Search

Additional file 4: Figure S4. Effect of a single intraperitoneal administration of vehicle (kolliphor 5% in saline, v/v) or PEA-OXA (10 mg/kg) on the extracellular levels of norepinephrine (NE) and (HA) in the hippocampus CA3 in sham and SNI mice. Experiments have been carried out 30 days after SNI or sham surgery. The black arrow indicates the administration of the vehicle or PEA-OXA. Each point represents the mean ± S.E.M of 8 animals per group. RM Two-way ANOVA, followed by Dunnett’s or Tukey's post hoc tests for multiple comparisons tests were performed for comparison vs BL and among groups during the time course, respectively. * indicates significant differences vs sham/veh (p

Additional file 1: Figure S1: Cell viability assay performed in histamine H3 and H4 receptors transfected COS cells treated with PEA-OXA. (A) Bar graph showing the cell viability assay measured in COS H3 (B) and H4 (C) cells using MTT assay. Each data represents the mean ± S.E.M. of four separate determinations.

Additional file 2: Figure S2: Effect of PEA-OXA in COS cells stably expressing human histamine H4 and H1 receptors. (A) Scatter plots showing the effect of PEA-OXA in COS cells expressing histamine H4 receptors on intracellular cAMP levels. (B) Bar graph showing the quantification of [Ca2 +]i measurements performed in histamine H1 receptor transfected COS cells. (C, D) Representative images showing the Ca2+ oscillations in COS H1 cells following the preincubation with PEA-OXA 5 µM and stimulation with histamine 100 µM and/or thapsigargin 5 µM. (D) Data represent the mean ± SEM of ≥ 5 determinations. Data sets were compared by use of one-way ANOVA followed by Bonferroni’s test. The asterisk denotes a p value ≤ 0.05.

Additional file 3: Figure S3. Effect of the chronic treatment with vehicle (kolliphor 5% in saline, v/v) or PEA-OXA (10 mg/kg) on anxiety-like behavior. “A” shows the effect of vehicle or PEA-OXA on the percentage of open arm-choice in the elevate plus-maze in sham and SNI mice. “B” and “C” show the effect of vehicle or PEA-OXA on the time spent in the dark box in seconds and the number of transitions in the light–dark box, respectively. “D” and “E” show the effect of vehicle or PEA-OXA on number of diggings and marble buried in the marble burying. Experiments have been carried out 30 days after SNI or sham surgery. Each point represents the mean ± S.E.M. Two-way ANOVA, followed by Tukey's post hoc test for multiple comparisons test were used for statistical analysis. p

Chronic social isolation generates a persistent state of stress associated with obesity along with some neuro-endocrine disorders and central behavioral sequelae (eg anxiety, depression, aggression, and allodynia). In this study, we evaluated the effect of social isolation on body weight, depressive- and anxious-aggressive-like behavior, as well as on phenotypic changes of adipocytes from visceral adipose tissue of control (group-housed) or socially isolated (single-housed) male mice. The effect of treatment with pentadecyl-2-oxazoline (PEA-OXA), a natural alpha2 antagonist and histamine H3 protean partial agonist, on these alterations was also evaluated. Single or group-housed mice treated with vehicle or PEA-OXA underwent body weight, mechanical allodynia, anxious-, depressive- and aggressive-like behavior measurements. Proliferation rate, apoptosis, senescence, expression of fat lineage genes, lipid droplets and proinflammatory cytokines were measured on white adipose tissue adipocytes from group- or single-housed mice. Single housed mice developed weight gain, mechanical allodynia at the von Frey test, aggressiveness in the resident intruder test, depression- and anxiety-like behavior in the tail suspension and hole drop tests, respectively. Single housed mice receiving PEA-OXA showed a general resolution of both, physical-metabolic and behavioral alterations associated with social isolation. Furthermore, adipocytes from the adipose tissue of socially isolated mice showed an evident inflamed phenotype (i.e. a reduced rate of proliferation, apoptosis, senescence, and ROS hyper-production together with an increased expression of IL-1β, IL-10, IL-17, and TNF-α and a decrease of IL-6). The treatment with PEA-OXA on adipocytes from single housed mice produced a protective/anti-inflammatory phenotype with an increased expression of brown adipose tissue biomarker. This study confirms that persistent stress caused by social isolation predisposes to obesity and neuropsychiatric disorders. PEA-OXA, through its multi-target activity on alpha2 adrenoceptor and histamine H3 receptors, which have recently aroused great interest in the neuropsychiatric field, reduces weight gain, systemic pro-inflammatory state, allodynia, and affective disorders associated with social isolation.

Following injury, the endocannabinoid system is activated in the brain suggesting a strategic role in the self-repair mechanisms. Indeed endocannabinoid system manipulation ameliorates traumatic brain injury (TBI) symptoms. Cannabidiol (CBD), together with △9-tetrahydrocannabinol (THC), is the main phytocannabinoid extracted from the plant Cannabis sativa, and it plays anti-inflammatory, antioxidant, neuroprotective, anticonvulsant, hypnotic, and antiemetic effects and has proven to be useful in neuropsychiatric, neurodegenerative, post-traumatic stress, and ischemic disorders. Unlike THC, CBD is not psychoactive and enhances the beneficial and reduces the side effects of THC. CBD has negligible action on cannabinoid receptors and modulates the endocannabinoid system throughout the inhibition of endocannabinoid degradation and reuptake. It also stimulates serotonin 1A (5-HT1A), adenosine 2A (A2A), transient receptor potential vanilloid subtype 1 (TRPV1), and nuclear peroxisome proliferator-activated receptor γ (PPARγ). We collect in this chapter all the preclinical and clinical evidence on the beneficial effects of CBD in the TBI considering it important for two main reasons: the lack of effective therapy for the TBI and the good tolerability of the CBD.

Central post-stroke pain (CPSP) and associated depression remain poorly understood and pharmacological treatments are unsatisfactory. Recently, microglia activation was suggested to be involved in CPSP pathophysiology. The goal of this study was to investigate the effectiveness of a co-ultramicronized combination of N-palmitoylethanolamide and luteolin (PEALut) in a mouse model of thalamic hemorrhage (TH)-induced CPSP. TH was established through the collagenase-IV injection in thalamic ventral-posterolateral-nucleus. PEALut effects in CPSP-associated behaviors were evaluated during a 28-days observation period. We found that repeated administrations of co-ultra PEALut significantly reduced mechanical hypersensitivity after TH, as compared to vehicle, by reducing the early microglial activation in the perilesional site. Moreover, PEALut prevented the development of depressive-like behavior (21 days post-TH). These effects were associated with the restoration of synaptic plasticity in LEC-DG pathway and monoamines levels found impaired in TH mice. Hippocampal MED1 and TrkB expressions were significantly increased in TH compared to sham mice 21 days post-TH, whereas BDNF levels were decreased. PEALut restored MED1/TrkB/BDNF expression in mice. Remarkably, we found significant overexpression of MED1 in the human autoptic brain specimens after stroke, indicating a translational potential of our findings. These results pave the way for better-investigating depression in TH- induced CPSP, together with the involvement of MED1/TrkB/BDNF pathway, proposing PEALut as an adjuvant treatment.

Neuropathic pain has long-term consequences in terms of affective and cognitive disturbances suggesting the involvement of supraspinal mechanisms. In the present study, we used the spared nerve injury (SNI) model to characterize the development of sensory and aversive components of neuropathic pain, and to determine their electrophysiological impact across PFC and limbic regions. Moreover, we evaluated the regulation of several genes involved in immune response and inflammation triggered by the SNI.We showed that SNI led to sensorial hypersensitivity (cold and mechanical stimuli) and depressive-like behavior lasting 12 months after nerve injury. Interestingly, changes in non-emotional cognitive tasks (novel object recognition and Y maze) showed in 1-month SNI mice, were not evident normal in 12 months-SNI animals. In vivo electrophysiology revealed an impaired the Long Term Potentiation (LTP) at prefrontal cortex (PFC)- nucleus accumbens core (NAcore) pathway in both 1 and 12 months SNI. On the other hand, a reduced neural activity was recorded in the lateral entorhinal cortex (LEC)-dentate gyrus (DG) pathway in 1 month-, but not in 12 months- SNI mice. Finally, we observed the upregulation of specific genes involved in involved in immune response in the hippocampus of 1 month-, but not 12 months-SNI mice, suggesting a neuroinflammatory response which may contribute to the SNI phenotype.These data suggest that distinct brain circuits may drive the psychiatric components of neuropathic pain and pave the way for better investigate the long-term consequences of peripheral nerve injury in which most of the available drugs are to date unsatisfactory.

Neuropathic pain is a pathological condition induced by a lesion or disease affecting the somatosensory system, with symptoms like allodynia and hyperalgesia. It has a multifaceted pathogenesis as it implicates several molecular signaling pathways involving peripheral and central nervous systems. Affective and cognitive dysfunctions have been reported as comorbidities of neuropathic pain states, supporting the notion that pain and mood disorders share some common pathogenetic mechanisms. The understanding of these pathophysiological mechanisms requires the development of animal models mimicking, as far as possible, clinical neuropathic pain symptoms. Among them, the Spared Nerve Injury (SNI) model has been largely characterized in terms of behavioral and functional alterations. This model is associated with changes in neuronal firing activity at spinal and supraspinal levels, and induces late neuropsychiatric disorders (such as anxious-like and depressive-like behaviors, and cognitive impairments) comparable to an advanced phase of neuropathy. The goal of this review is to summarize current findings in preclinical research, employing the SNI model as a tool for identifying pathophysiological mechanisms of neuropathic pain and testing pharmacological agent.

Depressive symptoms and other neuropsychiatric dysfunctions are common in neurodegenerative disorders, including chronic pain and dementia. A correlation between the β-amyloid protein accumulation and the development of depression has been suggested, however the underlying mechanisms are unknown. d-Aspartate (d-Asp) is a free d-amino acid found in the mammalian brain and involved in neurological and psychiatric processes, such as cognition and affective disorders. In this study we have investigated the effects of a repeated treatment with d-Asp in a long-lasting (12 months) model of neuropathic pain, the spared nerve injury (SNI), in mice. Specifically, we evaluated i) the pain sensitivity and related emotional/cognitive dysfunctions induced by SNI, ii) possible changes in the β-amyloid protein accumulation in specific brain regions involved in pain mechanisms ii) possible changes in steroids level in neuropathic animals with or without d-Asp in the same brain areas. SNI mice showed an increase of the insoluble form of Aβ1-42 at hippocampal level and displayed cognitive impairments, stereotypical and depressive-like behaviours. d-Asp treatment reduced abnormal behaviours and normalized the β-amyloid protein expression. Moreover, d-Asp dramatically increased steroids level measured in the prefrontal cortex and in the hippocampus. Our findings provide new insights into pain mechanisms and suggest a possible role of β-amyloid protein in neuropsychiatric dysfunctions associated with chronic pain.

Traumatic brain injury (TBI) represents a major public health problem, which is associated with neurological dysfunction. In severe or moderate cases of TBI, in addition to its high mortality rate, subjects may encounter diverse behavioural dysfunctions. Previous reports suggest that an association between TBI and chronic pain syndromes tends to be more common in patients with mild forms of brain injury. Despite causing minimal brain damage, mild TBI (mTBI) often leads to persistent psychologically debilitating symptoms, which can include anxiety, various forms of memory and learning deficits, and depression. At present, no effective treatment options are available for these symptoms, and little is known about the complex cellular activity affecting neuronal activity that occurs in response to TBI during its late phase. Here, we used a mouse model to investigate the effect of Palmitoylethanolamide (PEA) on both the sensorial and neuropsychiatric dysfunctions associated with mTBI through behavioural, electrophysiological, and biomolecular approaches. Fourteen-day mTBI mice developed anxious, aggressive, and reckless behaviour, whilst depressive-like behaviour and impaired social interactions were observed from the 60th day onwards. Altered behaviour was associated with changes in interleukin 1 beta (IL-1β) expression levels and neuronal firing activity in the medial prefrontal cortex (m-PFC). Compared with vehicle, PEA restored the behavioural phenotype and partially normalised the biochemical and functional changes occurring at the supraspinal level. In conclusion, our findings reveal some of the supraspinal modifications responsible for the behavioural alterations associated with mTBI and suggest PEA as a pharmacological tool to ameliorate neurological dysfunction induced by the trauma.