Inhibition of ovarian aromatase by prolactin in vivo.

C. H. Tsai-Morris, M. Ghosh, A. N. Hirshfield, P. M. Wise, A. M. Brodie

    Research output: Contribution to journalArticlepeer-review


    Ovarian aromatase activity was inhibited by prolactin treatment in both cycling rats and immature gonadotropin-primed animals. Cycling rats were injected s.c. with prolactin (4 mg/kg BW) beginning on diestrus 1. Aromatase activity in the largest follicles on diestrus 2 and on proestrus was reduced relative to controls. None of the prolactin-treated animals had ovulated when examined on the expected estrus morning. In other experiments, the immature pregnant mare's serum gonadotropin (PMSG)-primed rat was used as a model for the cycling rat. Microsomal aromatase activity but not the activity of the C17-21 lyase was reduced in ovaries of animals injected with prolactin [6 IU (200 micrograms)/rat] 48 h after PMSG administration and sacrificed 4 h later. Furthermore, aromatase activity was significantly increased when endogenous prolactin was inhibited by bromocryptine (CB-154). The effect of LH treatment, on the other hand, was to increase both aromatase and lyase activities. However, prolactin pretreatment did not consistently prevent the LH-induced increase in aromatase activity. The results suggest that inhibition of ovulation by prolactin is mediated, at least in part, by direct inhibition of aromatase activity.

    Original languageEnglish (US)
    Pages (from-to)342-346
    Number of pages5
    JournalBiology of reproduction
    Issue number2
    StatePublished - Sep 1983

    ASJC Scopus subject areas

    • Reproductive Medicine
    • Cell Biology


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