Abstract
Summary
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 fourth and ninth week 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 weeks of age. During the first 3 weeks of life, SHR were more sensitive to the dexamethasone-induced increases in both the PNMT activity of the brain and the epinephrine content of the ganglia.
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