Interleukin-1β Down-Regulates the Oxytocin Receptor in Cultured Uterine Smooth Muscle Cells

Authors

  • PHILLIP N. RAUK,

    1. Magee-Womens Research Institute and the Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania
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  • ULRIKE FRIEBE-HOFFMANN

    1. Magee-Womens Research Institute and the Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania
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Address reprint requests to Phillip N. Rauk, M.D., Magee-Womens Research Institute, 204 Craft Avenue, Pittsburgh, PA 15213. E-mail: rsipnr@mail.magee.edu

Abstract

PROBLEM: Intrauterine infection accounts for 20% of preterm labor and results in the production of decidual inflammatory cytokines, including interleukin-1 (IL-1). The oxytocin receptor plays a key role in the onset of preterm labor. Cytokines likely regulate oxytocin receptor expression through several cytokine-induced DNA-binding proteins. METHOD OF STUDY: The objective of this study was to evaluate the effect of the IL-1 alone on oxytocin receptor number as measured by radioligand binding and immunocytochemistry, and oxytocin receptor mRNA as measured by reverse transriptase-polymerase chain reaction (RT-PCR) in cultured uterine myocytes. RESULTS: Unexpectedly, IL-1 treatment decreased oxytocin receptor number from 111,067 to 23,941 receptors/cell. Loss of oxytocin receptor binding began after 8 hr of IL-1 treatment and was reversible after IL-1 removal. Immunocytochemistry confirmed a loss of cellular oxytocin receptors. Oxytocin receptor mRNA decreased beginning after 2 hr of IL-1 treatment. CONCLUSIONS: IL-1 down-regulates the uterine oxytocin receptor in a time- and dose-dependent fashion.

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