Effects Of Ovarian Hormone On 5-HT3 Receptors MRNA Expression In The Rats Colon With Restraint Stress-induced Bowel Dysfunction

AIM: To examine the effects of ovarian hormone on the expression of 5-hydroxytryptamine 3 receptors (5-HT3R) in the rats colon with restraint stress-induced bowel dysfunction or not and the pathophysiological implications for irritable bowel syndrome (IBS). METHODS: Forty-eight female Sprague-Dawley rats were randomly divided into three groups of 16 each: sham operation (Sham), ovariectomy (OVX) and ovariectomy with estrogen (E2) and progesterone (P) replacement therapy (OVX+E2+P). Three groups were randomly divided into restraint-stress group and non-restraint-stress group four weeks after operation. The restraint-stress group rats were subjected to 1-h restraint stress. The changes were monitored by collection of fecal pellets. The expression of 5-HT3R mRNA in the colon was studied by RT-PCR. RESULTS: Compared with Sham group and OVX+E2+P group, OVX group rats showed increase in fecal pellets and decrease in the time of vitreous pellets excretion (P<0.01). Compared with Sham group, OVX+E2+P group rats showed decrease in the fecal pellets output and increase in the time of glass pellets output (stress group: P<0.05; non-stress group: PO.01). Compared with non-restraint -stress group, restraint-stress group showed increase in fecal pellets and decrease in the time of vitreous pellets excretion (P<0.01). The levels of 5-HT3R mRNA in the colon of ovariectomized rats were significantly increased, the expression of 5-HT3R mRNA was significantly decreased in the hormone replacement therapy group (P<0.01). However, the expression of 5-HT3R mRNA showed no significant difference between restraint-stress group and non-restraint-stress group (P>0.05). CONCLUSION: Restraint-stress increase in fecal pellets of rats, there were similarities between the intestinal effects of restraint-stress in rats and IBS in human. Low ovarian hormone increase in fecal pellets of rats with restraint-stress or not. Ovarian hormone plays a role in the regulation of 5-HT3R expression in the rats colon with restraint-stress or not. Restraint-stress had no effects on the expression of 5-HT3R in the rats colon.