Central dopaminergic neurons during development of genetic and doca-salt hypertension in the rat

Abstract

The in vivo binding of [ 3H]spiroperidol was measured in discrete areas of the brain in 7-, 9- and 16-week-old spontaneously hypertensive rats (SHR) and age-matched normotensive Wistar-Kyoto (WKY) controls. An increase in the [ 3H]spiroperidol binding in the striatum, tuberculum olfactorium and frontal cortex but not in the cerebellum was detected at all ages in SHR. The increase was more pronounced in 7- than in 9- or 16-week-old SHR. In vitro data indicated an increase in B max but no variation in K d in the striatum of 7-week-old SHR. Moreover no difference was detectable in the dopaminergic cell bodies (A9, A10). This increase was specific to [ 3H]spiroperidol binding sites since no difference was observed in the in vivo binding of [ 3H]QNB and [ 3H]LSD in the same brain regions. No variation in dopamine level or dopamine utilization, as estimated by measuring the disappearance of the amine induced by a-methyl- p-tyrosine, was observed. The DOPA accumulation after injection of the DOPA decarboxylase inhibitor NSD 1015 was greater in the tuberculum olfactorium from 7-week-old SHR. An increase in [ 3H]spiroperidol binding sites was also observed in the striatum and tuberculum olfactorium after 7 weeks of DOCA-salt treatment. These results suggest that dopaminergic neurons might be implicated in the onset of hypertension in the rat.