Is interleukin-1α a luteotrophic or luteolytic agent in cattle?

Abstract

Cytokines are thought to regulate prostaglandin (PG) secretion in the bovine endometrium. However, there is no consensus about the role of interleukin-1α (IL1A) on PG secretion. The objective of this study was to examine the influence of IL1A on basal and interferon-τ (IFNT)-regulated PGin vitrosecretion, as well its effects on PG secretion, progesterone (P4) output, and corpus luteum (CL)in vivolifespan. Explants of bovine endometrium (days 16–17 of the estrous cycle or early pregnancy) were stimulated with IL1A (10 ng/ml), IFNT (30 ng/ml), or IL1A combined with IFN. IL1A alone strongly stimulated luteotrophic PGE2secretion by endometrial tissues of both pregnant and nonpregnant cows. IL1A also stimulated luteolytic PGF2αoutput in the late luteal phase. IFNT augmented the stimulatory effect of IL1A on PGE2secretion. In anin vivoexperiment, saline or IL1A at different doses (0.001–10 μg/per animal) was applied to the uterine lumen on day 16 of the cycle. Only the highest dose of IL1A caused a temporal increase in PGF2αsecretion, while it had no effect on P4secretion or CL lifespan. Application of 0.1 and 1 μg IL1A stimulated P4and PGE2output and prolonged the CL lifespan. Although IL1A may stimulatein vitroluteolytic PGF2αsecretion during the estrous cycle, it only acts as a luteotrophic factorin vivo. IL1A increased luteotrophic PGE2and P4output, inhibiting spontaneous luteolysis. These luteotrophic effects may result in appropriate luteal development and function in cows during the estrous cycle and early pregnancy.