The paraventricular nucleus is uniquely responsive to the feeding stimulatory effects of steroid hormones

The paraventricular nucleus is uniquely responsive to the feeding stimulatory effects of steroid hormones (Tempel, D.L., Kim, T. and Leibowitz, S.F. Brain Research 00: 000-000). This study tested the effects of hypothalamic as well as extrahypothalamic implants of the adrenal steroids, corticosterone (CORT) and aldosterone (ALDO), on food intake and macronutrient selection in sham-operated and adrenalectomized (ADX) rats 1 h after administration. Consistent with a previous experiment, implants of CORT and ALDO in the hypothalamic paraventricular nucleus (PVN) were effective in stimulating food intake. These tests, conducted at the onset of the active feeding cycle, showed PVN implants of CORT to potentiate specifically carbohydrate intake in ADX rats, while having no effect in sham rats. This was in contrast to PVN ALDO which predominantly stimulated fat intake in sham as well as ADX rats. Neither CORT nor ALDO had any effect on food intake after implantation into other hypothalamic or extrahypothalamic sites tested. These unresponsive hypothalamic sites were the dorsomedial and ventromedial nuclei, perifornical lateral hypothalamus, and arcuate nucleus. Extrahypothalamic sites including the dorsal CA1 region of the hippocampus, the central nucleus of the amygdala and the lateral septum were also unresponsive to steroid implants. These results identify the PVN, and the steroid receptors located within it, as having a specific function in mediating the action of CORT and ALDO on carbohydrate and fat intake, respectively.