Protection Of Gynostemma Pentaphyllum Polysaccharides On Oxidative Damage Of Liver In Mice By Heat Stressed

High temperature can break the balance of body temperature regulation of animals,cause oxidative stress,and lead to the decline of animal production performance and damage to health.The liver is not only the most important organ of synthesis and metabolism in animal body,but also the main organ of stress response.In order to investigate the protective effect of Gynostemma Pentaphyllum polysaccharide(GPP)on liver oxidative injury induced by heat stress(HS),mice were randomly divided into blank control group,HS group,GPP-L group(50mg/kg),GPP-M group(100mg/kg)and GPP-H group(200mg/kg).The body weight,liver index,liver morphology and function,liver antioxidant capacity,Nrf2 signal pathway and the expression of heat shock protein related factors in mice were detected,The main results were as follows:(1)During the period of polysaccharide injection,the body weight of mice in GPP-H group was significantly higher than that in HS group during heat stress(P< 0.05).(2)The liver index of GPP-M and GPP-H groups was significantly higher than that of HS group and GPP-L group(P< 0.05),but there was no significant difference with the blank control group,the steatosis,necrosis and bleeding of liver in GPP-M and GPP-H groups were significantly decreased,and the ratio of hepatic cord area in GPP groups was significantly higher than that in HS group(P< 0.05).(3)GPP can enhance the antioxidant activity of mouse liver under HS condition.The content of ROS in GPP-M group was significantly lower than that in HS group(P< 0.05),the contents of CAT and SOD in GPP-M group were significantly higher than those in HS group(P< 0.05),the contents of GSH-Px and T-AOC in all dose groups of GPP were significantly higher than those in HS group(P< 0.05),and the contents of MDA,ALT,AST and ALP in each dose group of GPP were significantly lower than those in HS group(P<0.05).(4)GPP could up-regulate the expression of heat shock protein-related factors in the liver of mice under HS condition.The m RNA expression levels of HSP27 and HSP90 in GPP-M group and GPP-H group were significantly higher than those in HS group(P< 0.05),the m RNA expression of HSP70 in GPP-M group was significantly higher than that in HS group(P< 0.05),and the average optical densities of HSP27,HSP70 and HSP90 in GPP-M groups were significantly higher than those in HS group(P< 0.05).(5)GPP could activate Nrf2 signal pathway and activate the expression of a large number of downstream antioxidant genes in the liver of heat stressed mice.The m RNA expression of Nrf2,HO-1,NQO1,CAT,GPX and SOD in GPP-M and GPP-H groups was significantly higher than that in HS group(P<0.05),and the expression levels of Nrf2 and HO-1 in GPP-L and GPP-M groups were significantly higher than those in HS group(P< 0.05).In conclusion,GPP can relieve the weight loss,liver index decrease and liver function index of heat stress mice,and effectively alleviate the morphological and structural damage of liver caused by heat stress;it can protect the liver and antioxidant injury by up-regulating the expression of heat shock protein and activating Nrf2 signal pathway;GPP-M group had the best protective effect on the liver of heat stress mice.