뇌실내 Calcitonin 투여가 위산분비에 미치는 영향에 관한 연구

Peptides that are common to the brain and gut are thought to plav intermediary roles as neurotrans- mitters or neuromodulators in the regulation of gut function. Calcitonin is a polypetide hormone of 32 amino acid residues. Intracerebroventricular (ICV) administration of calcitonin does not alter plasma calcium or phosphorus concentrations. Recently, much evidence is accumulating to suggest that calcitonin may inhibit gastric acid secretion by a central action. But the neurohumoral pathways mediating antitsecretory effects of calcitonin in rats are not well elucidated. In the present study, using a gastric perfusion technique, effects of ICV administration of calcitonin on gastric acicl secretion and stress ulceration and its mechanism were investigated in rats. The results obtained are as follows: 1) ICV administration of calcitonin suppressed basal gastric acid secretion in a dose-dependent manner. 2) Gastric acid secretion stimulated by histamine, bethanechol or pentagastrin was not suppressed by ICV administration of calcitonin. 3) Gastric acid secretion stimulated by TRIl was markedly suppressed by ICV administratioti of calcitoninl. 4) Bilateral vagotomy did not influence calcitonin-induced gastric acid suppressionl. 5)Pretreatment metyrosine did not itnfluence cailcitoinin-induced gaitric acid suppression. 6) Intravenous administration of high dose (25 IU) of calcitonin suppressed gastric acid secretion. Central administration of calcitonin was approximately 250 times more sensitive than intravenous administration. 7) Stress ulcers induced by cold restraint and TRH administration were diminished by ICV admitnistration of calcitonin. In this study it is demonstrated that calcitonin suppresses gastric acid secretion, and this inhibitory effcct is centrally mediated. In particular, calcitonin suppresses TRH induced gastric acid secretion and stres ulcer formation. And it is suggested that calcitonin seems to play an inhibitorv role in gastric acid secretion as a neuromodulator in the central nervous system.