Endocrine Influences on Rat Ovarian Proteinase Activity

Abstract

Lyophilized ovaries collected from intact rats were shown to possess proteolytic activity in both acid and alkaline pH ranges, with apparent optima at about pH 4 and 8. Administration of ovine FSH (folliclestimulating hormone) and HCG (human chorionic gonadotropin) resulted in a decrease in the level of proteolytic activity at pH's more acid than pH 5, and an increased level of proteolytic activity at pH's alkaline to pH 5, with a maximum increase around pH 8. Treatment of intact rats with partially purified ovine FSH alone, as well as with partially purified ovine TSH (thyroid-stimulating hormone) or partially purified ovine LH (luteinizing hormone), resulted in increased levels of activity of the pH 8 enzyme. HCG alone does not produce this effect. Hypophysectomy is followed by a decrease in the level of the pH 8 enzyme, with no change being observed in the level of the pH 4 enzyme. The activity of the pH 8 proteinase can be increased to levels above those in intact controls by treatment with partially purified ovine FSH, either by itself or with HCG. Purified bovine growth hormone also exerts a stimulatory effect, whereas HCG alone does not. Partially purified ovine LH and TSH have slight stimulatory effects on the pH 8 ovarian proteinase. The pH 8 active enzyme is not inhibited significantly by EDTA (ethylenediaminetetraacetate), KCN or cysteine at 10⁻²m, but is decreased about 50% by 10⁻⁴m parahydroxy mercuribenzo ate.