[Leptin: a genetic solution to obesity?]

Abstract

LEPTINE: Produced by adipose tissue, leptine is a regulatory hormone controlling body fat mass.

Genetics: The human gene coding for leptine was first cloned in 1984. Its receptor, a member of the class 1 cytokine receptor family, has also been identified. VARIABLE SERUM LEVELS: Plasma levels of leptine in normal-weight subjects are in the 5ng/ml range and reach 50 ng/ml in obese subjects. Weight gain leads to higher blood levels and weight loss to lower levels. The effect of leptine is to approach a weight equilibrium. Leptine level is correlated with energy balance.

Mode of action: Leptine acts on hypothalamic centers controlling satiety. One of the essential mediators is neuropeptide Y. Resistance to leptine has been evidenced in human obesity. Resistance can occur as several levels and would be one of the explanations for massive obesity involving genetic factors. Leptine may also play a role in certain types of infertility.