HYPOTHALAMIC MECHANISMS OF AGING AND OF SPECIFIC AGE PATHOLOGY .2. SENSITIVITY THRESHOLD OF HYPOTHALAMO-PITUITARY COMPLEX TO HOMEOSTATIC STIMULI IN ADAPTIVE HOMEOSTASIS

We find that the threshold of sensitivity of the hypothalamo-pituitary complex to inhibition by glucocorticoids (dexamethasone) rises both in rats and humans with ageing. The resistance of the hypothalamo-pituitary complex to inhibition by dexamethasone is higher in patients with mental depression (which is characterized by a reduced level of biogenic amines in the brain) than in normal subjects. Tryptophan and L-dopa loading was found to raise the sensitivity of the hypothalamo-pituitary complex to inhibition by dexamethasone. Moreover, pinealectomy decreased, while treatment with pineal polypeptide extract or an antidiabetic drug-phenformin-increased, sensitivity to inhibition by dexamethasone. Elevation of hypothalamic threshold of sensitivity occurs during stress and is also more pronouced in cases of atherosclerosis, endogenous depression, endometrial carcinoma and prostatic cancer. All these data serve to indicate that specific age pathology is characterized by signs of intensified ageing. © 1979.