Biochemical and morphologic study of catecholamine metabolism in spontaneously hypertensive rats

Catecholamines and catecholamine-synthesizing enzymes have been studied quantitatively in specific brain areas of spontaneously (genetically) hypertensive rats by means of a combination of sensitive enzymatic-isotopic methods and a microdissecting technique. Changes in catecholamine metabolism were found to be localized to regions of the brain implicated in the regulation of blood pressure. Noradrenaline levels were decreased in specific nuclei of the anterior hypothalamus and in the nucleus interstitialis striae terminalis ventralis. The activity of the adrenaline-forming enzyme, phenyl-ethanolamine-N-methyl transferase, was increased in the A1 and A2 areas of the brain stem. These results implicate catecholamine-forming neurons in the hypothalamus and brain stem in the development of spontaneous hypertension in rats.