Heme oxygenase-1-related carbon monoxide and flavonoids in ischemic/reperfused rat retina

PURPOSE. There is increasing evidence to show cytoprotective effects of various flavonoid-rich extracts and the tissue-protective capacity of flavonoid-rich extract of sour cherry is due to flavonoid components of seeds. Sour cherry seed flavonoids were evaluated for their contribution to postischemic recovery related to endogenous carbon monoxide ( CO) production in rat retinas subjected to ischemia/reperfusion. METHODS. Rats were orally treated with selected doses of flavonoid-rich extract of sour cherry seeds for 2 weeks. Animals were anesthetized, and a suture was placed behind the globe including the central retinal artery. Next, retinas were subjected to 90 minutes of ischemia followed by 24 hours of reperfusion. After this procedure, heme oxygenase-1 (HO-1) related protein expression and enzyme activity, HO-1-related endogenous CO production, and ionic imbalance including tissue Na+, K+, and Ca2+ in untreated and treated ischemic/ reperfused retinas were measured. RESULTS. Retinal ischemia/reperfusion resulted in a significant reduction ( to 10%) in HO-1 protein expression, enzyme activity, and HO-1-related endogenous CO production in the retina. These changes were accompanied by increases in retinal Na+ and Ca2+ gains and loss of K+. In rats treated with 10 and 30 mg/kg of sour cherry flavonoid - rich extract, after 24 hours of reperfusion, tissue Na+ and Ca2+ accumulation and K+ loss were prevented in comparison with the drug-free control. CONCLUSIONS. Sour cherry seed flavonoid - rich extract showed a protective effect against reperfusion-induced injury through its ability to reduce the changes in concentrations of retinal ions through HO-1 - related endogenous CO production in the ischemic/ reperfused retina.