The Impact Of Age And Visual Experience On The Expression GABA_ARα₁ Subunit Of GABA Receptor In Visual Cortex Of Rats

Objective:(1)To observe the changes of expression in quantity of GABA_ARα₁ subunit from neonatal to 90-day wistar rats in visual cortex.(2)To study the effect of monocular deprivation on the expression of GABA_ARα₁ in the visual cortex of critical period rats;(3)â‘ To observe the effect of visual deprivation on the expression of GABA_ARα₁ in the visual cortex of critical period rats;â‘¡To observe the effect of the late-onset visual deprivation on the expression of GABA_ARα₁ in the visual cortex of adult rats,to provide the molecular mechanism of the visual plasticity.Method:(1)Forty five neonatal healthy pureblooded Wistar rats were divided into nine groups randomly,five in each group and then were killed at nine time-point 0,7,14,21,28,35,45,60,90d respectively.(2)15 14-day-old healthy Wistar rats were randomly divided into 3 groups,5 in every group.The eyelids of the 15 rats were sutured at P14 to obtain animal model,the time for experiment at postnatal day 21,28,45.(3)â‘ Five neonatal Wistar rats with their mother were raised in complete darkness to P21,the control group was five rats borne in the alike environment,which were raised on a 12h light/dark cycle to P21.â‘¡Five 80-day-old healthy Wistar rats were placed into a completely dark room for 10d.5μm thick sections were cut from paraffin imbedded tissue of visual cortex in coronary side then the expression of GABA_ARα₁ subunit in the visual cortex of rats were examined by immunohistochemical methods with monoclonal anti-GABA_ARα₁ antibody.After streptomycin avidin biotin peroxidase complex(SABC)staining,microscope and computer-assisted image analyses were used to explore the developing changes of GABA_ARα₁ subunits protein.Pictures were collected with Olympus micro-image system,integrated optical density(IOD) were determined with image analysis system.Analyzed and compared the IOD,experiment data was indicated with mean±standard deviation.Analyzed data with SPSS16.0.Result:(1)The expression of GABA_ARα₁ in different ages:The expression of GABA_ARα₁ increased developmentally with age.The quantity of the expression of GABA_ARα₁ in neonatal rats is very low,then increased gradually,at P21 it increased to 127.04±9.97,and at P35 reached the climax value.Afterward maintained at high level.Significant deviation existed among different ages with one-factor analysis of variance(P<0.05).(2)For the rats of critical period:the expression of GABA_ARα₁ in visual cortex of monocular deprivation rats were obviously lower than the normal groups.(3)â‘ For the rats of critical period:the IOD of GABA_ARα₁ in visual cortex of visual deprivation rats was obviously higher than the normal group;â‘¡For the adult rats:the IOD of GABA_ARα₁ in visual cortex of visual deprivation rats was 235.23±18.36,the normal group was 231.52±21.65(t=-0.41,P>0.05),there were no discrimination of the two groups.Conclusion:(1)The quantity of the expression of GABA_ARα₁ correlated with the onset and decline of the critical period.(2)In critical period,monocular deprivation can decrease the GABA_ARα₁ expression in the visual cortex,we supposed that GABA_ARα₁ may involve in regulation of neuron plasticity in visual cortex in critical period.(3)â‘ In critical period visual deprivation can increase the expression of GABA_ARα₁,the result indicated the dynamic changes of GABA receptor depended on the visual experience in critical period.â‘¡In this study,the expression of GABA_ARα₁ didn't changed with the visual experience.It supposed that the visual system of adult animal changed more stable,visual experience had little influence on the visual cortex's plasticity.