OBJECTIVETo investigate the impact of intrauterine infection induced by LPS injection on long-term brain development of premature rats.

METHODSEighteen day-gestation pregnant rats were randomly assigned to a control group receiving an intraperitoneal injection of normal saline, and two infection groups that were intraperitoneally injected with 0.3 mg/kg or 0.6 mg/kg LPS. Twenty-four hours after injection, 7 pregnant rats of each group were sacrificed. The pathological changes of the placenta after hematoxylin and eosin staining were observed under a light microscope. The neural cell apoptosis of fetal brains was examined by the TUNEL assay. The remained pregnant rats were induced to labour before 21 gestation days. The long-term brain development of premature rats was tested with the Y type electric maze on postnatal day 42.

RESULTSObvious pathological changes were observed in the placenta in the infection groups. The apoptotic neural cells in the fetal brain increased in the infection groups compared with that in the control group (32.41+/-5.36 in the 0.3 mg/kg infection group and 66.41+/-7.61 in the 0.6 mg/kg infection group vs 8.00+/-0.36 in the control group; P<0.01). The number of trials to criterion in the Y type maze test in the infection groups was much more than that in the control group [117.8+/-8.7 (0.3 mg/kg infection group) and 194.4+/-13.7 (0.6 mg/kg infection group) vs 56.8+/-3.7 (control group); P<0.01]. The number of correct reactions in memory retaining in the infection groups was lower than that in the control group (0.62+/-0.09 in the 0.3 mg/kg infection group and 0.37+/-0.09 in the 0.6 mg/kg infection group vs 0.92+/-0.06 in the control group; P<0.05).

CONCLUSIONSIntrauterine infection can cause fetal rats' neural cell apoptosis and affect adversely long-term brain development of neonatal rats.