ABSTRACT
· AIM: To explore the relationship between the expression of Fas/FasL and the apoptosis in retinal ischemia/reperfusion injury of rats, as well as the therapeutic effects of basic fibroblast growth factor (bFGF)on the ischemic retina.injury were made by transiently elevating introcular pressure. A total of 28 rats were divided into Normal Group and Operative Group. The latter were subdivided into 1, 6, 12, 24, 48 and 72h after reperfusion, in which the left eyes of the rats were in the ischemia/reperfusion groups and the right ones were in the treatment groups (bFGF intracameral injection). Apoptosis was assessed by the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labelling (TUNEL) method, and theexpression of Fas/FasL ligand was studied by strept avidin-biotin complex (SABC) immunohistochemistry.mai rats' retinae, but there were a significant number of TUNEL positive cells in 6-24h after transient ischemia followed by a decrease at 48h. The number of TUNEL positive cells reached a maximum at 24h after ischemia.The expression of Fas gradually increased as early as at 6h, reached a peak at 24h, then decreased at 48h. Similarly, the expression of Fas ligand was at peak in 24-48h in GCL and INL of retina. bFGF ministered before reperfusion inhibited apoptotsis and ameliorated the tissue damage. It also diminished Fas and FasL expression in ischemic/reperfused retina.siently elevated IOP induced apoptosis of cells in the retina. Fas/FasL may have an important role in the early events of the apoptotic pathways. bFGF can rescue RGCs from retinal ischemia/reperfusion injury through down-regulation of Fas and Fas ligand expression and may represent an important mechanism for therapeutic neuroprotection.
ABSTRACT
<p><b>BACKGROUND</b>Basic fibroblast growth factor (bFGF) plays important roles in retina degeneration, light injury, mechanical injury, especially in retina ischemia-reperfusion injury (RIRI). This study was to investigate the therapeutical effect of bFGF on RIRI and its mechanisms.</p><p><b>METHODS</b>Experimental RIRI was induced by increasing intraocular pressure (IOP) in the eyes of 48 rats. These rats were divided into normal control, ischemia-reperfusion and bFGF-treated groups. Histological and ultrastructural changes of in the retina of different groups were observed, and the number of retinal ganglion cells (RGCs) was quantitatively analyzed under microscopy. Apoptotic cells were detected using the TdT-dUTP terminal nick-end labeling (TUNEL) method. The expression of caspase-3 was determined by streptavidin peroxidase (SP) immunohistochemistry. Atomic absorption spectrum method was used to evaluate the intracellular calcium changes.</p><p><b>RESULTS</b>At the early stage of retinal ischemia-reperfusion injury, retina edema in the treated group was significantly eliminated compared with the untreated ischemic animals. RGCs in the bFGF-treated group was more than those in the untreated ischemic group during the post-reperfusion stages. In ischemic group, apoptotic cells could be found at 6th hour after reperfusion and reached the peak at 24 hours. At 72nd hour no apoptotic cells could be found.The changes in caspase-3 expression had a similar manner. The intracellular calcium of rat retina began to increase at 1st hour, reached the peak at 24 hours, and began to decrease at 72 hours. The change of the three markers in the treatment group showed a similar pattern, but they were all relatively less obvious.</p><p><b>CONCLUSION</b>Apoptosis may play a vital role in RIRI. bFGF may has therapeutical effects on RIRI by inhibiting the increase of intracellular calcium and caspase-3 expression.</p>