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Synucleinopathies, including Parkinson's disease and dementia with Lewy bodies, are neurodegenerative disorders characterized by the aberrant accumulation of α-synuclein (α-syn). Although no treatment is effective for synucleinopathies, the suppression of α-syn aggregation may contribute to the development of numerous novel therapeutic targets. Recent research revealed that nicotinic acetylcholine (nACh) receptor activation has neuroprotective effects and promotes the degradation of amyloid protein by activating autophagy. In an in vitro human-derived cell line model, we demonstrated that galantamine, the nAChR allosteric potentiating ligand, significantly reduced the cell number of SH-SY5Y cells with intracellular Lewy body-like aggregates by enhancing the sensitivity of α 7 -nAChR. In addition, galantamine promoted autophagic flux, and prevented the formation of Lewy body-resembled aggregates. In an in vivo synucleinopathy mouse model, the propagation of α-syn aggregation in the cerebral cortex was inhibited by galantamine administration for 90 days. These results suggest that α 7 -nAChR is expected to be a novel therapeutic target, and galantamine is a potential agent for synucleinopathies., (Copyright © 2024 The Authors. Production and hosting by Elsevier B.V. All rights reserved.)

Previously, we have shown that pyrogallol alleviated nasal symptoms and suppressed IL-9 gene up-regulation in allergy model rats by inhibiting calcineurin/NFAT signaling. As pyrogallol has antioxidative activity, it may be responsible for inhibiting calcineurin/NFAT signaling-mediated IL-9 gene expression. However, the relationship between antioxidative activity and suppression of IL-9 gene expression has not been elucidated yet. Here, we conducted the structure-activity relationship studies of pyrogallol and its structurally related compounds to understand the mechanism of IL-9 gene suppression by pyrogallol. 2, 2-Diphenyl-1-picrylhydrazyl radical scavenging assay showed that the antioxidative activity of catechol, resorcinol, phloroglucinol, and gallic acid is 60.1%, 10.4%, 18.8%, and 113.5% of pyrogallol, respectively. Catechol, resorcinol, and phloroglucinol did not suppress NFAT dephosphorylation. Gallic acid suppressed dephosphorylation of NFAT. Gallic acid also suppressed ionomycin-induced up-regulation of IL-9 gene expression with the IC 50 value of 82.6 μM. However, catechol, resorcinol and phloroglucinol showed no suppressive activity. In addition, using gallic acid-immobilized beads, we isolated and identified Poly(U)-binding-splicing factor 60 (PUF60) as a pyrogallol binding protein. These results suggest that the antioxidative activity of pyrogallol is not likely to be the mechanism of IL-9 gene suppression. Data also suggest that PUF60 is one of its target molecules responsible for the suppression of calcineurin/NFAT signaling by pyrogallol., Competing Interests: Declaration of competing interest The authors declare no conflicts of interest., (Copyright © 2024 The Authors. Production and hosting by Elsevier B.V. All rights reserved.)

We have reported that nicotine has a neurotrophic action on peripheral adrenergic nerves in vivo, which is mediated by α7 nicotinic acetylcholine receptors (nAChRs). To clarify the possible mechanisms, the present study further investigated the effect of nicotine on neurite outgrowth in tyrosine hydroxylase (TH)-positive superior cervical ganglia (SCG) cells isolated from neonatal rats in vitro. Nicotine at low concentrations (0.01-0.3 mM) increased the number of neurite outgrowths in TH-immunopositive SCG cells, while high concentrations of nicotine (1-10 mM) gradually reduced it, and only 10 mM nicotine was markedly inhibited compared to the control. A 100 μM of nicotine-induced increase in neurite numbers depended on the exposure time and was inhibited by treatment with the nAChR antagonist hexamethonium (Hex) and α7 nAChR antagonist α-bungarotoxin (α-Bgtx). The nicotine (10 mM)-induced a significant decrease in neurite outgrowth in SCG, which was perfectly canceled by Hex to the control level but not by α-Bgtx. These results suggest that nicotine has a regulatory neurotrophic action mediated by both α7 nAChR and other subtypes in TH-positive SCG cells of rats., Competing Interests: Declaration of competing interest This study was supported by the Smoking Research Foundation., (Copyright © 2021 The Authors. Production and hosting by Elsevier B.V. All rights reserved.)

Oxidative stress is associated with the progression of the neurodegenerative diseases Parkinson's disease (PD) and cerebral ischemia. Recently, 5-aminolevulinic acid (5-ALA), an intermediate in the porphyrin synthesis pathway, was reported to exert antioxidative effects on macrophages and cardiomyocytes. Here, we demonstrated the neuroprotective effects of 5-ALA using rat models of PD and ischemia as well as in vitro in SH-SY5Y cells. 5-ALA partially prevented neurodegeneration in each condition. These results suggest that 5-ALA has a potential for promising therapeutic agent to protect against neurodegeneration exacerbated by oxidative stress., Competing Interests: Declaration of Competing Interest None., (Copyright © 2020 The Authors. Production and hosting by Elsevier B.V. All rights reserved.)

We examined whether combination treatment with doxorubicin and cyclophosphamide, a traditional chemotherapy for breast cancer, induced anxiety-like behavior in rats. Furthermore, we evaluated the role of the serotonin (5-HT) 2A receptor subtype in the anxiety-like behavior induced by such chemotherapy. Rats were intraperitoneally injected with doxorubicin and cyclophosphamide once a week for 2 weeks. This caused the rats to display anxiety-like behavior during the light-dark test. In addition, we examined the rats' 5-HT 2A receptor-mediated behavioral responses. Combination treatment with doxorubicin and cyclophosphamide significantly increased (±)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane, (a 5-HT 2A receptor agonist)-induced wet-dog shake activity. This anxiety-like behavior was significantly inhibited by mirtazapine, a 5-HT 2A receptor antagonist/5-HT 1A receptor agonist, and tandospirone, a partial 5-HT 1A receptor agonist, but not by fluoxetine, a selective serotonin reuptake inhibitor. The anxiety-like behavior induced by doxorubicin and cyclophosphamide combination treatment is mediated by hyperfunctioning of the 5-HT 2A receptor. Thus, 5-HT 2A receptor antagonists or 5-HT 1A receptor agonists might be useful for treating chemotherapy-induced anxiety disorders., (Copyright © 2018 The Authors. Production and hosting by Elsevier B.V. All rights reserved.)

Narrowband-ultraviolet B (NB-UVB) phototherapy is used for the treatment of atopic dermatitis. Previously, we reported that irradiation with 200 mJ/cm 2 of 310 nm NB-UVB suppressed phorbol-12-myristate-13-acetate (PMA)-induced up-regulation of histamine H 1 receptor (H1R) gene expression without induction of apoptosis in HeLa cells. However, the effect of NB-UVB irradiation on nasal symptoms is still unclear. Here, we show that low dose irradiation with 310 nm NB-UVB alleviates nasal symptoms in toluene 2,4-diisocyanate (TDI)-sensitized allergy model rats. Irradiation with 310 nm NB-UVB suppressed PMA-induced H1R mRNA up-regulation in HeLa cells dose-dependently at doses of 75-200 mJ/cm 2 and reversibly at a dose of 150 mJ/cm 2 without induction of apoptosis. While, at doses of more than 200 mJ/cm 2 , irradiation with 310 nm NB-UVB induced apoptosis. Western blot analysis showed that the suppressive effect of NB-UVB irradiation on H1R gene expression was through the inhibition of ERK phosphorylation. In TDI-sensitized rat, intranasal irradiation with 310 nm NB-UVB at an estimated dose of 100 mJ/cm 2 once a day for three days suppressed TDI-induced sneezes and up-regulation of H1R mRNA in nasal mucosa without induction of apoptosis. These findings suggest that repeated intranasal irradiation with low dose of NB-UVB could be clinically used as phototherapy of AR., (Copyright © 2018 The Authors. Production and hosting by Elsevier B.V. All rights reserved.)

Antihistamines inhibit histamine signaling by blocking histamine H1 receptor (H1R) or suppressing H1R signaling as inverse agonists. The H1R gene is upregulated in patients with pollinosis, and its expression level is correlated with the severity of nasal symptoms. Here, we show that antihistamine suppressed upregulation of histidine decarboxylase (HDC) mRNA expression in patients with pollinosis, and its expression level was correlated with that of H1R mRNA. Certain antihistamines, including mepyramine and diphenhydramine, suppress toluene-2,4-diisocyanate (TDI)-induced upregulation of HDC gene expression and increase HDC activity in TDI-sensitized rats. However, d-chlorpheniramine did not demonstrate any effect. The potencies of antihistamine suppressive effects on HDC mRNA elevation were different from their H1R receptor binding affinities. In TDI-sensitized rats, the potencies of antihistamine inhibitory effects on sneezing in the early phase were related to H1R binding. In contrast, the potencies of their inhibitory effects on sneezing in the late phase were correlated with those of suppressive effects on HDC mRNA elevation. Data suggest that in addition to the antihistaminic and inverse agonistic activities, certain antihistamines possess additional properties unrelated to receptor binding and alleviate nasal symptoms in the late phase by inhibiting synthesis and release of histamine by suppressing HDC gene transcription., (Copyright © 2016 The Authors. Production and hosting by Elsevier B.V. All rights reserved.)

Histamine H1 receptor (H1R) gene is upregulated in patients with pollinosis; its expression level is highly correlated with the nasal symptom severity. Antihistamines are widely used as allergy treatments because they inhibit histamine signaling by blocking H1R or suppressing H1R signaling as inverse agonists. However, long-term treatment with antihistamines does not completely resolve toluene-2,4-diisocyanate (TDI)-induced nasal symptoms, although it can decrease H1R gene expression to the basal level, suggesting additional signaling is responsible for the pathogenesis of the allergic symptoms. Here, we show that treatment with suplatast tosilate in combination with antihistamines markedly alleviates nasal symptoms in TDI-sensitized rats. Suplatast suppressed TDI-induced upregulation of IL-9 gene expression. Suplatast also suppressed ionomycin/phorbol-12-myristate-13-acetate-induced upregulation of IL-2 gene expression in Jurkat cells, in which calcineurin (CN)/nuclear factor of activated T-cells (NFAT) signaling is known to be involved. Immunoblot analysis demonstrated that suplatast inhibited binding of NFAT to DNA. Furthermore, suplatast suppressed ionomycin-induced IL-9 mRNA upregulation in RBL-2H3 cells, in which CN/NFAT signaling is also involved. These data suggest that suplatast suppressed NFAT-mediated IL-9 gene expression in TDI-sensitized rats and this might be the underlying mechanism of the therapeutic effects of combined therapy of suplatast with antihistamine., (Copyright © 2016 Japanese Pharmacological Society. Production and hosting by Elsevier B.V. All rights reserved.)

In the present study, we examined the effects of antihistamine on the up-regulation of H1R mRNA in the nasal mucosa of patients with pollinosis induced by controlled exposure to pollen using an environmental exposure unit. Out of 20 patients, we designated 14 responders, whose levels of H1R mRNA in the nasal mucosa were increased after the first pollen exposure and excluded 6 non-responders. Accordingly, the first exposure to pollen without treatment significantly induced both nasal symptoms and the up-regulation of H1R mRNA in the nasal mucosa of the responders. Subsequently, prophylactic administration of antihistamine prior to the second pollen exposure significantly inhibited both of the above effects in the responders. Moreover, the nasal expression of H1R mRNA before the second pollen exposure in the responders pretreated with antihistamine was significantly decreased, as compared with that before the first pollen exposure without treatment. These findings suggest that antihistamines suppressed histamine-induced transcriptional activation of H1R gene in the nasal mucosa, in addition to their blocking effect against histamine on H1R, resulting in a decrease of nasal symptoms. These findings further suggest that by their inverse agonistic activity, antihistamines suppress the basal transcription of nasal H1R in the absence of histamine in responders., (Copyright © 2015 Japanese Pharmacological Society. Production and hosting by Elsevier B.V. All rights reserved.)

Parkinson's disease (PD) is caused by dopaminergic cell death in the substantia nigra, leading to a reduced level of dopamine in the striatum. Oxidative stress is one of the causes of PD. Since symptomatic PD therapies are used, identification of compounds or proteins that inhibit oxidative stress-induced neuronal cell death is necessary. DJ-1 is a causative gene product of familial PD and plays a role in anti-oxidative stress reaction. We have identified various DJ-1-binding compounds, including compound-23, that restored neuronal cell death and locomotion defects observed in neurotoxin-induced PD models. In this study, wild-type and DJ-1-knockout mice were injected intraperitoneally with 1 mg/kg of compound-23 and then with 30 mg/kg of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) at 1 h after injection. Five days after administration, the effects of compound-23 on MPTP-induced locomotion deficits, on dopaminergic cell death and on brain dopamine levels were analyzed by rotor rod tests, by staining cells with an anti-TH antibody and by an HPLC, respectively. The results showed that compound-23 inhibited MPTP-induced reduction of retention time on the rotor rod bar, neuronal cell death in the substantia nigra and striatum and dopamine content in wild-type mice but not in DJ-1-knockout mice, indicating a DJ-1-dependent effect of compound-23., (Copyright © 2015 The Authors. Production and hosting by Elsevier B.V. All rights reserved.)

In clinical studies, electroconvulsive stimuli have been associated with improvements in both depression and treatment-resistant depression. In a previous study, treatment with adrenocorticotropic hormone (ACTH) for 14 days decreased adult hippocampal cell proliferation. Furthermore, electroconvulsive stimuli significantly decreased the duration of immobility following repeated administration of ACTH for 14 days in rats. The present study was undertaken to further characterize the mechanism of treatmentresistant antidepressant effects of electroconvulsive stimuli by measuring cell proliferation, brain-derived neurotrophic factor (BDNF) levels, and phosphorylated and total cyclic adenosine monophosphate (cAMP) response element-binding protein (pCREB/CREB) levels in the hippocampus of ACTH-treated rats. Electroconvulsive stimuli increased cell proliferation in both saline-treated and ACTH-treated rats. Mature-BDNF protein levels showed a tendency to decrease in ACTH-treated rats. Electroconvulsive stimuli treatment increased mature-BDNF protein levels in the hippocampus of both saline-treated and ACTH-treated rats. Furthermore, electroconvulsive stimuli increased phospho-Ser133-CREB (pCREB) levels and the ratio of pCREB/CREB in both saline-treated and ACTH-treated rats. These findings suggest that the treatment-resistant antidepressant effects of electroconvulsive stimuli may be attributed, at least in part, to an enhancement of hippocampal cell proliferation.

An attempt was made to clarify the additive suppressive effects of pranlukast, a cysteinyl leukotriene-receptor (LTR) antagonist, in combination with chlorpheniramine, an antihistamine, on the up-regulation of histamine H1-receptor (H1R) mRNA in toluene 2,4-diisocyanate (TDI)-sensitized rats. Although pre-treatment with pranlukast partially, but significantly, suppressed TDI-induced up-regulation of H1R mRNA and nasal symptoms, pre-treatment with the combination of pranlukast and chlorpheniramine significantly suppressed them in a manner greater than either drug alone. These findings suggest that the additive therapeutic effect of the combination of LTR antagonist and antihistamine is due to their additive suppression of H1R up-regulation.

L-Dihydroxyphenylalanine (L-DOPA) is considered the gold standard for the treatment of Parkinson's disease (PD). However, long-term administration of L-DOPA can induce abnormal side effects. On the other hand, selective serotonin reuptake inhibitors (SSRIs) including fluoxetine have gained tremendous popularity in the treatment of depression in PD. SSRIs are thought to influence motor function in PD via pharmacological modification of interactions between serotonergic and dopaminergic networks, which are complex and not yet fully understand. In this study, intranigral injection of 6-hydroxydopamine (6-OHDA) in rats caused a significant loss of tyrosine hydroxylase immunoreactivity in the striatum and substantia nigra. However, tryptophan hydroxylase immunoreactivity of the striatum and raphe nucleus was unaffected by 6-OHDA. Immunohistochemical analysis reveal that the serotonergic system was unaffected by the injection of 6-OHDA. We demonstrated also that pre-treatment with fluoxetine significantly suppressed L-DOPA-induced rotational behavior. Additionally, fluoxetine suppressed L-DOPA-induced ERK1/2 and histone H3 phosphorylation. These effects of fluoxetine were abolished by pre-treatment with WAY 100135, a 5-HT(1A) antagonist. These results suggest that fluoxetine may influence motor function in PD via pharmacological modification of interactions between serotonergic and dopaminergic neuronal networks.

The endothelium in rat mesenteric vascular beds has been demonstrated to regulate vascular tone by releasing mainly endothelium-derived hyperpolarizing factor (EDHF), which is involved in the activation of K(+) channels and gap-junctions. However, it is unclear whether the endothelial system in mouse resistance arteries contributes to regulation of the vascular tone. The present study was designed to investigate the role of the endothelium using acetylcholine and A23187 (Ca(2+) ionophore) in mesenteric vascular beds isolated from male C57BL/6 mice and perfused with Krebs solution to measure perfusion pressure. In preparations with active tone produced by methoxamine in the presence of guanethidine, injections of acetylcholine, A23187, and sodium nitroprusside (SNP) caused a concentration-dependent decrease in perfusion pressure due to vasodilation. The vasodilator responses to acetylcholine and A23187, but not SNP, were abolished by endothelium dysfunction and significantly inhibited by N(ω)-nitro-L-arginine methyl ester (nitric oxide synthase inhibitor) and tetraethylammonium (K(+)-channel inhibitor) but not glibenclamide (ATP-sensitive K(+)-channel inhibitor). Indomethacin (cyclooxygenase inhibitor) significantly blunted only A23187-induced vasodilation, while 18α-glycyrrhetinic acid (gap-junction inhibitor) attenuated only acetylcholine-induced vasodilation. These results suggest that the endothelium in mouse mesenteric arteries regulates vascular tone by prostanoids, EDHF, and partially by nitric oxide, different from the endothelium of rat mesenteric arteries.

Pathological hallmarks of Alzheimer's disease (AD) include senile plaques, neurofibrillary tangles (NFTs), synaptic loss, and neurodegeneration. Senile plaques are composed of amyloid-β (Aβ) and are surrounded by microglia, a primary immune effector cell in the central nervous system. NFTs are formed by the intraneuronal accumulation of hyperphosphorylated tau, and progressive synaptic and neuronal losses closely correlate with cognitive deficits in AD. Studies on responsible genes of familial AD and temporal patterns of pathological changes in brains of patients with Down's syndrome (Trisomy 21), who invariably develop neuropathology of AD, have suggested that Aβ accumulation is a primary event that influences other AD pathologies. Although details of the interaction between AD pathologies remain unclear, experimental evidences to discuss this issue have been accumulated. In this paper, we review and discuss recent findings that link the AD pathologies to each other. Further studies on the interaction between pathologies induced in AD brain may contribute to provide deep insight into the pathogenesis of AD and to develop novel therapeutic, prophylactic, and early diagnostic strategies for AD.

DJ-1, Parkinson's disease PARK7, acts as an oxidative stress sensor in neural cells. Recently, we identified the DJ-1 modulator UCP0054278 by in silico virtual screening. However, the effect of the peripheral administration of UCP0054278 on an in vivo Parkinson's disease (PD) model is unclear. Therefore, in the present study, we examined the effects of the peripheral administration of UCP0054278 on both 6-OHDA-microinjected rats and rotenone-treated mice as acute and chronic animal models of PD, respectively. The peripheral administration of UCP0054278 prevented 6-OHDA- and rotenone-induced dopaminergic neural cell death and restored the defect in locomotion in these models of PD. In addition, 6-OHDA- or rotenone-induced neural cell death and the production of reactive oxygen species were significantly inhibited by UCP0054278 in normal SH-SY5Y cells, but not in DJ-1-knockdown cells. These results suggest that UCP0054278 interacts with endogenous DJ-1 and then produces antioxidant and neuroprotective responses in both in vivo and in vitro models of PD. The present study raises the possibility that DJ-1 stimulatory modulators, such as UCP0054278, may be a new type of dopaminergic neuroprotective drug for the treatment of PD.

Endothelium regulates vascular tone via release of endothelium-derived relaxing factors (EDRF) including nitric oxide (NO), prostaglandin I₂ (PGI₂), and endothelium-derived hyperpolarizing factor (EDHF). The mesenteric vascular bed produces vascular resistance to develop blood pressure and regulate tissue blood flow that plays an important role in maintenance of systemic blood pressure. There is now strong evidence that in these small resistance arteries, EDHF plays a major role in the response to vasoactive substances and regulation of vascular tone. Pharmacological analysis to investigate the role of the vascular endothelium in the regulation of α₁-adrenoceptor agonist (methoxamine)-induced vasoconstriction in rat mesenteric vascular beds showed that vasoconstriction induced by continuous perfusion of methoxamine (7 µM), but not high KCl (60 mM), time-dependently decreased to 20% of the initial constriction. The time-dependent reduction of methoxamine-induced vasoconstriction was inhibited by endothelium removal, inhibitor of EDHF (30 mM KCl, K+-channel blockers), and gap-junction inhibitor, but not NO synthase inhibitor and cyclooxygenase inhibitor and ageing. These results suggest that vascular endothelium counteracts to normalize excess vasoconstriction of the mesenteric resistance arteries by releasing EDHF, which is associated with activation of multiple K+-channels and gap junction involvement and markedly decreases with ageing.

A better understanding of the neurochemical mechanisms mediating the aversive consequences of drug withdrawal is important for understanding drug addiction. We previously demonstrated that the inhibitory effect of glutamate receptor antagonists on the conditioned place aversion (CPA) induced by naloxone-precipitated withdrawal after a single morphine exposure could be blocked by dopamine receptor antagonists. Thus, a glutamatergic-dopaminergic interaction may participate in this phenomenon. The current study was undertaken to further characterize this interaction by employing both D(1) (SCH 23390) and D(2) (raclopride and eticlopride) dopamine receptor antagonists. The influence of these antagonists on the attenuation of CPA by MK-801 (NMDA receptor antagonist), GYKI 52466 (AMPA receptor antagonist), and MCPG (metabotropic glutamate receptor antagonist) was determined in rats receiving a single dose of morphine. The dopamine antagonists showed either a significant reversal or a tendency to reverse the effects of MK-801 on CPA. The effect of GYKI 52466 was also attenuated by the blockade of either D(1) or D(2) receptors. The effect of MCPG, however, was only blocked by D(2) antagonists and not by the D(1) antagonist SCH 23390. These results add evidence to the hypothesis that a glutamatergic-dopaminergic interaction may be involved in the CPA induced by naloxone-precipitated withdrawal following a single morphine exposure and suggest that both D(1) and D(2) dopamine receptor signaling mechanisms play a role in mediating the aversive aspects of acute dependence.

The protective effects of hesperidin against hypercholesterolemia and fatty liver were examined in male Wistar rats fed a high-cholesterol diet for 12 weeks. Compared with a standard diet, a high-cholesterol diet not only increased body weights, liver weights, and serum concentration of cholesterol, but also induced the fatty degeneration (steatosis) of liver. Hesperidin (0.08%) reduced levels of hepatic steatosis, adipose tissue and liver weights (P < 0.05), serum total cholesterol and retinol binding protein (RBP) 4 concentrations (P < 0.05) in rats fed with high-cholesterol diet, while reduction in low-density lipoprotein cholesterol levels and triglyceride concentrations was not significant. It also attenuated the marked changes in mRNA expression of lipid metabolism-related proteins: RBP, heart fatty acid-binding protein (H-FABP), and cutaneous fatty acid-binding protein (C-FABP), in liver and adipose tissue. According to the results of gas chromatography, serum concentrations of total cholesterol and biomarkers of cholesterol synthesis (lathosterol) and absorption (campesterol, β-sitosterol) were lower, and concentrations of cholesterol in feces were higher in the rats given hesperidin (P < 0.05). Hesperidin may improve hypercholesterolemia and fatty liver by inhibiting both the synthesis and absorption of cholesterol and regulating the expression of mRNA for RBP, C-FABP, and H-FABP.

Nerve growth factor (NGF) facilitates reinnervation of perivascular nerves that regulate vascular tone and blood flow. This study investigated whether NGF prevents tumor growth by promoting neuronal regulation of tumor blood flow. The growth rate of DU145 prostate carcinoma cells subcutaneously implanted into nude mice was significantly inhibited by subcutaneous NGF administration. Significant suppression of tumor growth continued after withdrawing NGF. NGF increased vascular smooth muscle cells in tumor tissues, but had no cytotoxic action on tumor cells in vitro. These results suggest that NGF prevents tumor growth via an indirect effect, probably innervation or maturation of the tumor neovasculature.

We previously reported that endothelium-derived hyperpolarizing factor (EDHF)-mediated response time-dependently suppressed methoxamine-induced vasoconstriction in mesenteric vascular beds isolated from 8-week-old rats. We investigated age-related changes in endothelial regulation of methoxamine-induced vasoconstriction. Mesenteric vascular beds isolated from young (8-week-old) to adult (16-week-old) rats were perfused, and changes in perfusion pressure induced by continuous perfusion of methoxamine or high KCl (60 mM) were measured over 180 min. In young preparations with intact endothelium, methoxamine-induced vasoconstriction time-dependently decreased to 20% of the initial levels, while time-dependent reduction was not observed in adult preparations. High KCl-induced vasoconstriction in young and adult preparations did not show time-dependent reduction. Endothelium removal abolished time-dependent reduction of methoxamine-induced vasoconstriction in young preparations and significantly attenuated vasoconstriction in adult preparations. Indomethacin, seratrodast, or tempol but not catalase significantly reduced methoxamine-induced vasoconstriction in adult preparations with endothelium. A23187 (Ca(2+)-ionophore)-, but not acetylcholine-, induced endothelium-dependent vasodilation in the presence of N(G)-L-nitro arginine methyl ether in adult preparations was significantly smaller than that in young preparations. These findings suggest that the inhibitory effect of mesenteric vascular endothelium on methoxamine-induced vasoconstriction disappears with aging by reducing EDHF and increasing endothelium-derived contracting factors and reactive oxygen species.

The present study was performed to investigate the effects of kavain on the sleep-wake cycle in comparison with that of rilmazafone and diphenhydramine using sleep-disturbed rats. Electrodes for the electroencephalogram (EEG) and electromyogram (EMG) were implanted into Wistar rats. Total awake time, non-rapid eye movement (non-REM) sleep and rapid eye movement (REM) sleep were measured for 6 h. Kavain and rilmazafone showed a significant shortening in sleep latency, decreased awake time, and increased non-REM sleep time. On the other hand, significant shortening of the sleep latency was observed following the administration of diphenhydramine, while no effects were observed on the awake and non-REM sleep time. Moreover, kavain showed a significant increase in delta activity during non-REM sleep in sleep-disturbed rats, whereas a significant decrease in delta power during non-REM sleep was observed with rilmazafone. These results clearly indicate that kavain is a compound with not only hypnotic effects, but also sleep quality-enhancement effects.

Although a loss-of-function type mutation was identified in familial Parkinson's disease PARK7, the wild-type of DJ-1 is known to act as an oxidative stress sensor in neuronal cells. Recently, we found a DJ-1 modulator UCP0054278 by in silico virtual screening. In this study, we determined the neuroprotective effects of UCP0054278 against focal ischemia-induced neurodegeneration in rats. Hydrogen peroxide-induced cell death and the production of reactive oxygen species were significantly inhibited by UCP0054278 in normal SH-SY5Y cells, but not in DJ-1-knockdown cells. These results suggest that UCP0054278 interacts with endogenous DJ-1 and then exhibits antioxidant and neuroprotective responses.

Hepatic growth factor (HGF) has neurotrophic effects in the motor neurons and central nervous system. However, there has been no report about the neurotrophic action on perivascular nerves innervating the resistance artery. We investigated whether HGF can restore innervation or function of perivascular nerves, including neuropeptide Y (NPY)-containing sympathetic adrenergic nerves and calcitonin gene-related peptide (CGRP)-containing nerves, in rat mesenteric artery. To investigate HGF-mediated neurotrophic effects, Wistar rats under pentobarbital-Na anesthesia underwent in vivo perivascular denervation by topical application of phenol on the superior mesenteric artery, and then HGF or nerve growth factor (NGF) was administered for 7 days using an osmotic mini-pump after phenol-treatment. HGF significantly increased the density and number of CGRP-like immunoreactivity (LI)-containing nerve fibers compared with saline administration, while HGF did not affect the density of NPY-containing adrenergic nerve fibers. After 7-day treatment with HGF and phenol, the vascular response of vasodilation was recovered from nerve injury by phenol treatment, but vasoconstriction was not. HGF and NGF induced neurite outgrowth in rat cultured dorsal root ganglia (DRG). These results suggest that HGF has a specific neurotrophic action on reinnervation of vascular CGRP-LI-containing nerve fibers in the rat mesenteric artery and DRG.

Recently, it was demonstrated that the priming stimulation effect (PSE) of intracranial self-stimulation (ICSS) with the runway method can be used as a model system to study the motivation that contributes to specific behaviors. It was postulated that these behaviors could be used to compare the effects of various drugs on the mechanism of motivation. In the present study, the influences of nicotine, methyllycaconitine (alpha7 nicotine-receptor antagonist), and dihydro-beta-erythroidine (alpha4beta2 nicotine-receptor antagonist) on motivation were examined using the runway method for ICSS. Electrodes were implanted into the medial forebrain bundle of Wistar rats. The rats ran to the goal lever to get the reward (50 - 200 microA, 0.2 ms, 60 Hz) and pretrial electric stimulation (priming stimulation) in the medial forebrain bundle was performed. The experiment measured the running time from the start box until the rat pressed the goal lever for the reward stimulation. Under these reward and priming stimulation conditions, nicotine (0.2 mg/kg) induced a significant increase in running speed. The nicotine receptor antagonist alpha4beta2 rather than alpha7 showed a dose-dependent antagonistic action on the effect of nicotine on running speed. These results demonstrate that nicotine enhances the running speed towards the goal lever via alpha4beta2 nicotinic receptors and suggest that alpha4beta2 nicotinic receptors influence the brain mechanism of motivation.

Antihistamines are effective for treatment of seasonal nasal allergy. Recently, prophylactic treatment with antihistamines in patients with pollinosis was reported to be more effective when started before the pollen season. The administration with antihistamines from 2 to 6 weeks before onset of the pollen season is recommended for management of allergic rhinitis in Japan. To determine the reason for the effectiveness of prophylactic treatment with antihistamines, the effects of repeated pre-treatment with antihistamines before provocation with toluene 2,4-diisocyanate (TDI) on their nasal allergy-like behavior and up-regulations of histamine H(1) receptors (H1R) and interleukin (IL)-4 mRNAs in their nasal mucosa were examined. Provocation with TDI induced sneezing and up-regulations of H1R and IL-4 mRNAs in the nasal mucosa of TDI-sensitized rats. Repeated pre-treatments with antihistamines including epinastine, olopatadine, or d-chlorpheniramine for 1 to 5 weeks before provocation with TDI suppressed TDI-induced sneezing and the up-regulations of H1R and IL-4 mRNAs in the nasal mucosa more than their administrations once or for 3 days before TDI provocation. Our data indicate that repeated pre-treatment with antihistamines before provocation with TDI is more effective than their single treatment in reducing nasal allergy-like behavior by causing additional suppression of up-regulations of H1R and IL-4 mRNAs in the nasal mucosa.

Vascular endothelium regulates vascular tone by releasing endothelium-derived vasoactive substances. We performed this study to characterize the inhibitory effect of the endothelium on vasoconstrictor stimuli in rat mesenteric vascular beds. Changes in perfusion pressure induced by continuous perfusion of Krebs solution containing methoxamine (alpha(1)-adrenoceptor agonist) or high KCl were measured over 180 min. In preparations with intact endothelium, methoxamine-induced vasoconstriction was time-dependently decreased to cause 60% - 80% reduction of the initial vasoconstriction level, while no reduction was observed in high-KCl-induced vasoconstriction. Endothelium removal significantly blunted the time-dependent reduction of methoxamine-induced vasoconstriction without affecting high-KCl-induced vasoconstriction. Neither a nitric oxide synthase inhibitor (L-NAME) nor indomethacin (cyclooxygenase inhibitor) altered the time-dependent reduction of vasoconstriction. High KCl, K(+)-channel inhibitors tetraethylammonium and apamin plus charybdotoxin, and 18alpha-glycyrrhetinic acid (18alpha-GA, a gap-junction inhibitor) significantly inhibited the time-dependent reduction of methoxamine-induced vasoconstriction. In preconstricted preparations, bolus injection of acetylcholine and Ca(2+)-ionophore A23187 (A23187) evoked a sharp vasodilation, which was inhibited by endothelium removal, high KCl and tetraethylammonium, but not indomethacin, L-NAME, or 18alpha-GA. However, 18alpha-GA plus L-NAME inhibited vasodilation induced by A23187, but not acetylcholine. These findings suggest that endothelium-derived hyperpolarizing factor (EDHF) via gap junctions mainly counteracts vasoconstriction induced by methoxamine in mesenteric resistance arteries.

Intracranial self-stimulation (ICSS) behavior is an experimental methodology to study reward and motivational effects. We have established a paradigm to evaluate enhancing motivation by drugs in the runway method using the priming stimulation of ICSS. In the present study, we investigated the effects of diazepam on the experimental extinction process of non-reinforcing reward and pre-trial electric priming stimulations in lateral hypothalamic self-stimulation. The extinction process in the runway method consisted of these 15 trials. Diazepam, an anti-anxiety drug, at doses of 0.5 and 1 mg/kg (i.p.) delayed the extinction of running behavior when priming stimulation was given. The GABAergic antagonist flumazenil at doses of 5 and 10 mg/kg (i.p.) totally prevented the effect of diazepam. These results demonstrate that diazepam delays the extinction of running behavior on ICSS in the runway method and flumazenil, a GABAergic antagonist, eliminates the delayed effect of diazepam, that is, indicating that the delayed extinction effect of diazepam may be related to facilitation of motivation, which was promoted via the GABAergic system in the ICSS behavior.

In the present study, we investigated the effect of adrenocorticotropic hormone (ACTH) on the immobilization of rats in the forced swim test after the administration of selegiline, a selective and irreversible monoamine oxidase (MAO)-B inhibitor. Single and repeated administration of selegiline significantly decreased the duration of immobility in normal rats. When selegiline was administered for 15 days, we observed a significant decrease in immobility in rats treated with ACTH for 14 days. The immobility-decreasing effect of selegiline was blocked by nafadotride, a selective dopamine D(3)-receptor antagonist in normal and ACTH-treated rats. Selegiline may be useful in an animal model of depressive conditions resistant to tricyclic antidepressant treatment via the dopamine D(3) receptor.

We examined the influence of imipramine, a traditional tricyclic antidepressant, on the binding to serotonin (5-HT)(2) receptors and levels of 5-HT(2A)-receptor mRNA in the frontal cortex of rats treated with adrenocorticotropic hormone (ACTH). Chronic treatment with ACTH significantly increased the binding of [(3)H]-ketanserin to 5-HT(2) receptors and the expression of 5-HT(2A)-receptor mRNA in the frontal cortex. However, it did not alter the concentration of 5-HT or 5-hydroxyindole acetic acid. The effect of chronic ACTH treatment on 5-HT(2) receptor and 5-HT(2A)-receptor mRNA levels was not altered by the chronic administration of imipramine. Also, imipramine did not affect the hyperfunction of 5-HT(2A) receptors caused by chronic ACTH treatment. These findings suggest that chronic treatment with ACTH acts to increase 5-HT(2A)-receptor synthesis through increased gene transcription, without modulating presynaptic serotonergic neurotransmission.

In order to determine the differential effects of flavonoids on cerebral ischemia, we investigated the effects of (-)-epigallocatechin gallate (EGCG), catechin, rutin, and quercetin on spatial memory impairment and neuronal death induced by repeated cerebral ischemia in rats. Both rutin and quercetin (50 mg/kg x 2) improved spatial memory impairment in the 8-arm radial maze task and neuronal death in the hippocampal CA1 area; however, catechin (200 mg/kg x 2) and EGCG (50 mg/kg x 1) did not. Administration of EGCG (50 mg/kg x 2) resulted in a high mortality rate. These results suggest that in this repeated cerebral ischemia model, the 4-oxo group and the 2,3-double bond in the C ring of rutin and quercetin are related to their neuroprotective action.

Histamine is a major mediator in allergy acting mainly through the histamine H(1) receptor (H1R). Although H1R up-regulation has been suggested as an important step for induction of allergic symptoms, little is known about the regulation of H1R level. Here we report that the activation of H1R up-regulates H1R through augmentation of H1R mRNA expression in HeLa cells. Histamine stimulation significantly increased both H1R promoter activity and mRNA level without alteration in mRNA stability. H1R protein was also up-regulated by histamine. An H1R antagonist but not histamine H(2) receptor antagonist blocked histamine-induced up-regulation of both promoter activity and mRNA expression. A protein kinase C (PKC) activator, phorbol-12-myristate-13-acetate, increased H1R mRNA expression, whereas an activator of PKA or PKG (8-Br-cAMP or 8-Br-cGMP, respectively) did not. Furthermore, histamine-induced up-regulation of both promoter activity and mRNA level were completely suppressed by the PKC inhibitor Ro-31-8220. H1R antagonists have long been thought to block H1R and inhibit immediate allergy symptoms. In addition to this short-term effect, our data propose their long-term inhibitory effect against allergic diseases by suppressing PKC-mediated H1R gene transcription. This finding provides new insights into the therapeutic target of H1R antagonist in allergic diseases.

Presenilin 1 (PS1) is a multifunctional protein, and its mutations are highly related to familial Alzheimer's disease (AD). In this study, we examined the effects of PS1 overexpression on neuronal morphology using SH-SY5Y cells. Overexpression of dominant-negative D385A PS1 induced morphological change and impairment of neurite formation, while those of wild-type and pathogenic P117L mutant PS1 did not change cellular morphology compared with native cells. Moreover, filopodium-formation-related proteins were decreased only in cells overexpressing D385A PS1. Therefore, PS1 may be involved in neuritogenesis and morphological change in SH-SY5Y cells, and P117L mutation may linked to AD by different mechanisms.

DJ-1 has multiple functions and its dysfunction may be linked to the onset of familial Parkinson's disease PARK7. However, the function and distribution of DJ-1 is unclear. In this study, we determined DJ-1 distribution and change after intranigral injection of 6-hydroxydopamine (6-OHDA). Although distribution of DJ-1 immunoreactivity was not changed in cerebral cortex and striatum, 6-OHDA caused increase of DJ-1 in the particulate fraction and decrease in the cytosolic fraction in substantia nigra. At that time, DJ-1 shifted to acid forms. These results suggest that distributional changes, translocation, and acidic shift of DJ-1 may be compensatory responses to protect against 6-OHDA-induced oxidative stress.

In this study, we investigated the effect of vesicular zinc on ischemic neuronal injury. In cultured neurons, addition of a low concentration (under 100 microM) of zinc inhibited both glutamate-induced calcium influx and neuronal death. In contrast, a higher concentration (over 150 microM) of zinc decreased neuronal viability, although calcium influx was inhibited. These results indicate that zinc exhibits biphasic effects depending on its concentration. Furthermore, in cultured neurons, co-addition of glutamate and CaEDTA, which binds extra-cellular zinc, increased glutamate-induced calcium influx and aggravated the neurotoxicity of glutamate. In a rat transient middle cerebral artery occlusion (MCAO) model, the infarction volume, which is related to the neurotoxicity of glutamate, increased rapidly on the intracerebral ventricular injection of CaEDTA 30 min prior to occlusion. These results suggest that zinc released from synaptic vesicles may provide a protective effect against ischemic neuronal injury.

Parkinson's disease is characterized by dopaminergic neuronal death and the presence of Lewy bodies in the substantia nigra pars compacta (SNpc). alpha-Synuclein and ubiquitin are components of Lewy bodies, but the process of Lewy body formation and the relationship between inclusion formation and dopaminergic neuronal death have not been resolved. In this study, unilateral intranigral microinjection of 6-hydroxydopamine caused a significant loss of tyrosine hydroxylase-immunopositive neurons in both the substantia nigra and striatum and apomorphine-induced contralateral rotation. The co-administration of proteasome inhibitors, such as lactacystin or carbobenzoxy-L-leucyl-L-leucyl-L-leucinal (MG-132), significantly prevented both dopaminergic neurodegeneration and apomorphine-induced rotational asymmetry. Proteasome inhibitors markedly formed intracellular protein inclusions labeled by thioflavin-S in the SNpc. Inclusion-like immunoreactivities for alpha-synuclein and ubiquitin were detected after 4 weeks. These results suggest that proteasome plays an important role in both the early phase of dopaminergic neuronal death and inclusion body formation.

The function of microglia in the brain parenchyma is not fully understood. Occlusion of the middle cerebral artery (MCA) and reperfusion caused behavioral dysfunction with massive neuronal loss in the rat cerebral cortex and striatum. When exogenous microglia were microinjected into the intracerebroventricle (i.c.v.) during MCA occlusion, focal ischemia-induced behavioral dysfunction was significantly inhibited. At that time, many microglia migrated into the ischemic lesion, and microglia-derived neuron-like cells were barely detectable. These results suggest that exogenous microglia protect against focal ischemia-induced neurodegeneration and improve behavioral dysfunction.

Embryonic stem (ES) cells have many of the characteristics of an optimal cell source for cell-replacement therapy. Although the usefulness of the in vitro generation of dopamine (DA)-neural precursors from ES cells has been widely discussed, functional recovery in animal models of Parkinson's disease is not fully understood. In 6-hydroxydopamine-lesioned rats, apomorphine markedly induced contralateral rotation. Apomorphine-induced rotation was significantly reduced by transplantation of neuron-like cells that had differentiated from mouse ES cells using nicotinamide, but not L-lysine. In addition, methamphetamine-induced ipsilateral rotation was significantly reduced. On the other hand, picrotoxin did not inhibit apomorphine-induced rotational asymmetry. Fluoxetine alone and fenfluramine alone induced slight contralateral rotation and rotation in both directions, respectively, and these effects were similar in transplanted rats. Although immunoreactivity for tyrosine hydroxylase (TH) was almost completely lost in the ipsilateral striatum in hemiparkinsonian rats, TH immunoreactivity was detected in transplanted cells and sprouting fibers. In contrast, immunoreactivities for gamma-aminobutyric acid (GABA) and serotonin (5-HT) neurons were not changed. These results suggest that improvement of rotational behavior may be induced predominantly by transplantation of nicotinamide-treated ES cell-derived DA neurons, rather than by changes in the activities of GABA or 5-HT neural systems, in hemiparkinsonian rats.

Microglia are macrophage-like phagocytic cells in the brain parenchyma. However, microglial function after neurodegeneration is not fully understood. In this study, occlusion of the middle cerebral artery (MCA) and reperfusion caused massive neuronal loss in the rat cerebral cortex and striatum after 3 days. When exogenous microglia were microinjected into the intracerebroventricle during MCA occlusion, neurodegenerative areas significantly decreased. At that time, migrated microglia were detected in the ischemic lesion. These results suggest that exogenous microglia can migrate into brain parenchyma and then protect against neurodegeneration induced by MCA occlusion and reperfusion.

The effects of imipramine on 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT), the 5-hydroxytryptamine (5-HT)(1A)-receptor full agonist, -induced hypothermia was examined in rats. Single administration of imipramine (30 mg/kg, i.p.) attenuated 8-OH-DPAT-induced hypothermia. This effect of imipramine was blocked by the 5-HT(2A)-receptor antagonist ketanserin. 8-OH-DPAT-induced hypothermia was not altered 24 h after repeated administration of imipramine (1 - 10 mg/kg per day) for 14 days. However, 8-OH-DPAT-induced hypothermia was significantly enhanced in repeated imipramine (10 mg/kg per day)-treated rats that received 8-OH-DPAT plus imipramine 24 h after the final imipramine administration for 14 days. The 5-HT(2A)-receptor agonist 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane ((+/-)-DOI) attenuated the 8-OH-DPAT-induced hypothermia in drug naive rats. The inhibitory effect of (+/-)-DOI (0.3 mg/kg, s.c.) on 8-OH-DPAT-induced hypothermia was attenuated by repeated administration of imipramine (10 mg/kg per day) for 14 days. These findings suggest that enhancement of the 5-HT(1A) receptors by repeated administration of imipramine may be due to reduction of the inhibitory effects from the 5-HT(2A) receptors to the 5-HT(1A) receptors.

Recently, it has been shown that endoplasmic reticulum (ER) stress causes apoptosis. However, the mechanism of the ER stress-dependent pathway is not fully understood. In human neuroblastoma SH-SY5Y cells, we detected a caspase-12-like protein that has a molecular mass (approximately 60 kDa) similar to that of mouse caspase-12. Thapsigargin, an inhibitor of ER-associated Ca(2+)-ATPase, induced the degradation of caspase-12-like protein. In addition, the degradation of caspases-9 and -3, cleavage of poly(ADP-ribose) polymerase, DNA fragmentation, and cell death were also observed. Pretreatment with phorbol-12-myristate-13-acetate, which induces the expression of antiapoptotic Bcl-2, inhibited thapsigargin-induced degradation of caspases-9 and -3, but not caspase-12-like protein degradation. A caspase inhibitor, benzyloxycarbonyl-Val-Ala-Asp(OCH(3))-CH(2)F, inhibited the degradation of caspase-12-like protein, but not that of caspases-9 and -3. These results suggest that thapsigargin may induce the activation of both ER- and mitochondria-dependent pathways in human SH-SY5Y cells.

It has been known that rotenone and 1-methyl-4-phenylpyridinium ion (MPP(+), a metabolite of MPTP), which inhibit mitochondrial complex I, are useful tools for parkinsonian models in vertebrates such as primates and rodents. Planarian, an invertebrate flatworm, has a high potential for regeneration, and dopamine plays a key role in its behavior. In the present study, we examined a cloned planarian, the GI strain from Dugesia japonica. Planarians that were treated with rotenone or MPTP underwent autolysis and individual death in a concentration- and time-dependent manner. In addition, these effects induced by rotenone or MPTP were inhibited by several antiparkinsonian drugs and caspase inhibitors. These results suggest that the degeneration of planarian dopaminergic system induced by rotenone or MPTP may be mediated through caspase-like activation.

Alzheimer's disease (AD) is characterized by the accumulation of extracellular amyloid-beta (A beta) fibrils with microglia. Recently, there has been great interest in the microglial phagocytosis of A beta, because the microglial pathway is considered to be one of the A beta clearance pathways in the brain parenchyma. However, the mechanism of microglial phagocytosis of A beta is not fully understood and, thus, was investigated in this study. At one minute after exposure to A beta(1-42) (A beta 42), A beta immunoreactivity was detected at the cell surface of microglia. After 1 h, marked immunoreactivity was observed in the cytosolic vesicles. At 12 h, delayed phagocytosis of fibrillar A beta 42 was also observed with the formation of a large phagocytic cup. The microglial cell shape rapidly changed to an ameboid form during the process of phagocytosis. Although neither neural Wiskott-Aldrich syndrome protein (N-WASP) nor WASP interacting SH3 protein (WISH) immunoreactivity was co-localized with filamentous actin (F-actin) distribution, both WASP family verprolin-homologous protein (WAVE) and Rac1 immunoreactivity was co-localized with F-actin in the lamellipodia of phogocytic microglia. These results suggest that WAVE and Rac1 participate in the phagocytosis of A beta 42 by microglia.

In Alzheimer's disease, fibrillar amyloid-beta (Abeta) peptides form senile plaques associated with microglia. However, the relationship between Abeta peptides and microglia is not fully understood. In this study, the incubation of Abeta1-40 (Abeta40) produced small oligomers, while incubation with Abeta1-42 (Abeta42) caused large molecular aggregates. Microglial production of nitrite, interleukin-6 and tumor necrosis factor-alpha was induced by Abeta40, but not Abeta42. This production was significantly reduced by 15-deoxy-Delta(12,14) prostaglandin J(2), and it was completely suppressed by beta-sheet breaker peptide, Leu-Pro-Phe-Phe-Asp. These results suggest that small oligomers, rather than large molecular aggregates, mediate microglial activation induced by Abeta peptides.

Tritium-labeled 4-(4-chlorophenyl)-1-[4-(4-fluorophenyl)-4-oxobutyl]pyridinium ion (HPP+) was synthesized enzymatically from [3H]haloperidol using rat liver microsomal preparations, and using prepared [3H]HPP+, the passage of HPP+ into the brain was investigated. Consequently, HPP+ showed a moderate brain uptake index, indicating that it is able to permeate the blood-brain barrier. Furthermore, HPP+ was detected in murine brains after being intravenously injected. These results suggested that HPP+, produced mainly in the liver, is taken up into the brain and induces damage to brain dopaminergic neurons.

In our previous study, beta-hydroxybutyrate (BHB) was found to prolong survival time and to inhibit cerebral edema by improving energy metabolism in the hypoxia, anoxia and global cerebral ischemia models. In this study, the cerebroprotective effect of BHB was examined in rats with permanent (p)-occlusion and transient (t)-occlusion of middle cerebral artery (MCA). BHB (30 mg x kg(-1) x h(-1) was continuously administered through the femoral vein. In rats with p-MCA occlusion, BHB significantly reduced infarct area at 24 h after the occlusion, but not at 72 h after the occlusion. In rats with 2-h t-MCA occlusion followed by 22-h reperfusion, BHB significantly reduced cerebral infarct area, edema formation, lipid peroxidation and neurological deficits. Moreover, in the t-MCA occlusion model, delayed administration of BHB started at 1 h after the initiation of the MCA occlusion also significantly reduced cerebral infarct area. Taking together the results obtained in our previous study into account, these results indicate that BHB decreased cerebral edema formation and infarct area by improving of the cerebral energy metabolism during ischemia and by inhibition of lipid peroxidation after reperfusion.

Hyperexcitation of glutamatergic neurons may play a key role in ischemia-related neurodegeneration. Recent studies have suggested that the zinc ion (Zn2+), which is present in the central nervous system, has a modulatory role in glutamatergic neuron activity. Zinc ions block glutamate-induced depolarizing currents and neuronal damage by binding with zinc sites on the NMDA subtypes. Therefore, we examined the usefulness of zinc as a therapeutic agent for the prevention of ischemic neuronal damage in the brain. In our previous study, 2,3-butanedione bis(N4-dimethylthiosemicarbazonato) zinc complex (Zn-ATSM2), with high brain uptake, showed significant neuroprotective effects against cerebral ischemia in rats when administered systemically. In this study, to elucidate the mechanism of the neuroprotective effect of Zn-ATSM2, we first examined its in vitro protective effects against glutamate-, NMDA- and kainite-induced neurotoxicity in primary cultures of hippocampal neurons. Zn-ATSM2 elicited protective effects against this glutamate- and NMDA-induced neurotoxicity, but did not affect kainite-induced cytotoxicity. In addition, we studied the effects of Zn-ATSM2 on influx of Ca2+, which undergoes modification subsequent to NMDA activation. Zn-ATSM2 significantly decreased glutamate-induced 45Ca2+ uptake. Thus, Zn-ATSM2 protected against glutamate-induced neurotoxicity and its protective effect was, at least in part, due to the blockage of NMDA receptor-mediated Ca2+ influx.

In contrast to Alzheimer's disease, effective therapeutic options are available for Parkinson's disease. Therapy of dopamine replacement such as levodopa improves the symptoms of this disease, but does not inhibit neurodegeneration in the substantia nigra. Numerous studies have suggested that endogenous and environmental neurotoxins, and oxidative stress may participate in this disease, but the detailed mechanisms are still unclear. Recent genetic studies in familial Parkinson's disease and parkinsonism show several gene mutations. This new information regarding pathogenesis offers novel prospects for therapy. To develop novel neuroprotective drugs, it is necessary to have a model for each type of parkinsonism. This review summarizes current findings regarding parkinsonian models in vertebrates and invertebrates and discusses their value.

It is now generally accepted that massive neuronal death due to oxidative stress is a common characteristic of brains in neurodegenerative diseases. Recently, numerous apoptosis-regulating factors and multiple pathways have been identified, and apoptotic cell death has been implicated in neuronal loss in Alzheimer's disease. Although glial cells are more resistant to oxidative stress than neurons, extensive oxidative stress seems to cause apoptotic cell death in glial cells. In fact, signs of apoptosis are observed in both neurons and glial cells in the brains of patients with Alzheimer's disease. This review summarizes current findings regarding apoptotic processes and discusses the possible involvement of apoptosis-regulating factors in the pathology of Alzheimer's disease.

The planarian, a flatworm, has a high potential for regeneration, and dopamine plays a key role in its behavior. Planarians treated with MPTP underwent autolysis and individual death in a concentration-dependent manner. When the planarian body was cut into anterior, middle and posterior pieces, each piece subsequently regenerated and reorganized to form a new individual within approximately 10 days. The anterior piece was significantly more sensitive than the middle and posterior pieces to MPTP cytotoxicity. Concomitant treatment with talipexole, an anti-parkinsonian drug, inhibited MPTP-induced autolysis and individual death in a concentration-dependent manner. Pramipexole showed a similar protective effect. In addition, post-treatment with talipexole at 1 hr after MPTP completely inhibited MPTP-induced individual death. Although MPTP treatment caused 30% of the planarians to undergo autolysis and individual death within 12 hr, post-treatment with talipexole even at 12 hr completely rescued the remaining 70% of the planarians from death. These results suggest that the MPTP-treated planarian may be useful as a novel parkinsonian model in which talipexole has a protective effect even in the case of post-treatment.