The epididymal and retroperitoneal fat content of 180-day-old male Wistar rats, coming from litters of eight pups was correlated with their RNA content in ventromedial hypothalamus (VMH) and lateral hypothalamic area (LHA) neurons. A significant negative correlation was found between the RNA content in VMH neurons and epididymal and retroperitoneal fat content. The results indicate a closed relationship between the body fat content and the functional activity of VMH.