| Abstract: | The effects of daily intraperitoneal (150 mg/kg of body weight) injections of alpha-methyl-dl-tyrosine (MT), an inhibitor of tyrosine hydroxylase, on the 2nd to 4th, 5th to 7th or 10th to 12th days of life on the pituitary-adrenal function and brain adrenaline level in 3 to 4-month old rats were studied. MT treatment on the 5th to 7th days resulted in a decrease of noradrenaline content in hypothalamus and midbrain and chronic decrease of basal corticosterone level in blood, its diurnal fluctuations being preserved. MT injections on the 10th to 12th days were accompanied by a decrease of the basal corticosterone level, but the brain noradrenaline level remained unchanged. A study of pituitary-adrenal stress reactivity of adult rats has revealed no specific MT effect. A conclusion was drawn that the MT treatment applied exerted a long-term effect, predominantly, on the regulation of tonic corticosterone secretion. |
