Attenuation of Gastrointestinal Tract Propulsion in Rats by Zinc Acetate: Investigation into Serotonergic and Dopaminergic Mechanisms

Abstract

This study evaluated the influence of orally administered zinc acetate on gastrointestinal tract propulsion of rats. It also evaluated the effects of the salt on faecal output and gastrointestinal transit time in the rats. The effects of zinc acetate on feeding as well as water intake were determined. The dose of zinc acetate which produced the maximal effect was used to investigate the receptors involved in the alteration of gastrointestinal motility by the salts. All the three doses of zinc acetate (50 mg/kg, 80 mg/kg and 110 mg/kg) produced a significant reduction in the number of total faecal pellets produced in eight hours of study (2.67 ± 0.67, 10.75 ± 0.60, 5 ± 0.52) respectively when compared with the control group (15.67 ± 0.52). Also, the three doses of zinc acetate produced a dose-dependent significant reduction in the faecal mass (1.23 ± 0.08g, 0.96 ± 0.07g, 0.59 ± 0.07g) respectively when compared with control group (3.39 ± 0.25g).The total transit time in rats treated with 50 mg/kg of zinc acetate (746.2 ± 5.95 minutes) increased significantly compared to the control group (251.2 ± 5.48 minutes). The three doses of zinc acetate produced a dose-dependent reduction (p < 0.05) in food intake (9.67 ± 0.61, 9.17 ± 0.62 and 5.00 ± 0.39) respectively compared to the control group (18.33 ± 0.67). Pre-treatment with metoclopramide (5HT 3 & D 2 blocker/5HT 4 serotonergic agonist) significantly increased faecal pellet output in zinc acetate treated rats (4.80 ± 0.20) when compared with rats treated with zinc acetate alone (2.67 ± 0.67).The study concluded that zinc acetate reduced gastrointestinal tract propulsion in rats evidenced as increased intestinal transit time of rats and reduced faecal pellet output via stimulation of 5HT 3 and 5HT 4 serotonergic and dopaminergic receptors.