[Reinvestigation of streptozotocin induced diabetic cataract as a standard experimental model]

In order to find an appropriate model of experimentally induced streptozotocin diabetic cataract rat for evaluation of the anti-cataract agents. Experimental diabetic cataracts were induced in 3 rat strains (Sprague-Dawley SD, Brown Norway BN, Wistar WIS), age 5 and 7 weeks old, by intravenous injection of 70 mg/kg streptozotocin. The cataract progression was followed by morphological and biochemical assessment. Two types of initial cataractous change were observed in SD and WIS rats which mainly consisted of water-vacuole formation in the peripheral area and a diffuse cloudiness progressing around the anterior Y-suture area. The initial change of BN rats was a Y-suture dissociation and fine water-clefts with dot-like vacuoles. Those initial changes in SD and WIS rats differed from those in BN. No difference in aldose reductase activities among the three strains was found, but BN rats had significantly higher sorbitol dehydrogenase activity than SD or WIS rats. It seems that 7-week-old BN rats are more suitable for experimental diabetic cataract models than SD or WIS.