Serum leptin and regional cerebral blood flow during exposure to food in obese and normal-weight women

Leptin is an adipocyte-derived product of the ob gene thought to be involve d in the regulation of eating. Receptors for leptin have been found in mult iple regions in the brain. In particular, hypothalamic receptors seem to be of fundamental importance for the biological effects of leptin. However, t he association of leptin with cerebral function in humans has not been stud ied. Therefore, in order to assess the possible functional relationships be tween leptin and cerebral activity in humans, simultaneous serum leptin and regional cerebral blood flow (rCBF) measurements were made in 10 obese [BM I 33.5 (29.3-39.1) kg/m(2)] and 12 normal-weight [BMI 22.2 (20.3-24.6) kg/m 2] women during exposure to food. The rCBF measurements were performed by T c-99m-ethyl-cysteine-dimer single photon emission computed tomography. A st rong inverse association was observed between the leptin and rCBF of hypoth alamus during the exposure to food in the obese (r = -0.73, p = 0.02, n = 1 0), but not in the normal-weight subjects (r = 0.22, p = 0.48, n = 12). Thi s suggests that the association of leptin with cerebral activity could be d ifferent in obese and normal-weight women; depressed activity of hypothalam ic neurones in response to the high peripheral leptin concentration could b e postulated to occur in obese women during exposure to food.