Contents of myelin-basic protein and S-100 in serum and brain tissue of neonatal rats with intrauterine infection-caused brain injury

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Abstract

BACKGROUND:

The change of the content of myelin basic protein (MBP) in serum and brain tissue is the biochemical diadynamic index of amyelination. S-100 is a specific and sensitive marker of central nervous system (CNS) injury. Whether or not the content of S-100 and MBP in blood and brain tissue can be used as the quantitative index for early diagnosing the intrauterine infection-caused brain injury still needs investigation.

OBJECTIVE:

To observe whether or not MBP and S-100 detection can be used as the biochemical indexes for early diagnosing the intrauterine infection-caused brain injury.

DESIGN:

Randomized controlled animal experiment.

SETTING:

Laboratory of Pediatric Neuro-rehabilitation, Medical College of Rehabilitation, Jiamusi University.

MATERIALS:

Sixty female and thirty male common Wistar rats, weighing from 180 to 240 g, were provided by the Experimental Animal Center of Jiamusi University. Reagent: Lipopolysaccharide(LPS, serological type 055: B5, SIGMA Company of USA); MBP enzyme linked immunosobent assay (ELISA) immunoreagent kit (Preclinical Recombination DNA Laboratory, Chengdu Huaxi Medical Center, Sichuan Province); S-100 ELISA immunoreagent kit (Department of Physiology, the Fourth Military Medical University of Chinese PLA) and bovine serum albumin (Haitaike Biotechnology Co.,Ltd.).

METHODS:

This experiment was carried out in the Laboratory of Pediatric Neuro-Rehabilitation, Experimental Animal Center, Department of Pathology and Central Laboratory of Jiamusi University from July 2005 to March 2006. ① Preparation of models and grouping: The female and male rats were placed in one cage at 2:1 at 17:00 o'clock. Vaginal smear was checked at 8:00 on the next morning. Sperm was found and 0 day of pregnancy was recorded. Pregnant rats were bred in another cage. The pregnant 47 rats were randomly divided into 2 groups: control group (n =10) and experimental group (n =37). The experimental pregnant rats were intraperitoneally injected with LPS 500 μg/kg per day at embryonic 18 days in following 2 days. As controls, 10 pregnant rats were intraperitoneally injected with the same dose of normal saline at the same time. ② After delivery, mother rats in both groups were sacrificed, and then the infection status of uterus and placenta was observed through haematoxylin and eosin (HE) staining. A great quantity of neutrophilic leukocytes infiltrated, which was the identification standard. Twenty control neonatal rats and 20 experimental neonatal rats (7 days) were selected randomly. The changes of ultrastructure in cortex, hippocamp, internal capsule and callus were detected under an electron microscope, and MBP and S-100 in serum and brain tissues were detected by ELISA method. ③ t test was used for comparing the differences of measurement data.

MAIN OUTCOME MEASURES:

① The content of MBP and S-100 in serum and brain tissue of neonatal rats between two groups. ② Pathological detection results of uterus and placenta of neonatal rats. ③ Detection results of brain tissue under an electron microscope.

RESULTS:

Forty-seven pregnant rats and forty neonatal rats were involved in the result analysis. ① The content of MBP in serum and brain tissue of neonatal rats: MBP content in brain tissue of neonatal rats in the experimental group was significantly lower than that in the control group (5.898±1.050) μg/L vs. (7.006±1.071) μg/L, t=3.221, P < 0.01], while MBP content in the serum of neonatal rats in the experimental group was significantly higher than that in the control group[(3.912±0.783) μg/L vs. (2.625±0.766) μg/L, t=5.120, P< 0.01]. ② The content of S-100 in serum and brain tissue of neonatal rats: The content of S-100 in brain tissue and serum of neonatal rats in the experimental group was significantly higher than that in the control group, respectively, (6.412±0.820) μg/L vs. ( 5.377±0.712) μg/L;( 3.393±0.550) μg/L vs.( 2.298±0.614)μg/L, t=4.154, 5.791, P < 0.01]. ③ Pathological detection results of uterus and placenta of neonatal rats: Uterine wall and placenta of pregnant rats were found with vascular engorgement and edema, and a great quantity of neutrophilic leukocyte infiltrated. Meanwhile, there was not evident inflammatory reaction in the pregnant rats in the control group. ④ Detection of brain tissue of neonatal rats under an electron microscope: Obvious brain injury was found in the neonatal rats of the experimental rats, but was not found in the control group.

CONCLUSION:

LPS successfully causes intrauterine infection of pregnant rats, and the neonatal rats born by which have obvious brain injury. Through detecting the changes of the content of MBP and S-100 on these animal models, it is concluded that MBP and S-100 can be used as the indexes to early diagnose brain injury, and they are the sensitive biochemical indexes to reflect the extent of early brain injury.

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