Increased Gastrointestinal Motility in Vitro following Chronic Estrogen Treatment in Male Rats 1

Abstract

Abstract

The influence of 17β-estradiol (E₂) on contractile activity of three gastrointestinal regional tissues was evaluated. One of three dose levels (75, 300, and 600 mg/kg/day) of E₂ was administered sc to groups of male rats daily for 4 days. E₂ blood concentrations measured with radioimmunoassay on the fourth day were 3.9, 28.9, and 51.4 ng/ml for the respective treatment groups. Significant differences were demonstrated in contractile activity responses between tissues from E₂-exposed and nontreated control animals when the tissues were challenged with a cholinergic agonist in vitro. Evaluation of the data with regression analysis suggests differences in sensitivity among the three regional tissue responses when correlated with serum E₂ concentrations; i.e., colonic responses > esophageal responses > antral responses. A causal relationship between elevated serum estrogen concentration and gastrointestinal hyperactivity is suggested.