PROBLEM: Is the endotoxin-induced glomerular inflammatory response of the female rat under ovarian control?
METHOD OF STUDY: Ovariectomized rats (OVX), with or without progesterone (OVX-P) or estradiol (OVX-E) treatment, as well as rats in the follicular or luteal phase of the ovulatory cycle were infused with endotoxin or saline and sacrificed 3 days later. Cryostat kidney sections were immunohistologically stained for the presence of neutrophils and monocytes (MØ) and the expression of adhesion molecules.
RESULTS: After endotoxin, the glomerular number of neutrophils and the number of MAC-1 positive cells were increased in luteal-phase and in OVX-P rats, and the number of glomerular MØ was increased in luteal-phase, OVX, OVX-E, and OVX-P rats. Endotoxin increased ICAM-1 expression in all groups of rats, except in follicular-phase rats. The glomerular number of LFA-1– and VLA-4-positive cells following endotoxin were only increased in OVX rats.
CONCLUSIONS: It is concluded that endotoxin-induced monocyte infiltration and ICAM-1 expression are inhibited by a factor produced during the follicular phase, probably by developing follicles. Infiltration of neutrophils and expression of MAC-1, LFA-1, VLA-4 seem to be under control of progesterone or estradiol.