近红外光照射可显著改善大鼠抑郁所致的肠功能紊乱

Near-infrared light therapy ameliorates depression-induced intestinal dysfunction in rats possibly by activating PGC-1α/Nrf2 signaling and increasing hippocampal BDNF expression

目的探究近红外光对抑郁所致肠功能紊乱的影响及其可能的机制。方法32只SPF级雄性SD大鼠,随机分为对照组(Control)、模型组(Model)、近红外光低剂量组(Low NIR)、近红外光高剂量组(High NIR),8只/组。除对照组外,其他组进行慢性束缚应激4周,近红外光低、高剂量组给予头部近红外光照射。以悬尾及强迫游泳实验来评价大鼠抑郁水平,结直肠扩张反射测试、肠道推进测试以及粪便含水量、粒数衡量大鼠肠道功能改变。大鼠海马、结肠的HE染色检测组织病理变化情况,Western blotting检测大鼠海马体脑源性神经生长因子(BDNF)、Nrf2、PGC-1α蛋白水平的表达。结果与对照组相比,模型组悬尾及强迫游泳实验不动时间和内脏敏感性增加,粪便粒数与含水量下降;海马体内BDNF、Nrf2、PGC-1α表达降低,差异均有统计学意义(P<0.05,P<0.01);海马体锥体细胞排列疏松,神经元损伤率升高,结肠有明显炎性细胞浸润,黏膜腺体排列欠整齐,病理损伤评分较高。与模型组相比较,高剂量近红外光组悬尾及强迫游泳实验不动时间和内脏敏感性下降,粪便粒数与含水量上升,差异均有统计学意义(P<0.05);海马体锥体细胞排列紧密,神经元损伤率下降,结肠炎性细胞浸润明显减少,腺体排列整齐,病理学损伤评分降低;大鼠大脑海马体内BDNF、Nrf2、PGC-1α表达增强(P<0.05,P<0.01)。结论近红外光照射可显著改善大鼠抑郁样行为和肠道功能,其机制可能与PGC-1α/Nrf2信号通路抗氧化应激作用并升高大鼠大脑海马体内BDNF水平有关。

Objective To investigate the effect of near-infrared(NIR)light therapy on depression-induced intestinal dysfunction in rats and explore the possible mechanism.Methods Thirty-two male SD rats were randomly divided into control group,model group,low-dose NIR light group and high-dose NIR light group.All the rats except for those in the control group were subjected to chronic restrained stress(CRS)for 4 weeks,and NIR light therapy of the head was administered in the two NIR light groups.The depression-like behaviors,intestinal functions,fecal water content and number of fecal pellets of the rats were evaluated.HE staining was used for detecting histopathological changes in the hippocampus and colon,and hippocampal expressions of BDNF,Nrf2 and PGC-1αwere detected with Western blotting.Results The rats in the CRS model group showed significantly increased immobility time and visceral sensitivity in the behavioral tests,decreased fecal pellets and fecal water content,and lowered expressions of BDNF,Nrf2,and PGC-1αin the hippocampus(P<0.05).Histopathological examination of the CRS rats revealed loosely arranged hippocampal pyramidal cells,obvious neuronal damages,and obvious inflammatory cell infiltration in the colon with irregularly arranged mucosal glands and a high pathological score.High-dose NIR light therapy significantly lowered the immobility time and visceral sensitivity,increased the number of fecal pellets and fecal water content(P<0.05),and enhanced hippocampal expressions of BDNF,Nrf2,and PGC-1α(P<0.05)of the depressive rats.The rats receiving high-dose NIR light therapy also exhibited close arrangement of the hippocampal pyramidal cells with significantly reduced neuronal damage and colonic inflammatory cell infiltration,neatly arranged mucosal glands,and lowered pathological score.Conclusion NIR light therapy can significantly improve depression-like behavior and intestinal function in rats possibly by ameliorating oxidative stress via the PGC-1α/Nrf2 signaling pathway and increasing BDNF level in the hippocampus.