MODE OF ACTION OF OB PROTEIN (LEPTIN) ON FEEDING

OB protein (leptin) decreases food intake in a variety of species. Her e we investigated the effects of the intracerebroventricular administr ation of recombinant murine OB protein on food consumption and meal pa rameters in Wistar rats maintained ad libitum. The intracerebroventric ular administration of OB protein (0.56-3.5 mu g/rat) decreased feedin g in a dose-dependent manner. Computer analysis of meal parameters dem onstrated that OB protein (3.5 mu g/rat, n = 10) decreased nighttime m eal size by 42%, whereas meal frequency and meal duration were unaffec ted. Derived analyses for the nighttime also showed that OB protein de creased the feeding rate (meal size/meal duration) by 30%, whereas the satiety ratio (intermeal intervals/meal size) increased by 100%. A si milar profile was observed during the daytime and total daily periods. The intracerebroventricular administration of heat-inactivated OB pro tein (3.5 mu g/rat, n = 10) had no effect on any meal parameter. The r esults show that OB protein administered intracerebroventricularly inh ibits feeding through a specific reduction of meal size.