220 /. J. Christian 



to secrete steroids with cortical or androgenic activity. Hill (1948) has 

 shown that under the proper conditions, the ovaries of mice can assume 

 adrenocortical function when transplanted to the ears. Under other circum- 

 stances the ovaries can be made to secrete androgens (Hill, 1937; Delost, 

 1955) . It must be apparent that the whole field of adrenal-gonadal relation- 

 ships is poorly understood, especially with regard to species differences. 



There is one area of adrenal-gonadal relationships, however, which seems 

 to be on relatively solid ground. Selye (1939) called attention to the fact 

 that a variety of stimuli which elicited increased adrenocortical activity 

 also inhibited reproductive activity. Female rats subjected to a variety of 

 alarming stimuli exhibited ovarian atrophy and more or less permanent 

 anestrus. These observations have been confirmed and extended for a 

 variety of species, including mice, voles, man, and others, and for a wide 

 variety of stimuli (Christian, 1959b). The entire and exact mechanisms by 

 which inhibition of reproductive function is brought about are not known 

 with certainty. It may be due in part to a direct suppressive action of the 

 carbohydrate-active corticoids on the reproductive organs; for example, it 

 has been shown that cortisone and hydrocortisone depress the ovarian re- 

 sponse to chorionic gonadotropins in intact rats (Smith, 1955), possibly 

 by direct action on the vasculature. However, it is more likely that the 

 suppression results primarily from an inhibition of the secretion of gonado- 

 tropins from the anterior pituitary when there is an increased production 

 of adrenocorticotropin. Selye (1939) suggested that there is a "shift" in 

 pituitary function; the production of gonadotropins is sacrificed in order 

 to increase the production of "life-maintaining" ACTH. But it is equally, 

 if not more, likely that the secretion of gonadotropin is inhibited by in- 

 creased amounts of cortical androgens following stimulation by ACTH. 

 The ability of androstenedione and other related weakly androgenic 

 steroids to suppress pituitary gonadotropic activity has already been 

 discussed and it has also been stated that these steroids appear to be major 

 natural secretory products of house mice, rats, man and probably other 

 species. It is particularly interesting, especially to those studying popula- 

 tion phenomena, that immature mice are significantly more susceptible 

 than mature mice to the suppressive effects of steroids on the secretion of 

 gonadotropins (Byrnes and Shipley, 1950; Byrnes and Meyer, 1951) . There 

 is also the possibility that nervous stimuli, acting directly through the 

 hypothalamus, can depress gonadotropin secretion. 



Whether one or all of these mechanisms is involved, there is a decrease in 

 the secretion of gonadotropin with the result that the secretion of sex 

 steroids by the gonads is inhibited and the secondary sex organs may ap- 

 proach the appearance seen following gonadectomy or hypophysectomy 

 (Selye, 1939; Christian, 1959b). The germinal cells of the gonads also 



