Nicardipine, a calcium antagonist, does not aggravate intracerebral haemorrhage in an intracerebral haemorrhage model in rats.

Despite controversy over their safety in patients with intracerebral haemorrhage, calcium antagonists are widely used in the treatment of hypertensive emergencies. Here, we investigated the effects of nicardipine on haematoma size and neurological deficit in a rat model of collagenase-induced intracerebral haemorrhage. Injection of collagenase (0.014 U) into the striatum induced haematoma (19.9+/-3.4 mm(3)) in the striatum and brain oedema. Drugs were infused from 30 min after collagenase injection for 3 h under conscious conditions. Nicardipine intravenously at 0.1, 1 and 10 microg kg(-1) min(-1) affected neither haematoma size nor the degree of brain oedema. Nicardipine at these doses provided a stable and dose-dependent decrease in mean blood pressure of 6%, 13% and 33%, respectively, with an increase in heart rate that was apparently caused reflexively. Further, nicardipine did not aggravate the neurological deficits in these intracerebral haemorrhage rats, primarily forearm flexion behaviour on suspension by the tail and circling behaviour. These results indicate that nicardipine infusion stably decreased blood pressure without affecting intracerebral haemorrhage in an intracerebral haemorrhage model in rats.

Effects of solifenacin succinate (YM905) on detrusor overactivity in conscious cerebral infarcted rats.

Solifenacin succinate [YM905, (+)-(1S,3'R)-quinuclidin-3'-yl 1-phenyl-1,2,3,4-tetrahydroisoquinoline-2-carboxylate monosuccinate] is a novel muscarinic receptor antagonist. We examined the effects of solifenacin and two other muscarinic receptor antagonists, tolterodine and propiverine, on detrusor overactivity in cerebral infarcted rats. Evaluation was done under conscious conditions using cystometry 1 day after middle cerebral artery occlusion. The cerebral infarcted rats showed decreases in bladder capacity and voided volume and an increase in residual volume, but no change in micturition pressure. Solifenacin increased bladder capacity and voided volume at doses of 0.03 mg/kg i.v. or more. Tolterodine increased bladder capacity and voided volume at 0.03 and 0.1 mg/kg i.v., while propiverine increased bladder capacity and voided volume at 1 mg/kg i.v. and at 0.3 and 1 mg/kg i.v., respectively. In contrast, none of the three drugs affected residual volume or micturition pressure. These results suggest that solifenacin may improve detrusor overactivity without causing urinary retention and may be a promising drug in the treatment of patients with overactive bladder syndrome.

Agonist diversity in 5-HT(2C) receptor-mediated weight control in rats.

RATIONALE: Food intake and energy expenditure are the two main determinants of body weight. Given that 5-HT(2C) receptor agonists are reported to have effects on both energy expenditure and food intake, this strongly suggests that 5-HT(2C) receptor agonists have excellent potential for development as antiobesitiy drugs. One important issue in antiobesity drug development is whether the effects of the compound are maintained during chronic drug treatment. OBJECTIVES: The purpose of the present study was to investigate the effect of repeated oral administration of three 5-HT(2C) receptor agonists, m-chlorophenylpiperazine (mCPP), d(S)-2-(6-chloro-5-fluoroindol-1-yl)-1-methylethylamine (RO60-0175) and (S)-2-(7-ethyl-1H-furo[2,3-g]indazol-1-yl)-1-methylethylamine (YM348), on food intake and energy expenditure in rats. RESULTS: In the food intake study, mCPP, RO60-0175 and YM348 decreased food intake in a dose-dependent manner on day 1 of administration. On day 14 of repeated administration, the hypophagic effect of YM348 was lost and that of mCPP was reduced. In contrast, the hypophagic effect of RO60-0175 was maintained even after repeated administration. The hypophagic effects of all agonists were significantly inhibited by a 5-HT(2C) receptor antagonist, SB242084. In contrast to the hypophagic effects, no drug tolerance developed with respect to the hyperthermic effects of mCPP, RO60-0175, and YM348. The hyperthermic effects of these drugs were also inhibited by SB242084. CONCLUSIONS: Together, the difference between compounds in their hypophagic effects and the similarity in their hyperthermic effects suggest a diversity in agonists in 5-HT(2C) receptor-mediated weight control in rats.

Thermogenic effect of YM348, a novel 5-HT2C-receptor agonist, in rats.

We have investigated the effect of S-2-(7-ethyl-1H-furo[2,3-g]indazol-1-yl)-1-methylethylamine (YM348), a novel 5-HT(2C)-receptor agonist, on body temperature and energy expenditure in Wistar rats. m-Chlorophenylpiperazine (mCPP) and S-2-(6-chloro-5-fluoroindol-1-yl)-1-methylethylamine (RO 60-0175) were used as reference 5-HT(2C)-receptor agonists. Administration of YM348, mCPP and RO 60-0175 dose-dependently and significantly increased body temperature in rats. YM348- or RO 60-0175-induced hyperthermia was significantly attenuated by the non-selective 5-HT(2)-receptor antagonist methysergide and the selective 5-HT(2C)-receptor antagonist SB242084, but not by the selective 5-HT(2A)-receptor antagonist MDL100907. mCPP-induced hyperthermia was significantly attenuated by methysergide, SB242084 and MDL100907. In addition to the increase in body temperature, YM348, mCPP and RO 60-0175 produced dose-related and significant increases in energy expenditure. YM348-, mCPP- and RO 60-0175-induced increases in energy expenditure were significantly attenuated by methysergide and SB242084 but not by MDL100907. These results suggested that 5-HT(2C)-receptor stimulation increased body temperature and energy expenditure and that the 5-HT(2C)-receptor was the target receptor in the thermogenic effect of YM348 in Wistar rats.

Post-stroke atorvastatin treatment reduces neurological deficits and mortality rate in the stroke-prone spontaneously hypertensive rat.

Several large clinical trials have demonstrated that 3-hydroxy-3-methylglutaryl (HMG)-CoA reductase inhibitors decreased the incidence of stroke independently of their cholesterol-lowering effect. We have investigated the effect of post-stroke treatment with atorvastatin on neurological deficits and mortality in stroke-prone spontaneously hypertensive rats (SHR-SP). The vehicle-treated group showed significantly aggravated neurological deficits compared with those observed on the first day of stroke. In contrast, the post-stroke oral administration of atorvastatin at 3 or 30 mg kg(-1)/day significantly ameliorated these neurological deficits. Atorvastatin improved the survival rate in a dose-dependent manner, with this effect being significant at 30 mg kg(-1)/day. Atorvastatin did not affect blood pressure, heart rate or total cholesterol in SHR-SP at either dose. In contrast, it significantly increased plasma nitric oxide (NO) levels at both doses. These results indicated that post-stroke administration of atorvastatin ameliorated neurological deficits and prolonged survival, which might have resulted from increased plasma NO, apart from its effect on cholesterol level and blood pressure in SHR-SP. In conclusion, this study demonstrated the protective effects of post-stroke administration of atorvastatin against stroke in SHR-SP.

Antiobesity effect of YM348, a novel 5-HT2C receptor agonist, in Zucker rats.

The purpose of the present study was to investigate the potency of (S)-2-(7-ethyl-1H-furo[2,3-g]indazol-1-yl)-1-methylethylamine (YM348), a 5-HT2C receptor agonist, as an antiobesity agent in Zucker rats. Single oral administration of YM348 at 0.1, 0.3, 1 and 3 mg/kg significantly reduced food intake in a dose-dependent manner. This effect of YM348 on food intake was inhibited by SB242084, a selective 5-HT2C receptor antagonist. In addition, single administration of YM348 significantly increased body temperature and calorie expenditure at doses of 0.3, 1 and 3 mg/kg, and 1 and 3 mg/kg p.o., respectively. The increasing effect of YM348 on body temperature and calorie expenditure was inhibited by SB242084. Chronic subcutaneous infusion of YM348 (3 and 30 mg/kg/day) for 2 weeks also decreased food intake. However, this hypophagic effect of YM348 was marked during the initial week of infusion but only minor in the second. In contrast, no diminution of effect on body temperature and calorie expenditure was seen on repeated administration of YM348 (1 mg/kg p.o.). Two weeks' subcutaneous infusion of YM348 (3 and 30 mg/kg/day) resulted in a significant decrease in body weight gain throughout the experiment. These results suggest that the maintenance of thermogenesis contributed to the reduced body weight by YM348. The ability of YM348 to decrease body weight in Zucker rats suggests its strong potential for development as an antiobesity agent in humans.