Effect of Hypothalamic Lesions on Steroid-Induced Atrophy of Adrenal Cortex in the Dog. ∗

Abstract

Summary

1. Normal dogs, dogs with lesions of the median eminence, and dogs with lesions elsewhere in the brain were subjected to left adrenalectomy, then treated with hydrocortisone for 14 days and their right adrenals removed. Some of the animals received 50 mg of hydrocortisone for a day and the remainder received 6.25 mg every other day. 2. Normal dogs showed a 20% decrease in adrenal weight and histologic atrophy on the larger steroid dose, while the smaller dose produced no weight change, being just sufficient to prevent the expected compensatory adrenal hypertrophy. 3. Dogs with destruction of the median eminence of the hypothalamus show no atrophy of the left adrenal removed one month after their lesions were produced, and the same degree of decline in adrenal weight after administration of the larger dose of steroid as the controls. On the other hand, they show a 9% decrease in adrenal weight on the smaller dose of hydrocortisone. 4. Dogs with hypothalamic lesions sparing the median eminence show essentially the same pattern of response as the normal dogs. 5. It is concluded that an intact median eminence is necessary for the increase in ACTH secretion in response to stress, but not for the decrease that follows steroid injection.