Immunologic Impairment of Δ5-3B Hydroxysteroid Dehydrogenase and Its Effect on Ovarian Function: The Use of a Purified Enzyme
The effects of actively immunizing rats with a purified preparation of Δ5-3B-OHSDH are reported. The following parameters were examined: (1) vaginal cytology; (2) pregnancy; (3) antibody titres; (4) Δ5-3B-OHSDH activity in the ovary by (a) histochemical, (b) biochemical methods; (5) 20 α-OHSDH activity in the ovary determined histochemically; (6) progesterone levels in plasma.
The enzyme was prepared by the growth of pseudomonas testosteroni ATCC 11996 in medium containing testosterone, and purified according to the methods described by Talalay(1962),(2) and Dixon and Webb(1964),(3).
By six-seven weeks following the completion of immunization, 80% of the rats were anestrousand 20% showed irregularity of the cycles. The Δ5-3B-OHSDH activity, as demonstrated histochemically, showed marked reduction in both the interstitial tissue and the corpora lutea in the ovaries of immunized rats. This was confirmed by the biochemical assay. The enzyme activity was found to be 13.9 ± 1.6 and 7.4 ± 1.3 ug androstenedione/mgm ovarian weight/minute in the control and immunized group respectively. The difference is highly significant (P < 0.005). The plasma progesterone levels dropped in the immunized group in comparison with the controls. The drop was statistically significant during the estrus and the first diestrus day (P < 0.05). Although mating occurred, the majority showed failure of implantation or various degrees of resorption in those animals that demonstrated high levels of antibody titers.
This work supports our previous findings using the crude enzyme and, in addition, it indicates that the effects are not due to impurities asα-hydroxysteroid dehydrogenase or cell debris, both of which have been eliminated by the purification process. It also suggests that purification of the enzyme did not interfere with its immunologic activity.
Active immunization using a purified Δ5-3B-OHSDH demonstrated that the interstitial tissue and corpus luteum are important sites for the enzyme activity and also for the process of steroidogenesis in the ovary. By immunologic suppression of the enzyme activity in the ovary, there resulted interference with the normal cycles and interference with implantations. This was shown to be due to the reduction in the progesterone levels but it might also suggest a reduction in the estrogen surge necessary for implantation. During normal pregnancy there is an increase in the Δ5-3B-OHSDH activity with a reduction in 20 α-OHSDH activity in the corpora lutea. In the animals that showed resorption or absence of implantations there was a reduction in Δ5-3B-OHSDH activity and an increase in 20 α-OHSDH. This is in support of the work of others that proved the association of 20 α-OHSDH with luteal regression. Since 20 α-OHSDH mediates catabolism of progesterone to 20 α-dihydroprogesterone, these changes in the ovarian enzyme activities following immunization with Δ5-3B-OHSDH might suggest an upset of the ratio of progesterone: 20 α-dihydroprogesterone with failure to maintain the pregnancy.
KeywordsCorpus Luteum Progesterone Level Interstitial Tissue Hydroxysteroid Dehydrogenase Vaginal Cytology
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