Suppression by developing ovarian follicles of the low-dose endotoxin-induced glomerular inflammatory reaction in the pregnant rat

Objective: In the current study the role of developing ovarian follicles in the control of the endotoxin-induced pregnancy-specific inflammatory reaction was evaluated. Study Design: Follicular development was induced in pregnant rats (n = 20) by means of daily intraperitoneal injections of follicle-stimulating hormone from day 11 of pregnancy until the end of the experiment. Control pregnant rats (n = 20) received daily sodium chloride injections. All pregnant rats were infused for 1 hour with either 2 mL endotoxin solution (1.0 μg/kg body weight) or 2 mL sodium chloride solution on day 14 and killed 4 hours or 3 days later. At death, the left kidneys were snap-frozen and immunohistologically stained for the presence of polymorphonuclear leukocytes and monocytes. Results: The results show that in control pregnant rats endotoxin significantly increased glomerular polymorphonuclear leukocyte and monocyte numbers at both 4 hours and 3 days after endotoxin infusion. Induction of follicular development did not affect glomerular polymorphonuclear leukocyte number after endotoxin infusion but significantly decreased the number of monocytes in the glomeruli at both 4 hours and 3 days after endotoxin infusion. Conclusion: We conclude that follicles stimulated with follicle-stimulating hormone produce a follicular factor or factors that are able to prevent the endotoxin-induced influx of monocytes into the glomeruli of pregnant rats. It is suggested that these factors play a role in the control of inflammatory processes associated with reproduction, including the disease of pregnancy, preeclampsia. (Am J Obstet Gynecol 2000;183:89-93.)