Observation To Early Neural Degeneration Of The Retina In Db/db Mice

Purpose: For further study of the pathogenesis of diabetic retinopathy throughobserving the early neural degeneration of the retina in the spontaneous type2diabetes mice model, thus affording certain evidence in early diabetic retinopathyinterventions.Methods: Both BKS-DB-/-mice and same week old wild type BKS-DB+/+mice are20. Select4in each team randomly at different weeks old(12,16,20,24,28), thenrecord their weight and random blood sugar separately. Mice were anesthetized withintraperitoneal injection of a mixture of urethane and chloral hydrate(equal mixture of10%urethane and5%chloral hydrate,0.15ml/10g body mass) and given PERG andfluorescence fundus angiography(FFA). Afterwards kill them via cervical dislocation,then their eyes were enuncleated and processed to paraffin-embedded sections toanalyse retinal nerve fiber layer thickness(RNFLT) and changes in the number ofganglion cells by HE staining, and detect apoptosis of retinal gangliocytes by TUNEL.Use SPSS for data statistics, with the results in the form of X±s. Groups wereanalyzed using unpaired t test. P<0.05was considered statistically significant.Results: We observed and compared to the control group, the weight of db/db mice isincreased obviously and the blood sugar of db/db mice is increased obviously.Bothhave a significant difference(n=4). Weight value of two groups of mice was analyzedusing unpaired t test at12,16,20,24,28weeks. Respectively p values were0.0334,0.0022,0.0001,0.0005,0.0014;Blood sugar value of two groups of mice was also analyzed using unpaired t test, Respectively p values were0.0001,0.0002,0.0015,0.0001,0.0003. PERG results show(n=8):db/db mice comparedto the control group, the incubation period of N1wave is a little extended at12,16,20weeks but did not reach statistical difference (p-values were0.189,0.3364,0.3064),while the incubation period of N1wave is a little extended at24,28weeks and the groups reached statistical difference. Db/db mice compared tothe control group, the incubation period of P wave is a little extended at12,16,20weeks but did not reach statistical difference (p-values were0.1161,0.5302,0.0789),while the incubation period of P wave is a little extended at24,28weeks and the groups reached statistical difference(p-values were0.0159,0.0277). Db/db mice compared to the control group, the amplitude of P waveat12and16weeks was slightly decreas, but did not reach statistical difference(p-values were0.7812,0.2829);while from20weeks the amplitude of P-wavedecreased significantly and reached statistical difference (p-values were0.0152,0.0114).HE staining of paraffin sections of mouse retina displayed the db/dbmice retinal thickness gradually thinning since20weeks, the decrease in the numberof retinal ganglion cells per unit area, while the control group observed to28weekshas no significant changes. TUNEL detection shows there is apoptosis of retinalgangliocytes in db/db mice at20weeks, per high power field appear at most0-1more,24weeks up to4-5cells/high power field Positive apoptotic cells decreased at28weeks2-3cells/high power field,20,24,28weeks of retinal ganglion cellapoptosis index were as follows:4.35%;14.16%;8.02%, control group of mice at28weeks were not found in obvious apoptosis.Conclusion: Independent retinal neural degeneration occurs earlier than diabetic retinal vascular change in db/db mice, showing ganglion cell apoptosis and thechange of visual electrophysiology(lower amplitude, prolongation latencies);offertargeted neuroprotective medicine might be an effective early diabetes intervention.