Blood Pressure in Female and Male Rats Following Ventromedial Hypothalamic Lesions Placed at Four Different Ages. ∗

Abstract

Summary

1. Ventromedial hypothalamic lesions placed in female and male rats at the age of 21 and 26 days respectively, prevented the rise of blood pressure normally observed in intact rats of this age; lesions placed at the age of 59, 75 and 140 days did not show this effect. 2. Rats that had been lesioned at 59, 75 and 140 days of age ingested more sodium than their respective intact controls; this was more pronounced in the female rats than in the male animals. 3. The increased sodium intake due to hypothalamic hyperphagia may be responsible for the alleviation of the hypotensive effect of the lesions resulting from neuroendocrine deficiencies. 4. The fact that ventromedial lesions prevented blood pressure and adrenal weight from attaining magnitudes appropriate for intact controls in weanling rats only, i.e., during a phase of most active growth, suggests that the lesions interfered with the finer neuroendocrine regulation of adrenocorticotrophic hormone and perhaps growth hormone.