Effects Of Subchronic Exposure To 1,2-dichloroethane On GABA Metabolism And Its Receptors In The Prefrontal Cortex Of Mice

Objective:1,2-Dichloroethane(1,2-dichloroethane,1,2-DCE)is a colorless,volatile halogenated hydrocarbon compound used primarily to synthesize vinyl chloride monomer.1,2-DCE is a highly toxic neurotoxicant,and brain tissue is the main accumulation and damage of the target organ;long-term low-dose 1,2-DCE exposure will cause anxiety,depression,cognitive impairment,and other adverse reactions.The prefrontal cortex(PFC)is the brain center controlling emotion and memory.Studies have shown that regulating emotion by PFC relies on gamma-Aminobutyric acid(GABA)metabolism in the prefrontal cortex.GABA is one of the most important inhibitory amino acid neurotransmitters in the central nervous system(CNS)and plays a decisive role in regulating neuronal excitability.GABA in the synaptic cleft is metabolized generally through the“glutamate/γ-aminobutyric acid-glutamine”cycle and binds to GABA receptors on the presynaptic and posterior membranes to mediate inhibitory signals.Therefore,if 1,2-DCE exposure causes any damage to GABA metabolism and its receptors,it will severely interfere with the information transmission of GABAergic synapses,resulting in emotional abnormalities and neurobehavioral disorders.In this study,the effect of subchronic exposure to 1,2-DCE on GABA metabolism and receptor in the prefrontal cortex of mice was discussed,which provided experimental reference data for revealing the mechanism of neurotoxicity caused by long-term exposure of 1,2-DCE.Methods:In this study,healthy and clean female Kunming mice were randomly divided into a control group and 1,2-DCE exposure groups of 0.225,0.45 and 0.9 g/m~3 after adaptive feeding.It was poisoned by static inhalation for 3.5 h a day for 8 weeks.First,the open field test and the elevated plus maze experiment were performed.Then the mice were anesthetized,the prefrontal cortex tissue was extracted,and the contents of GABA,glutamate,glutamine(Glu)and glutamine(Gln)in the prefrontal cortex tissue of mice were detected;The activities of glutamate decarboxylase(GAD)and GABA transaminase(GABA-T)in the prefrontal cortex of mice were detected.Determination of GABA transporter-1(GABA transporter-1,GAT-1),GABA transporter-3(GABA transporter-3,GAT-3),vesicular GABA transporter(VGAT),GABA A Receptor alpha 2(GABA_ARα2),GABA A Receptor gamma 2(GABA_ARγ2),Na-K-2Cl cotransporter isoform 1(NKCC1),K-Cl cotransporter isoform 2(KCC2),GABA B Receptor 1(GABA_BR1),GABA B Receptor 2(GABA_BR2)transcription and protein expression levels.The fluorescence intensity of GABA_ARα2 and GABA_BR2 in prefrontal cortex tissues was observed by immunofluorescence staining.Result:In the open field test,the times of entering the central area,the time staying in the central area,and the number of upright times of each group of mice decreased significantly with the exposure dose.In the elevated plus maze,the percentage of the number of arm openings and the percentage of the time of arm opening gradually decreased with the increase of the dose.Compared with the control group,the content of GABA and Gln in the prefrontal cortex of mice in the exposure group decreased,and the Glu and Glu/GABA ratio increased.GAD activity decreases and GABA-T activity increases.With the increase of the exposure dose,the protein and m RNA expression levels of GAT-1 and NKCC1increased to varying degrees,while the protein and m RNA expression levels of GAT-3,VGAT,GABA_ARα2,GABA_ARγ2,KCC2,GABA_BR1 and GABA_BR2 decreased.Compared with the control group,the expression of GABA_ARα2 and GABA_BR2 in the prefrontal cortex of mice in the infected group was significantly downregulated by immunofluorescence staining.Conclusion:1.Subchronic exposure to 1,2-DCE can lead to neurobehavioral disorders in mice.2.The neurobehavioral disorders in mice induced by 1,2-DCE exposure may be related to the effect of 1,2-DCE on GABA metabolism in the prefrontal cortex of mice and the decrease of its receptor expression.