烟酰胺单核苷酸对睡眠剥夺幼鼠神经发生减退的影响

Effect of nicotinamide mononucleotide on neurogenesis decline in sleep-deprived infancy rats

目的评价烟酰胺单核苷酸对睡眠剥夺幼鼠神经发生减退的影响。方法清洁级健康雄性SD大鼠78只,7日龄,体重10~15 g,采用随机数字表法分为3组(n=26):对照组(Con组)、睡眠剥夺组(SD组)和睡眠剥夺+烟酰胺单核苷酸组(SD+NMN组)。采用毛刷轻柔刺激法制备幼鼠睡眠剥夺模型,每天睡眠剥夺10 h,连续14 d。SD+NMN组腹腔注射烟酰胺单核苷酸500 mg/kg,连续14 d。Con组和SD组腹腔注射等容量蒸馏水。于睡眠剥夺结束后即刻腹腔注射5-溴脱氧尿苷(BrdU)100 mg/kg标记新生细胞,睡眠剥夺完成后24 h时分别采用免疫荧光和免疫组化法计数海马DG区干细胞多能性转录因子(SOX2)和双肾上腺皮质激素(DCX)阳性细胞,采用正电子发射型计算机断层显像观察海马18F-氟代脱氧葡萄糖的代谢水平。睡眠剥夺完成后4周采用免疫荧光法计数海马神经元核抗原(NeuN)/BrdU和神经胶质酸性蛋白(GFAP)/BrdU阳性细胞,采用新物体识别试验测试认知功能。结果与Con组比较,SD组大鼠SOX2和DCX阳性细胞数减少,海马葡萄糖标准摄取值降低,NeuN/BrdU和GFAP/BrdU阳性细胞数减少,新物体辨别指数降低(P<0.05);与SD组比较,SD+NMN组SOX2、DCX、NeuN/BrdU和GFAP/BrdU阳性细胞数增加,海马葡萄糖标准摄取值升高,新物体辨别指数升高(P<0.05)。结论烟酰胺单核苷酸可促进睡眠剥夺幼鼠的神经发生,从而改善认知功能,其机制与提高海马葡萄糖代谢水平有关。

Objective To evaluate the effect of nicotinamide mononucleotide(NMN)on neurogenesis decline in sleep-deprived infancy rats.Methods Seventy-eight clean-grade healthy male Sprague-Dawley rats,aged 7 days,weighing 10-15 g,were divided into 3 groups(n=26 each)using a random number table method:control group(group Con),sleep deprivation group(group SD)and sleep deprivation plus NMN group(group SD+NMN).Sleep deprivation model was established by gentle stimulation method with a brush(10 h per day)for 14 consecutive days.NMN 500 mg/kg was intraperitoneally injected in group SD+NMN,while the equal volume of aqua pura was given instead in Con and SD groups.5′-bromo-2′-deoxyuridine(BrdU)100 mg/kg was intraperitoneally injected immediately after the end of sleep deprivation to label the new-born cells.At 24 h after completion of sleep deprivation,the stem cell pluripotency transcription factor(SOX2)and doublecortin(DCX)positive cells in the hippocampal DG region were counted using immunofluorescence and immunohistochemical methods,and positron emission tomography-computed tomography was used to observe the metabolism of 18F-fluorodeoxyglucose in the hippocampus.At 4 weeks after completion of sleep deprivation,the number of neuronal nuclei antigen(NeuN)/BrdU and glial fibrillary acid protein(GFAP)/BrdU positive cells in hippocampal DG region was recorded using immunofluorescence,and novel object recognition test was performed to evaluate the cognitive function.Results Compared with group Con,the number of SOX2 and DCX positive cells was significantly reduced,the standard uptake value of glucose in the hippocampus was decreased,the number of NeuN/BrdU and GFAP/BrdU positive cells was reduced,and discrimination index in novel object recognition test was decreased in group SD(P<0.05).Compared with group SD,the number of SOX2,DCX NeuN/BrdU and GFAP/BrdU positive cells was increased,the standard uptake value of glucose in the hippocampus was increased,and discrimination index in novel object recognition test was increased in group SD+NMN(P<0.05).Conclusion Nicotinamide mononucleotide can promote neurogenesis,thus improving cognitive function,and the mechanism is related to increasing the metabolism of hippocampal glucose in sleep-deprived infancy rats.