Glutamine supplementation attenuates intestinal apoptosis by inducing heat shock protein 70 in heatstroke rats

Abstract

BACKGROUND: Heatstroke is the most hazardous heat-related illness and has a high fatality rate. We investigated whether glutamine supplementation could have a protective effect on heatstroke rats. METHODS: Twenty-five 12-week-old male Wistar rats (weight 305±16 g) were randomly divided into a control group (n=5), heatstroke (HS) group (n=10), and heatstroke+glutamine (HSG) group (n=10). Seven days before heat exposure, glutamine (0.4 g/[kg·d]) was administered to the rats in the HSG group by gavage every day. Three hours after heat exposure, serum samples were collected to detect white blood cells, coagulation indicators, blood biochemical indicators, and inflammatory cytokines in the rats. The small intestine tissue was stained to analyze pathological structural changes and apoptosis. Finally, immunohistochemistry and Western blotting were used to analyze the expression levels of heat shock protein 70 (HSP70). Multiple comparisons were analyzed by using one-way analysis of variance, and the Bonferroni test was conducted for the post hoc comparisons. RESULTS: After heat exposure, the core temperature of the HS group (40.65±0.31 °C) was higher than the criterion of heatstroke, whereas the core temperature of the HSG group (39.45±0.14 °C) was lower than the criterion. Glutamine supplementation restored the increased white blood cells, coagulation indicators, blood biochemical indicators, and inflammatory cytokines that were induced by heatstroke to normal levels. The intestinal mucosa was injured, and the structure of tight junctions was damaged in the HS group; however, the structure of intestinal mucosal epithelial cells was stable in the HSG group. Glutamine supplementation alleviated intestinal apoptosis and up-regulated HSP70 expression. CONCLUSION: Glutamine supplementation may alleviate intestinal apoptosis by inducing the expression of HSP70 and have a protective effect on heatstroke rats.