Effect of zinc treatments on lead exposed periparturient bovine lymphocytes in vitro on their proliferation and superoxide dismutase (SOD) expression

Abstract

The study was conducted to observe adverse effects of lead (Pb) treatments and protective effect of zinc on lymphocyte proliferation and to quantify the expression levels of superoxide dismutase (Cu/ZnSOD) genes involved in antioxidant’s defenses in periparturient Karan Fries (Tharparker × Holstein-Friesian) cow. Blood samples were collected from peripartum Karan Fries cow at 30 and 15 days prepartum, at day of calving (0 day) and 15 and 30 days postpartum for estimation of lymphocytes proliferation and SOD expression. A fixed number of cells (2×106) were grown in culture for 72 h with different levels of Pb (10–4, 10–5, 10-6 M) and their adverse effects were counteracted by Zn (50, 55, 60 μM) and analysed for the lymphocyte proliferation (MTT assay) and for the expression level of Cu/ZnSOD using the realtime PCR technique with light upon extension (LUX) fluorogenic primers. Pb dosage had no adverse effect and the overall mean proliferation values indicated that 60μM Zn may be optimum for maximizing lymphocyte proliferation. The Cu/ZnSOD mRNA expression in lymphocytes was higher at higher dosage of Pb in comparison to lower dosage in all the 3 (50, 55, 60 μM) Zn treatments. There was no significant difference at different levels of Zn on SOD expression. Cu/ZnSOD mRNA expression decreased from –30 days to 0 days but increased from 0 to 30 days after calving. The results suggested that the zinc may have an ameliorative effect on lead exposed oxidative stress on lymphocytes proliferation and Cu/ZnSOD mRNA expression through modulation of superoxide dismutase expression