The ob gene product, called leptin, is a recently discovered hormone secreted by the adipose cells. By acting as a satiety factor and increasing energy expenditure, leptin plays a major role in body weight homeostasis in @entity19 . Ob gene and leptin production by the adipose cells are under the control of various hormonal and metabolic factors. Ob mRNA levels are markedly reduced by fasting and restored to normal by refeeding. High-fat feeding increases ob gene and plasma leptin, and induces a state of resistance to leptin. Two hormones, insulin and @entity2819 , increase leptin production in rodent and @entity1 adipose cells. In contrast, the activity of the sympathetic nervous system exerts an opposite effect, mainly through activation of the adipose beta 3-adrenergic receptors. Leptin synthesis is also decreased by @entity12721 , a new class of antidiabetic drugs. The obese Zucker fa/fa @entity35 bear a mutation in the leptin receptor gene ( @entity29614 ) and are leptin resistant. In these @entity35 , ob mRNA levels are increased early in life and are not reduced by fasting. This suggests that functional OB-Rs are required for the generation of the signal(s) that downregulates ob gene expression in the adipose cell. The extent to which this is relevant to @entity1 @entity28 , which are characterized by increased leptin levels, remains to be determined.

Regulation of ob gene and overexpression in XXXX .

@entity1 :: ('9606', 'Species') :: ['human'] @entity28 :: ('MESH:D009765', 'Disease') :: ['obesities'] @entity19 :: ('10090', 'Species') :: ['mice'] @entity2819 :: ('MESH:D003345', 'Chemical') :: ['corticosterone'] @entity12721 :: ('MESH:D045162', 'Chemical') :: ['thiazolidinediones'] @entity29614 :: ('24536(Tax:10116)', 'Gene') :: ['OB-R'] @entity35 :: ('10116', 'Species') :: ['rats']
@entity28 :: (MESH:D009765,Disease) :: ['obesity']
