Abstract：The experiment was conducted to study the response of bovine mammary epithelial cells induced by heat stress. Bovine mammary epithelial cells were exposed to 42 ℃ as the heat stress model and 38℃ as control, the transcription of targeted genes including heat shock proteins(HSPs) family, apoptosis, mlik protein and fatty acid biosynthesis, were detected by RT-qPCR. Results showed that the mRNA expression level of hsp27, hsp70 and hsp90, and heat shock factor-1(hsf-1) increased after 0.5 h at 42 ℃, and among them hsp70 increased sharply, then decreased with the extended time of treatment. The apoptosis genes Bcl-2 and Bax had different transcription, Bcl-2 upregulated during 24 h, while Bax upregulated first and downregulated later. Heat stress decreased the mRNA level of milk protein and fatty acids genes (α- and β-casein(CSN2), butyrophilin(BTN), and fatty acid synthase), increased transcription of fatty acid biosynthesis correlative genes (acetyl CoA carboxylase (ACACA), proxiomepro liferater activatedreceptor-gama (PPARG), and sterol response element binding protein (SREBF-1)), but did not influence the expression of roxiomepro liferater activatedreceptor-alfa(PPARA). It is suggested that heat shock induced the stress responses of bovine mammary peithelial cells, remarkably impacted the secretion of milk protein and fat, and arose tolerance of cell itself.
