Ken-ichi Tanaka

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Nitric oxide (NO) may play a role in the established processes of learning and memory. We examined the effects of N(omega)-nitro-L-arginine methylester (L-NAME), a nonselective inhibitor of NO synthase (NOS), on the performance of mice in a Y-maze task. L-NAME (100 mg/kg) markedly impaired spontaneous alternation behavior. However, galantamine (0.5 mg/kg)(More)
We have previously reported that ropinirole, a non-ergot dopamine agonist, has neuroprotective effects against 6-hydroxydopamine in mice based on in vivo antioxidant properties such as the glutathione (GSH)-activating effect. In the present study, we determined that the effects of ropinirole on the level of expression of GSH-related enzyme mRNA, these(More)
Metallothionein (MT)-III is a metal binding protein, called growth inhibitory factor, and is mainly expressed in the central nervous system. Since MT-III decreases in the brain of Alzheimer's disease (AD), a growing interest has been focused on its relationship to neurodegenerative diseases. To clarify age-related changes in the MT-III expression and its(More)
To clarify the possible role of in the in vivo toxic effects of 6-hydroxydopamine (6-OHDA), especially caspase activations, we examined its effects on striatal lipid peroxidation (LPO) and caspase activations in 6-OHDA-lesioned mice. Both dopamine (DA) levels and DA turnover were significantly changed by the 6-OHDA i.c.v. injection compared with the(More)
We examined the effects of chronic cerebral hypoperfusion on the endogenous oxidative stress-related indices, nitrite and nitrate (NOx) concentration, glutathione (GSH) content, superoxide dismutase and catalase activities, and thiobarbituric acid-reactive substances level in the rat striatum, to clarify the participation of oxidative stress in the chronic(More)
The effects of two major isoforms of metallothioneins (MTs), MT-I and -II, on dopaminergic neurotoxicity of 6-hydroxydopamine (6-OHDA) were examined using intracerebroventricularly 6-OHDA-injected MT-I, II knock-out (KO) mice. The loss of dopamine neurons in the substantia nigra pars compacta induced by the 6-OHDA injection was significantly aggravated in(More)
We investigated both the antioxidant activities of GPI1046, a non-immunosuppressive derivative of FK506, and the in vivo neuroprotective properties against toxicity of intracerebroventricular 6-hydroxydopamine (6-OHDA) in mice. The 6-OHDA-induced reduction in dopamine and its metabolites in the striatum was significantly normalized by daily administration(More)
Levodopa therapy is the gold standard for symptomatic treatment of Parkinson's disease (PD), but levodopa and/or dopamine (DA)-induced neurotoxicity have been reported in both in vitro and in vivo experimental studies. To clarify the beneficial effects of combining DA agonists with levodopa in PD, the present study examines the effects of cabergoline, a DA(More)
Based on the fact that several recent reports have indicated that non-immunosuppressive immunophilin ligands (IPLs) can activate neurite outgrowth or nerve regeneration, we investigated the neurotrophic factor-activating abilities of IPLs in vivo in order to clarify the molecular basis of neurotrophic-like activity. Both FK506 (an immunosuppressive IPL) and(More)