Hypothalamic Lesions, Hypovolemia, and the Regulation of Water Balance in the Rat

Abstract

<p>Groups of rats were prepared with lesions of major hypothalamic areas, and their drinking responses and regulation of plasma sodium concentration during hypovolemia were observed. No evidence was found to suggest that the lesions of any group removed inhibitory control of drinking during hypovolemia, but evidence was obtained that lesions of the medial preoptic area interfered with the systems controlling water intake and the regulation of body water during hypovolemia. This observation was replicated in a second experiment, which also found that medial preoptic lesions induced a period of adipsia and aphagia, followed by recovery with residual deficits, including chronic hypernatremia. As a partial explanation of the observed results, it was suggested that the lesions altered the set-point for regulation of plasma sodium concentration.</p>