Regulation of lipolysis and leptin biosynthesis in rodent adipose tissue by growth hormone.

The present study examined the effects of growth hormone (GH) on lipolysis and leptin release by cultured adipose tissue from rats and mice incubated for 24 hours in primary culture. A stimulation of leptin release by GH in rat adipose tissue was found in the presence of 25 nmol/L dexamethasone, and this was accompanied by a 28% increase in leptin mRNA content. GH stimulated lipolysis in rat adipose tissue in the presence of 0.1 nmol/L CL 316,243. In contrast, basal lipolysis in mouse adipose tissue was stimulated by GH, but this was not accompanied by an increase in leptin release. However, in the presence of insulin plus triiodothyronine (T3), the stimulation of lipolysis by GH was abolished and GH increased leptin release. These results indicate that GH can stimulate leptin release by both mouse and rat adipose tissue in the absence of a stimulation of lipolysis. In contrast, under conditions in which lipolysis is stimulated by GH, there is no effect on leptin release.