The Effect of Hydroalcoholic Extract of Olive Leaves on Blood Pressure in Rat Model of Two-Kidney, One-Clip Goldblatt Hypertension

Background: In Iran’s traditional medicine, the leaves of olive treeare of value for the treatment of hypertension. This study was designed toexamine the effects of hydroalcoholic extract of olive leaves in rat model oftwo-kidney, one-clip hypertension and to further explore whether its hypotensiveactivity was mediated by enhancing the basal release of endothelium-derivednitric oxide.Methods: Animals were divided into two main groups includingsham-operated and renal artery-clipped ones. The latter was further divided into5 groups of untreated rats, vehicle-treated rats, which received daily oraladministrations of one ml distilled water, and extract-treated rats receivingolive leaves extract at 50, 150 or 500 mg/kg in the same volume of vehiclestarting the next day after the operation. Four weeks later, mean blood pressureand heart rate were measured under anesthesia before and after theadministration of NG-nitro-L-arginine methyl ester (L-NAME).Results: Mean arterial pressures, and right kidney and heart weights ofuntreated and vehicle-treated renal artery-clipped rats were significantlyhigher but left kidney weights were significantly lower than those ofshamoperated animals. However, there was no significant difference between theheart rates of these groups. Compared to vehicle-treated renal artery-clippedrats, treatment with hydroalcoholic extracts of olive leaves at 50, 150 or 500mg/kg/day was associated with significantly lower mean arterial pressure, rightkidney and heart weights but did not affect heart rate or left kidney weights.The intravenous administration of L-NAME resulted in a significant increase inmean arterial pressure in sham-operated and extract-treated rats whereas therewas no change in renal artery clipped or vehicle-treated groups.Conclusion: The findings of the study show that hydroalcoholic extract ofolive leaves prevents the clipinduced increase in mean arterial pressure, whichmight be partly mediated by enhancing the basal release of nitric oxide.