Contribution of afferent renal nerves to the metabolic activity of central structures involved in the control of the circulation

Abstract

Afferent renal nerves (ARN) are thought to be an important link in the pathogenesis of hypertension because of their influence on neuronal circuits involved in the control of arterial pressure and body fluid homeostasis. However, the central neural pathways involved in mediating ARN information have not been completely elucidated. In the present study, regions of the brainstem and forebrain, whose metabolic activity was altered after renal denervation, were functionally identified using hexokinase histochemistry in the rat. No differences in arterial pressure or heart rate were observed in either the 3-day or 13-day ARN-transected (tARN) animals compared with the respective sham ARN-transected (sARN) groups. Significant increases in the hexokinase reaction product were seen in the parvocellular component of the paraventricular nucleus of the hypothalamus, the supraoptic nucleus, the arcuate nucleus, the subfornical organ, the median preoptic nucleus, and the medial nucleus of the amygdala in both the 3-day and 13-day tARN animals. The bed nucleus of the stria terminalis was observed to have a significant decrease in hexokinase activity in the tARN groups, as were the caudal and medial aspects of the nucleus of the solitary tract. In the 3-day tARN group only, a significant decrease in hexokinase activity was observed in the region of the brainstem containing the A5 cell group, compared with sARN animals. The magnocellular component of the paraventricular nucleus of the hypothalamus and the lateral hypothalamus was seen to have increased hexokinase activity in the 13-day tARN animals only.(ABSTRACT TRUNCATED AT 250 WORDS)