Paraventricular hypothalamic obesity in rats: role of corticosterone

The role of adrenal glucocorticoid hormones in the weight gain produced by lesions of the paraventricular nuclei was explored in two experiments. In the first experiment, female rats with PVN lesions were found to have normal a.m. plasma corticosterone concentrations and blunted, albeit still elevated, p.m. concentrations. Nighttime corticosterone levels were moderately correlated with plasma insulin levels. In the second experiment, adrenalectomy markedly suppressed weight gain in animals with very large PVN lesions (mean weight gain of 33.0 g/20 days compared to 137.6 g/20 days for PVN rats with sham adrenalectomies). In the ADX-PVN group, there was a +0.90 correlation between plasma corticosterone levels and weight gain. Administration of corticosterone restored the abnormal weight gain in ADX-PVN animals. It is concluded that the steroid receptors mediating this effect of corticosterone lie outside the hypothalamus.