Effect of Choline on the Estrous Cycle of the White Rat

Abstract

Moore and Price 1 presented the hypothesis that the hypophyseal hormones excite gonadal production of germ cells and hormone secretion, and that the gonad hormones of either sex suppress pituitary secretion. This hypothesis is in agreement with the conclusions of Ihrke and D'Amour 2 that injections of male hormone concentrates from bull testis-tissue prepared by Gallagher and Koch caused a suppression of the estrous cycle of female rats as determined by the vaginal smear. This effect on the cycle, immediately abolished by the addition of pituitary substance, was explained by Ihrke and D'Amour on the basis of a diminution of pituitary secretions and a resulting suppression of the normal gametogenic and hormonal activities of the ovaries.

In 1937, however, Duncan, Gallagher and Koch 3 reported that crude male hormone preparations from testis tissue inhibit the normal estrous cycle in rats, but that this response is not due to the inhibitory action of the male hormone on the hypophysis, but solely to the phospholipin fraction free from male hormone. They further stated that crude choline obtained by hydrolyzing the phospholipins, and pure choline prepared synthetically likewise produced the same inhibition, but that pure testosterone in doses 20 times those found in crude testis-tissue concentrate did not inhibit the estrous cycle. The papers by Robson, 4 and Browman, 5 however, show that testosterone does cause a suppression of the estrous cycle in both mice and rats. The present work was undertaken in the attempt to confirm the r'eport of Duncan, Gallagher and Koch 3 that synthetically prepared choline causes an inhibition of the estrous cycle of the white rat.