Joint Effects of Heat Stress and PM2.5 Exposure on Glucose Metabolism and Hepatic Insulin Signaling

Background: Heatwave events are occurring more frequently, accompanied by a significant increase in the ambient concentration of fine particulate matter (PM2.5). Epidemiological studies have suggested that heat stress or PM2.5 exposure would impair glucose homeostasis and insulin sensitivity, but the combined effect and the exact mechanisms are not well understood.Methods: C57BL/6 mice were randomly divided into filtered air (FA), fine particulate matter (PM) group, filtered air combined with heat stress (FH) group, and fine particulate matter combined with heat stress (PH) group for a 4-week PM2.5 exposure, followed by a 2-week heat stress exposure, via a whole-body exposure system. Systemic glucose homeostasis, insulin sensitivity, and circulating inflammatory cytokines were examined. HSP72 expression and insulin signaling in the liver were measured.Results: Glucose tolerance and insulin sensitivity were impaired in response to heat stress, accompanied by lessened hepatic GLUT2 expression and inhibited insulin signaling pathway. No synergistic effects of heat stress and PM2.5 exposure on glucose homeostasis were observed, while heat-upregulated HSP72 expression was attenuated with accumulated TNF-α induced by further PM2.5 exposure.Conclusions: Heat stress combined with PM2.5 exposure induced TNF-α, which could inhibit heat-elevated hepatic HSP72 expression. Elevated circulating TNF-α impaired hepatic insulin signaling and GLUT2 expression. Then, glucose homeostasis was perturbed, and insulin action was impaired.

The observation of blood biochemistry and HSP72 expression changing rules in peripheral blood of flying-saucer-athletes under high temperature training

Objective: To study the effect of training under high temperature on blood and heat shock protein 72(HSP72)expression of flying saucer athletes. Methods: The numbers of training group and control group are 30. Twenty-four flying saucer athletes in Zhejiang province were selected and randomly divided into training group and control group, 15 in each group. Peripheral venous blood of each group was taken before and after the experiment. The HSP72 content of lymphocyte, blood routine and biochemical indexes were measured respectively. Results: There was significant difference in white blood cell in training group count before and after the experiment（P< 0.05）. The expression of HSP72 and the white blood cell in training group was higher than that control group（P< 0.05）. Conclusions: Organism could be affected and turned to stress state due to training under high temperature. It is necessary to provide the safeguard for the flying saucer athletes under high temperature in order to prevent the damage.

Impaired heat shock protein 72 expression in women with polycystic ovary syndrome following a supervised exercise programme

Induction of heat shock protein expression and the heat shock (stress) response are seen in exercise. This exercise-induced response is thought protective against cellular stress through the expression of heat shock proteins. The highly inducible heat shock protein 72 (HSP72) has been shown to be expressed in a number of stress-related conditions, but not investigated in women with polycystic ovary syndrome (PCOS). Twenty-one women (10 controls, 11 with PCOS) concluded an 8-week supervised, moderate-intensity exercise programme. Monocytes and lymphocytes were analysed by flow cytometry for HSP72 expression from blood samples prior to, mid-way and at the completion of the programme. The monocyte HSP72 expression showed an increase from baseline values through mid-way (p = 0.025), and at the completion of the programme (p = 0.011) only in the control group, the PCOS group showed no significant change. This pattern was similar for lymphocyte HSP72 expression where a significant increase was found at the completion of the programme (p = 0.01) only in the control group. The magnitude of increased HSP72 expression following completion of the programme was linked to baseline values only in the control group. In conclusion, increased HSP72 expression to exercise over an 8-week period was seen in control but not in PCOS women, suggesting that there is an impairment of HSP72 expression in response to exercise in these women.