Role of MAPKs in HSP70's Protection against Heat Stress-Induced Injury in Rat Small Intestine.

Yue Hao,Jielei Li,Yuejin Feng,Xianhong Gu

doi:10.1155/2018/1571406

Abstract

Aim To evaluate the role of heat shock protein 70 (HSP70) on the MAPK pathway activation with quercetin treatment and its protection against small intestine impairments of heat stressed rats. Methods Forty-eight male Sprague-Dawley rats aged 6 weeks were randomized to three groups (n=16/group), namely, control (CON), heat stress (HS), and heat stress + quercetin (HQ). The experiment lasted for 14 days with daily 50 min of heat stress treatment (43°C) for the HS and HQ groups. Rats of HQ group were intragastrically given 0.5 ml quercetin solution (50 mg/kg body weight) before the heat stress treatment. Half of the animals were sacrificed on day 7 and the rest on day 14 for tissue sampling. Intestinal morphology, small intestine morphology and permeability, protein expression of HSP70, phosphorylation of extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), p38 mitogen-activated protein kinase (MAPK), and caspase-3 activity were examined. Results Heat stress caused morphological damage to the small intestine and increased intestinal permeability. HSP70 expression and MAPK activity in the small intestine were increased by heat stress. Inhibition of HSP70 by quercetin did not change intestinal permeability compared with the HS group but aggravated intestinal injury and affected the activation of MAPKs and caspase-3. Conclusions HSP70 may modulate stress-activated signaling and acts in a protective manner via MAPK signaling. Affecting HSP70 protective mechanisms could be useful for protection against heat stress-induced injury in rat small intestine.

Highlights

As a result of global warming, heat stress has become one of the main environmental stressors that negatively affects animal performance, health, and economy [1, 2]
These results indicated that heat shock protein 70 (HSP70) expression had no significant effect on body weight under heat stress
We investigated the involvement of HSP70 in the induction of mitogen-activated protein kinase (MAPK) and the mechanism of protection of intestine after heat stress

Summary

Introduction

As a result of global warming, heat stress has become one of the main environmental stressors that negatively affects animal performance, health, and economy [1, 2]. HSPs play an important role in the survival of stressed cells and the stabilization of the internal environment [10]. Recent studies reported that there was a correlation between protective HSP70 expression and activation of the MAPK pathway [20, 21]. To the best of our knowledge, the exact role of HSP70 in MAPK signaling pathways under heat stress remains unknown, especially in animal models. Quercetin inhibits the HSP70-mediated protective effects against endoplasmic reticulum stress-induced apoptosis [28]. We hypothesize that inhibition of HSP70 by quercetin would exacerbate intestinal injury and the involvement of MAPK pathway in this effect is expected. Quercetin was applied in present study to examine the role of HSP70 expression on activation of the MAPK pathway in the small intestine of heat stressed rats

Materials and Methods

Results

Conclusion