Effects of Superovulation on Ovarian Δ5-3β-Hydroxysteroid Dehydrogenase Activity in Rats of Different Ages

Abstract

Administration of gonadotrophic hormones to rats, utilizing a procedure that produces superovulation, resulted, as expected, in increases in ovarian Δ5-3β-hydroxysteroid dehydrogenase activity. However, differences in the magnitude of the response were observed depending upon the ages of the rats used. The maximum degree of response was seen in immature rats (22–43 days of age when treatment was initiated). There is a distinct diminution of responsiveness in animals 3–4 months of age. Mature animals (over 5 months of age) responded, but to higher doses, and less consistently, than immature rats. Moreover, increases in enzymic activity generally paralleled increases in ovarian weight, while the specific activity of the enzyme remained, as a rule, unchanged. The magnitude of the increase appeared to parallel the increased volume of luteal tissue. (Endocrinology76: 382, 1965)