suppresses progesterone production in vitro by granulosa cells of laying hens

It is known that high environmental temperature (heat stress, HS) significantly reduces egg production, in part at least through disruption of reproductive hormones, progesterone P4, luteinizing hormone (LH), and estrogen. There are many well-documented systemic effects of HS that may affect these hormones, but very little is known about local mechanisms through which HS acts. IL-1 is increased by stress, including HS, and recently, in mammals, it has been shown that cytokines interleukin-1α and β (IL-1α, IL- 1β) play a role in ovarian function. The role(s) of cytokines in the bird remains unclear. The aim of this study was to determine whether IL-1β has a role in ovarian function of the laying hen and whether it might be a viable candidate for HS-induced reductions in the granulosa cell production of P4. The largest preovulatory follicles (F1) were collected from laying hens, and the granulosa cells dispersed enzymatically. The granulosa cell preparation was divided into two equal portions and each was incubated in RPMI medium with (IL treatment) or without (Control) 100ng IL-1β per ml for 5h at 39C, washed, and viability determined. Approximately 100,000-viable cell aliquots from both abstracts of papers 51 IL and Control incubations were further incubated in duplicate in 1.8 ml RPMI; cells from the IL treatment were incubated with 70ng/ml IL-1β and with (IL+LH) or without (IL-LH) 100ng LH for an additional 4h at 39C. Control cell aliquots were also incubated for the additional 4h with (Control+LH) or without (Control) LH. P4 was measured in the supernatant by RIA. Compared to basal production of P4 (from Control cells), P4 in Control+IL samples was significantly (P=0.0001) lower. LH stimulation increased (P=0.0001) P4 in both Control+LH (by ≥600%) and IL+LH (by ≥500%) samples, but P4 was lower (P=0.057) in samples incubated with IL-1β. We hypothesize that IL-1β does plays a role in ovarian function of hens and that HS may induce macrophages to produce it