| BackgroundHuman immunodeficiency virus 1(HIV-1)infection can cause cognitive impairment(HAND).High-efficiency antiretroviral therapy(HAART)can effectively reduce the HIV-1 viral load of the central nervous system(CNS),but mild and moderate HAND is still widespread and affects patients' quality of life.Co-morbidity is one of the causes of neurological complications in AIDS patients,among which smoking is a common factor.Nicotine(NT)as the main component in tobacco is an ?7nAchR(A7R)agonist.Studies have found that the expression of A7R is up-regulated in the brains of HIV-1-infected patients and gp120 transgenic mice.The specific mechanism is not clear.ObjectiveThe purpose of this article is to explore the mechanism of nicotine(NT)and gp120 co-morbidity through A7R-mediated neuronal apoptosis,and the protective effects of A7R inhibitor memantine hydrochloride on neuronal apoptosis.It will provide the research basis for the pathogenesis of HAND in patients with nicotine and HIV-1 comorbidities,and provide new ideas for the subsequent development of new drugs.Methods1.Identification and reproduction of gp120 transgenic(Tg)mouse models:gp120 transgenic mice were trimmed at 3 weeks to extract mouse tissue DNA to identify them by RT-PCR,and screen gp 120-positive mice for experimental use.The mice were 10-13 months old.2.Gp120 and NT treated microglial BV2 and neuron cells:gp120 and NT,A7R inhibitors,agonists,memantine hydrochloride,and siRNA were used to treat BV2cells,then collected supernatant to treated neuronal cells or directly acted on neuronal cells.BV2 cell supernatants and cell proteins were collected.Western blot(WB)to detect the expression levels of P53,Omi/XIAP and Caspase-3,and flow cytometry were used to detect ROS motivation and the apoptosis of neurons induced by gp120 and NT.3.Intraperitoneal injection of NT and MLA in gp120 Tg mice:gp120 Tg mice(10-13 months of age)and WT wild mice are divided into 8 groups(seven of each):WT+vehicle,WT+MLA,NT,gp120Tg,NT+gp120,NT+MLA,gp120Tg+MLA,NT+gp120+MLA.The vehicle was sterile PBS,with a NT concentration of 1 mg/kg(dissolved in sterile PBS),MLA concentration was 3mg/kg(dissolved with sterile PBS)to injecte mice by which each mouse was injected intraperitoneally with 200ul/per 3 days for 60 days.Results1.Gp120 Tg mice can stably express gp120,and the number of mice and their age can meet the experimental needs.2.The expression of A7R in BV2 cells treated with gp120 and NT increased,and it could cause increased neuronal apoptosis,but decreased after treatment with inhibitors,suggesting that A7R could mediate neuron apoptosis induced by NT and gp120.However,when gp120 and NT directly interact with neurons,they can not cause neuronal apoptosis.3.Gp120 and nicotine-treated mice detected up-regulation of A7R expression in the cerebral cortex and hippocampus of mice,and increased Ib?-1 expression and increased neuronal apoptosis.After treatment with A7R inhibitors Ib?-1 expression decreased and neuronal apoptosis decreased.4.Gp120 and nicotine treated BV2 cells,increased cell ROS activation detected at the same time,p53,OMI,Caspase-3 expression increased,while the expression of A7R inhibitor and siRNA decreased.It is suggested that gp120 and nicotine can cause Caspase-3 expression up-regulation and neuronal apoptosis through A7R.By treating BV2 cells with different time gradients and concentration gradients,Caspase-3 showed a time and dose dependent trend.5.The expression trends of ROS,p53,OMI and Caspase-3 induced by gp120 and NT after pretreatment with memantine hydrochloride were consistent with the results of A7R inhibitor.6.After treatment of BV2 cells with A7R agonist,the expression of ROS,p53,OMI and Caspase-3 in cells decreased.Conclusions1.Gp120 and NT cause nervous system damage through gp120+NT-A7R-p53-Caspase-3 pathway.2.Inhibition of A7R can reduce gp120+NT-A7R-p53-Caspase-3 pathway activation and neurotoxicity.3.Memantine hydrochloride can improve neurotoxicity,cognitive function and neuroprotection caused by gp120 and nicotine. |
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