C. Creuzot–Garcher

Changes of the Inducible Heat Shock Protein 70 mRNA Level in Rat Retina After Ischemia and Reperfusion

The heat shock protein 70 (HSP-70) mRNA level was evaluated in Long Evans rat retinas after ischemia and after reperfusion following ischemia. Retinal ischemia was induced by ligation of the optic nerve and vessels. Rats were sacrificed after 90 min of ischemia or 120 min of reperfusion following ischemia. Retinas were dissected. Total mRNA was extracted and inducible HSP-70 (iHSP-70) gene expression was analyzed by quantification of transcripts using an RT-PCR assay. Results were expressed in arbitrary units as a ratio of the optical density of iHSP-70/β-actin electrophoretic bands. iHSP-70 gene expression was 0.220 ± 0.027 (n = 5), 0.502 ± 0.045 (n = 5) and 0.468 ± 0.032 (n = 5) for the sham-operated, ischemia only and ischemia and reperfusion groups, respectively. There was a statistically significant difference between the control and ischemia groups, and between the control and ischemia and reperfusion groups (p < 0.001), suggesting a rapid HSP-70 mRNA expression of the retina due to an ischemic injury.

CHANGES OF CATALASE ACTIVITY AFTER ISCHEMIA-REPERFUSION IN RAT RETINA

Catalase activity was evaluated in Long Evans rat retina after ischemia and reperfusion. Ischemia was induced by ligation of the optic nerve and vessels. Rats were sacrificed after 15 and 120 min of reperfusion, respectively. Catalase activity was assessed by Claibornes method and was expressed as U/mg of protein. In the first group, retinas of each animal were pooled. In the second group, ischemia was induced in the right eye with the left eye serving as control. In the first group, enzyme activity was 7.39 +/- 0.26 (n = 11), 7.67 +/- 0.27 (n = 9) and 9.15 +/- 0.45 (n = 7) for the sham-operated, 15- and 120-min reperfusion groups, respectively. There was a significant difference between the control and 120-min reperfusion groups (p < 0.001). In the second group, there was a significant (p < 0.01) increase in catalase activity in the ischemic eye compared to the non-ischemic eye after 15 (n = 7) and 120 min (n = 9) of reperfusion. These findings may suggest a rapid activation of catalase activity during the ischemia-reperfusion sequence.