Effects of 5-hydroxytryptamine 4 receptor agonist and antagonist on visceral sensitivity and plasma serotonin level in rats under partial restraint stress / 中华消化杂志

ABSTRACT

Objective To study the influence of partial restraint stress (PRS) on visceral sensitivity and plasma 5-hydroxytryptamine (5-HT) concentration in rats and to study the effects of 5-HT 4 receptor agonist and antagonist on visceral sensitivity and plasma 5-HT level in rats under PRS.Methods Male Wistar rats (n=32) were divided into four test groups. After two hours of PRS or sham-stress, 1-methyl-2-pyrrolidinone (solvent), tegaserod(a partial 5-HT 4 receptor agonist), and GR113808(a 5-HT 4 receptor antagonist) were administered intraperitoneally to the corresponding groups respectively. Thirty minutes after intraperitoneal injection, visceral sensitivity of rats, which was reflected by abdominal cramps induced by rectal distension, was recorded. Rectal distension was performed by insertion and inflation of a balloon(0.4-1.2 ml). Abdominal contractions were recorded by electromyography. Plasma 5-HT concentration was determined by fluorometry. Results Stress enhanced the number of abdominal cramps induced by rectal distension compared with sham-stress for all volumes of distension (0.4 ml:10.00?3.74 vs. 6.57?1.40; 0.8 ml: 16.75?2.92 vs.11.86?3.44; 1.2 ml: 19.50?4.24 vs. 14.86?3.19,P