Ovaries of 120- to 140-day-old rats were examined histochemically throughout the estrous cycle for changes in distribution and intensity of the activities of 3 carbohydratemetabolizing and 2 steroid-converting enzymes. The enzymes of carbohydrate oxidation were: lactic dehydrogenase (LD), succinic dehydrogenase (SD), and glucose-6-phosphate dehydrogenase (G6PD). 20α-Hydroxypregn-4-en-3-one and dehydroepiandrosterone were used as substrates for the study of 20α-hydroxysteroid dehydrogenase (20α-OHD) and Δ6-3β-hydroxysteroid dehydrogenase (3β-OHD) activities, respectively. Infoldings of the germinal epithelium were distinguished from the rest of the surface epithelium by a stronger activity of certain carbohydrate-metabolizing enzymes. Primary follicles, closely associated with these epithelial infoldings, exhibited identical histochemical characteristics. In the granulosa cells in some of the graafian follicles, 3β-OHD activity became demonstrable and G6PD activity increased markedly on the second day of diestrus, at the time of the presumed “estrogen surge.” The 20α-OHD activity was confined to corpora lutea, where it appeared 3 1/2 days after their formation, i.e., during the following proestrus. The activity of the 2 DPN-dependent enzymes, LD and 3β- OHD, increased in the corpora lutea during the first cycle following their formation and decreased thereafter. On the other hand, the activity of the 2 TPN-dependent enzymes, G6PD and 20α-OHD, increased continuously from the time they were histochemically demonstrable throughout the involution of the corpora lutea. Thus, 2 enzyme patterns were recognizable during the aging of the corpora lutea: one for the DPNlinked and another for the TPN-linked enzymes. (Endocrinology79: 316,1966)
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Pupkin et al. (1966) studied this question.