Interleukin-1β (IL-1β) reduces the activity of 3β-hydroxysteroid dehydrogenase (3β-HSD) in granulose 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 (E2). There are many well documented systemic effects ofHS that may affect these hormones, but very little is known about local mechanisms through which HS acts. Interleukin-1 is increased by stress, including HS, and recently, in mammals, it has been shown that cytokines interleukin-1α and IL-1β play a role in ovarian function. The role(s) ofcytokines in the bird remain unclear. The aim ofthis study was to determine the effect ofHS and IL-1β on the activity of3 β-HSD, one ofthe major enzymes involved in steroidogenesis, in the granulose cells (GC) ofthe laying hen. Two groups ofhens were used in this study; one group was subjected to 24C, 30%RH (control), the other group to 36C, 60%RH (HS treatment). At the end ofHS, the F1 follicles were collected from both groups and the GC dispersed enzymatically. The GC preparation from the control group was divided into three aliquots. One served as a control for the HS treatment; the other two were incubated with 100ng/ml IL-1β or without IL-1β (IL control) for 5h at 39C. Approximately 10,000 viable GC from each treatment were incubated in 1.5 ml ofmedium (PBS, pregnenolone, NAD, and nitroblue tetrazolium, pH 7.4) using 24-well flat-bottom plates at 39C for 90 min. After the incubation period, wells were examined with inverted microscope for dark blue formazan precipitate. A total of at least 100 cells per sample were examined to determine the percentage ofcells that stained positive for 3β-HSD (dark blue cells). Both HS and IL-1β significantly reduced the percentage of3 β-HSD positive cells (P=0.000, 0.053, respectively). We hypothesize that HS reduces the activity of3 β-HSD in the granulosa, and that reduction may be in part, at least, mediated through IL-1β