THE LIPOLYTIC RESPONSE TO CORTICOTROPIN12

Abstract

Exposure of isolated rat adipose tissue to small concentrations of corticotropin (.001 μg/ml.) caused accumulation of free fatty acid in tissue and medium, a finding previously reported by others. The effect of corticotropin was inhibited by glucose and insulin, presumably due to promotion of esterification of the free acids. Corticotropin was also found to be active in vivo; intravenous administration of this hormone to acutely adrenalectomized rats produced rapid increase of free fatty acids in adipose tissue and plasma. The lipolytic activity of homogenates of rat adipose tissue was increased by brief exposure of the intact tissue to corticotropin and epinephrine. The activity affected by ACTH differed from that of lipoprotein lipase in pH optimum. These results suggest that corticotropin may produce its adipokinetic effect by directly activating a lipase in adipose tissue.