Clostridium botulinum toxin A significantly inhibits uterine contractions in rats undergoing mifepristone-induced preterm labor

Objective We investigated the in vivo tocolytic effect of Clostridium botulinum toxin A (BoNT/A) on mifepristone-induced preterm labor in rats. Methods On day 17 of gestation, an incision was made to expose the uterus, and BoNT/A (normal saline or 20 units) was injected into the uterine horns. On day 18, mifepristone was used to induce uterine contractions. Electrical activity of uterine contractions was measured via electromyography on day 19. Results In rats treated with 20 units of BoNT/A, the amplitude of uterine contractions was significantly decreased by 45.2 ± 18.4 (P