Protective Effect Of Baicalin On Retinal Ganglion Cells In Diabetic Rats And Its Mechanism

Objectives To evaluate whether baicalin can protect the retinal ganglion cells of diabetic rats and explore its mechanismMethods 60 healthy male SD rats,without anterior segment and fundus lesions,weighing200-220g,and fasting blood glucose of 3-6mmol/L,were randomly devided into 40 in the STZ group and 20 into normal group.Forty rats with one-time intraperitoneal injection of STZ to establish a rat model of diabetic nephropathy.And the remaining 20 rats were intraperitoneally injected with the same volume of normal saline instead.The latter was labeled as the normal model group（group N）.After successful modeling,40 rats were randomly divided into 20 diabetic model group（group D）and 20 baicalin treatment group（group B）.Group B rats were given baicalin aqueous solution（50mg/kg）by gavage,and the other two groups of rats were given normal saline（50mg/kg）correspondingly as a control.At 1,4,8,and 12 weeks,the fasting blood glucose values of the three groups of rats were measured and recorded with a blood glucose meter and recorded.At 12 weeks,the rats with poor physiological status,large body weight differences,and dead rats were eliminated.In each group,12 rats were randomly selected total of 36 rats,to continue the experimental research.Hematoxylin-eosin staining（HE）was used to observe the number of retinal ganglion cells and the overall morphology of the retina,the TUNEL method was used to observe the apoptotic cells of the ganglion,and the apoptosis index（AI）of retinal ganglion cells was calculated,immunohistochemistry method was used to detect the protein expression level of CD68,nitrate reductase method was used to measure the content of nitric oxide（NO）,immunofluorescence method was used to detect the protein expression level of signal sransducer and activator of transcription 3（STAT3）and real-time quantitative pcr detecting system（q PCR）was used to observe the expression of STAT3m RNA and interleukin 6m RNA（IL-6）in rat retina.Results 1 Blood glucose:At same observation points,compared with the N group rats,the blood glucose levels in D group rats were significantly increased.After baicalin treatment,compared with the D group rats were decreased.The difference between the three groups was statistically significant(F_group=948.217,P_group<0.05).The blood glucose values of the three groups of rats can exclude the time factor(F_time=0.837,P_time>0.05).2HE staining:Compared with group N rats,we observed that the retinal ganglion cells were lost,nuclear pyknosis occurred,and the total thickness of the retina was decreased in group D rats.After baicalin treatment,compared with the D group rats the number of ganglion cells increased,and the retina became thicker.3 TUNEL and AI values:There were apoptotic cells in all three groups,and the apoptotic cells in group D was significantly higher than that in groups N and B rats.Further testing the AI value,we observed that compared with the N group rats,the AI levels in D group rats were significantly increased.After baicalin treatment,compared with group D,the value of group B decreased.（P<0.05）.4 CD68 protein expression and distribution:The CD68 protein of N group rats only had a little in the inner nuclear layer:,the CD68 protein of D group rats was distributed in all layers of the retina,and compared with N group rats the expression was significantly up-regulated.After baicalin treatment,the distribution of CD68 in group B rats was limited than that in group D rats.And B group rats CD68 expression was down-regulated（P<0.05）.Further testing the average object desktop（AOD）value,we observed that compared with the N group rats,the AOD levels in D group rats were significantly increased.After baicalin treatment,compared with group D,the value of group B decreased（P<0.05）.5Retinal NO content:we observed that compared with the N group rats,the NO content in D group rats were significantly increased.After baicalin treatment,compared with group D,the content of group B decreased（P<0.05）.6 STAT3 immunofluorescence:There are a large number of positive expressions of STAT3 in each layer of the retina in group D,while the expression of STAT3 in the retina of group N is mainly distributed in the inner plexiform layer.The positive expression of rats in group B is less in each layer than group D.7 Relative expression levels of STAT3m RNA and IL-6m RNA:We observed that compared with the N group rats,the STAT3m RNA and IL-6m RNA in D group rats were significantly increased.After baicalin treatment,compared with group D rats,the relative expression levels group B decreased.（P<0.05）.Conclusions 1 Baicalin has a certain protective effect on ganglion cells of diabetic rats.2The protective effect of baicalin on ganglion cells is related to the inhibition of microglia activation and IL-6/STAT3 signaling pathway.Figure10;Table13;Reference147...