Effects of growth hormone on leptin gene expression in rats.

RECENTLY the obesity gene was identified and its gene product, leptin, has demonstrated [1]. It is expressed exclusively in adipocytes, secreted into the blood stream and appears to signal to the hypothalamus through its specific receptor. It reduces appetite and stimulates energy expenditure. Thus it serves an endocrine function in body weight regulation of energy consumption and storage. Since leptin plays a pivotal role in the regulation of adiposity and energy homeostasis, the level of its expression is likely to fluctuate under various physiological, nutritional and disease conditions. On the other hand, GH-deficient patients are often associated with increase body fat and GH treatment in GH-deficient patients significantly reduced the total fat mass and intra-abdominal adipose tissue [2]. Some reports have demonstrated the beneficial effect of GH administration in obese [3-5] or obese diet-restricted humans [6]. We therefore studied the effect of GH on leptin gene expression in order to identify the possible role of leptin in GH treatment for obese subjects.