Role of Antilipolytic Mechanisms in Adipose Tissue Distribution and Function in Man

Regional differences have been found in the hormone regulation of adipose tissue lipolysis. Lipolytic activity is greater in omental than in subcutaneous adipocytes owing, in part, to a less marked insulin action and lower alpha 2-adrenoceptor antilipolytic activity in the omental region. In the subcutaneous region catecholamines are less lipolytic in gluteal/femoral than in subcutaneous abdominal adipocytes, which is partly due to enhanced alpha 2-adrenoceptor responsiveness in the gluteal/femoral cells. Insulin action also differs in the two subcutaneous adipose regions in a complex way that is influenced by the degree of obesity and nutritional factors. The regional differences in the antilipolytic effects of hormones seem to be caused by site variations in the receptors as well as in the signals from the receptors. The site variations may be involved in the development of regional forms of obesity, such as android or gynoid obesity and may raise the free fatty acid levels in the portal system and therefore impair metabolism of glucose and insulin by the liver.