Effects Of Gradual High And Low Temperature On Gene Expression And Immune Function Of Black-line Hamster KiSS-1/GPR54

The immune system protects animals against the invading pathogens in the environment,which determines the survival of animals.Reproduction is a very energy consuming physiological process,and it is one of the fitness components.Environmental temperature is an important ecological factor influencing animals’ immune function and reproduction.The striped hamster(Cricetulus barabeniss)distributes mainly in the northern China and show seasonal changes in immune function and reproduction.In the present study,we want to know how high and low temperature would affect immune responses and reproductive capacity.To mimic seasonal changes in temperature,the high and low temperature was to be increased or decreased gradually.The immunological parameters including innate,cellular and humoral immunity,the levels of cytokines were detected to reflect the survival ability,and the gene expression of KiSS-1,Gn RH and GPR54 genes in the hypothalamus,ovary and uterus were also examined to reflect the reproductive capacity.The main results are as follows:1.The body mass and body temperature of striped hamsters were not affected by low temperature.The food intake of hamsters in low temperature group increased significantly from 21 days,and the small intestine and contents,colon and contents also increased significantly.The body mass and body temperature of striped hamsters were not affected by high temperature.The food intake of striped hamsters in high temperature group decreased significantly from 21 days,the stomach and contents increased significantly.High and low temperature had no significant effect on the wet masses of thymus and spleen.2.Low temperature did not affect the blood glucose level,estradiol(E2)and corticosterone(CORT)concentration of striped hamsters,and the blood glucose level,serum leptin and corticosterone concentration were not affected by high temperature,but leptin(LEP)concentration increased significantly in hypothermia group,the serum estradiol concentration of high temperature group was significantly lower than the other two groups.3.Low temperature decreased the serum bactericidal capacity of striped hamsters,but did not affect white blood cells,PHA(Phytohemagglutinin)reaction and serum Ig G,Ig M concentrations,and it did not affect the concents of serum IL-4,IFN-γ,TNF-α.High temperature significantly reduced the serum Ig M concentration of hamsters,and increased the PHA response after 24 hours of PHA injection.The white blood cells,serum Ig G concentration,serum bactericidal ability,the concents of serum IL-4,IFN-γ and TNF-α were not affected by high temperature.High and low temperature had significant effect on the content of serum IL-2 of striped hamsters.The results of correlation analysis showed that: LEP was positively correlated with IL-2,IL-4,IFN-γ and TNF-α.E2 was negatively correlated with PHA response(6h),but positively correlated with IL-2 and TNF-α,which indicates that leptin and estradiol may promote the secretion of IL-2.The enhanced PHA response of striped hamsters under high temperature conditions may be related to the decrease of estradiol content.4.Low temperature did not affect the gene expression of KiSS-1,Gn RH and GPR54 in the hypothalamus,ovary and uterus.High temperature did not affect the gene expression of KiSS-1,Gn RH and GPR54 in hypothalamus,nor did it affect the gene expression of KiSS-1,Gn RH and GPR54 in ovary and uterus.Blood glucose was positively correlated with hypothalamic GPR54 and uterine GPR54,suggesting that blood glucose may promote the expression of GPR54 gene in hypothalamus and ovary.5.Correlation analysis found that,innate immunity was positively correlated with Gn RH expression in hypothalamus,but negatively correlated with Gn RH expression in ovary.Ig M was negatively correlated with Gn RH expression in hypothalamus,IL-2 was positively correlated with KiSS-1 expression in uterus.IL-4was positively correlated with KiSS-1 expression in ovary.Other immune indices such as innate immunity,PHA reaction,and humoral immunity were not correlated with KiSS-1 and GPR54 expression in hypothalamus,ovary and uterus.These results suggest that there may be no trade-off between immunity and reproduction under the condition of gradual high and low temperature.In summary,our results showed that hypothermia inhibited the innate immunity of striped hamsters.High temperature inhibited the humoral immunity of striped hamsters,enhanced the cellular immunity after 24 hours.Low temperature and high temperature did not affect the expression of KiSS-1,Gn RH and GPR54 related genes in striped hamsters.And there may be no trade-off between immunity and reproduction under high or low temperature.