Chiharu Kanamori1, Katsuhiko Yasuda2, Genichiro Sumi1, Yutaka Kimura3, Tomoko Tsuzuki4, Hisayuu Cho4, Hidetaka Okada4, Hideharu Kanzaki4. 1. Department of Obstetrics and Gynecology, Affiliated Takii Hospital, Kansai Medical University, Osaka, Japan. 2. Department of Obstetrics and Gynecology, Affiliated Takii Hospital, Kansai Medical University, Osaka, Japan. Electronic address: yasuda@takii.kmu.ac.jp. 3. Division of Cardiology, Department of Medicine II, Kansai Medical University, Osaka, Japan. 4. Department of Obstetrics and Gynecology, Kansai Medical University, Osaka, Japan.
Abstract
OBJECTIVES: Although smoking is the most important modifiable risk factor associated with preterm delivery, the underlying mechanism by which smoking stimulates premature uterine contractions is still poorly understood. In the present study, we investigated whether cigarette smoking affects the contractile sensitivity of uterine myometrium to oxytocin in pregnant women. STUDY DESIGN: Cigarette smoking habits of pregnant women were evaluated by direct interviews and by measuring exhaled carbon monoxide (CO). We isolated myometrial strips from pregnant smokers and non-smokers and evaluated uterine contractile sensitivity to oxytocin. Gene expression levels of oxytocin receptors (OTR) were compared between myometrial strips obtained from smokers and non-smokers by real-time PCR. OTR protein levels in the myometrium were evaluated by Western blotting. RESULTS: The reported number of cigarettes smoked per day by the interviewee significantly correlated with the concentration of exhaled CO. Oxytocin sensitivity increased significantly in smokers (n=6) compared with non-smokers (n=11). Real-time PCR analysis did not reveal any significant difference in OTR mRNA expression between smokers and non-smokers. Western blotting revealed that OTR level was significantly increased in smokers compared with non-smokers. Both number of cigarettes smoked per day and the concentration of exhaled CO correlated with oxytocin sensitivity. CONCLUSION: Our findings suggest that smoking increases oxytocin sensitivity of pregnant myometrium by increasing OTR levels even though OTR mRNA expression remains unaltered, thereby increasing the risk of preterm delivery in women who smoke during pregnancy. The sensitivity is dependent on number of cigarettes smoked per day.
OBJECTIVES: Although smoking is the most important modifiable risk factor associated with preterm delivery, the underlying mechanism by which smoking stimulates premature uterine contractions is still poorly understood. In the present study, we investigated whether cigarette smoking affects the contractile sensitivity of uterine myometrium to oxytocin in pregnant women. STUDY DESIGN: Cigarette smoking habits of pregnant women were evaluated by direct interviews and by measuring exhaled carbon monoxide (CO). We isolated myometrial strips from pregnant smokers and non-smokers and evaluated uterine contractile sensitivity to oxytocin. Gene expression levels of oxytocin receptors (OTR) were compared between myometrial strips obtained from smokers and non-smokers by real-time PCR. OTR protein levels in the myometrium were evaluated by Western blotting. RESULTS: The reported number of cigarettes smoked per day by the interviewee significantly correlated with the concentration of exhaled CO. Oxytocin sensitivity increased significantly in smokers (n=6) compared with non-smokers (n=11). Real-time PCR analysis did not reveal any significant difference in OTR mRNA expression between smokers and non-smokers. Western blotting revealed that OTR level was significantly increased in smokers compared with non-smokers. Both number of cigarettes smoked per day and the concentration of exhaled CO correlated with oxytocin sensitivity. CONCLUSION: Our findings suggest that smoking increases oxytocin sensitivity of pregnant myometrium by increasing OTR levels even though OTR mRNA expression remains unaltered, thereby increasing the risk of preterm delivery in women who smoke during pregnancy. The sensitivity is dependent on number of cigarettes smoked per day.
Authors: Tyler B Grove; Kyle J Burghardt; A Zarina Kraal; Ryan J Dougherty; Stephan F Taylor; Vicki L Ellingrod Journal: Mol Neuropsychiatry Date: 2016-08-13
Authors: Tamara Merz; Britta Lukaschewski; Daniela Wigger; Aileen Rupprecht; Martin Wepler; Michael Gröger; Clair Hartmann; Matthew Whiteman; Csaba Szabo; Rui Wang; Christiane Waller; Peter Radermacher; Oscar McCook Journal: Intensive Care Med Exp Date: 2018-10-19