| Objective: This study, aimed to evaluate the effects of metabolic and humoralabnormalities on the diabetic retinoppthy (DR) against the expression changes ofaquaporin-4(AQP-4) in the diabetic rat retina. By observing the diabetic rats treatedwith aminoguanidine (AG), this study further analyzed the correlation between theexpression changes of AQP-4and the advanced glycation end products (AGEs), andexplored the role of AGEs in the expression changes of AQP-4.Methods: Fifty-one depuratory male Sprague-Dawley (SD) rats weighing about200gm, about2month old were randomly divided into three groups: a control group(normal, nondiabetic), a diabetic group, and an AG-treated diabetic group.The controlgroup induced by intraperitoneal injuction of physiologicl saline.The other two groupswere diabetic models induced by intraperitoneal injuction of steptozotocin (STZ).Among them, rats in the AG-treated diabetic group were treated by injecting intostomach with aminoguanidine. Generally, the retinal tissues of rats in each group weremeasured and analyzed respectively after1month,3months, and6months. Giventhese rat retinal tissues, the immunohistochemical technique was used to observe theirpathological changes in the control group and the diabetic group. Besides, theWestern Blot method would be deployed to investigate the expression and changes ofAQP-4in the retinal tissues in each group. Furthermore, the ELISA method was usedto detect the expression and changes of AGEs in the retinal tissues in each group, anddetermined the correlation between the expression changes of AQP-4and AGEs. Theresults were shown using the computer image, and the statistics were analyzed withthe SPSS17.0software. Here, the data were illustrated using x±s, the comparisonbetween the mean was mainly done by t tests, and the multivariate analysis, varianceanalysis and linear correlation analysis on the data were maded based on repeatedmeasurements. Furthermore, α is set to be0.05for significant inspection standard. Results: Data showed that with the increasing of the feeding time, the normal ratsgave an increased level of the body mass and maintained a normal level of the bloodglucose (<5.7mmol/L).The diabetic rats while produced a significant decreased levelof the body mass after12hs and introduced significantly higher level of the bloodglucose reaching the standard of DR (>17.6mmol/L). Compared with the normal rats,the diabetic rats had higher blood glucose levels with the development of diabetes andthe difference was very significant (P<0.05). However, no significant difference onthe body mass or on the blood glucose was found between the two diabetic groups(P>0.05).Rats with diabetic for1month, the structure of retinal layers were clearness andmorphological changes of cells were obviously. Rats with diabetic for3months, thestructure were porosity in outer plexiform layer, inner plexiform layer and ganglioncell layer of the retinal. Rats with diabetic for6months, edema in the retinal layerwere terrier obviously, the outer plexiform layer and inner plexiform layer showedpathological changes, moreover, there were cavity affects in ganglion cell layer andinner nuclear layer.The expressions of AGEs and AQP-4in the retinal tissues of rats were shown ineach group. Compared with the normal rats, the diabetic rats had higher expressionsof AGEs and AQP-4in the retinal tissues. The difference became more significant(P<0.05), with the development of diabetes when the abservation time was increasingfrom1month to6months. While the AG-treated diabatic rats gave a decreasing levelof the expression of AGEs in the serum and the retinal tissues, this produced asignificant difference (P<0.05) with the diabatic rats without threatment and nosignicant difference (P>0.05) with the normal rats. The change of the expression ofAQP-4showed similar trends as that of AGEs in the retinal tissues of the AG-treateddiabetic rats. At1month, it had significant difference compared to that of the normalrats (P<0.05). At3months, it showed no difference with that of the normal rats(P>0.05). However at6months, the difference with that of the normal rats wouldreturn to become very significant (0.01<P<0.05). Meanwhile, the differencecompared with the diabetic rats without treatment maintained a very significant level through the above three time periods (P>0.05). In summary, the linear correlationanalysis results showed there was a positive correlation between the expressionchanges of AQP-4and AGEs in the retinal tissues of diabetic rats (r=0.943, P=0.005)and in the diabetic rats treated with AG (r=0.886, P=0.019).Conclusion: The metabolic and humoral abnormalities could affect theoccurrence and development of the rat diabetic retinopathy. In the retinal tissues withdiabetes, the expression changes of AQP-4might be associated with the changes ofAGEs. Furthermore, treatment with AG to improve DR might be caused by repressingthe expression AQP-4in the retinal tissues. |
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