Central nervous system catecholamine content and norepinephrine release after AV3V ablation

Abstract

Electrolytic ablation of the periventricular tissue surrounding the anteroventral third cerebral ventricle (AV3V-X) results in immediate increases in norepinephrine release in the paraventricular hypothalamic nucleus/anterior hypothalamus (P/A) and in the dorsomedial medulla (DM) and depletion of norepinephrine and epinephrine throughout the brain. The present study determined whether catecholamine depletion and/or altered norepinephrine release persisted after recovery from the acute effects of AV3V-X. Fourteen to eighteen days after surgery, catecholamine concentrations throughout the brain and norepinephrine release in the P/A and DM during hemorrhage were measured in control-operated and AV3V-X rats. AV3V-X decreased epinephrine content only in the midbrain, increased norepinephrine only in the cortex, and produced no differences in central nervous system dopamine. Hemorrhage-induced norepinephrine release was significantly greater in the P/A of AV3V-X rats than in control animals, whereas norepinephrine release in the DM increased equally in both groups. Thus AV3V-X does not result in chronic global central nervous system catecholamine depletion and enhances norepinephrine release in the P/A during hemorrhage.