title: Effects of relaxin on in vivo uterine contractions in conscious and unrestrained estrogen-treated and steroid-untreated ovariectomized rats.
abstract: The effect of extended infusions of highly purified porcine relaxin on uterine activity was tested in vivo in conscious unrestrained rats. Relaxin was found to inhibit oxytocin- and prostaglandin F2 alpha-induced uterine contractions in estrogen-treated ovariectomized rats as well as spontaneous contractions in both estrogen-treated and steroid-untreated ovariectomized rats. The inhibition of both induced and spontaneous uterine contractions was more effective in the early phases of relaxin infusion than after prolonged exposure to the hormone. However, this desensitization was not complete, and the inhibition was effective even with extended (up to 72 h in the oxytocin experiments) infusion of relaxin. The results indicate that relaxin may be important in controlling uterine activity in the rat near the end of gestation, and that estrogen priming in ovariectomized rats is not necessary for relaxin to exert its biological effects.
mesh_terms: D000818:Animals; D002369:Castration; D002940:Circadian Rhythm / Q000187:drug effects; D015237:Dinoprost; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D010121:Oxytocin / Q000494:pharmacology; D011460:Prostaglandins F / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012065:Relaxin / Q000097:blood / Q000494:pharmacology*; D014590:Uterine Contraction / Q000187:drug effects*
chemical_list: D011460:Prostaglandins F; D004958:Estradiol; D010121:Oxytocin; D012065:Relaxin; D015237:Dinoprost