Based On The TNF-α/p38 Signaling Pathway To Explore The Protective Effect And Mechanism Of Melatonin On Hippocampal Injury Induced By Chronic Stress In Rat

Chronic stress can seriously affect the internal environment of animal body,endanger animal health and produce depression-like behavior.The hippocampus is an important place for learning and memory and the most sensitive brain region to stress stimulation.Chronic stress will lead to degeneration of the hippocampus,affect the survival and plasticity of neurons and even lead to loss of neurons,causing serious damage to the structure and function of the hippocampus.Therefore,this study through the establishment of chronic stress model,give the TNF-α inhibitors,from the organization and the molecular level to explore the mechanism of chronic stress induced rat hippocampal cells apoptosis,giving melatonin probe into its ease chronic stress cause hippocampal damage mechanism,the theoretical basis for clinical to explore the effective treatment for the future and to provide experiment basis.This experiment takes 60 healthy male Wistar rats,were randomly divided into blank control group(CON group),chronic stress group(CS group),melatonin group(CS+MT group),melatonin solvent group(CS+ALC group),TNF-α inhibitor group(CS+THAL group),TNF-α inhibitors,solvent group(CS+CMC group),CS group,the CS+MT group,the CS+ALC group,CS+THAL group,the CS+CMC group for a 21 d bound every 6 h,In the CS+MT group,the CS+ALC group was intraperitoneally injected with 10 mg/kg melatonin and 0.2% ALC 30 min before bondage,and the CS+THAL and CS+CMC groups were intraperitoneally injected with 100 mg/kg THAL and 0.5%CMC 30 min before bondage,respectively,starting from day 15.During the modeling process,the body weight of rats in each group was measured every 3 days during 21 days,and the behavior test was conducted at the end of 21 days of bondage.After that,heart blood was collected and sacrificed,and hippocampal tissues were collected for later use.According to the result of weight,OFT,CORT content in serum and to verify that the chronic stress model,through the rat hippocampal pathological histology and ultrastructure changes was observed in the rat hippocampal damage,by detecting the rat hippocampal neural glial cells to observe whether the activation markers indicators,the detection of TNF-α/p38 lightning related pathways and apoptosis index to explore chronic stress caused by injury of rat hippocampal neurons apoptosis mechanism and melatonin protection mechanism.The results showed that the body weight of the CS group decreased significantly compared with that of the CON group,and the body weight of the CS+THAL group and the CS+MT group tended to increase compared with that of the CS group.The total distance,standing times and crosscell times of CS group were significantly lower than those of CON group(p < 0.01),and the total distance,standing times and cross-cell times of CS+THAL group and CS+MT group were significantly higher than those of CS group(p < 0.01).The results of serum CORT showed that compared with CON,the CORT content in CS group was significantly increased(p < 0.01),while the CORT content in CS+THAL group was significantly decreased compared with CS+MT group(p < 0.01).The morphology of hippocampal neurons in the CS group was irregular and loose,with nuclear pyropysis and nuclear membrane indentation inward.Compared with the CS+THAL group,the damage of hippocampal neurons in the CS+MT group was alleviated.Compared with CON group,the expression of glial cell activation markers Iba-1 and GFAP in CS group was significantly increased(p < 0.01),while the expression of CS+MT group was significantly decreased compared with CS+THAL group(p < 0.05).Compared with CS group,the expression levels of TNF-α/p38 signaling pathway related proteins TNF-α,TNF-R1,p-p38 /p38 and p-p53 /p53 in CS group were significantly increased(p < 0.01),and the expression levels of related proteins in CS+THAL group and CS+MT group were significantly decreased(p < 0.05).Compared with CON group,the expression levels of apoptotic related factors Bax/Bcl-2,Cyt C,Cleaved case9,Cleaved caspase-3in CS group were significantly increased(p < 0.01).The number of Cleaved caspase-3immunohistochemical positive cells was also significantly increased(p < 0.01),while the expression of apoptosis-related factors in CS+THAL group and CS+MT group was decreased compared with CS group(p < 0.01),and the number of Cleaved caspase-3 positive cells was decreased accordingly(p < 0.01).In conclusion,chronic stress can activate microglia and astrocytes and release TNF-α,thereby mediating the apoptosis of rat hippocampal neurons through TNF-α/p38 signaling pathway.Melatonin alleviates the apoptosis of hippocampal neurons induced by chronic stress by reducing TNF-α secretion and inhibiting TNF-α/p38 signaling pathway.