| Abstract: | To study the sensitivity of the hypothalamic sex center to the inhibitory action of estrogens, estradiol-17 was injected into the third ventricle of hemicastrated rats. The dose of estrogen needed to inhibit compensatory hypertrophy of the ovary by 50 and 100% in old animals (14–16 months) was 4 to 5 times greater than in young rats (3 months). The results point to an age increase in the threshold of sensitivity of the tonic region of the hypothalamic sex center to inhibition by estrogens and they can be used to explain the mechanisms of the age increase in gonadotropin secretion and the termination of reproductive function.Aging Mechanisms Group, Laboratory of Endocrinology, Professor N. N. Petrov Research Institute of Oncology, Ministry of Health of the USSR, Leningrad. (Presented by Academician of the Academy of Medical Sciences of the USSR N. P. Bekhtereva.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 86, No. 8, pp. 228–230, August, 1978. |
