Study on soluble and insoluble lens proteins in contusion cataract of rat model

Abstract

To study the water soluble and insoluble lens proteins in contusion cataract of rat model, and to study the influence of heat shock (thermotolerance) or quercetin (heat shock protein inhibitor) on the lens proteins. Sprague-Dawley (SD) rats were randomized into four groups (6 in each group): (1) A group, control group. (2) B group, contusion group. (3) C group, heat shock group. (4) D group, quercetin group. In contusion group, contusion of eyes was induced by dropping steel ball against the eyeball (20 g ball dropped from 20 cm height for 100 times each week for 5 weeks). In heat shock group, heat shock was induced by raising the body temperature to 40.5 - 41.5 degrees Celsius for 8 min, 2 - 3 h before the eye contusion (as previously described). Heat shock and contusion was given each week for 5 weeks. In quercetin group, rats were fed with quercetin (100 mg/kg weight) 2-3 h before the contusion. Quercetin and contusion was given each week for 5 weeks. Amount of proteins was measured by using Bradford methods. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was used for the separation and analysis of lens proteins. Five weeks after contusion, the mean water soluble protein of heat shock group was 22.71 + or - 1.99, increased significantly than that of the other three groups. The mean insoluble protein of contusion group was 2.60 + or - 0.48, increased than that of the other three groups. From the analysis of SDS-PAGE, we found that there was a high molecular band near 66 KD in opaque lens and the band became more prominent with the growing opacification of the lens. In contusion cataract, water insoluble lens protein is increased and water soluble lens protein is decreased. SDS-PAGE showed that lens injury resulted in lens proteins moving toward high molecular band.