Abstract

The aim of the present study is to investigate the effect of experimentally induced bacterial mastitis on mammary gland biochemical and oxidative stress parameters in lactating mice. 25 Lactating mice were divided into five groups, PBS vehicle served as control and four induced groups of 5 mice each i.e., Lipopolysaccharide (LPS) an endotoxin, Staphylococcus aureus, Escherichia coli and Bacillus subtilis were used to induce mastitis by intramammary inoculation into the mammary gland of mice. Clinical observations, rectal temperature (ºC) of mice and body weight (g) were recorded for every 12 h of post infection during the study period. After 48 h of infection blood was collected through cardiac puncture for analysis of oxidative stress parameters, mice were euthanized and mammary glands were dissected out for the evaluation of biochemical contents such as DNA, RNA, protein, glycogen, cholesterol, lactate dehydrogenase (LDH), succinic dehydrogenase (SDH), acid phosphatase (ACP), alkaline phosphatase (AKP) activities and oxidative stress parameters such as, levels of glutathione (GSH), thiobarbaturic acid reactive substances (TBARS); superoxide dismutase (SOD), catalase (CAT) and glutathione-S-transferase (GST) activities. Histopathological responses of the tissue damage were studied. The results exhibited contrasting indications depicting the effects of experimentally induced bacterial mastitis on mammary gland biochemical and oxidative stress parameters in lactating mice. There was a significant decrease in biochemical contents such as DNA, RNA, protein, glycogen levels with increased cholesterol level in the induced groups compared to control group. LDH and AKP activities were significantly increased with decreased SDH and ACP activities compared to control group. Equally oxidative stress parameters such as level of GSH and SOD, CAT and GST activities were decreased with increase in the level of TBARS in induced groups compared to control group of both mammary gland tissue and blood serum. Histopathological evidences revealed massive infiltration of polymorphonuclear neutrophil leukocytes (PMN), damage of alveoli and secretory products in the induced groups compared to control group of the mammary gland tissue.