mRNA expression of apoptosis-related genes in mammary tissue and milk cells in response to lipopolysaccharide challenge and during subclinical mastitis

摘要

Two experiments were conducted to investigate alterations of mRNA expression of apoptosis-related genes (Caspase-3, Caspase-7 and Fas) by means of real-time reverse transcriptase-polymerase chain reaction. Experiment I (6 cows) was performed on mammary tissue during intramammary lipopolysaccharide {LPS) challenge. All genes under study showed a significant increase of mRNA expression in LPS treated quarters compared to NaCI treated quarters. Highest expression levels were already reached within 3-6 hafter LPS application.Experiment 11 included a total of 15 cows. All control animals (8) had a somatic cell count {SCC) < 150.000 cells/ml in all quarters. Another seven cows had partially elevated SCC with at least one quarter > 150.000 cells/ml and one quarter with < 150.000 cells/ml. Milk cells weresampled the day before and udder tissue after slaughter and subjected to real-time RT-PCR. Milk cells did not show significant differences in mRNA expression comparing control quarters with those having elevated SCC. In udder tissue Fas and Caspase-3 expression was significantly higher in quarters with elevated SCC. In summary, apoptosis-related gene expression in mammary tissue is altered during mastitis which is possibly one important factor in immune defence of the mammarygland under various in-vivo conditions.