Effect fo Nitric Oxide on Control of Insulin Secretion in Rat Pancreas / 대한내분비학회지

ABSTRACT

BACKGROUND: NO (nitric oxide), derived from L-arginine through the action of nitric oxide synthase (NOS), is a short-lived free radical transmitting cellular signals for vasodilation, neurotransmission, and cytotoxicity. Recently, this molecule has been reported to be involved in the various glandular secretion. Although the relationship between NO and the pancreatic endocrine secretion has been widely investigated, the role of NO on insulin secretion has not been elucidated. Therefore, the present study was designed to reveal the precise action of NO on the secretion and synthesis of insulin following administration of NAME (L-NG -nitroarginine methyl ester) or L-arginine using immunocytochemistry and in situ hybridization techniques. METHODS: NAME or L-arginine was administered into jugular vein of the male Sprague-Dawley rat (180~200 g, b,w.) exhibiting normoglycemia (80~120mg/dL). Blood glucose concentrations were measured at intervals of 30 minutes for 2 hours after drug treatment. The pancreatic tissues were taken out at 30 and 90 minutes following drugs administration for insulin immunocytochemistry and in situ hybridization. RESULTS: Both NAME and L-arginine treatments diminished blood glucose levels. The decrease of blood glucose level was more prominent in NAME-treated rats than that of L-arginine. Insulin immunoreactivity in drugs-treated rat pancreas decreased compared to that in normal control, while the expression of insulin mRNA was significantly increased. CONCLUSION: On the basis of present study, it is concluded that the transient changes of NO con-centration, regardless of increase or decrease, in Langerhans islet might act as a potent stimulant in insulin secretion and its synthesis.