Purpose: To investigate whether grape seed proanthocyanidins (GSP) might protect the heart against myocardial injury (MI) induced by isoproterenol (ISO), in a rat model.
Methods: GSP was administered orally to Wistar albino rats (150-180 g) in three different doses, by gastric gavage (50, 100 and 150 mg kg(-1) GSP), 6 days a week for 5 weeks. At the end of this period, all the rats, except the normal untreated rats that served as the control group, were administered ISO, 85 mg kg(-1) subcutaneously, for 2 consecutive days to induce myocardial injury. After 48 h, rats (n=6 per group) were anaesthetized with anesthetic ether, sacrificed and the levels of biochemical and histological observations of the heart tissues were performed.
Result: Our results suggest that prior administration of GSP maintained the levels of the marker enzymes (AST, ALT, LDH and CK) in all the treatment groups (GSP-50-ISO, GSP-100-ISO and GSP-150-ISO) when compared to ISO-injected rats. The entire baseline groups also showed no significant alterations in serum marker enzyme levels in comparison to that of control group. Interestingly, in this study, there was no significant change in the basal levels of myocardial TBARS, GST, SOD and CAT on administration of GSP in all the three dosages (GSP-50-BL, GSP-100-BL and GSP-150-BL). However, a significant decrease occurred in the levels of GSH and GPx in group GSP-50-BL, which in the absence of any cellular injury (as evidenced by histological studies), is considered to be non-lethal. In the ISO-injected group there was a significant rise in TBARS and a significant decrease in GSH, GPx, GST, SOD and CAT when compared to group control. The administration of GSP maintained the activities of these enzymes close to normal levels when compared to group ISO, which proves the stress stabilizing action of GSP. The biochemical and histological evidence from this study shows that 100 and 150 mg kg(-1) of GSP protected against ISO-induced myocardial injury.
Conclusion: This study demonstrates that GSP has a significant effect in the protection of heart against MI induced by ISO. We believe that pretreatment with GSP may contribute to developing novel strategies in the prevention and treatment of cardiotoxic effects of elevated levels of catecholamine.