Pharmacologic doses of interleukin 8 suppositories induce follicular maturation in rabbits

Interleukin 8 (IL-8) is a neutrophil chemoattractant/activating factor that plays a role in the ovarian physiology leads to investigate the effects of IL-8 on follicular maturation. Experiments were conducted using suppositories containing 100 ng, 200 ng, 400 ng IL-8, 500 microl Witepsol-base (control), human menopausal gonadotropin (im) and conjugate of fluorescein isithiocyanate-labelled IL-8. The levels of IL-8 in ovarian fluid were also measured. Histology of ovaries treated with 200 ng IL-8 showed large antral follicles filled with follicular fluid. The theca layer was divided into an interna and an externa with large extracellular spaces. The granulosa cells were loosened and appeared to be detaching from the granulosa layer. Neutrophils were localized predominantly in the theca and medulla (P<0.0001, P<0.004), and relative collagen concentration was significantly decreased in ovaries of 200 ng IL-8 (P<0.0001) compared with controls. The IL-8 was detected in ovarian fluid after 6 h (P<0.0001), 12 h (P<0.001), and 18 h (P<0.01) compared with 0 h. Fluorescein isithiocyanate-labelled IL-8 conjugate was seen in the follicular wall and endometrium. We conclude that pharmacological dosage of exogenous IL-8 exerts an effect on follicular maturation through granulocyte chemotaxis and activation.