Clostridium botulinum toxin inhibits myometrial activity in vitro: Possible application on the prevention of preterm labor after fetal surgery

Abstract

Background/Purpose: The current study aimed to analyze the effects of Clostridium botulinum toxin (Botox) on pregnant myometrium activity in vitro. Methods: Strips of myometrium were obtained from pregnant Wistar rats on gestational day 13 through 15 and placed under controlled conditions within tissue baths containing DeJalon solution. Muscular activity, including amplitude and frequency of contractions, was recorded by a force transducer connected to a polygraph. After stable baseline values were recorded, different concentrations of Botox were added to the tissue baths. Myometrial activity data points for each drug concentration were entered as mean percentual variations of the baseline. A total of 26 uterine samples from 13 animals were studied. Statistical analysis was by single-factor analysis of variance (ANOVA) with P <.05 considered significant. Results: Except for a narrow concentration range, when the effects were nonmonotonic, both amplitude and frequency of myometrial contractions were significantly depressed (P <.05) and eventually totally abolished at most concentrations studied, albeit in a potentially biphasic pattern. Those effects could be reversed by a complete washout of the tissue bath. Conclusions: Within appropriate concentrations, Botox consistently inhibits or completely arrests myometrial activity in potentially reversible fashion. This agent may prove valuable in premature labor prevention after fetal surgery. J Pediatr Surg 38:511-513. Copyright 2003, Elsevier Science (USA). All rights reserved.