Effects of paraventricular nucleus lesions on chronic renal hypertension

The contribution of the paraventricular nucleus region of the hypothalamus (PVN) to the maintenance of one-kidney, figure-8 renal wrap hypertension was determined in this study. Electrolytic ablation of the PVN was performed 4 wk after the production of hypertension or sham operation. Ablation of the PVN region significantly reduced mean arterial pressure (MAP) from 150 +/- 9 to 110 +/- 3 mmHg in the hypertensive rats. In the sham-hypertensive group, the lesion decreased MAP from 118 +/- 2 to 99 +/- 4 mmHg. In both groups of animals MAP from 118 +/- 2 to 99 +/- 4 mmHg. In both groups of animals MAP returned to prelesion values by day 7 postlesion. When ganglionic blockade was performed on day 7 postlesion, the fall in MAP was greater in hypertensive rats (-44 +/- 5 mmHg) than in normotensive rats (-26 +/- 3 mmHg). In a separate group of rats studied 3 days after PVN ablation, ganglionic blockade produced similar decreases in MAP in the wrapped and sham-operated animals. These studies suggest that the PVN contributes to the increased functional sympathetic nervous system associated with one-kidney, figure-8 renal hypertension. Although ablation of the PVN region decreases MAP, neural mechanisms compensate to return MAP to hypertensive levels.