褪黑素对抑郁症睡眠障碍模型大鼠行为的影响及机制的研究

Effect of melatonin on behavior and its mechanism in depression sleep disorder model rats

目的探讨褪黑素对抑郁症睡眠障碍模型大鼠的改善作用和可能机制。方法大鼠构建抑郁症睡眠障碍模型。造模成功的大鼠随机分为模型组、褪黑素低、中、高剂量组(10、20和40 mg·kg^(-1)褪黑素腹腔注射给药),连续21 d,正常大鼠为对照组,每组11只。采用新奇抑制摄食实验评估对大鼠抑郁样行为。比色法检测大鼠脑组织中超氧化歧化酶(SOD)活性、丙二醛(MDA)含量。酶联免疫吸附测定法检测大鼠血清中5-羟色胺(5-HT)、谷氨酸(Glu)和γ-氨基丁酸(GABA)含量。蛋白质印迹法和免疫组化法检测大鼠脑组织中脑源性神经营养因子(BDNF)、酪氨酸激酶B(TrkB)和cAMP反应元件结合蛋白(CREB)蛋白表达水平。结果对照组、模型组、褪黑素低、中、高剂量实验组大鼠进食潜伏期分别为(281.75±34.77),(567.30±51.56),(514.52±33.65),(405.21±46.94)和(395.73±35.04)s;SOD活性分别为(62.28±8.80),(38.97±2.67),(44.99±2.32),(49.49±3.59)和(52.39±6.34)U·mL^(-1);MDA含量分别为(3.31±0.38),(6.11±0.61),(5.02±0.44),(4.07±0.40),(3.99±0.44)nmol·mg^(-1);5-HT含量分别为(566.78±78.85),(342.28±46.63),(400.15±37.07),(480.35±22.90)和(566.34±54.45)pg·mL^(-1);Glu含量分别为(39.96±3.26),(68.28±9.48),(51.68±3.24),(45.74±3.78),(40.11±2.62)ng·mL^(-1);GABA含量分别为(32.53±2.45),(46.58±5.45),(41.45±3.88),(37.18±4.70),(35.71±3.02)ng·mL^(-1);BDNF蛋白表达水平分别为(0.85±0.07),(0.24±0.04),(0.45±0.07),(0.57±0.06),(0.57±0.06);TrkB蛋白表达水平分别为(0.78±0.10),(0.29±0.04),(0.45±0.07),(0.58±0.05),(0.69±0.10);CREB蛋白表达水平分别为(1.00±0.07),(0.43±0.06),(0.63±0.05),(0.75±0.08),(0.83±0.08)。上述指标,对照组与模型组相比,褪黑素低、中、高剂量组与模型组相比,差异均有统计学意义(均P<0.05)。结论褪黑素可能通过上调BDNF/TrkB/CREB通路来调控神经递质水平、抑制氧化应激反应,进而改善抑郁症睡眠障碍。

Objective To explore the improvement effect and possible mechanism of melatonin on depression sleep disorder model rats.Methods The rat model of depression sleep disorder was established.The rats with successful modeling were randomly divided into the model group,low,medium and high dose of melatonin(10,20 and 40 mg·kg^(-1) melatonin intraperitoneal injection),for 21 consecutive days,and the normal rats were the control group,with 11 rats in each group.The novel anti-feeding test was used to evaluate depression-like behaviors in rats.Colorimetric method was used to detect the activity of superoxide dismutase(SOD)and the content of malondialdehyde(MDA)in rat brain tissue.Enzyme-linked immunosorbent assay was used to detect the levels of 5-hydroxytryptamine(5-HT),glutamic acid(Glu)andγ-aminobutyric acid(GABA)in rat serum.Western blotting was applied to detect the protein levels of brain-derived neurotrophic factor(BDNF),tyrosine kinase B(TrkB)and cAMP responsive element binding protein(CREB)in rat brain tissues.Results The eating latency of rats in the control group,model group,low,medium and high melatonin dose experimental groups were(281.75±34.77),(567.30±51.56),(514.52±33.65),(405.21±46.94),(395.73±35.04)s;SOD activity were(62.28±8.80),(38.97±2.67),(44.99±2.32),(49.49±3.59),(52.39±6.34)U·mL^(-1);MDA contents were(3.31±0.38),(6.11±0.61),(5.02±0.44),(4.07±0.40),(3.99±0.44)nmol·mg^(-1);and the 5-HT contents were(566.78±78.85),(342.28±46.63),(400.15±37.07),(480.35±22.90),(566.34±54.45)pg·mL^(-1);Glu content were(39.96±3.26),(68.28±9.48),(51.68±3.24),(45.74±3.78),(40.11±2.62)ng·mL^(-1);GABA content were(32.53±2.45),(46.58±5.45),(41.45±3.88),(37.18±4.70),(35.71±3.02)ng·mL^(-1);the BDNF protein levels were(0.85±0.07),(0.24±0.04),(0.45±0.07),(0.57±0.06),(0.57±0.06);and the TrkB protein levels were(0.78±0.10),(0.29±0.04),(0.45±0.07),(0.58±0.05),(0.69±0.10);CREB protein levels were(1.00±0.07),(0.43±0.06),(0.63±0.05),(0.75±0.08),(0.83±0.08).For the above indicators,compared with the model group,the melatonin low,medium,and high dose groups were significantly different from the model group(all P<0.05).Conclusion Melatonin may regulate neurotransmitter level and inhibit oxidative stress response by up-regulating the BDNF/TrkB/CREB pathway,thus improving sleep disorders in depression.