Lipolysis and cyclic AMP levels in epididymal adipose tissue of obese-hyperglycaemic mice

Abstract

Glycerol release from epididymal fat fragments of young adult (3-month old) ob/ob mice was three times lower than normal, on a tissue weight basis. Dose-response curves in response to isoproterenol and ACTH-(1--24) indicated that the capacity of the lipolytic process was reduced. However, the sensitivity to both hormones was normal, i.e. greater for ACTH than for isoproterenol. The burst of cyclic AMP observed at 7 minutes was affected even more than the lipolytic capacity in adipose tissue from obese mice. This was already observed in 1-month old animals, i.e. at a time when total body weight was still normal. It is concluded that the adenylate cyclase system is defective in adipose tissue of ob/ob mice. Besides, glucagon, vasoactive intestinal polypeptide, and secretin failed to stimulate glycerol release and cyclic AMP accumulation in both ob/ob, ob+/ob+, and HA-ICR mice, suggesting that mouse adipose tissue does not possess receptors for this group of hormones.