Antiserum to Somatostatin Reverses Starvation-Induced Inhibition of Growth Hormone but Not Insulin Secretion*

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Abstract
The role of SRIF [somatostatin] in starvation-induced inhibition of GH [growth hormone] and insulin secretion was assessed by passive immunization with anti-SRIF serum. Six hour secretory profiles obtained from chronically cannulated male rats deprived of food for 72 h showed marked suppression of GH secretory bursts and significant depression of plasma insulin levels. Administration of 1 ml SRIF antiserum (SRIF AS) i.v. to starved rats resulted in rapid (within 15 min) restoration of high amplitude GH pulses (600-800 ng/ml) and significant elevation of GH trough values. The mean 6 h GH level of starved SRIF, AS-treated rats (189.2 .+-. 23.9 ng/ml) was significantly higher than that of starved, normal sheep serum-treated control animals (62.8 .+-. 5.8 ng/ml) (P < 0.005). In contrast to the effects on GH, plasma insulin levels in starved rats administered SRIF AS remained low. No significant difference was observed in the mean 6 h plasma insulin level of starved-SRIF, AS-treated rats when compared to starved, normal sheep serum-treated controls. Circulating SRIF may be physiological regulator of starvation-induced GH suppression but is not involved in mediating the inhibition of insulin.