Effects of porcine relaxin on the length of gestation and duration of parturition in the rat.
Experiments were carried out to investigate the effects of porcine relaxin on the course of gestation and delivery in the rat. Plasma relaxin was maintained at approximately 600 nmol/l from day 19 to day 23 of gestation by i.v. infusion from chronically implanted minipumps. Relaxin significantly (P less than 0.001) prolonged the length of gestation in 17 rats compared with controls, without causing dystocia or affecting the number of live births. Six rats gave birth during relaxin infusion. In these animals there was a significant (P less than 0.001) increase in the interval between successive deliveries compared with control animals, resulting in prolonged labour. The remaining 11 rats gave birth after the infusion was completed, when the interval between successive deliveries was significantly (P less than 0.025) shorter than controls. The results are consistent with the hypothesis that relaxin has a central action suppressing the release of oxytocin as well as a peripheral action on the myometrium and cervix.
Jones
S A
SA
Summerlee
A J
AJ
D000818:Animals; D005260:Female; D005865:Gestational Age; D007743:Labor, Obstetric / Q000187:drug effects*; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000187:drug effects*; D051381:Rats; D011919:Rats, Inbred Strains; D012065:Relaxin / Q000097:blood / Q000494:pharmacology*
D012065:Relaxin