EXPRESSION OF MANGANESE SUPEROXIDE-DISMUTASE MESSENGER-RNA IN REPRODUCTIVE-ORGANS DURING THE OVULATORY PROCESS AND THE ESTROUS-CYCLE OF THERAT

Expression of manganese superoxide dismutase (Mn-SOD) mRNA during the pregnant mare serum gonadotrophin (PMSG)/human chorionic gonadotrophin (HCG)-induced ovulatory process, and during the estrous cycle was exa mined in rat female reproductive organs. Mn-SOD mRNA levels in theca i nterna cells markedly increased in PMSG-primed rats and high levels of the transcripts were maintained after HCG injection. The PMSG-enhance d expression of Mn-SOD mRNA in follicular epithelial cells increased c oncomitantly with luteinization of these cells. The levels of Mn-SOD m RNA remained high and became equivalent in both granulosa and theca lu tein cells 24 h after HCG injection. Neither luteinization nor the exp ression of Mn-SOD mRNA was observed in the epithelial cells of unovula ted follicles. Luteal bodies had formed 3 days after HCG injection, an d the same level of Mn-SOD mRNA expression continued in lutein cells, but not in stromal cells. During the estrous cycle, Mn-SOD mRNA was lo calized to theca interna cells on proestrus, to the epithelial cells o f luteinizing follicles on estrus, and to newly formed luteal bodies o n diestrus. The epithelial cells in the oviduct did not express Mn-SOD mRNA throughout the ovulatory process or the estrous cycle. Expressio n of Mn-SOD mRNA in the luminal epithelial cells of the uterus increas ed after PMSG injection, reaching a maximum after 24 h, and became rel atively negative 3 days after HCG injection when corpora lutea had for med in the ovary. During the estrous cycle, uterine epithelial cells a nd leukocytes showed marked increases in Mn-SOD mRNA expression on est rus and on proestrus, respectively. Expression in the vaginal epitheli um became apparent 3 days after HCG injection and continued for at lea st 12 days after HCG injection. The expression was localized to the su perficial layer of the epithelium. During the estrous cycle, expressio n occurs in the basal layer on proestrus and estrus, transferring to t he superficial layer on diestrus day 1, and expression stops on diestr us day 2. The relationship between the expression of Mn-SOD mRNA and h ormone-induced metabolic changes, including steroidogenesis, is discus sed.