Abstract
The objective was to characterize effects of Escherichia coli LPS (given i.v.) on corpus luteum (CL) and embryonic viability in early pregnant cattle. Eight non-lactating German Holstein cows were given 0.5µg/kg LPS on 35±3 day (mean±s.e.m.) of pregnancy, whereas seven heifers, 41±6 day pregnant, were given 10mL saline (control group). Transrectal B-mode examinations of the CL were done at −1, 3, 6, 12, 24, 48, 72 and 96h relative to treatment. Blood samples were collected at −1, 0.5, 1, 2, 3, 4, 6, 9, 12, 24, 48, 72 and 96h. At 12 and 48h, the CL was biopsied. None of the cows still in the experiment 10 day after LPS (n=7) had embryonic loss. In LPS-treated cows, luteal area decreased (from 4.1 to 3.1cm2; P≤0.05) within 6h and until 48h. Luteal blood flow decreased by 39% (P≤0.05) within the first 6h after LPS, but returned to pre-treatment values by 48h. Plasma P4 decreased by 62% (P≤0.05), reached a nadir (2.7±0.6ng/mL) at 12h after LPS and was not restored to pre-treatment (P≤0.05). In luteal tissue, mRNAs for STAR and for FGF1 were lower (P≤0.05) in LPS than in saline-treated cattle at 12h, with no difference between groups at 48h. Levels of mRNAs for CASP3 and FGF2 were not different between groups (P>0.05) at 12 or 48h after treatment. In conclusion, LPS transiently suppressed CL function, but did not induce embryonic mortality.