RAT PANCREATIC-ISLET FUNCTION DURING PROLONGED GLUCOSE STIMULATION IN-VITRO - EFFECT OF SEX AND REPRODUCTIVE STATE

Prolonged stimulation with glucose may induce desensitisation of pancr eatic beta-cell function in male rats. The effects of such a treatment on pancreatic islets of pregnant (P) rats, in which beta-cell functio n is enhanced, were studied in a perifusion design and compared with t he effects on islets of cyclic female (C) and male (M) rats. The treat ment induced in all three groups of islets a transient increase in bot h insulin and amylin secretion, followed by a gradual decline (desensi tisation). Islets of P-rats released more insulin, but not amylin, tha n the other types of islets. Furthermore, desensitisation occurred lat er in islets of P-rats (after 2.5 h) than in islets of C- and M-rats ( after 0.5 h) The amount of insulin, but not of amylin, stored in islet s of P-rats was also much higher than in the islets of C- and M-rats. Glucagon release in all three groups of islets was suppressed during g lucose stimulation, but tended to increase again after 3 h of continuo us stimulation. It is concluded that the control of beta-cell function is similar in M- and C-rats, but is significantly altered in P-rats. It is suggested that desensitisation of the beta-cells is associated w ith desensitisation of the alpha-cells.