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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.

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.

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-HT2A receptor-mediated behavioral responses. Combination treatment with doxorubicin and cyclophosphamide significantly increased (±)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane, (a 5-HT2A receptor agonist)-induced wet-dog shake activity. This anxiety-like behavior was significantly inhibited by mirtazapine, a 5-HT2A receptor antagonist/5-HT1A receptor agonist, and tandospirone, a partial 5-HT1A 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-HT2A receptor. Thus, 5-HT2A receptor antagonists or 5-HT1A receptor agonists might be useful for treating chemotherapy-induced anxiety disorders. Keywords: Doxorubicin, Cyclophosphamide, 5-HT2A receptor, Anxiety

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.

Astrocytes are abundant neuron-supporting glial cells that harbor a powerful arsenal of neuroprotective antioxidative molecules and neurotrophic factors. Here we examined whether enrichment with healthy striatal astrocytes can provide neuroprotection against progressive dopaminergic neurodegeneration. Serotonin 1A (5-HT1A) agonist 8-OH-DPAT induced astrocyte proliferation and increased metallothionein-1/-2 (MT-1/-2), antioxidative molecules, in cultured astrocytes and the striatum of mice. Primary cultured mesencephalic dopamine neurons were protected against oxidative stress by preincubation with conditioned media from 8-OH-DPAT-treated astrocytes. These protective effects were canceled by 5-HT1A antagonist or MT-1/-2-specific antibody. Furthermore, reduction of nigrostriatal dopaminergic neurons in 6-hydroxydopamine-lesioned parkinsonian model mice was significantly abrogated by repeated injections of 8-OH-DPAT. Treatment with 8-OH-DPAT markedly increased the expression of MT in striatal astrocytes in the hemi-parkinsonian mice. Our study provides a promising therapeutic strategy of neuroprotection against oxidative stress and progressive dopaminergic neurodegeneration by demonstrating the efficacy of targeting 5-HT1A receptors in astrocytes.

Abstract.: 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 treatment-resistant 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. Keywords:: adrenocorticotropic hormone, electroconvulsive stimuli, cell proliferation, brain-derived neurotrophic factor, cAMP response element binding protein

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-HT1A antagonist. These results suggest that fluoxetine may influence motor function in PD via pharmacological modification of interactions between serotonergic and dopaminergic neuronal networks. Keywords:: Parkinson’s disease, selective serotonin reuptake inhibitor, fluoxetine, l-dihydroxyphenylalanine, 6-hydroxydopamine

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 (Ca2+ 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 Nω-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. Keywords:: endothelium-dependent vasodilation, acetylcholine, Ca2+ ionophore, mesenteric vascular bed

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. Keywords:: amyloid-β, tau, actin, microglia, interaction, Alzheimer’s disease

Abstract.: 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. Keywords:: Parkinson’s disease, DJ-1, 6-hydroxydopamine, rotenone, neuroprotection

Abstract.: 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. Keywords:: endothelium-derived hyperpolarizing factor, endothelial regulation of vasoconstriction, age, rat mesenteric artery, cardiovascular disease

Abstract.: 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 D1 (SCH 23390) and D2 (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 D1 or D2 receptors. The effect of MCPG, however, was only blocked by D2 antagonists and not by the D1 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 D1 and D2 dopamine receptor signaling mechanisms play a role in mediating the aversive aspects of acute dependence. Keywords:: morphine, acute dependence, conditioned place aversion, glutamatergic, dopaminergic

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. Keywords:: nerve growth factor, prostate tumor growth, angiogenesis

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. Keywords:: DJ-1 modulator, anti-oxidative effect, neuroprotection

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 (Ca2+-ionophore)–, but not acetylcholine-, induced endothelium-dependent vasodilation in the presence of NG-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. Keywords:: aging, methoxamine-induced vasoconstriction, endothelium-derived hyperpolarizing factor, endothelium-derived contracting factor, rat mesenteric resistance artery

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. Keywords:: kavain, hypnotic effect, kava-kava, sleep

We examined the influence of imipramine, a traditional tricyclic antidepressant, on the binding to serotonin (5-HT)2receptors and levels of 5-HT2A–receptor mRNA in the frontal cortex of rats treated with adrenocorticotropic hormone (ACTH). Chronic treatment with ACTH significantly increased the binding of [3H]-ketanserin to 5-HT2receptors and the expression of 5-HT2A–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-HT2receptor and 5-HT2A–receptor mRNA levels was not altered by the chronic administration of imipramine. Also, imipramine did not affect the hyperfunction of 5-HT2Areceptors caused by chronic ACTH treatment. These findings suggest that chronic treatment with ACTH acts to increase 5-HT2A– receptor synthesis through increased gene transcription, without modulating presynaptic serotonergic neurotransmission. Keywords:: 5-HT2Areceptor, adrenocorticotropic hormone, wet-dog shake, receptor binding, receptor mRNA

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 (α1-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 18α-glycyrrhetinic acid (18α-GA, a gap-junction inhibitor) significantly inhibited the time-dependent reduction of methoxamine-induced vasoconstriction. In preconstricted preparations, bolus injection of acetylcholine and Ca2+-ionophore A23187 (A23187) evoked a sharp vasodilation, which was inhibited by endothelium removal, high KCl and tetraethylammonium, but not indomethacin, L-NAME, or 18α-GA. However, 18α-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. Keywords:: methoxamine-induced vasoconstriction, endothelium-derived hyperpolarizing factor, rat mesenteric resistance artery, gap junction

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 nonreinforcing 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 facillitation of motivation, which was promoted via the GABAergic system in the ICSS behavior. Keywords:: diazepam, intracranial self-stimulation, motivational effect

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. Keywords:: hepatic growth factor (HGF), neurotrophic effect, calcitonin gene-related peptide (CGRP)-containing nerve, neuropeptide Y (NPY)-containing nerve, phenol-induced perivascular nerve injury

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 (α7 nicotine-receptor antagonist), and dihydro-β-erythroidine (α4β2 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 μA, 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 α4β2 rather than α7 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 α4β2 nicotinic receptors and suggest that α4β2 nicotinic receptors influence the brain mechanism of motivation. Keywords:: nicotine, methyllycaconitine, dihydro-β-erythroidine, intracranial self-stimulation, motivation

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 D3–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 D3receptor. Keywords:: selegiline, monoamine oxidase-B, treatment-resistance depression, forced swim test, dopamine D3receptor

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 × 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 × 2) and EGCG (50 mg/kg × 1) did not. Administration of EGCG (50 mg/kg × 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. Keywords:: (−)-epigallocatechin gallate (EGCG), catechin, rutin, quercetin, repeated cerebral ischemia model

DJ-1 has recently been shown to be responsible for onset of familial Parkinson’s disease (PD), PARK7. DJ-1 has been shown to play roles in transcriptional regulation and anti-oxidative stress, and loss of its function is thought to trigger onset of PD. In this study, a recombinant DJ-1 protein was administrated into the brain of PD model rats that had been injected to 6-hydroxydopamine (6-OHDA) in the left substantia nigra. PD phenotypes, including dopaminergic neuron death in the substantia nigra, decrease in dopamine, and dopamine transporter levels in the striatum, and motor abnormality, were dramatically improved by wild-type DJ-1 but not L166P DJ-1, a mutant form of DJ-1 found in PD patients. Furthermore, production of reactive oxygen species and cell death induced by 6-OHDA in SH-SY5Y cells and mesencephalic neurons were inhibited by addition of the recombinant DJ-1. These findings suggest that DJ-1 is a therapeutic target for PD.

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. Keywords:: DJ-1, 6-hydroxydopamine, Parkinson’s disease

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. Keywords:: presenilin 1, SH-SY5Y cell, neuritogenesis

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. Keywords:: behavioral recovery, microglia, focal brain ischemia

Parkinson’s disease is characterized by dopaminergic neuronal death and the presence of Lewy bodies in the substantia nigra pars compacta (SNpc). α-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 α-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. Keywords:: proteasome inhibitor, neuroprotection, dopaminergic neuron, substantia nigra, Parkinson’s disease

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. Keywords:: microglia, neuroprotection, focal brain ischemia

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 γ-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. Keywords:: mouse embryonic stem cell, dopaminergic differentiation, transplantation, rat striatum, Parkinson’s disease

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 Ca2+-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(OCH3)-CH2F, 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.

ABSTRACT: 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-HT2A-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-HT2A-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-HT1A receptors by repeated administration of imipramine may be due to reduction of the inhibitory effects from the 5-HT2A receptors to the 5-HT1A receptors.

Alzheimer’s disease (AD) is characterized by the accumulation of extracellular amyloid-β (Aβ) fibrils with microglia. Recently, there has been great interest in the microglial phagocytosis of Aβ, because the microglial pathway is considered to be one of the Aβ clearance pathways in the brain parenchyma. However, the mechanism of microglial phagocytosis of Aβ is not fully understood and, thus, was investigated in this study. At one minute after exposure to Aβ(1 – 42) (Aβ42), Aβ 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 Aβ42 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 Aβ42 by microglia.

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.

In Alzheimer’s disease, fibrillar amyloid-β (Aβ) peptides form senile plaques associated with microglia. However, the relationship between Aβ peptides and microglia is not fully understood. In this study, the incubation of Aβ1-40 (Aβ40) produced small oligomers, while incubation with Aβ1-42 (Aβ42) caused large molecular aggregates. Microglial production of nitrite, interleukin-6 and tumor necrosis factor-a was induced by Aβ40, but not Aβ42. This production was significantly reduced by 15-deoxy-Δ12,14 prostaglandin J2, and it was completely suppressed by β-sheet breaker peptide, Leu-Pro-Phe-Phe-Asp. These results suggest that small oligomers, rather than large molecular aggregates, mediate microglial activation induced by Aβ peptides.