Thymus daenensis extract prevents scopolamine-induced memory impairment through declining oxidative stress in rats

Abstract

Memory and cognitive impairment induced by oxidative stress are among the main hallmarks of Alzheimer’s disease’s (AD) pathology. The present study aimed to investigate the potential neuroprotective effects of Thymus daenensis (T. daenensis) extract against scopolamine-induced memory impairment and oxidative stress in rats. T. daenensis, widely distributed in Iran and Europe, is known to be a rich source of natural antioxidants and has been traditionally used for various medical purposes. The present study investigated the post-treatment effects of T. daenensis on learning and memory functions, antioxidant cellular defense, and oxidative stress using the scopolamine rat model of AD. The experiments were performed by intraperitoneal injection of scopolamine for 10 consecutive days in Wistar male rats (180–220 g). Additionally, the animals received T. daenensis extract (50-200 mg/kg) by gavage for 14 consecutive days after induction of memory impairment. The animals were divided into 8 groups, namely: control, 200 mg/kg of T. daenensis extract (D200), donepezil (DON), scopolamine (ALZ), ALZ animals treated with different doses of the extract (ALZ+D50 or 100 or 200 mg/kg) and ALZ animals treated with (ALZ+DON). The animals were then subjected to the Morris water maze (MWM) paradigm as a standard criterion for memory function assessment, and after extracting the brain tissues, the related biochemical oxidative stress parameters were determined in the brain. Our results indicated that T. daenensis extract significantly improved animals’ performance in the MWM while significantly reducing oxidative stress and antioxidant imbalance. Furthermore, the extract did not show hepatotoxic effects on treated animals. In addition, the extract treatment significantly decreased both cellular malondialdehyde (MDA) and protein carbonyl (PCO) content while conversely increasing the total reduced glutathione (GSH) content and also the levels of total and endogenous antioxidants in the ferric reducing antioxidant power (FRAP) assay. It seems that the administration of T. daenensis significantly improved both cellular biochemical aspects and memory performance in animal models. Conclusively, it could be beneficial for scopolamine-induced neurotoxicity.