There is considerable evidence that luteolysis in the cow and other species involves components of the immune system. In this study, we examined the expression of the mRNAs for TNF-α, IFN-γ, IL-1β, IL-2, and IL-2 receptor (IL-2R) by reverse transcription-polymerase chain reaction (RT-PCR) using bovine-specific primers. Expression was examined in corpora lutea (CL) of the early (day 5), mid (days 11-12), and late (day 18) luteal phase, and at 1, 4, and 24 hours following a luteolytic dose of prostaglandin (PG) F(2α). Tumor necrosis factor-α, IFN-γ, and IL-1β mRNAs were detectable by RT-PCR at all stages of the cycle examined. Densitometric intensities of the electrophoresed IFN-γ PCR products revealed a drop in RNA expression during late diestrus and at one hour of prostaglandin-induced luteolysis (P < 0.05). The mRNA for TNF-α seemed to remain constant during the cycle, and rose slightly during luteolysis. Interleukin-1β mRNA also did not vary during the cycle or during luteolysis. Finally, expression of mRNAs for IL-2 and IL-2 receptor was not evident in CL by the methods employed in this study. These results are the first to describe mRNA expression for TNF-α, IFN-γ, and IL- 1β in the bovine corpus luteum, and support a role for these cytokines in luteal function and regression.
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