Interleukin-1 beta down-regulates the oxytocin receptor in cultured uterine smooth muscle cells.
OBJECTIVE
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.


METHODS
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 transcriptase-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.
Rauk
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PN
Magee-Womens Research Institute and the Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Pittsburgh, Pennsylvania, USA. rsipnr@mail.magee.edu
Friebe-Hoffmann
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U
D002478:Cells, Cultured; D015536:Down-Regulation / Q000276:immunology*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007375:Interleukin-1 / Q000502:physiology*; D009130:Muscle, Smooth / Q000737:chemistry / Q000166:cytology* / Q000276:immunology / Q000378:metabolism*; D018045:Receptors, Oxytocin / Q000096:biosynthesis / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014599:Uterus / Q000737:chemistry / Q000166:cytology / Q000276:immunology / Q000378:metabolism*
D007375:Interleukin-1; D018045:Receptors, Oxytocin