Heat stress is an important domain of research in livestock due to its negative impact on production and disease resistance. The augmentation of stress in the body stimulates the antioxidative activity comprising various enzymes (viz., catalase, superoxide dismutase), metabolites (reduced glutathione, etc.), vitamins, minerals, etc. to combat the situation. The major key players involved in regulation of heat shock response in eukaryotes are the transcription factors, called as heat shock factors (HSF). They activate the heat shock protein (HSP) genes by binding to their promoters. Lymphocytes are considered to be the best model to evaluate the immunity in any living body as it contains plethora of white blood cells (WBCs).In this study, the peripheral blood mononuclear cells (PBMC) obtained from non-lactating Sahiwal vis-à-vis crossbred (Holstein Friesian × Sahiwal) cattle with 75% or more exotic inheritance were subjected to heat shock at 39, 41, and 43 °C in three different incubators, in vitro. The cell count and viability test of pre and post heat stress of concerned PBMCs indicated that the crossbreeds are more prone to heat stress as compared to Sahiwal. The reverse transcription PCR (qRT-PCR) expression data revealed an increment in HSF1 expression at 41 °C which subsequently declined (non-significantly) at 43 °C in both breeds post 1 h heat shock. However, the association between the HSF 1 expression and antioxidative activity through correlation analysis was found to be non-significant (P < 0.05), though enzymatic activity appeared to behave in a similar fashion in both breeds at 5% level of significance (P < 0.05). This rule out the role of HSF1 expression level on the activity of enzymes involved in oxidative stress in vitro in zebu and crossbred cattle.
Keywords: Antioxidative enzymes; Crossbred; HSF1; Heat shock; In vitro; PBMC; Sahiwal.