Experimentally Altering Galactin Content of the Rat Pituitary

In earlier communications we reported that the injection of the estrogens increased the galactin content of the male rat pituitary gland and that the galactin content of pituitary glands taken from male rats castrated for 60 days was not altered.

This report consists of further attempts experimentally to change the galactin content of the rat pituitary gland. Animals were paired upon the basis of body weight. At the close of the experimental period the control and experimental animals were sacrificed, their pituitary glands removed and assayed by injecting them over the crop glands of the Same pigeons. The results are summarized in Table I.

Ovariectomy brings about a definite decrease in the galactin content of the pituitary gland. The injection of estrogenic hormones (theelin and Progynon-B†) into ovariectomized animals increased the galactin content of their pituitary glands over that of the ovariectomized, non-treated controls. It is interesting to note that the injection of 200 I.U. daily of Progynon-B brought about a greater increase in galactin content than did the daily injection of l000 I.U. of Progynon-B. The mammary glands of the injected animals were quite extensive and well filled with secretion. Inasmuch as we have found that the pituitary glands of pregnant rats are somewhat lower in galactin than those of normal estrous cycle females and in light of the above observations it would seem that the estrogens do not cause a galactin storage or inhibition of galactin secretion during pregnancy. Theelin injections into castrated males increased the galactin content per pituitary gland but did not change the concentration of galactin per 1 mg. of fresh pituitary tissue, while theelin injections into normal males, 500 I.U. daily, increased the galactin content per pituitary gland as well as the concentration within the gland.