Effect of Hypothalamic Lesions on the Adrenal Cortical Response to Stress in the Rat

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Abstract
Hypothalamic lesions (Horsley-Clarke) were produced in a large series of adult male rats. After a 3-wk. recovery period, the pituitary adrenal cortical response to stress was studied in these rats utilizing 2 methods of assessing ACTH output: eosinopenia induced by epinephrine, and reduction in adrenal ascorbic acid concn. induced by unilateral adrenalectomy. Normal rats and those with lesions in various hypothalamic areas gave normal responses to both of these stimuli. If the lesions completely or largely destroyed the median eminence of the tuber cinereum or hypophyseal stalk, epinephrine induced eosinopenia and the reduction in adrenal ascorbic acid concn. were completely abolished. Rats with lesions of the median eminence had normal sized adrenals, but the majority had testicular atrophy. Lesions of the stalk uniformly produced both adrenal and testicular atrophy. The anterior lobe of the pituitary of most rats with lesions of the median eminence was histo-logically normal. Severe anterior lobe damage uniformly followed lesions of the stalk. The results suggest that the hypo-thalamus controls adrenal cortical function in the rat.