Role of prostaglandins in pathogenesis of bovine mastitis induced by Escherichia coli endotoxin
Giri, S.N.; Chen, Z.; Carroll, E.J.; Mueller, R.; Schiedt, M.J.; Panico, L.
American Journal of Veterinary Research 45(3): 586-591
1984
ISSN/ISBN: 0002-9645 PMID: 6370059 Document Number: 223959
Four doses (5 to 100 micro g, 1 dose/quarter) of E. coli endotoxin were introduced into lactating mammary glands of 2 cows. There was no effect on milk prostaglandin (PG) E2 concentration, except that the concentration was increased from 200 pg/ml of milk to 1060 pg/ml at post-treatment hour (PTH) 8 in cow 1 and from 75 to 420 pg/ml at PTH 4 in cow 2 after the highest dose 100 micro g. Endotoxin caused a dose-dependent increase in milk PGF2 alpha concentrations in both cows. After the highest dose, PGF 2 alpha was maximally increased from 200 to 3500 pg/ml at PTH 4 in cow 1 and from 250 to 2000 pg/ml in cow 2 at PTH 8. The instillation of 50 micro g of endotoxin in all 8 quarters of 2 more lactating cows caused no significant changes in milk PGE2 and thromboxane B2 concentrations, whereas milk PGF2 alpha was significantly increased from the base-line value of 642 to 2683, 1189, and 2281 pg/ml at PTH 4, 8, and 12, respectively. The 6-keto-PGF1 alpha was also significantly increased from the base-line value of 305 to 871, 631, and 600 pg/ml at the corresponding times, respectively. A sharp increase in vascular permeability, as judged by high concentrations of serum albumin in the whey, was observed as early as PTH 4 and peaked at PTH 12 followed by a gradual decline, although it remained significantly increased over the control for 48 hours after treatment. Somatic cell counts in milk gradually increased and peaked at PTH 12 followed by a precipitous decrease at PTH 24. However, cell counts remained significantly increased over the control for 60 hours. Seemingly, metabolites of arachidonic acid might be involved in endotoxin-induced mastitis.