Epinephrine Contents of Sympathetic Ganglia and Brain Regions of Spontaneously Hypertensive Rats of Different Ages

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Abstract
The activity of phenylethanolamine N-methyltransferase (PNMT), the enzyme that catalyzes the synthesis of epinephrine from norepinephrine, was higher in a section of the medulla containing nucleus tractus solitarius from a genetic strain of spontaneously hypertensive rats (SHR) than in appropriate Wistar Kyoto (WKY) control rats. The concentration of epinephrine, but not of other catecholamines, was higher in the hypothalamus of SHR. These differences appeared between the 4th and 9th wk of life and continued into adulthood. The contents of norepinephrine, dopamine and epinephrine in the superior cervical ganglia of SHR were also higher than in WKY; these differences were first noted at 4 wk of age. During the first 3 wk of life, SHR were more sensitive to the dexamethasone-induced increases of both the PNMT activity of the brain and the epinephrine content of the ganglia.