The Estrous Cycle and the Adrenal Glands. ∗

Abstract

About 2 years ago experiments were reported from this laboratory showing important interrelationships between the adrenal cortex and the gonads. It was definitely shown that very early maturation of the sex glands could be induced by treatment of animals with cortico-adrenal extract. 1 The present brief report mainly indicates the effects of cortico-adrenal extract on the estrous cycle in normal and adrenalectomized rats. The influence of other sex hormones is also touched upon.

We have carried out observations on about 50 animals under various experimental conditions. Vaginal smears have been made daily over periods of several weeks according to the method of Long and Evans. 2 The extract of the adrenal cortex employed was similar to that previously described. 3 , 4 The potency of the preparations was proved by its restorative effect when injected into adrenalectomized cats showing insufficiency symptoms. A modified Swingle-Pfififner method of extraction was used. 5 The chief results may be summarized as follows: Cortico-adrenal extract when injected into normal rats produced a modification of the estrous cycle in the direction of increased activity, the estrous type of smear being often observed for several days continuously. Later, in many cases, an apparent inhibition of estrus was noted.

Removal of the adrenal glands resulted in complete suppression of the estrous cycle in about 90% of cases (in agreement with the observations of Martin 6 ).

In adrenalectomized animals in which estrus had been inhibited for various long periods, cortico-adrenal extract restored the cycle to normal, and maintained their lives indefinitely. When extract administration was stopped, in such cases, the estrous cycle was again completely inhibited, and the animals succumbed with characteristic symptoms.