[Expression of Bcl-2 and Bax on retinal with a rat model for ocular ischemic syndrome]

To tell the difference of Bcl-2 and Bax expression on the retina between the ocular ischemic syndrome group and the sham group.

Experimental study. To establish the ocular ischemic syndrome model by bilateral common carotid arteries obliteration (BCCAO) in BN rats. Twenty BN rats were divided into two groups randomly: 12 in the model group and 8 in the sham group. In model group, midline incised in the neck and bilateral common carotid artery obliterated. While in the sham group, midline incised in the neck with no obliteration. Pupillary reflex were detected in both groups. After 1 month, rats underwent fundus fluorescein angiography (FFA) examination. Optical coherence tomography (OCT) was used to measure and tell the retina thickness difference in both groups. Expression of Bcl-2 and Bax on rat retina and change of the Bcl-2/Bax ratio were detected by immunohistochemical staining. Chisquare test was used for classification variable, two independent samples T test was used for quantitative data.

Compared to the sham group, only 1 eye of BCCAO group maintained its direct pupillary reflex, other eyes of the group appeared either lost or weakened their direct pupillary reflex. However, all rats in the sham group maintained their pupillary reflex. FFA showed that in the BCCAO group, retinal circulation time was significantly longer than it was in the sham group (aterial phase:t=6.19,P<0.01; arteriovenous phase:t=8.24,P<0.01; venous phase:t=2.73,P<0.05). And in the model group, the background choroidal patchy hypofluorescence and typical arterial forward phenomenon in the early phase of arterial time were observed. OCT showed that in the model group, an obvious decrease of the thickness of neuroepithelial layer of retina was observed, which was (195.67±8.84) µm in the model group and (219.31± 6.92) µm in the sham group. It had statistically significant difference (P<0.05). Immunohistochemical staining results showed imbalance of Bcl-2, Bax expression on rat retina. Compared with the sham group, expression level of bax which was (5.67±0.84) µm in the model group was significantly increased (P<0.05) , while it was (2.34 ± 0.57) µm in the sham group. There was no significant difference (P>0.05) in Bcl-2 expression in both groups, which was (5.61±0.98) µm in the model group and which was (5.63±0.88) µm in the sham group. And Bcl-2/Bax ratio was observed statistically significant decreased (P<0.05) in the BCCAO group compared with that in the sham group, which was (1.01 ± 0.23) in the model group, and which was (2.47±0.47) in the sham group.

BCCAO of rats lead to the injury of retina function, diminish of retinal thickness, imbalance of Bax and Bcl-2 expression.