Food deprivation decreases vasopressin mRNA in the supraoptic and paraventricular nuclei of the hypothalamus in rats.

We examined the effect of food deprivation for three days on hypothalamic arginine vasopressin (AVP) mRNA in rats. Simultaneously the effect of water deprivation for the same period was examined as a model of dehydration. Levels of AVP mRNA in the supraoptic nucleus (SON) and the paraventricular nucleus (PVN) were determined by semiquantitative in situ hybridization histochemistry. Water deprivation increased AVP mRNA in both nuclei as previously reported. In contrast, food deprivation decreased AVP mRNA in these nuclei. The changes in AVP mRNA levels in the PVN were observed in the magnocellular subdivision of the nucleus. Plasma levels of ACTH and corticosterone were greatly increased in both treated groups of rats. Plasma AVP and osmolality levels were significantly elevated in water-deprived rats but not in food-deprived rats. These observations indicated that both food deprivation and water deprivation stimulated the pituitary-adrenal axis and that a reduction in AVP mRNA levels in food-deprived rats was caused by food deprivation but not by glucocorticoid feedback suppression nor by altered plasma osmolality.