Chronic ingestion of bisphenol A decreases the cholinergically evoked and spontaneous contractions of rat uterus in vitro

Abstract

Background: Bisphenol A (BPA), a chemical used in the manufacture of plastics, has toxic effects on reproductive, developmental, and metabolic systems. It is implicated as a causative factor for infertility. The uterine and tubal contractility play a vital role in fertilization and implantation of zygote. The chronic exposure to BPA on myometrial contractions is not known. Aims and Objectives: The aim of this study is to examine the effect of chronic ingestion of BPA on rat uterine contractions evoked by acetylcholine. Materials and Methods: Rats weighing 90-150 g were fed BPA (2 μg/kg/day) or placebo containing pellets (time-matched control; TMC) orally for 28 days. The contractility of the uterus was also assessed in group of rats at the beginning (initial control [IC]). After 28 days, animals showing estrous phase were chosen for in vitro recording of uterine contractions (35 ± 1°C). Evoked contractions to different concentrations of acetylcholine were recorded followed by the effect on spontaneous contractions. Results: Acetylcholine evoked uterine contractions in vitro in a concentration-dependent manner. The contractions were similar in magnitude in IC and TMC. The uterus from BPA-fed animal exhibited decreased responsiveness to acetylcholine-evoked contractions as compared to TMC. In the presence of acetylcholine, frequency and force of spontaneous contractions increased in a concentration-dependent manner. However, in BPA-fed group, the frequency and force of spontaneous contractions were significantly attenuated. Conclusions: The results indicate that chronic exposure to BPA decreased the acetylcholine-evoked contractions as well as the spontaneous uterine contractions. The decreased contractility may account for the infertility seen after exposure to BPA.