摘要
目的探讨胸腺肽a1对新生小鼠持续感染所致学习记忆障碍的影响及其相关机制。方法(1)新生C57BL/6小鼠24只按随机数字表法分为生理盐水组、0-3mg/kg脂多糖(LPS)剂量组、0.6mg/kgLPS剂量组、0.9mg/kgLPS剂量组,分别连续5d注射等量生理盐水和不同剂量LPS。观察各组小鼠体质量、相对肝重变化及血清、脑组织肿瘤坏死因子-α(TNF-α)含量,以确定模拟临床新生儿感染的LPS剂量。(2)取60只新生小鼠按随机数字表分为3组:对照组、LPS组、胸腺肽a1处理组,分别连续5d注射等量生理盐水、LPS(0.6mg/kg)和胸腺肽a1(0.4mg/kg)+LPS(0.6mg/kg)。在4周和8周时,采用Morris水迷宫实验检测各组小鼠的学习记忆能力,采用ELISA法检测海马组织TNF-α、白介素-1β(IL-1β)、脑源性神经营养因子(BDNF)和神经生长因子(NGF)含量,采用Western blotting检测海马组织Toll样受体4(TLR4)和核转录因子-κB(NF-κB)蛋白表达水平。结果(1)与生理盐水组相比,0.6mg/kgLPS剂量组小鼠生长缓慢[(2.23±0.22)g vs (1.18±0.21)g]、相对肝重增加(0.052±0.004 vs 0.072±0.007)、血清及脑组织TNF-α含量[(62.01±3.32)pg/mL vs(151.06±14.51)pg/mL;(186.03±13.24)pg/mL vs(298.71±41.61)pg/mL]明显增高,差异均有统计学意义(P〈0.05)。(2)与LPS组相比,胸腺肽a1处理组小鼠定位航行实验中逃避潜伏期明显缩短,空间探索实验中目标象限停留时间明显延长,海马组织TNF-α、IL.1B、TLR4、NF-κB蛋白表达明显降低[(73.32±5.18)pg/mL vs(58.61±4.03)pg/mL;(99.15±8.30)pg/mL vs(75.56±6.13)pg/mL;2.32±0.29 vs 1.71±0.26;1.77±0.24 vs 1.26±0.141,BDNF、NGF蛋白表达明显增高[(1.33±0.12)pg/mL/)8(1.69±0.25)pg/mL;(41.45±3.47)pg/mL vs(50.38±5.02)pg/mL],差异均有统计学意义(P<0.05)。结论胸腺肽a1可以改善小鼠新生期感染导致的学习记忆障碍和神经炎症,其途径是通过抑制TLR4/NF-κB信号通路传导和提高神经营养因子水平。
Objective To explore the effect ofthymosin alpha-1 (Tal) on postnatal systemic inflammation-induced learning and memory impairment in mice and their relevant mechanism. Methods (I) Twenty-four neonatal C57BL/6 mice were randomly assigned into normal saline group, lipopolysaccharide (LPS, 0.3 mg/kg) group, LPS (0.6 mg/kg) group, and LPS (0.9 mg/kg) group. And the animals were intraperitoneally injected with different doses of LPS or equal volume of saline for 5 days. The variations of body weight, liver weight relative to the body and tumor necrosis factor-α (TNF-α) level in serum and brain tissues were observed to determine the appropriate dose of LPS for simulating neonatal clinical infection. (2) A total of 60 newborn mice were randomly divided into three groups: control group, LPS group and Tal treatment group; mice in each group were continuously injected with equal volume saline, LPS (0.6 mg/kg) and Tal (0.4 mg/kg)±LPS (0.6 mg/kg) for 5 days. On day 28 and on day 56, Morris water maze was used to measure the spatial learning and memory abilities of mice; the concentrations of TNF-α, interleukin-1β (IL-1β), brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) in the hippocampus were examined by ELISA, and the expressions of toll-like receptor 4 (TLR4) and nuclear factor-κB (NF-κB) were measured by Western blotting. Results (1) As compared with the normal saline group, the mice in the LPS group (0.6 mg/kg) had significantly slower growth ([2.23±0.22] g vs. [1.18±0.21] g), increased relative liver weight to the body (0.052±0.004 vs. 0.072±0.007) and increased TNF-α levels in serum and brain tissues ([62.01 ±3.32] pg/mL vs. [151.06± 14.51] pg/mL; [186.03±13.24] pg/mL vs. [298.71±41.61] pg/mL, P〈0.05). (2) As compared with the LPS group, Tal treatment group had significantly shortened average escape latency in place navigation test, prolonged active time in spatial probe test, statistically decreased hippocampal TNF-α, IL-1β, TLR4 and NF-κB levels ([73.32±5.18] pg/mL vs. [58.61±4.03] pg/mL; [99.15±8.30] pg/mL vs. [75.56±6.13] pg/mL; 2.32±0.29 vs. 1.71±0.26; 1.77±0.24 vs. 1.26±0.14) and significantly increased BDNF and NGF levels ([1.33±0.12] pg/mL vs. [1.69±0.25] pg/mL; [41.45±3.47] pg/mL vs. [50.38±5.02] pg/mL, P〈0.05). Conclusion Tal improves learning and memory functions and alleviates neuro-inflammation in postnatal infection of mice, and the underlying mechanism probably involves in inhibiting TLR4/NF-κB signaling pathway activation and increasing neurotrophic factors.
出处
《中华神经医学杂志》
CAS
CSCD
北大核心
2017年第2期121-126,共6页
Chinese Journal of Neuromedicine
基金
广东省自然科学基金(2015A030313153、2014A030310343)
衢州市科技计划项目(2015103)