The rat intraovarian interleukin (IL)-1 system: cellular localization, cyclic variation and hormonal regulation of IL-1β and of the type I and type II IL-1 receptors

Abstract An increasing body of evidence supports the possibility that intraovarian interleukin (IL)-1 plays an intermediary role in the periovulatory cascade. To gain further insight into the intraovarian IL-1 hypothesis, we studied the cellular localization cyclic variation and hormonal regulation of IL-1β, as well as of the type I and type II IL-1 receptors (IL-1R) in immature rats. In situ hybridization localized IL-1β and type I IL-1R transcripts to the granulosa cell compartment, the innermost layers of the theca interna and to the oocyte of the untreated immature ovary. Molecular probing of whole ovarian material in the course of a simulated estrous cycle revealed a progressive preovulatory increase in IL-1β and type I IL-1R transcripts to an in vivo peak at the time of ovulation (3.0- and 2.5-fold increases over untreated controls; P P P P