| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1989: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1988: ¥1,400,000 (Direct Cost: ¥1,400,000)
|
|---|
| Research Abstract |
From our recent studies on a mechanism of bombesin-induced central inhibition of gastric acid secretion, it was suggested that a dysfunction of the sympathetic or of the adrenomedullary system may well be compensated for by the system with unaltered function. Then, effects of bombesin intracerebroventricularaly applied (i.c.v.) on the plasma levels of catecholamines were neuropharmacoligically examined using urethaneanestetized rats.
Results obtained are as follows. 1) Bombesin i.c.v. dose-dependently (0.3-10 nmole) increased plasma levels of adrenaline (AD) and noradrenaline (NA) [Control: AD; 170 + 28, NA; 429 + 33 pg/ml (n=20).Thirty min after 3 nmole of bombesin: AD; 1145 + 247, NA 719 + 162 pg/ml (n=50)]. Chemical sympathitectomy with 6-hydroxydopamine markedly potentiated this bombesin-induced increase in AD level[Thirty min after 3 nmol of bombesin ; 3600 + 357 pg/ml (n=5)]. Surgical adrenalectomy did not affect the bombesin-induced increase in NA level. 2) Electrical stimu-lation of the preoptic area, central site of action of bombesin, increased both the levels of AD and NA as observed with bombesin. 3) Time of appearance of bombesin-induced increase in the level of AD but not of NA was hastened by pretreatment with an alpha-adrenoceptor blockade, phentolamine (s.c.), but not with a beta-adrenoceptor blockade, propranolol. 4) Intravenous infusion of nicotine increased the levels of both AD and NA in the splanchnicectomized rats. This nicotine-induced increases were not modified by chemical sympathitectomy with 6-hydroxydopamine.
These results suggest that sympathetic nervous system has an inhibitory role in the regulatory mechanism of AD secretion. Furthermore, sites of this regulatory mechanism is probably resides in the brain but not in the peripheral target organ, adrenal glands.
|
