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 f emale rat under ovarian control? METHOD OF STUDY: Ovariectomized rats (OVX), with or without progesterone (O VX-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 a nd sacrificed 3 days later. Cryostat kidney sections were immunohistologica lly stained for the presence of neutrophils and monocytes (MO) and the expr ession of adhesion molecules. RESULTS: After endotoxin, the glomerular number of neutrophils and the numb er of MAC-1 positive cells were increased in luteal-phase and in OVX-P rats , and the number of glomerular MO was increased in luteal-phase, OVX, OVX-E , and OVX-P rats. Endotoxin increased ICAM-1 expression in all groups of ra ts, except in follicular-phase rats. The glomerular number of LFA-1- and VL A-4-positive cells following endotoxin were only increased in OVX rats. CONCLUSIONS: It is concluded that endotoxin-induced monocyte infiltration a nd ICAM-1 expression are inhibited by a factor produced during the follicul ar 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.