A study on changes of brain tissue inflammatory cytokines in neonatal rats with periventricular leukomalacia / 中国新生儿科杂志

ABSTRACT

Objective To study inflammatory cytokines changes in brain tissue of neonatal rats with periventricular leukomalacia (PVL).Method A total of 80 neonatal SD rats (P3) were randomly assigned into 2 equal groups,sham-operated group and PVL group.Rats in each group were further assigned into four subgroups (12,24,48,72 h),with 10 rats in each subgroup.The hypoxic-ischemic PVL modal were established following the procedurefirst,isolation and ligation of left common carotid artery,and then exposed to 8％ O2 and 92％ N2 for 2.5 h.The sham-operated rats were processed with isolation of left common carotid artery only.Rats of the four subgroups were sacrificed at 12,24,48 h and 72 h respectively,then the brains were rapidly removed in corresponding time.Pathological changes of brain tissues were observed using HE stain.The mRNA expression levels of tumor necrosis factor α(TNF-α)and inter leukin-1β (IL-1β) were assessed using real-time quantitative PCR assays,the protein levels of TNF-α and IL-1β were detected using enzyme linked immunosorbent assay method.Result The brains tissues of rats in PVL group showed remarkably hyperemia and edema,with left ventricle enlargement.Periventricular white matter structure was disintegrated comparing with sham-operated group.The expression of TNF-α and IL-1 β mRNA in PVL group increased significantly,reaching peak by 24 h and then gradually decreased 72 h after the procedure.The mRNA levels of TNF-c and IL-1 β were significantly different between each two time points of 12,24 h and 48 h in PVL group (P ＜0.05).However,there was no differences between 72 h and 48 h within PVL and sham-operated group group(P ＞0.05).In PVL group,the protein expression trends of TNF-α and IL-1 β were similar to mRNA expression trends.Moreover,the protein levels were significantly different between each two time points of TNF-α and IL-1 β,respectively (P ＜ 0.01).The protein expression levels of TNF-α were different at each time point between PVL group and sham-operated group[(189.2 ± 20.4) pg/ml vs.(131.4 ±5.2) pg/ml at 12 h,(213.8 ± 16.7) pg/ml vs.(127.7 ±7.4) pg/ml at 24 h,(181.7 ± 15.0) pg/ml vs.(126.3 ± 6.0) pg/ml at 48 h,(159.6 ± 25.3) pg/ml vs.(131.4 ± 6.0) pg/ml at 72 h;P ＜0.01].The protein levels of IL-1β were different between the two groups only at 24 h and 48 h.[(121.8 ±30.0) pg/ml vs.(67.4 ± 13.7) pg/ml,(83.3 ± 15.7) pg/ml vs.(65.3 ± 14.9) pg/ml;P ＜0.05].In sham-operated group,no differences of TNF-α and IL-1 β protein levels were found between any different time points (P ＞ 0.05).Conclusion Inflammatory cytokines such as TNF-α and IL-1β are involved in ischemic-hypoxia induced PVL.Dynamic detection of inflammatory factors is expected to be an important method of early diagnosis,assessment of treatment efficacy and prognosis of PVL.