Effects of Thymus vulgaris on passive avoidance learning and oxidative stress in pentylenetetrazole-induced model of memory impairment in the male Wistar rats

Abstract

Thyme with the scientific moniker of Thymus vulgaris has been used in traditional medicine for treatment of respiratory and gastrointestinal disease. Its extract has also been adopted to treat epilepsy and other central nervous system (CNS) disorders. To evaluate the effect of T. vulgaris extract (TVE), the experimental model of memory impairment caused by seizures was performed in rats. Seizures in Wistar rats (200-250 g) were induced with a challenge dose (60 mg/kg) of pentylenetetrazole (PTZ). Animal treated with either TVE (100 mg/kg) or sodium valproate (100 mg/kg) alone or in combination intraperitoneally 30 min before PTZ administration. The effect of memory was assessed using passive avoidance test (PA). At the end of the experiment, the rats were put down painlessly via deep anesthesia and their serums were isolated for oxidant/antioxidant assay (nitric oxide (NO), catalase (CAT), superoxide dismutase (SOD)). PTZ-treated groups revealed memory deficit seizures compared with the control group. TVE exhibited protection at the dose of 100 mg/kg in the PTZ-induced seizures. TVE also reduced seizure-induced memory impairment, which resulted in a significant improvement in memory retention in PA compared with the PTZ-treated group. In addition, TVE treatment protects the seizure-induced memory deficit by lowering NO and restore the antioxidant enzyme CAT and SOD levels. The findings revealed that TVE exhibits significant inhibitory activity and impedes seizure-induced memory impairment by inhibiting oxidative stress damage.