The Protection Of Scalp Sites Of Medicine Injection On Brain Injury Of Preterm Rats Caused By Intrauterine Infection

BackgroundWith the improvement of technology in obstetrics and neonatal intensive care, more and more preterm infants have been survival. However, the incidence of brain injury caused by premature is also increasing, followed by the increase of patients with cerebral palsy. Immaturity and vulnerability are two main reasons for brain injury in preterm infants. Periventricular leukomalacia (PVL) is one of the most common forms of brain injury, resulting in several neurological sequelae, such as cerebral palsy, epilepsy, mental retardation, cognitive impairment. These sequelae not only affect the quality of life in these children but also bring spiritual and economic burden for the family. Therefore, it is extremely important for these children to make early diagnosis of the brain injury and to provide effective intervention timely. More and more researchers have focused on the strategies of reducing the sequelae and improving the quality of life in these preterm infants with brain injury.ObjectiveScalp site of medicine injection is a relative new approach to treat brain injury and its mechanism is still unclear. This study is to investigate the effects of scalp sites of medicine injection on expression of myelin basic protein (MBP), neuron-specific enolase (NSE), glial fibrillary acidic protein (GFAP) in brain tissue of preterm rats caused by intrauterine infection. We also test the neurobehavioral change in these animals to confirm the protective effect of scalp sites of medicine injection, which might provide a theoretical basis for clinical treatment for preterm infants with brain injury.Materials and methods50female (250±20g) and25male (280±20g) Wistar rats with clean grade (purchased from Experimental Animal Center of Henan Province) were combined in one cage to make them breed at5pm. Vaginal secretions were tested under an optical microscope the next8am. Gestation0(GO) was defined if sperms were found in the secretions.37pregnant rats were randomly subjected to intraperitoneal injection of lipopolysaccharide (LPS,350μg.Kg-1, n=32) or9g.L-1saline (n=5) on gestation16d and17d.The preterm pups (birth before gestation22d) in the LPS group were respectively treated with scalp sites of VitB1, VitB12injection (group A), ample environment intervention (group B) and no intervention (group C) from postnatal7(P7). Pups suffered from perfusion on P7and P25. Immunohistochemistry was performed for measure of MBP, NSE and GFAP, and neurological behavior was processed before the sacrifice on P25.Data was presented as χ±S and SPSS17.0was used to analyze the difference. Independent-sample T test was used when comparing means between two groups and ANOVA (Fischer’s LSD) were used among three groups. P<0.05indicates a statistical difference.Results1. HE StainingA total of14pregnant rats in LPS group made delivery before gestation22days, and the placental tissues in these rats had obvious congestion and edema with massive neutrophils infiltration, as shown as HE staining. However, none of rats in vehicle group generated preterm pups, and the placental tissues showed no vascular congestion or inflammation.2. Immunohistochemistry StainingThe expressions of MBP and NSE in LPS P7pups were significantly lower than that in9g.L-1saline group (P<0.01; P<0.05), whereas the GFAP positive cells both in cortex and hippocampus dentate gyrus (DG) were more than that in vehicle group (P<0.05; P<0.05); In P25time point, group A and group B had much higher expression of MBP than group C (P<0.01, P<0.01). Group C had lower expression of NSE than group A (P<0.01) and B (P<0.01). The GFAP positive cells of cortex in group A and B are significantly less than group C (P<0.01, P<0.05). However, only group B had less GFAP positive cells in DG area than group C (P<0.05).3. Results of Behavioral TestIn the neurologic behavior, the scores of suspension tests in group A were much higher than group C (P<0.01), so is the group B (P<0.01). Importantly, both group A and group B had a higher score in open field test than group C, with a significant P value (P<0.01; P<0.01). In the slope test, there was a significant difference between any two of the three groups, among which group B got the shortest time, and group A got a shorter time than group C(P<0.01).Conclusion1. LPS-induced intrauterine infection can result in premature delivery.2. Scalp sites of drug injection has protective effect for preterm rats caused by intrauterine infection3. Scalp sites of drug injection can increase the expression of MBP/NSE and inhibit the over expression of GFAP in brain tissue with preterm rats, which are beneficial for the improvement of neurobehavioral.