Effects of anxiolytic doses of ZnO nanoparticle on ECG parameters in restraint and nonrestraint ovariectomized female rats

Objective(s): Based on our previous studies about nanoZnO effects on physiological behaviors, in this study we have investigated the effects of anxiolytic doses of nanoZnO on electrocardiogram (ECG) sings changes in the restraint and nonrestraint ovariectomized (OVX) female rats. Methods: Animals (160180 g) were divided into: control (nonOVX + saline) and OVX groups that received: saline, nanoZnO 1, 2.5 and 5 mg/kg, stress of 90 or 180 min + saline and stress of 180 min+ nanoZnO 2.5 mg/kg. Anxietylike behaviors were measured by the elevated plus maze (EPM) and hole board apparatus thirty min after intraperitoneally injections or stress induction. ECG parameters and serum zinc level were measured in all groups. Results: Ovariectomy induced anxiety and restraint stress in OVX rats increased it in the hole board test. NanoZnO 2.5 and 5 mg/kg improved anxietylike behaviors in the EPM test. NanoZnO 2.5 mg/kg improved anxiety induced by the restraint stress in the hole board test. NanoZnO increased zinc level in a dosedependent manner in the nonrestraint OVX groups. NanoZnO 1 mg/kg decreased QRS amplitude and all doses decreased QT interval to the level of nonOVX group. NanoZnO 5 mg/kg decreased QTc to the level of nonOVX group. Stress of 90 min increased QT interval while stress of 180 min decreased it. NanoZnO after stress induction could alleviate heart rate, RR interval and QRS interval to the level of nonOVX group. Conclusion: It seems that nanoZnO rather than could improve anxiety, alleviated ECG parameters in the restraint and nonrestraint OVX rats.