PROGONADOTROPIC AND ASPECIFIC EFFECTS OF THE SERUM OF A HORSE IMMUNIZED WITH EXTRACTS OF SHEEP PITUITARY GLANDS1

A horse was injected at varying intervals over a period of 2 yrs. with an aqueous extract of sheep pituitary glands. Samples of serum of the horse obtained during this time were studied for anti- and pro-gonadotrophic activity. The measurement of these activities was made by separate and simultaneous injs. of serum and gpnadotrophic preps. into 21-day-old $ rats. Within 34 days after the beginning of the treatment of the horse the sera augmented the extract of sheep pituitary glands concomitantly administered to immature $ rats. The augmenting effect increased from the 34th day, reached a maximum on the 45th day and disappeared by the 107th day of inj. All samples of sera obtained after the 107th day of treatment contained an antigonadotrophic substance. The sera containing the progonadotrophic ac-tivity failed to produce any demonstrable effects upon the ovaries, vaginae or uteri of normal, immature 5 rats when administered alone. The antigonadotrophic substance found in the horse serum inhibited the gonadotrophins of sheep, rat, beef, and human pituitary glands as well as the gonado-trophins of human urine of pregnancy and the serum of pregnant mares. The antigonadotrophic serum, however, failed to inhibit the gonadotrophic activity of horse, hog, and chicken pituitary glands. The antigonadotrophic horse serum contained no antithyrotrophic activity as it did not prevent the increase in O2 consumption of adult rats given thyrotrophic preps.