Intrauterine endotoxin infusion in rat pregnancy induces preterm delivery and increases placental prostaglandin F-2 alpha metabolite levels

OBJECTIVE: This study was designed to examine the effects of intrauterine e ndotoxin (lipopolysaccharide) on rat pregnancy. STUDY DESIGN: Pregnant Sprague-Dawley rats (N = 26) were implanted with ute rine catheters on day 15 or 16 of a 22-day gestation. Animals were randomly assigned to receive either lipopolysaccharide (25 or 50 mu g) or sodium ch loride solution (1 mL) on day 17 and then were either sacrificed on day 19 or observed until delivery. Placentas were harvested at the time of death, homogenates were prepared, and prostaglandin F-2 alpha metabolite levels we re determined by means of radioimmunoassay. Data were analyzed by analysis of variance, Student-Newman-Keuls, and Mann-Whitney tests. RESULTS: Lipopolysaccharide-treated groups (25 and 50 mu g) displayed a sho rter interval to delivery (mean +/- SE, 82 +/- 13 and 63 +/- 8 hours, respe ctively) than control animals (117 +/- 3 hours). Pups of lipopolysaccharide -treated (25 and 50 mu g) female animals had lower live birth weights (4.92 +/- 0.01 and 5.12 +/-: 0.24 g, respectively) compared with control animals (6.04 +/- 0.07 g). Placental homogenates from lipopolysaccharide-treated f emale animals contained higher levels of prostaglandin F-2 alpha metabolite (1567 +/- 64 and 1475 +/- 59 pg/mL) than those from sodium chloride soluti on-infused control animals (804 +/- 68 pg/mL). CONCLUSION: Bacterial products induce the preterm delivery of low-birth-wei ght pups in rats, possibly by increasing local prostaglandin biosynthesis.