockade of norepinephrine reuptake using desipramine did not demonstrate antinociceptive effects. The antinociceptive effect of amitriptyline, not clomipramine, was augmented by the selective iNOS inhibitor, aminoguanidine. Amitriptyline inhibited iNOS mRNA and protein expression in cerebellum and hippocampus. However, desipramine altered neither iNOS expression at mRNA level nor at post-transcriptional level. Based on our experimental findings, we conclude that the analgesic effect of the dual norepinepherine and serotonin reuptake inhibitor, amitriptyline, is partially due to inhibition of central iNOS., (Copyright © 2012 Elsevier Inc. All rights reserved.)

The cholinergic theory of depression highlights the involvement of muscarinic acetylcholine receptors in the neurobiology of mood disorders. The present study was designed to investigate the effect of sildenafil, a phosphodiesterase type 5 inhibitor which exhibits cholinomimetic properties, alone and in combination with scopolamine in the forced swim test in mice. Moreover, we assessed the ability of sildenafil to modify the antidepressant activity of two tricyclic antidepressants with distinct cholinolytic activity, amitriptyline and desipramine. Swim sessions were conducted by placing mice in glass cylinders filled with water for 6 min and the duration of behavioral immobility during the last 4 min of the test was evaluated. Locomotor activity was measured with photoresistor actimeters. To evaluate the potential pharmacokinetic interaction between amitriptyline and sildenafil, brain and serum concentrations of amitriptyline were determined by HPLC. Sildenafil (1.25-20 mg/kg) as well as scopolamine (0.5 mg/kg) and its combination with sildenafil (1.25 mg/kg) did not affect the total immobility time duration. However, joint administration of scopolamine with sildenafil at doses of 2.5 and 5 mg/kg significantly reduced immobility time as compared to control group. Moreover, co-administration of scopolamine with sildenafil at the highest dose (5 mg/kg) significantly decreased immobility time as compared to scopolamine-treated group. Sildenafil (1.25, 2.5 and 5 mg/kg) significantly enhanced the antidepressant activity of amitriptyline (5 mg/kg). No changes in anti-immobility action of desipramine (20 mg/kg) in combination with sildenafil (5, 10 and 20 mg/kg) were observed. Sildenafil did not affect amitriptyline level in both brain and serum. In conclusion, the present study suggests that sildenafil may enhance the activity of antidepressant drugs which exhibit cholinolytic activity.

The precise physiological effects of antidepressant drugs, and in particular their actions at non-monoamine transporter targets, are largely unknown. We have recently identified the tricyclic antidepressant drug desipramine (DMI) as a direct ligand at the α(2A) adrenergic receptor (AR) without itself driving heterotrimeric G protein/downstream effector activation [5]. In this study, we report our novel finding that DMI modulates α(2A)AR signaling in response to the endogenous agonist norepinephrine (NE). DMI acted as a signaling potentiator, selectively enhancing NE-induced α(2A)AR-mediated ERK1/2 MAPK signaling. This potentiation of ERK1/2 activation was observed as an increase in NE response sensitivity and a prolongation of the activation kinetics. DMI in a physiologically relevant ratio with NE effectively turned on ERK1/2 signaling that is lacking in response to physiological NE alone. Further, the DMI-induced ERK1/2 potentiation relied on heterotrimeric G(i/o) proteins and was arrestin-independent. This modulatory effect of DMI on NE signaling provides novel insight into the effects of this antidepressant drug on the noradrenergic system which it regulates, insight which enhances our understanding of the therapeutic mechanism for DMI., (Copyright © 2012 Elsevier Inc. All rights reserved.)

The neurobiological mechanisms of action underlying antidepressant drugs remain poorly understood. Desipramine (DMI) is an antidepressant classically characterized as an inhibitor of norepinephrine reuptake. Available evidence, however, suggests a mechanism more complex than simple reuptake inhibition. In the present study, we have characterized the direct interaction between DMI and the α(2A)-adrenergic receptor (α(2A)AR), a key regulator of noradrenergic neurotransmission with altered expression and function in depression. DMI alone was found to be sufficient to drive receptor internalization acutely and a robust down-regulation of α(2A)AR expression and signaling following prolonged stimulation in vitro. These effects are achieved through arrestin-biased regulation of the receptor, as DMI selectively induces recruitment of arrestin but not activation of heterotrimeric G proteins. Meanwhile, a physiologically relevant concentration of endogenous agonist (norepinephrine) was unable to sustain a down-regulation response. Prolonged in vivo administration of DMI resulted in significant down-regulation of synaptic α(2A)AR expression, a response that was lost in arrestin3-null animals. We contend that direct DMI-driven arrestin-mediated α(2A)AR down-regulation accounts for the therapeutically desirable but mechanistically unexplained adaptive alterations in receptor expression associated with this antidepressant. Our results provide novel insight into both the pharmacology of this antidepressant drug and the targeting of the α(2A)AR in depression.

Hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis in patients with depression can be reduced by antidepressants, which are thought to improve endogenous glucocorticoid-mediated negative feedback. A proportion of peripherally released glucocorticoids need to enter brain tissue, protected by the blood-brain barrier (BBB), in order to achieve this negative feedback effect at the level of the central nervous systems (CNS). The multidrug resistance transporter P-glycoprotein (P-gp) has been shown to actively transport glucocorticoid hormones and has been implicated in the regulation of glucocorticoid access to the CNS. Using an in situ brain/choroid plexus perfusion method, we tested the hypothesis that the antidepressant desipramine increases glucocorticoid accumulation in the mouse brain by inhibiting P-gp, following either chronic treatment (8 days, 20 mg/kg/day, IP) or acute administration (20 min brain perfusion in the presence of either 0.9 μM or 10 μM desipramine). Contrary to our hypothesis, chronic treatment with desipramine did not affect the accumulation of [³H]dexamethasone in any sample compared to saline-treated mice. Acute desipramine had limited and variable effects on glucocorticoid accumulation in the CNS, with accumulation of [³H]dexamethasone increased in the cerebellum, accumulation of [³H]cortisol reduced in the frontal cortex, hypothalamus, and cerebellum, and accumulation of [³H]corticosterone (the endogenous glucocorticoid in rodents) not affected. Overall, under the conditions tested, these results do not support the hypothesis that treatment with desipramine can inhibit P-gp at the BBB and subsequently increase the accumulation of glucocorticoids in the brain., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

The most common cause for adverse cardiac events by antidepressants is acquired long QT syndrome (acLQTS), which produces electrocardiographic abnormalities that have been associated with syncope, torsade de pointes arrhythmias, and sudden cardiac death. acLQTS is often caused by direct block of the cardiac potassium current I(Kr)/hERG, which is crucial for terminal repolarization in human heart. Importantly, desipramine belongs to a group of tricyclic antidepressant compounds that can simultaneously block hERG and inhibit its surface expression. Although up to 40% of all hERG blockers exert combined hERG block and trafficking inhibition, few of these compounds have been fully characterized at the cellular level. Here, we have studied in detail how desipramine inhibits hERG surface expression. We find a previously unrecognized combination of two entirely different mechanisms; desipramine increases hERG endocytosis and degradation as a consequence of drug-induced channel ubiquitination and simultaneously inhibits hERG forward trafficking from the endoplasmic reticulum. This unique combination of cellular effects in conjunction with acute channel block may explain why tricyclic antidepressants as a compound class are notorious for their association with arrhythmias and sudden cardiac death. Taken together, we describe the first example of drug-induced channel ubiquitination and degradation. Our data are directly relevant to the cardiac safety of not only tricyclic antidepressants but also other therapeutic compounds that exert multiple effects on hERG, as hERG trafficking and degradation phenotypes may go undetected in most preclinical safety assays designed to screen for acLQTS.

Aims: An automated experimental system applying a commercially available video image analyzer was developed for the simultaneous detection and measurement of three behavioral components; immobility, swimming (horizontal movements) and climbing (vertical movements) that occur in the murine forced swim test (FST). The system was validated using four typical antidepressants., Main Methods: System validity was confirmed by demonstrating no significant difference in 6 min time course of control group and imipramine-dosed group (30 mg/kg) between manual examinations and automated digital analysis for all the three behaviors (i.e., correlation coefficients were 0.96, 0.83 and 0.94 for immobility, swimming and climbing, respectively). The effects of acute single treatment with four antidepressants in clinical use, i.e., imipramine, desipramine, bupropion and fluvoxamine were evaluated at doses of 15, 30 and 60 mg/kg using the system., Key Findings: In 2-4 min time span analysis, all four antidepressants reduced immobility and increased climbing significantly, desipramine and bupropion increased swimming significantly, while imipramine and fluvoxamine did not., Significance: The automated experimental system enabled efficient and accurate analysis of the three murine behaviors during FST at once. Climbing could be more sensitive parameter to detect anti-depressant-like effect than immobility in this system., (Copyright © 2010 Elsevier Inc. All rights reserved.)

The immunomodulator drug Gilenya (FTY720), marketed as the first oral sphingosine-1-phosphate receptor (S1P-R) modulator for treatment of Multiple Sclerosis (MS) also inhibits lysosomal acid sphingomyelinase (ASMase). Treatment of cultured cells for 24 h with FTY720 (up to 10 μM) inhibited ASMase by >80% and this could be reversed by pre-treatment with the cathepsin protease inhibitor leupeptin (5 μM). In contrast, neutral sphingomyelinase activity was unaffected and sphingosine-1-phosphate treatment had no effect on ASMase. RT-PCR revealed no inhibition of ASMase mRNA and there was no direct (in vitro) inhibition of ASMase by either FTY720 or FTY720-phosphate. This suggests that its mechanism of inhibition is similar to that of tricyclic anti-depressants such as desipramine, which are also amphiphilic cationic drugs. Both Desipramine and FTY720 treatment reduced ASMase without significant inhibition of other lysosomal hydrolases but most hydrolases showed increased secretion (up to a 50% increase) providing more evidence of lysosomal disruption by these drugs., (Copyright © 2010 Elsevier Inc. All rights reserved.)

Various antidepressants, mainly tricyclic antidepressants (TCAs) and selective serotonin reuptake inhibitors (SSRIs), have exhibited potent anticancer properties in different cancer cell types. In the present study, desipramine (DMI), a representative of TCAs, was examined with respect to its apoptosis-inducing activity in rat C6 glioma cells and the underlying mechanism of action. DMI induced typical apoptotic morphology of chromatin condensation in rat glioma C6 cells and activated intracellular caspase 9 and caspase 3 with no change in mitochondrial membrane potential. Simultaneously, DMI significantly elevated expression of endoplasmic reticulum stress regulator CHOP/GADD153 and its targeting molecule GADD34. However, knockdown of CHOP by CHOP-specific short interfering RNA (siRNA) could decrease the activity of intracellular caspase 3 and the cytotoxicity of DMI to C6 cells. These results revealed that the CHOP-dependent endoplasmic reticulum (ER) stress pathway is responsible for DMI-induced apoptosis in C6 cells.

Transport of thyroid hormones across the plasma membrane is required for binding to their nuclear receptors. Monocarboxylate transporter 8 (MCT8) is a plasma membrane thyroid hormone transport protein, which has recently gained much attention, since mutations in MCT8 are associated with severe mental retardation in patients afflicted with the Allan-Herndon-Dudley syndrome. MCT8 is expressed along the blood-brain-barrier and on central neurons. We have found that desipramine (DMI), a tricyclic antidepressant, acts as an inhibitor of thyroid hormone transport by MCT8. Uptake of 3,5,3'-triiodo-L-thyronine (T(3)) into primary cortical neurons could be blocked with desipramine as well as with the known, but unspecific, inhibitor bromosulphtalein (BSP). T(3) uptake by neurons derived from Mct8-deficient cells was not further decreased by DMI. In a heterologous expression system, both human MCT8 and its close homolog, MCT10, were sensitive to inhibition by DMI. Kinetic experiments demonstrated a non-competitive mode of inhibition. Numerous interactions between thyroid hormones, depressive symptoms, and antidepressant treatments have been reported in the literature. Our findings add to the evidence that antidepressant drugs may affect CNS thyroid hormone function., ((c) 2010 Elsevier Ireland Ltd. All rights reserved.)

Nerve growth factor, a neurotrophin, may have other functions, including a role in depressive disorders. The present study sought to determine whether NGF would (1) have antidepressant-like effects and (2) behave similarly to or differently from other well-recognized antidepressants. Over a broad dose-range, NGF reduced the exaggerated swim test immobility exhibited by the Flinders Sensitive Line (FSL) rats, but at a standard dose of 40 ng/ml, it was not as effective as desipramine (DMI, 5 mg/kg). The low social interaction behavior and locomotor activity of the FSL rats were less affected by NGF than was the immobility. Acute treatment with NGF did not induce c-fos expression in brain regions known to be activated by other acute antidepressants. The fact that chronic treatment with DMI blunted the corticosterone response to fluoxetine was replicated in this study. However, chronic treatment with NGF did not alter this response. Similarly, chronic treatment with fluoxetine blunted 5-HT(1A) and 5-HT(2A) receptor-mediated responses, whereas chronic treatment with NGF was without effect. Thus, NGF has antidepressant-like effects but does not appear to have biochemical actions typical of other antidepressants., (Copyright 2009 Elsevier Inc. All rights reserved.)

Objective: A growing body of data indicates that an activation of proinflammatory cytokines such as interferon-gamma (IFN-gamma) is involved in the pathophysiology of depression and that the suppression of pro-inflammatory cytokine production by antidepressants may lead to an improvement of depressive symptoms. However, the influence of the serotonin and noradrenalin reuptake inhibitor (SNRI) venlafaxine and its metabolite O-desmethylvenlafaxine on the stimulated blood cell secretion of IFN-gamma has not been studied so far., Method: We measured IFN-gamma levels in the stimulated blood of healthy female subjects in a whole blood assay using the toxic shock syndrome toxin TSST-1 as stimulant. Blood was either supplemented with antidepressants or not., Results: Mean IFN-gamma concentrations differed between blood with and without antidepressant supplements (p = 0.026). Planned contrasts revealed that compared to non-supplemented blood, four of the blood samples supplemented with the tricyclic antidepressants (TCAs) reduced IFN-gamma levels: amitriptyline (adjusted p-value (p = 0.004), nortriptyline (p = 0.037), imipramine (p = 0.021), and desipramine (p = 0.048). There was no significant difference between the control condition and the venlafaxine or O-desmethylvenlafaxine condition., Conclusions: TCAs might, among other mechanisms, act as antidepressants by suppressing the production of pro-inflammatory cytokines, whereas no significant effect of venlafaxine and O-desmethylvenlafaxine on IFN-gamma secretion could be demonstrated.

The high incidence of depression in Parkinson's disease (PD) has been well documented in the clinic; however, the underlying molecular mechanisms of these overlapping pathologies remain elusive. Using a rodent model of depression, the Wistar-Kyoto (WKY) rat, we previously demonstrated that in the frontal cortex the altered expression and protein interactions of alpha- and gamma-synuclein (alpha-Syn, gamma-Syn) were associated with dysregulated trafficking of the norepinephrine transporter (NET). Chronic treatment with desipramine (DMI), a NET-selective antidepressant, caused a disappearance of depressive-like behavior that was accompanied by a change in alpha-Syn and gamma-Syn expression and their trafficking of NET. Using this same model, we examined the expression of NET, alpha-Syn and gamma-Syn in the hippocampus, amygdale, brainstem, and striatum, all regions implicated in the development or maintenance of depression or PD pathology. Following chronic treatment with DMI, we observed a significant decrease in NET in the hippocampus, amygdala, and brainstem; decrease in gamma-Syn in the hippocampus and amygdala; and, increase in alpha-Syn in the hippocampus and amygdala. Unexpectedly, we observed a significant decrease in alpha-Syn expression in the striatum of the WKY following chronic DMI treatment. The altered expression of NET, alpha-Syn and gamma-Syn in different brain suggest that DMI's ability to improve depressive-like behavior in a rodent is associated with region-specific changes in the regulation of NET by alpha- and gamma-Syn.

The purpose of this study was to examine the effect of tricyclic antidepressant desipramine (DMI) on the growth inhibition and translocation of the glucocorticoid receptor (GR) from the cytoplasm to the nucleus in cancerous and noncancerous cell lines and the effect of DMI on GR-mediated transcription. Nontumorigenic, immortalized keratinocytes cell line (3PC), papilloma (MT1/2), and squamous cell carcinoma (Ca3/7) cell lines were initially used to study the cell growth inhibition by DMI. Although, the growth of all three cell lines was suppressed by DMI, it was more effective in Ca3/7 cells. Therefore, we next examined the effect of DMI on Ca3/7 cells, resistant to growth inhibition by the synthetic glucocorticoid fluocinolone acetonide (FA). DMI inhibited cell proliferation in a time-dependent manner. The translocation of GR was induced by FA alone, DMI alone, and combination of both agents. FA induced GR-mediated transcription in Ca3/7 cells transfected with a luciferase reporter gene under the control of glucocorticoid response element (GRE), but DMI alone did not affect GR-mediated transcription. However, DMI inhibited FA-induced, GR-mediated transcription when both agents were given together. Pretreatment with DMI followed by combination of DMI and FA decreased GR-mediated transcription more than pretreatment with FA. The expression of metallothionein-1 (Mt-1) gene, which is regulated by GR, was induced significantly by the combination of DMI and FA, and enhanced significantly by pretreatment with FA but not DMI. DMI is suggested to inhibit the growth of Ca3/7 cells and to affect GR-mediated transcription.

1. It has been shown that the antidepressant desipramine is able to induce increases in [Ca(2+)](i) and cell death in MG63 human osteosacroma cells, but whether apoptosis is involved is unclear. In the present study, the effect of desipramine on apoptosis and the underlying mechanisms were explored. It was demonstrated that desipramine induced cell death in a concentration- and time-dependent manner. 2. Cells treated with 100-800 mmol/L desipramine showed typical apoptotic features, including an increase in sub-diploid nuclei and activation of caspase 3, indicating that these cells underwent apoptosis. Immunoblotting revealed that 100 mmol/L desipramine activated extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK). Although pretreatment of cells with 20 mmol/L PD98059 (an ERK inhibitor) or 20 mmol/L SP600125 (an inhibitor of JNK) did not inhibit cell death, the addition of 20 mmol/L SB203580 (a p38 MAPK inhibitor) partially rescued cells from apoptosis. Desipramine-induced caspase 3 activation required p38 MAPK activation. 3. Pretreatment of cells with BAPTA/AM (20 mmol/L) to prevent desipramine-induced increases in [Ca(2+)](i) did not protect cells from death. 4. The results of the present study suggest that, in MG63 human osteosarcoma cells, desipramine causes Ca(2+)-independent apoptosis by inducing p38 MAPK-associated activation of caspase 3.

The antidepressant desipramine inhibits the reuptake of norepinephrine (NE), leading to activation of both pre- and postsynaptic adrenergic receptors, including alpha-1, alpha-2, beta-1, and beta-2 subtypes. However, it is not clear which adrenergic receptors are involved in mediating its antidepressant effects. Treatment of mice with desipramine (20 mg/kg, i.p.) produced an antidepressant-like effect, as evidenced by decreased immobility in the forced-swim test; this was antagonized by pretreatment with the alpha-2 adrenergic antagonist idazoxan (0.1-2.5 mg/kg, i.p.). Similarly, idazoxan, administered peripherally (0.5-2.5 mg/kg, i.p.) or centrally (1-10 microg, i.c.v.), antagonized the antidepressant-like effect of desipramine in rats responding under a differential-reinforcement-of-low-rate (DRL) 72-s schedule, ie, decreased response rate and increased reinforcement rate. By contrast, pretreatment with the beta-adrenergic antagonists propranolol and CGP-12177 or the alpha-1 adrenergic antagonist prazosin did not alter the antidepressant-like effect of desipramine on DRL behavior. The lack of involvement of beta-adrenergic receptors in mediating the behavioral effects of desipramine was confirmed using knockout lines. In the forced-swim test, the desipramine-induced decrease in immobility was not altered in mice deficient in beta-1, beta-2, or both beta-1 and beta-2 adrenergic receptors. In addition, desipramine (3-30 mg/kg) produced an antidepressant-like effect on behavior under a DRL 36-s schedule in mice deficient in both beta-1 and beta-2 adrenergic receptors. As antagonism of presynaptic alpha-2 adrenergic receptors facilitates NE release, which potentiates the effects of desipramine, the present results suggest that postsynaptic alpha-2 adrenergic receptors play an important role in its antidepressant effects.

Objective: Tricyclic antidepressants (TCAs) are well established in the treatment of patients with irritable bowel syndrome (IBS). The effects are believed to be linked to serotoninergic antinociceptive properties, but data on the antinociceptive effects of various TCAs with variable serotoninergic and non-serotoninergic properties have not been investigated. The aim of this study was to compare the antinociceptive effects of different TCAs., Material and Methods: Colorectal distension (CRD) using a barostat device was carried out in rats and the visceromotor response (VMR) to CRD was quantified by abdominal wall electromyography. Prior to CRD, saline (control), amitriptyline (AM), desipramine (DES), reserpine (RES) or a combination of TCAs and RES (AM + RES or DES + RES) was applied intraperitoneally. Serum 5-HT levels were determined using high-performance liquid chromatography (HPLC). RES was used to antagonize the serotoninergic actions of TCAs in order to discriminate between these effects and others., Results: Both TCAs decreased the VMR compared to placebo. After RES application without TCAs, the VMR was increased compared to controls (6403 microV+/-1772 microV). Co-administration of AM and RES resulted in a modest decrease in VMR (5774 microV+/-1953 microV), while in rats treated with RES and DES the VMR again was significantly lower (3446 microV (+/-1347 microV; p <0.05)). 5-HT levels were higher in TCA pretreated rats than those in controls and significantly lower 5-HT levels were found in all rats pretreated with RES., Conclusions: AM and DES have antinociceptive properties while RES is pro-nociceptive. The antinociceptive effects of DES are not abolished by RES pretreatment, while AM only attenuates the pro-nociceptive effects of RES. The non-serotoninergic properties of TCAs substantially contribute to the differences in the antinococeptive effects of various TCAs.

The use of animal models (particularly rats) in research for developing drugs for central nervous system diseases is well validated. However a range of strains are often utilised in these models. The Lister-Hooded (LH) strain is beginning to be increasingly used in preclinical investigations. Thus, the objective of the present study was to investigate the comparative behavioural pharmacology of this strain, with the two most widely used rat strains, namely the Sprague-Dawley (SD), and Wistar (W) strains. The tests used were the forced swim test (FST) for antidepressants, the amphetamine-locomotor activity test for antipsychotics, the elevated plus maze (EPM) for anxiolytics, as well as tests of general locomotor activity using home cage monitoring (HCM) and the open field test. Continuous HCM revealed a significantly higher daily activity and lower nocturnal activity for LH compared to the other strains; there were no strain-related differences in the open field test. In the FST, there were no strain differences in immobility time and a similar magnitude of desipramine-induced reduction in immobility across strains. In the locomotor activity test, control LH rats showed significantly higher activity whilst significant amphetamine-induced hyperactivity was seen only with the LH and W strains. In the EPM, control LH rats had a significantly larger percentage of open arm entries, whilst only the SD strain displayed a significant diazepam-induced increase in this parameter. These findings suggest that strain variation can cause markedly different results in behavioural pharmacological tests where locomotor activity plays a significant role, and should be taken into account when selecting a strain for evaluating the behavioural effects of psychotropic drugs. Such differences in locomotor activity in the LH strain could be accounted for by an altered diurnal pattern in this strain.

Epidemiological studies indicate significant co-morbid expression of alcoholism, anxiety, and depression. These symptoms are often under-diagnosed and under-treated and can worsen prognostic and treatment outcome for alcoholism. Nonetheless, a causal relationship between alcoholism and these conditions is yet to be established. In this study we sought to determine the effects of daily alcohol administration on the indices of anxiety and depression in two rat strains, one of which exhibits inherent depressive-like characteristics. Moreover, it was of relevance to examine the effects of a clinically useful antidepressant on alcohol-induced behavioral changes. Wistar-Kyoto (WKY) rats derived from Wistar stock show low levels of locomotor activity in an open field and high levels of immobility in the forced swim test (FST) which is considered a measure of their helplessness and hence are considered a putative animal model of depression. Adult female WKY and Wistar rats were exposed for 3 hrs daily to 95% ethanol vapor to achieve a mean blood alcohol level (BAL) of approximately 150 mg/dL. Controls were exposed to air in similar inhalation chambers. Sixteen to 18 hrs following 7 or 14 days of exposure to alcohol, locomotor activity (LCA) in open field, duration of time spent in the open arm of the elevated plus-maze (EPM), reflective of anxiety-like behavior and immobility in FST were evaluated. Alcohol exposure for 7 or 14 days reduced LCA only in Wistar rats but enhanced FST immobility in both strains at both time points. Only 14 day alcohol exposure reduced EPM open arm time in both WKY and Wistar rats. Daily treatment with desipramine (8 mg/kg) blocked all the changes induced by alcohol in both strains. Thus, subchronic (7 day) exposure to alcohol induces depressive-like characteristics in Wistar rats and exacerbates that of WKY rats. Chronic (14 day) exposure, however, also induces an anxiety-like effect in both strains. The depressive- and anxiety-like behaviors induced by alcohol were blocked by daily treatment with a tricyclic antidepressant. It may be suggested that prophylactic treatment of alcoholics with an antidepressant prior to detoxification may improve treatment outcome for alcoholism.

Rationale: The transient behavioral deficit produced in rodents by typical learned helplessness (LH) procedures limits the utility of LH in identifying the therapeutic mechanisms associated with chronic antidepressant administration. In addition, LH procedures do not differentiate between different antidepressant classes as observed in the forced swim test., Objectives: To produce both a long lasting and antidepressant reversible behavioral deficit in a modified LH procedure that administers inescapable shock (IS) in the same operant chamber used for shuttle box escape testing., Results: A single IS session produced a robust increase in the number of escape failures (FR-2 escape contingency) that endured for at least 21 days. This escape deficit was reversed by desipramine (24 mg/kg/day, 6 days) at the first shuttle box session. Fluoxetine (5 mg/kg/day, 6 and 21 days) improved escape performance only after repeated test sessions. In contrast, fluoxetine (5 mg/kg/day, 21 days) completely reversed the first shuttle box test escape deficit induced by exposure to a chronic unpredictable stress procedure devoid of shocks or exposure to operant chambers. These differential drug effects may be due to the presence or absence of contextual cues during escape testing. Repeated re-exposure to the IS context enhanced the FR-2 escape deficit., Conclusions: These data suggest that performing escape testing and IS in the same environment improves the preclinical modeling of the time-dependency and behavioral pattern of antidepressant response observed clinically. Additionally, contextual information associated with the IS environment modulates escape performance and may interact differentially with discrete antidepressant classes.

Strain differences in immobility time in the forced swimming test were investigated in five strains of mice, namely, ICR, ddY, C57BL/6, DBA/2 and BALB/c mice. There were significant strain differences. The immobility times of ICR, ddY and C57BL/6 mice were longer than those of DBA/2 and BALB/c mice. Immobility times were not significantly related to locomotor activity in these strains. There were also differences in sensitivity to the selective serotonin reuptake inhibitor (SSRI) fluvoxamine. In ICR, ddY and C57BL/6 mice, fluvoxamine did not affect immobility time, while it reduced the immobility time of DBA/2 and BALB/c mice dose-dependently. The noradrenaline reuptake inhibitor desipramine decreased immobility time in all strains of mice. Serotonin (5-HT) transporter binding in the brains of all five strains of mice was also investigated. Analysis of 5-HT transporter binding revealed significant strain differences, being lower in DBA/2 and BALB/c mice than in other strains of mice. The amount of 5-HT transporter binding was correlated to baseline immobility time. However, there was no significant relation between noradrenaline transporter binding and immobility time. These results suggest that the duration of baseline immobility depends on the levels of 5-HT transporter binding, leading to apparent strain differences in immobility time in the forced swimming test. Furthermore, differences in 5-HT transporter binding may cause variations in responses to fluvoxamine.

There are documented clinical drug-drug interactions between bupropion and the CYP2D6-metabolized drug desipramine resulting in marked (5-fold) increases in desipramine exposure. This finding was unexpected as CYP2D6 does not play a significant role in bupropion clearance, and bupropion and its major active metabolite, hydroxybupropion, are not strong CYP2D6 inhibitors in vitro. The aims of this study were to investigate whether bupropion's reductive metabolites, threohydrobupropion and erythrohydrobupropion, contribute to the drug interaction with desipramine. In human liver microsomes using the CYP2D6 probe substrate bufuralol, erythrohydrobupropion and threohydrobupropion were more potent inhibitors of CYP2D6 activity (K(i) = 1.7 and 5.4 microM, respectively) than hydroxybupropion (K(i) = 13 microM) or bupropion (K(i) = 21 microM). Furthermore, neither bupropion nor its metabolites were metabolism-dependent CYP2D6 inhibitors. Using the in vitro kinetic constants and estimated liver concentrations of bupropion and its metabolites, modeling was able to predict within 2-fold the increase in desipramine exposure observed when coadministered with bupropion. This work indicates that the reductive metabolites of bupropion are potent competitive CYP2D6 inhibitors in vivo and provides a mechanistic explanation for the clinical drug-drug interaction between bupropion and desipramine.

Rationale: Antidepressant medications are effective only in a subpopulation of patients with depression, and some patients respond to certain drugs, but not others. The biological bases for these clinical observations remain unexplained., Objective: To investigate individual differences in response to antidepressants, we have examined the effects of the norepinephrine reuptake inhibitor desipramine (DMI) and the selective serotonin reutake inhibitor fluoxetine (FLU) in the forced swim test (FST) in rats that differ in their emotional behavior., Methods: As response to novelty correlates with numerous other measures of emotionality and substance abuse, we contrasted animals that are high responders (HR) in a novel environment with animals that are low responders (LR) and asked whether the two groups exhibit differential responses to DMI (10mg/kg) and FLU (20mg/kg)., Results: At the behavioral level, DMI caused a significant decrease in immobility in LR animals only, while FLU caused a significant reduction in immobility in both groups. Moreover, at the neural level, DMI treatment led to a decrease in FST-induced c-fos messenger RNA levels in medial prefrontal cortex (PFC) and paraventricular nucleus of the hypothalamus (PVN) in LR but not HR animals., Conclusions: Taken together, our results suggest that the HR-LR model is a useful tool to investigate individual differences in responses to norepinephrine reuptake inhibitors (NRIs) and that a differential activation of PFC and/or PVN could underlie some of the inter-individual differences in the efficacy of NRIs.

We have previously shown that chronic administration of the antidepressant desipramine, a norepinephrine transporter (NET) inhibitor to mice markedly enhanced convulsions induced by local anesthetics and that behavioral sensitization may be relevant to decreased [(3)H]norepinephrine uptake by the isolated hippocampus. The co-administration of local anesthetics with desipramine reversed the behavioral sensitization and down-regulation of NET function induced by desipramine. The present study aimed to elucidate whether chronic treatment with desipramine regulates the expression of NET protein examined in membrane fractions in various brain regions and whether co-administration of local anesthetics affects the desipramine-induced alteration of NET expression. Desipramine with or without local anesthetics was injected intraperitoneally once a day for 5 days. The animals were decapitated 48 h after the last administration of drugs and the whole cell fraction, membrane fraction and cell-surface protein fraction were prepared. [(3)H]nisoxetine binding was significantly reduced in the P2 fraction of the hippocampus by chronic administration of desipramine, and the reduction was overcome by co-administration of lidocaine with desipramine. Immunoreactive NET was detected by SDS-PAGE and immunoblotting in the murine hippocampus. NET protein expression in the whole cell fraction and membrane fraction was not affected by treatment with any drugs. However, administration of desipramine significantly reduced the amount of immunoreactive NET in the cell-surface protein fraction. This reduction was blocked by simultaneous injection of lidocaine, bupivacaine or tricaine. These results indicate that the NET down-regulation indicated by the reduction of [(3)H]nisoxetine binding was induced by administration of desipramine via decrease of NET localization on the cell surface. The antagonistic actions of local anesthetics against NET down-regulation by desipramine were related to alterations of the cell-surface localization of NET.

Although there are similarities in the clinical presentation of adolescent and adult depression, there are differences in the biological correlates and the responses to pharmacologic treatment. Selective serotonin reuptake inhibitor-type antidepressants are efficacious, but tricyclic antidepressants have no or limited efficacy in treating adolescent patients. The forced swim test (FST) is a widely accepted animal model used to screen drugs for antidepressant activity. It is not known whether tricyclic antidepressants produce differential effects in peripubertal and adult rats, as is found in adolescent and adult humans. The objective of the study was to test the hypothesis that the tricyclic antidepressant desmethylimipramine (DMI) would show efficacy in the FST in adult, but not in peripubertal, rats. Thirty-day-old (peripubertal) and 112-day-old (young adult) rats were pretreated with saline or DMI and subjected to the FST. DMI reduced the amount of floating behavior and increased the amount of climbing behavior in both peripubertal and adult rats. Thus, the tricyclic antidepressant DMI has antidepressant-like activity in peripubertal rats in the FST. Owing to the discrepancy between the preclinical and clinical data, the predictive validity of the FST might need to be reevaluated across different age groups.

Major depressive disorder is a major health problem in adults and is now recognized as a substantial problem in children as well. Tricyclic antidepressants, including desipramine (DMI), are no better than placebo in treating childhood and adolescent depression, but are effective in treating adult depression. Several studies have suggested that normal BDNF (brain-derived neurotrophic factor) signaling is necessary for antidepressant drug action. Antidepressant drugs induce several plastic changes in the rodent brain which may be associated with changes in BDNF levels and/or with BDNF function. In the present study we report parallel measurements of BDNF mRNA and protein in the frontal cortex and hippocampus after four days of twice daily treatments with escitalopram, a selective serotonin reuptake inhibitor, and desipramine, a tricyclic antidepressant. Post-natal day 13, 21, 28 and adult rats were used in this study. TrkB (the primary receptor for BDNF) mRNA levels were also examined under the same treatment conditions. BDNF mRNA and protein levels, as well as TrkB mRNA levels, were increased significantly in post-natal day 13 pups after escitalopram treatment as compared to control, but desipramine failed to increase either BDNF or TrkB. The failure of desipramine to increase BDNF and TrkB levels in juvenile rats is consistent with the lack of efficacy of desipramine in children and adolescents. The serotonergic nervous system matures earlier than the noradrenergic system, which may explain why escitalopram, but not desipramine, increases BDNF and TrkB levels.