Using Proteomics To Analyze The Effect Of Heat Stress On Hypothalamus,Pituitary And Rumen Functions In Dairy Cows

Based on the proteomics and bioinformatics methods,this study revealed the mechanism of the effect of heat stress on the hypothalamus and pituitary of dairy cows by comparing the proteomic changes in the dairy cows under heat stress and heat stress-free.The main research contents and results are as follows:1.Proteomics analysis of hypothalamus tissue in cows under heat stress:In this experiment,the proteome of hypothalamus of six cows under heat stress and heat stressfree were compared and analyzed by liquid chromatography mass spectrometry(LCMS)/MS-dependent.The results showed that a total of 3,384 proteins were identified in the two groups,50 of which were differentially expressed in hypothalamus tissue between the two groups.Unique proteins in hypothalamus participate in regulating energy metabolism under heat stress,and the up-regulated proteins in hypothalamus tissues of the heat stress groups were mainly involved in Thyroid hormone signaling and Glucagon signaling pathway.Western Blot results show that the expression of SOD1,GLS and PLCB1 in hypothalamus of the heat stress were significantly higher than those of the heat stressfree(P<0.01).2.Proteomics analysis of pituitary tissue in cows under heat stress:In this experiment,the proteome of pituitary of six cows under heat stress and heat stress-free were compared and analyzed by liquid chromatography mass spectrometry(LCMS)/MSdependent.The results showed that a total of 3,891 proteins were identified in the two groups,129 of which were differentially expressed in pituitary tissues between the two groups.Unique proteins in pituitary are involved in maintaining the secretory function of cells under heat stress,and the up-regulated proteins in pituitary tissues of the heat stress groups were mainly involved in Protein processing in endoplasmic reticulum,Ribosome,Protein export and Aminoacyl-t RNA biosynthesis pathway.Western Blot results showed that the expression of HSPA5,HSP90B1 and SOD1 in pituitary of the heat stress were significantly higher than those of the heat stress-free(P<0.01),and the expression of PLCB1 of the heat stress-free group were significantly higher than that of the heat stress group(P<0.01).3.Proteomics analysis of rumen tissue in cows under heat stress:In this experiment,the proteome of rumen of six cows under heat stress and heat stress-free were compared and analyzed by liquid chromatography mass spectrometry(LCMS)/MSdependent.The results showed that a total of 3704 proteins were identified in the two groups,36 of which were differentially expressed in rumen tissues between the two groups.Unique proteins in rumen are involved in maintaining the defense and homeostasis under heat stress,and the up-regulated proteins in rumen tissues of the heat stress groups were mainly involved in in the processes of pyruvate metabolism,tricarboxylic acid cycle,and maintenance of protein homeostasis.Heat stress may reduce protein synthesis by activating glucagon secretion,D-glutamine and D-glutamate metabolic pathways in the hypothalamus,increasing the energy level of the internal environment,and maintaining normal activities of tissues and the body;molecular chaperones and transmembrane transporters in the endoplasmic reticulum was activated,enhancing the protein processing and transporting in the cell,weakens the endoplasmic reticulum stress,maintains protein homeostasis,and reduces the stress of the pituitary gland.The energy metabolism was changed to adjust to the heat stress by activating key enzymes.In addition,under heat stress,the biological regulation of the hypothalamus and pituitary gland of dairy cows is strengthened,the cell’s antioxidant capacity is improved,and excessive free radicals can be eliminated in time to reduce damage caused by oxidative stress.