Electrophoretic Comparison of Pituitary Glands from Male and Female Rats

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Abstract
Disc electrophoretic analysis of the anterior pituitary gland of the rat has demonstrated differences in 2 protein bands which are dependent upon sex and age. Pituitary extracts from mature male and female rats were compared by examining the width and depth of staining of protein bands. A slowly moving band having growth hormone activity, by tibial assay in the rat, was wide in the male and narrow in the female. A rapidly moving band, identified as prolactin by its activity in the pigeon crop sac assay, was wide and deeply stained in the female in contrast to the male. Weanlings showed no sexual difference in pattern. Using adult rats, ovariectomy resulted in widening of the growth band and narrowing of the prolactin band, causing the pituitary pattern to resemble that of the male. Restoration of the prolactin band occurred after daily administration of 17β-estradiol, which, when given to both the normal and the orchiectomized male, resulted in a heavily stained prolactin band such as was found in the normal female or ovariectomized female given estradiol. In contrast to ovariectomy, orchiectomy did not alter the growth band. (Endrocrinology76: 578, 1965)