Aromatase activity in cultured ovaries from neonatally thymectomized mice with ovarian dysgenesis

The autoimmune oophoritis resulting from thymectomy at 3 days of age (Tx-3) in B6A female mice is characterized by dysgenic ovaries and circulating auto-antibodies against the oocyte (AOA). Dysgenesis of the ovaries starts around 24 days of age with a decline in numbers of the oocytes and follicles and is accompanied by lymphocytic infiltration. By 60 days of age the ovarian dysgenesis (OD) is complete with a preponderance of interstitial cells associated with elevated levels of testosterone (T). From 60-120 days of age the ovaries become progressively smaller in size and T levels rise. Since ovarian interstitial cells can produce T, assessment of aromatase activity was determined using cultured ovaries from 20-, 30-, 60-, 90- and 120-day-old mice. Similar or enhanced ability in aromatizing T to estradiol-17 beta (E2) was demonstrated by the ovaries from all Tx-3 mice compared with those from intact mice. At 30 and 60 days of age Tx-3 mice had increased circulating levels of E2 then the levels of E2 returned to those of intact mice at 90 and 120 days of age. The results indicate that the ovaries in Tx-3 mice may have an ability to aromatize T to E2 in culture, but apparently are not doing so at 90 and 120 days of age in situ. Further, ovaries of Tx-3 animals are able to aromatize T to E2 in the absence of organized follicular cells. These abnormal responses of ovarian hormones clearly demonstrate that the presence of AOA have a damaging effect on the endocrine activity as well as the morphology of the ovary.