Objective To investigate the temporal and spatial expression pattern of Caspase3、Bax and Bclxl in NmethylNnitrosourea (MNU) damaged rat retina. Methods Twenty-four 50 dayold female Sprague-Dawley rats (n=24) received single intraperitoneal injection of MNU 40 mg/kg and were examined at 1, 3, 7 and 10 days after MNU treatment (6 rats sacrificed at each timepoint). As control, six rats were injected with saline (5 ml/kg) and sacrificed 3d after injection. Expressions of Caspase-3 and bax and bcl-xl were detected by RTPCR and immunofluorescence assays, photoreceptor cell apoptosis was measured by terminal deoxynucleotidyl transferasemediated deoxyuridine triphosphatedigoxigenin nick-end labeling (TUNEL). Results Animal models were successful established and confirmed by pathological studies. RTPCR results indicated that caspase3 and bax upregulated at 1 d (caspase-3 RA =83.23 plusmn;8.11,P= 0.009; bax-RA=72.73 plusmn;9.46,P=0.004) and peaked at 3 d (caspase-3 RA=140.48 plusmn;18.40,P=0.000;bax-RA=102.36 plusmn;13.97,P=0.001)compared with control (caspase-3 RA=62.45 plusmn;7.65; bax-RA =46.53 plusmn;4.41). Bcl-xl expression increased and peaked at 3d (3d RA=79.83 plusmn;5.58, P=0.000 vs control 45.98 plusmn;3.06). It was noted that the ratios of bax / bclxl expression at 1 d, 3 d and 7 d after MNU injection were enhanced (1 d 1.15 plusmn;0.14, P= 0.143; 3 d 1.28 plusmn;0.16, P=0.001; 7 d 1.17 plusmn;0.08, P= 0.079, vs control 1.01 plusmn;0.09), and at 3 d the ratio reached the peak, whereas at10 d bax / bcl-xl ratio (0.73 plusmn;0.07, P= 0.001) was decreased compared with the control. Immunofluorescence assays demonstrated that the changes of bax, bclxl and caspases3 protein expressions coincided with their RTPCR results respectively. The Bax positive cells were detected in the outer nuclear layer; while caspase3 and bclxl positive cells emerged in several layers of retina included the pigment epithelium layer, the photoreceptor cell inner segments, the outer nuclear layer, the outer plexiform layer, the inner plexiform layer and the ganglion cell layer. Photoreceptor cell apoptosis was only detected in the outer nuclear layer and peaked at 3 d in MNU treated rats (AI= 76.97 plusmn;5.83, P= 0.000 vs control 0.00 plusmn; 0.00). Conclusions These data suggest that bax and bcl-xl and caspases3 may involve in the MNUinduced rat photoreceptor cell apoptosis.
Citation: Gao Yang Xingguo Deng Qianna Sun Meifeng He Zhiqiang Zhong. Temporal and spatial expressions of caspase-3,bax and bcl-xl in rat retina with MNU -induced photoreceptor damages. Chinese Journal of Ocular Fundus Diseases, 2009, 25(2): 133-137. doi: Copy