Roles of Gonadal Steroids on Exocrine Secretion of Isolated Perfused Rat Pancreas

Roles of Gonadal Steroids on Exocrine Secretion of Isolated Perfused Rat Pancreas

To clarify the roles of gonadal steroids on pancreatic exocrine secretion, effects of progesterone and estradiol-17β on spontaneous and secretagogue-induced exocrine response of isolated perfused rat pancreas were investigated. Intra-arterial infusion of progesterone resulted in significant increase of the spontaneous pancreatic fluid and amylase secretion dose-dependently. However, estradiol-17β did not exert any influence on spontaneous pancreatic exocrine secretion. Exogenous secretin, cholecystokinin (CCK), and acetylcholine markedly stimulated pancreatic fluid and amylase secretion. Progesterone initially enhanced secretin-induced amylase secretion, but this stimulatory response declined thereafter to basal value. Moreover, secretin-induced fluid secretion was not affected by infusion of progesterone. Therefore, initial increase of secretion-induced amylase secretion by progesterone seems to be a non-specific action by washout effect of secretin. Estradiol-17β failed to change the secretin-induced fluid and amylase secretion. Both progesterone and estradiol-17β did not exert any influence on CCK-induced fluid and amylase secretion. Acetylcholine-induced exocrine secretion of isolated perfused pancreas also was not affected by intra-arterial infusion of progesterone or estradiol-17β. It is concluded from the above results that progesterone could enhance the spontaneous pancreatic fluid and amylase secretion of isolated perfused rat pancreas through non-genomic short- term action, and that these effects could be masked by more potent stimulants such as secretin, CCK, and acetylcholine.