Effect of estradiol and progesterone on the low-dose endotoxin-induced glomerular inflammatory response of the female rat.

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 (MO) 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.