Relative normophagia and organ growth in growth-retarded weanling rats with dorsomedial hypothalamic lesions.

Weanling rats with ventromedial (VMNL) and dorsomedial (DMNL) hypothalamic lesions and sham-operated controls were maintained up to 198 days after operation. Food intake was measured throughout the experiment and organ weights were recorded at various periods of sacrifice. Comparisons were made between controls and VMNL and DMNL rats, respectively. Food intake and organ weights were expressed in absolute terms and relative to body mass and Kleiber's "metabolic size." VMNL rats were always normophagic and showed lower organ weights, regardless of manner of computation. Rats with DMNL, on the other hand, were absolutely hypophagic but relatively normophagic for considerable periods of time when food intake was referred to body mass. A similar relationship obtained for organ weights. The data fit well with previous results and with a hypothesis that holds that DMNL bring about a "resetting" of some central nervous control system that not only allows the rat so operated to subsist on lower substrate levels but also regulates normal growth in relation to body mass.