Purpose: To investigate the dynamic expression of heat shock protein (Hsp)70 and Hsp27 in lens epithelial cells (LECs) of contused eyes and the effects of heat shock and quercetin.
Methods: Rat eyes were randomized into three groups: contusion, heat shock, and quercetin. Eye contusions were induced by dropping a 20 g steel ball from a height of 20 cm for 100 times. Heat shock was induced by raising the core body temperature to 40.5-41.5 degrees C for 8 min, 2-3 h before eye contusion. Quercetin, an inhibitor of Hsp expression, was given via gavage (100 mg/kg) 2-3 h before eye contusion. Experimental eyes were enucleated at 0, 1, 3, 6, and 24 h following each group treatment for the detection of Hsp70 and Hsp27 expression in LECs using RT-PCR. Lens sections were examined by immunohistochemistry with antibodies to Hsp70.
Results: Basic expression of Hsp70 and Hsp27 was observed in LECs. Expression of Hsp70 in LECs was increased after contusion in a time-dependent manner. Preconditioning hyperthemia (45 degrees C, 8 min) resulted in a significant increase of Hsp70 expression compared to the base level, and enhanced the expression in each subgroup in contrast to the corresponding subgroup in the contusion group. However, Hsp70 levels in the 1-6 h subgroup in the quercetin group was significantly lower. There was no notable change of expression of Hsp27 between each group. Immunostaining of Hsp70 was prominent in LECs of contusion eyes and heat shock eyes compared with those in normal eyes. Immunostaining of Hsp70 was faint in LECs of quercetin eyes.
Conclusions: Increased expression of Hsp70 in LECs of contused eyes may play a protective role against degeneration of lens protein. Thermal preconditioning possibly protects against lens injury by increasing the expression of Hsp70. Endogenous protective mechanisms may be important in eye contusion.