Keiji Yamagami

Calcium sensitization of smooth muscle mediated by a Rho-associated protein kinase in hypertension.

Abnormal smooth-muscle contractility may be a major cause of disease states such as hypertension, and a smooth-muscle relaxant that modulates this process would be useful therapeutically. Smooth-muscle contraction is regulated by the cytosolic Ca2+ concentration and by the Ca2+ sensitivity of myofilaments: the former activates myosin light-chain kinase and the latter is achieved partly by inhibition of myosin phosphatase. The small GTPase Rho and its target, Rho-associated kinase, participate in this latter mechanism in vitro, but their participation has not been demonstrated in intact muscles. Here we show that a pyridine derivative, Y-27632, selectively inhibits smooth-muscle contraction by inhibiting Ca2+ sensitization. We identified the Y-27632 target as a Rho-associated protein kinase, p160ROCK. Y-27632 consistently suppresses Rho-induced, p160ROCK-mediated formation of stress fibres in cultured cells and dramatically corrects hypertension in several hypertensive rat models. Our findings indicate that p160ROCK-mediated Ca2+ sensitization is involved in the pathophysiology of hypertension and suggest that compounds that inhibit this process might be useful therapeutically.

Neuropharmacological profile of a novel potential atypical antipsychotic drug Y-931 (8-fluoro-12-(4-methylpiperazin-1-yl)- 6H-[1]benzothieno[2,3-b][1,5] benzodiazepine maleate).

The neuropharmacological profile of Y-931, 8-fluoro-12- (4-methylpiperazin-1-yl)- 6H-[1]benzothieno [2,3-b][1,5]benzodiazepine maleate, was investigated in comparison with those of typical and claimed atypical antipsychotic drugs. Similar to clozapine and olanzapine, Y-931 interacted with multiple neurotransmitter receptors such as dopaminergic, serotonergic, α-adrenergic, muscarinic and histaminergic receptors. Y-931, as well as the other antipsychotics, was active in a dose-dependent manner in established tests which are indicative of potential antipsychotic activity such as inhibition of apomorphine-induced hyperactivity and suppression of conditioned avoidance responses, however, only Y-931 and clozapine were devoid of cataleptogenic potential. In models of N-methyl-D-aspartate (NMDA) receptor hypofunction, Y-931 demonstrated the most potent protective action against the dizocilpine-induced neurotoxicity (neuronal vacuolization) in the rat retrosplenial cortex ([Y-931 (ED50; 0.20 mg/kg, p.o.), olanzapine (1.1), clozapine (5.7), risperidone (6.9), haloperidol (19)). Furthermore, Y-931 and clozapine, unlike the other antipsychotics used, reversed the dizocilpine-induced social deficits at the same doses at which their neuroprotective action was exhibited. The present results suggest that Y-931 may be a novel potential atypical antipsychotic drug with a low risk of extrapyramidal syndrome (EPS) and the property to ameliorate NMDA receptor hypofunction.

Effects of antipsychotic drugs on neurotoxicity, expression of fos-like protein and c-fos mRNA in the retrosplenial cortex after administration of dizocilpine

In this study, we examined the effect of clozapine, olanzapine, risperidone and haloperidol on the neuropathology (i.e. neuronal vacuolization) and the expression of Fos-like protein and c-fos mRNA in the retrosplenial cortex of female Sprague-Dawley rats induced by the NMDA receptor antagonist dizocilpine. Pretreatment (15 min) with clozapine or olanzapine, but not risperidone or haloperidol, blocked the neuronal vacuolization produced by dizocilpine (0.5 mg/kg, s.c.) in the rat retrosplenial cortex in a dose-dependent manner. Furthermore, pretreatment (15 min) with clozapine or olanzapine, but not risperidone or haloperidol, significantly attenuated the expression of Fos-like protein in the retrosplenial cortex induced by dizocilpine (0.5 mg/kg, s.c.) in a dose-dependent manner. The marked expression of c-fos mRNA in the rat retrosplenial cortex induced by the administration of dizocilpine (0.5 mg/kg, s.c.) was significantly attenuated by pretreatment (15 min) with clozapine (10 mg/kg) or olanzapine (10 mg/kg), but not risperidone (10 mg/kg) or haloperidol (10 mg/kg). The present results suggest that pharmacologically relevant doses of clozapine or olanzapine, but not risperidone or haloperidol, block the neuropathological changes and the expression of Fos-like protein and c-fos mRNA in the rat retrosplenial cortex elicited by the administration of dizocilpine. It is possible that the blockade of dizocilpine-induced neuropathological changes by clozapine and olanzapine may be related to the unique antipsychotic actions of these drugs in schizophrenic patients, although this remains to be verified.

The effect of the antipsychotic drug mosapramine on the expression of Fos protein in the rat brain: Comparison with haloperidol, clozapine and risperidone

In this study, we examined the effect of the acute p.o. administration of the antipsychotic drug mosapramine, as well as the antipsychotic drugs clozapine, haloperidol and risperidone, on the expression of Fos protein in the medial prefrontal cortex, nucleus accumbens and dorsolateral striatum of rat brain. The administration of mosapramine (1 or 3 mg/kg) significantly increased the number of Fos protein positive neurons in the medial prefrontal cortex, but not in the dorsolateral striatum. In addition, mosapramine (1, 3 or 10 mg/kg) produced a dose-dependent increase in the number of Fos protein positive neurons in the nucleus accumbens. The acute administration of 10 mg/kg of mosapramine significantly increased the number of Fos protein positive neurons in all brain regions. The acute administration of clozapine (30 mg/kg), similarly to mosapramine at lower doses (1 or 3 mg/kg), significantly increased the number of Fos protein positive neurons in the medial prefrontal cortex and nucleus accumbens, but not dorsolateral striatum. In contrast, haloperidol (0.3 mg/kg) significantly increased the number of Fos protein positive neurons in the nucleus accumbens and dorsolateral striatum, but not medial prefrontal cortex. The acute administration of risperidone (0.3 or 1 mg/kg) did not affect the number of Fos protein positive neurons in the medial prefrontal cortex, nucleus accumbens or dorsolateral striatum of rat brain, whereas a 3 mg/kg dose of risperidone significantly increased the number of Fos protein positive neurons in all brain regions. These results suggest that the ability of mosapramine to enhance expression of Fos protein in the medial prefrontal cortex may contribute to a clozapine-like profile with respect to actions on negative symptoms in schizophrenia. Furthermore, the lack of effect of low doses of mosapramine on Fos protein expression in the dorsolateral striatum, an area believed to play a role in movement, suggests that it may have a lower tendency to induce neurological side effects.

Converging evidence that sequence variations in the novel candidate gene MAP2K7 (MKK7) are functionally associated with schizophrenia

Schizophrenia is a debilitating psychiatric disease with a strong genetic contribution, potentially linked to altered glutamatergic function in brain regions such as the prefrontal cortex (PFC). Here, we report converging evidence to support a functional candidate gene for schizophrenia. In post-mortem PFC from patients with schizophrenia, we detected decreased expression of MKK7/MAP2K7-a kinase activated by glutamatergic activity. While mice lacking one copy of the Map2k7 gene were overtly normal in a variety of behavioural tests, these mice showed a schizophrenia-like cognitive phenotype of impaired working memory. Additional support for MAP2K7 as a candidate gene came from a genetic association study. A substantial effect size (odds ratios: ~1.9) was observed for a common variant in a cohort of case and control samples collected in the Glasgow area and also in a replication cohort of samples of Northern European descent (most significant P-value: 3 × 10(-4)). While some caution is warranted until these association data are further replicated, these results are the first to implicate the candidate gene MAP2K7 in genetic risk for schizophrenia. Complete sequencing of all MAP2K7 exons did not reveal any non-synonymous mutations. However, the MAP2K7 haplotype appeared to have functional effects, in that it influenced the level of expression of MAP2K7 mRNA in human PFC. Taken together, the results imply that reduced function of the MAP2K7-c-Jun N-terminal kinase (JNK) signalling cascade may underlie some of the neurochemical changes and core symptoms in schizophrenia.

Dizocilpine-induced neuropathological changes in rat retrosplenial cortex are reversed by subsequent clozapine treatment

In this study, we examined the effect of post-treatment with clozapine on the neuropathological changes in the rat retrosplenial cortex induced by the administration of non-competitive NMDA receptor antagonist dizocilpine ((+)-MK-801). The maximal increase in vacuolized neurons, which are representative of neuropathology, was observed 4 hours after a single injection of dizocilpine (0.5 mg/kg s.c.), with a complete reversal of the neuropathology after 16-24 hours. The administration of clozapine (10 mg/kg, i.p.,) 4 hours after the administration of dizocilpine significantly decreased the number of vacuolized neurons in the retrosplenial cortex 6, 8 or 10 hours after administration of dizocilpine, compared to vehicle-treated animals. Furthermore, the administration of clozapine (5, 10 or 20 mg/kg i.p.) 4 hours after the administration of dizocilpine produced a significant decrease in the number of vacuolized neurons in the retrosplenial cortex in a dose-dependent manner when measure 6 hours post-dizocilpine. These results show that neuropathological changes in the rat retrosplenial cortex produced by dizocilpine can be attenuated by post-treatment with clozapine.

2-(2-Phenylmorpholin-4-yl)pyrimidin-4(3H)-ones; A new class of potent, selective and orally active glycogen synthase kinase-3β inhibitors

A series of 2-(2-phenylmorpholin-4-yl)pyrimidin-4(3H)-ones was synthesized and examined for their inhibitory activity against glycogen synthase kinase-3β (GSK-3β). We found 21, 29 and 30 to possess potent in vitro GSK-3β inhibitory activity with good in vitro PK profiles. 21 demonstrated significant decrease of tau phosphorylation after oral administration in mice and excellent PK profiles.

Syntheses and biological properties of novel aza-podophyllotoxin analogs prossessing pronounced antitumor activity

Abstract 2,4-Diaza-4-desoxypodophyllotoxin analogs have been synthesized from substituted anilines. Some of them showed promising antitumor activities against vincristine-resistant P388 murine leukemia and B16 melanoma in vivo.

Discovery of novel 2-(3-phenylpiperazin-1-yl)-pyrimidin-4-ones as glycogen synthase kinase-3β inhibitors

We herein describe the results of further evolution of glycogen synthase kinase (GSK)-3β inhibitors from our promising compounds containing a 2-phenylmorpholine moiety. Transformation of the morpholine moiety into a piperazine moiety resulted in potent GSK-3β inhibitors. SAR studies focused on the phenyl moiety revealed that a 4-fluoro-2-methoxy group afforded potent inhibitory activity toward GSK-3β. Based on docking studies, new hydrogen bonding between the nitrogen atom of the piperazine moiety and the oxygen atom of the main chain of Gln185 has been indicated, which may contribute to increased activity compared with that of the corresponding phenylmorpholine analogues. Effect of the stereochemistry of the phenylpiperazine moiety is also discussed.

Synthesis of 2,4-diaza-4-deoxypodophyllotoxin, a new analogue of podophyllotoxin possessing antitumour activity

2,4-Diaza-4-deoxypodophyllotoxin 4 and its cis analogue 14 are synthesised stereoselectively from 3,4-methylenedioxyaniline 5, and show significant activity against vincristine-resistant P-388 leukaemia in vivo.