Dha Attenuates Lipopolysaccharide-induced White Matter Injury In The Neonatal Rat Brain

Objective White matter (WM) lesion is frequently associated with cerebral palsy. Growing evidence has indicated that in addition to ischemia/reperfusion injury, cytokine-induced brain injury associated with maternal or fetal infection may also play an important role in the pathogenesis of PVL. Recent studies have shown that administration of lipopolysaccharide (LPS) to pregnant rats causes enhanced expression of the cytokines, i.e., IL-1β, TNF-α, and IL-6, in fetal brains. DHA is accrued in mammalian brain during active periods of perinatal cortical maturation, and that DHA plays an important role in neuronal differentiation, synaptogenesis, and synaptic function. In the present study we investigated the effect of DHA on LPS-induced WM injury in Sprague-Dawley ratsMethods In the current study, Sprague-Dawley (SD) rats (n=38) at day 17 and 18 of gestation (term=22.5 days) underwent treatment for two days. We set up the intrauterine infection rat model (LPS-treated group) through intraperitoneal LPS administration (350μg/kg, d17and 18), while the control group was administrated of the same volume of pyrogen-free saline (NS-treated group). DHA-treated group(intragastric administration of one pill of fish oil during the whole pregnancy)and intraperitoneal LPS administration (350μg/kg,d17and 18), Brain tissues were collected from the fetal rat at pregnant day 20, 21 and neonatal rat at postnatal day 1(P1), P3, P7 and P14. Real-time quantitative polymerase chain reaction (RT-PCR) analysis was used to test mRNA expression for IL-6 and TNF-αand immunohistochemistry was used to evaluate of GFAP and MBP expression in brain tissues.Results Pregnant rats of each group had normal activity and feeding after intraperitoneal injection. One pregnant rat was aborted in the LPS-treated group. One pregnant rat was stillbirth in the LPS-treated group. There was no pregnant rat aborted in the DHA-treated group. Animals treated with LPS delivered approximately 12 h earlier than did the controls. There was also no significant difference in the first day of performance for open-field activityor or suckling. The mean birth weight of the LPS-treated group neonatal rats was significant lower than the DHA-treated group (p<0.05). Placental hematoxylin-eosin staining showed obvious inflammatory response in the LPS-treated group. Inflammatory infiltration of the placental in the DHA-treated group was decreased. MBP staining was clearly observed in hippocampus of P7 neonatal brain, LPS-treated group was much weaker than in the control group(1.73±0.35* vs. 2.15±0.53,p<0.05);MBP staining was continue expressed in hippocampus of P14 neonatal brain, LPS-treated group was much weaker than in the control group (2.18±0.56* vs. 2.52±0.36,p<0.05);but GFAP staining in the LPS-treated group was more than in the control group in hippocampus and subcortex white matter of P7 neonatal brain (hippocampus 1.96±0.54* vs. 1.23±0.35,p<0.05;subcortex white matter?2.17±0.24* vs 1.53±0.11 p<0.05). GFAP-positive atrocities were observed in cortex and subcortex white matter of P14 neonatal rat brain, the number of GFAP-positive atrocities were more increasing in the LPS-treated group than in the control group(cortex 1.89±0.31* vs. 0.83±0.25,p<0.05;subcortex white matter 2.32±0.39* vs. 1.92±0.24,p<0.05). MBP staining of the DHA-treated group was much more than of the LPS-treated group in the same age ( p<0.05). GFAP staining of the DHA-treated group was much weaker than of the LPS-treated group in the same age(p<0.05). Real-time PCR showed general average of IL-1? ?mRNA a?nd TNF-αmRNA in LPS-treated group were significantly increasing than in NS-treated group (p<0.05); DHA treated group were significantly decreasing than in LPS-treated group (p<0.05); DHA treated group were significantly increasing than in control group (p<0.05). But there was distinction at different time point.Conclusions Intrauterine LPS infection could induce an inflammatory response of placenta and fetus, and resulted in neonatal low birth weight and WMD, which characterized by astrogliosis and hypomyelination. DHA was one of the main components of fish oil and indispensable polyunsaturated fatty acid in the central nervous system. It played an important role in neural development and function. DHA could modulate the expression of proinflammatory cytokines induced by LPS in the rat brain. The express of TNF-alpha, and IL-6 was reduced. Fetus and neonatal brain MBP positive staining was decreased and GFAP positive staining was increased after supplement of DHA during the whole pregnancy. DHA may be potential beneficial for perinatal brain injure. Further experimental studies will need to be performed to confirm such effects, including dose and therapeutic window studies.