Omega-3 polyunsaturated fatty acids supplementation attenuates microglia-induced inflammation after traumatic brain injury in rats / 中华临床营养杂志

ABSTRACT

Objective To investigate the effects of omega-3 polyunsaturated fatty acids (ω-3 PUFA) supplementation on neuron apoptosis,brain edema,activation of microglia,inflammatory response and neural function after traumatic brain injury (TBI) in rats,so as to understand the protection of ω-3 PUFA in rats following TBI and its mechanism.Methods TBI model was established using Feeney's method.Ninety SD rats were randomly divided into 5 groupssham operation group (sham group),TBI group,TBI + selective activator of c-Jun N-terminal kinase (JNK) anisomycin group (TBI + Aniso group),TBI + ω-3 PUFA supplementation group (TBI + ω-3 group),and TBI + ω-3 PUFA supplementation + JNK activation group (TBI + ω-3 + Aniso group).We measured rat behavioral outcomes by modified neurological severity score (mNSS) on day 1,3,and 7 after TBI.Brain water content was measured with wet-dry weight method.The neuron apoptosis and microglial activation (identified by specific marker IBA-1) in TBI cerebral cortex were determined by TUNEL staining and immunofluorescence.Inflammatory cytokines [tumor necrosis factor-α (TNF-α),interleukin (IL)-1α,IL-1β,and IL-6] and the JNK signaling pathway (JNK,pJNK) were tested with reverse transcription-polymerase chain reaction and Western blot,respectively.Results Compared with the sham group,the levels of brain cell apoptosis,brain edema,neuron apoptosis,and inflammatory-relatived factors (TNF-α,IL-1 α,IL-1β,and IL-6) were significantly increased in the other four groups (P ＜ 0.05).Compared with the TBl group,ω-3 PUFA supplementation reduced brain water content following TBI,especially on day 3 after TBI [(78.14 ± 0.57) ％ vs.(82.31 ± 0.81) ％,P ＜ 0.01],and improved neurological function score (P ＜ 0.05).Meanwhile,ω-3 PUFA supplementation suppressed neuron apoptosis,the activation of microglia,and the mRNA and protein expressions of inflammatory cytokines (TNF-α,IL-1α,IL-1 β,IL-6).The activation of JNK signaling pathway was also inhibited by ω-3 PUFA.Conclusion ω-3 PUFA supplementation may markedly reduce brain edema,suppress neuron apoptosis,and improve neurological outcomes after TBI in rats,possibly mediated by inhibiting JNK signaling pathway and microglial activation,reducing microglia-induced cerebral inflammatory responses,demonstrated as down-regulated expression of TNF-α,IL-1α,IL-1β,and IL-6.