Adrenaline depletion in the hypothalamus of the rat after chronic alpha-methyldopa.
1. Individual anterior hypothalamic-preoptic nuclei were dissected from the brains of control and alpha-methyldopa treated (2 x 40 mg/kg, 5 days) rats, and the concentrations of adrenaline and other catecholamines were estimated. 2. By a combination of radioenzymatic assay and paper chromatography the concentrations of adrenaline, noradrenaline, dopamine, alpha-methylnoradrenaline and alpha-methyldopamine were determined concurrently in the same sample. 3. alpha-Methyldopa reduced the adrenaline levels of the hypothalamic nuclei by 47--68% of control concentrations. 4. A differential displacement of the parent catecholamines was observed and the depletions were ranked: adrenaline less than dopamine less than noradrenaline. 5. alpha-Methylnoradrenaline and alpha-methyldopamine were found in all hypothalamic nuclei. 6. The depletion of hypothalamic adrenaline by alpha-methyldopa could represent a pharmacological mechanism contributing to the antihypertensive action of the drug.
D000818:Animals; D001794:Blood Pressure; D002395:Catecholamines / Q000378:metabolism; D004837:Epinephrine / Q000378:metabolism / Q000502:physiology*; D007031:Hypothalamus / Q000378:metabolism*; D008297:Male; D008750:Methyldopa / Q000494:pharmacology*; D010625:Phenylethanolamine N-Methyltransferase / Q000378:metabolism; D051381:Rats
D002395:Catecholamines; D008750:Methyldopa; D010625:Phenylethanolamine N-Methyltransferase; D004837:Epinephrine