Relationship between plasma corticosterone and insulin levels in rats with ventromedial hypothalamic lesions.

The effects of ventromedial hypothalamic (VMH) lesions on plasma corticosterone, insulin, and glucose levels were studied in food-restricted and ad lib fed female rats. VMH lesions resulted in significant elevations of corticosterone and insulin levels compared to control values during the first 25 days after surgery. However, unlike insulin values which were generally greater in VMH rats fed ad lib than in food-restricted animals, plasma corticosterone levels were unaffected by level of food intake. Corticosterone and insulin levels were unrelated preoperatively and in sham-operated animals, but were positively correlated (r = .82) by Day 25 in ad lib fed VMH rats. It is concluded that the elevation in plasma glucocorticoids observed in VMH rats is a primary effect of the lesion that is independent of food intake or initial weight gain.