Gαq Overexpression In Hippocampus Improved Learning And Memory Ability In Aging Mice

[Objective]Gaq is an important member of the a subunit family of G proteins and is an important signaling pathway protein in vivo.In our previous study,we found that overexpression of Gaq in human neuron-like cell line SY5Y and rat neuron-like cell line PC 12 significantly enhanced the antioxidant capacity of cells,the mechanism may be related to the activation of ERK,Nrf2 pathway and inhibition of NF-κB pathway by overexpression of Gaq.Further study showed that SFPQ was significantly upregulated in neuron-like cells overexpressing Gaq.SFPQ is a DNA/RNA binding protein that is involved in the pathogenesis and progression of a variety of neurodegenerative diseases.In view of the above results are only based on in vitro study,this program was proposed to detect the expression level of Gαq and SFPQ in hippocampus of different age of mice,so that the correlation between Gαq and SFPQ expression with age could be clear.By building D-galactose(DG)induced mice aging model,changes of learning and memory abilities in aging mice after Gaq overexpression in hippocampus and related mechanisms were probed,providing backup for Gaq to be used as a therapeutic target for anti-neuro-aging at the model animal level.[Methods](1)Five Kunming mice aged 1 day,7 days,14 days,2 months,6 months and 18 months were selected.Immediately after anesthesia,the mice were perfused with normal saline at 4℃,and the hippocampus were dissected and isolated.The protein expression levels of Gaq and SFPQ were detected by Western Blot(WB).(2)Forty 2-month-old male Kunming mice were randomly divided into 2 groups with 20 mice in each group.Model group(DG group)was intraperitoneally injected with D-galactose to establish the aging model of mice,while control group(NC group)was intraperitoneally injected with the same amount of normal saline.(3)Morris water maze(MWM)test was performed after building aging mice model,and the model group was randomly divided into 2 groups with 10 mice in each group.Adenovirus overexpressing Gaq was injected into the bilateral hippocampus of the treatment group(Gaq+DG group),and adenovirus containing empty VECTOR was injected into the bilateral hippocampus of the sham group(VECTOR+DG group).The control group was also randomly divided into two groups:Gaq+NC group and Vector+NC group in which the same treatments were given as the treatment group and the sham group respectively.(4)MWM test was used to determine the learning and memory ability of mice 4 weeks after virus injection.The mice were sacrificed immediately after the MMW experiment,and the activities of catalase(CAT),superoxide dismutase(SOD)and glutathione peroxidase(GSH-PX)in hippocampus were measured by chemical colorimetry.The expression levels of Gaq,SFPQ,glutathione mercaptotransferase(GST),heme oxygenase 1(HO-1),cyclic adenosine reaction element binding protein(CREB)and its phosphorylated form p-CREB were detected by WB assay.The expression levels of Gaq,SFPQ and Bcl-2 in mouse hippocampus were detected by immunofluorescence technique.[Results](1)The levels of Gaq and SFPQ in the hippocampus of mice decreased gradually with age,and the expression levels of Gaq and SFPQ were positively correlated with age.(2)After intraperitoneal injection of D-galactose for 4 weeks,the learning and memory abilities were significantly decreased,and the expression levels of SFPQ,antioxidant related protein GST,HO-1 and memory related protein p-CREB in the hippocampus were significantly down-regulated,and the activities of antioxidant enzymes such as CAT,SOD and GSH-PX in the hippocampus were significantly decreased.(3)Gaq overexpression in hippocampus significantly improved the learning and memory ability of aging model mice,up-regulated the expression levels of SFPQ,GST,HO-1,p-CREB and anti-apoptotic protein Bcl-2 in hippocampus,and enhanced the activities of antioxidant enzymes such as CAT,SOD and GSH-Px in hippocampus of aging model mice.[Conclusion](1)Gaq and SFPQ in the hippocampus of mice decreased gradually with the increase of age,and SFPQ was significantly up-regulated after the overexpression of Gaq in the hippocampus of aging model mice,suggesting that Gaq and SFPQ have an internal regulatory relationship in the process of neuro-aging and anti-neuro-aging.(2)Gaq overexpression in hippocampus could significantly improve the learning and memory ability of aging model mice,and Gαq can be used as a therapeutic target of anti-neural aging in vivo.(3)The overexpression of Gaq in hippocampus can restore the expression levels of SFPQ and antioxidant proteins GST and HO-1,enhance the activities of CAT,SOD,GSH-Px and other antioxidant enzymes,reduce the apoptosis of neurons and increase the content of memory-related protein p-CREB,thus improving the learning and memory ability of aging model mice.