The Role of Adrenal and Ovarian Steroids in the Control of Serum LH and FSH

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Abstract
The purpose of these experiments was to examine the pattern of gonadotropin response to alterations in the serum steroid milieu. Animals exhibiting five-day estrous cycles underwent bilateral ovariectomy (OVX), sham-ovariectomy (SOV), adrenalectomy (ADX), adrenalectomy plus ovariectomy (ADX-OVX) at 0800 h of proestrus, or were unoperated. Autopsies were done at 0830, 1300 or 1700 h of proestrus or 0830 h the following morning. The entire study was repeated on metestrus. with an additional autopsy time 48 h after surgery. After OVX on either proestrus or metestrus, FSH rose dramatically and remained high for the next 24 h. In contrast, LH rose after OVX only during the critical period on proestrus, and then only temporarily. Forty-eight hours later, LH began to rise in metestrus-OVX animals. Thus, a separation of LH and FSH release was verified under conditions of altered serum steroid backgrounds. Moreover, estradiol levels in OVX animals did not differ from control values on either proestrus or metestrus for 24 h, suggesting that this steroid does not exert negative feedback control on FSH. After both OVX and ADX, estradiol did drop to baseline, indicating that the adrenal can maintain serum estradiol levels at relatively normal levels. Following the stress of surgery, progesterone was elevated both in proestrous and metestrous animals, but for a more prolonged period on proestrus. ADX animals did not show this response. Estradiol was released after surgical stress only on proestrus; it was not released in ADX animals. These results indicate that the pattern of steroid secretion from the adrenal cortex following stress can fluctuate with stages of the female estrous cycle.