Sabinene improves memory in naive and scopolamine-induced amnesic mice by inhibiting neurotransmitter metabolic enzymes and attenuating oxidative stress

Abstract

Sabinene (SAB) is a monoterpene hydrocarbon found in various essential oils, known for its neuroprotective and antioxidant properties. However, its effect on cognitive functions remains unexplored. This study aimed to investigate the memory-enhancing and nootropic effects of SAB in mice. Herewith, groups 1 and 2 received normal saline; groups 3-5 were pretreated with SAB (5, 10, and 20 mg/kg) alone, while mice in group 6 received donepezil (DPZ) (1 mg/kg) orally. Additionally, mice in groups 2-6 were treated with scopolamine (3 mg/kg, i.p.) 30 min after each treatment with SAB, respectively, for 14 days. Behavioral tests, like novel-object recognition and Y-maze tests to evaluate cognitive function and motor activity, were employed. Biochemical assays were conducted to measure neurotransmitter levels, molybdenum-containing enzymes, oxidative stress, and nitrergic markers in the prefrontal cortex (PFC) and hippocampus. Treatments with SAB (5, 10, and 20 mg/kg) improved spatial and non-spatial working memory on cognitive tests but were associated with reduced motor reactivity. SAB improved glutathione and glutathione peroxidase levels in the PFC and hippocampus compared to scopolamine. SAB alone significantly increased glutathione and superoxide dismutase levels and reduced catalase, glutathione peroxidase, and acetylcholinesterase activities in the PFC and hippocampus, respectively. SAB reduced aldehyde oxidase and xanthine oxidase, while DPZ lowered sulphite oxidase in the PFC and hippocampus relative to the controls, respectively. This study suggests SAB improves cognitive performance and reverses scopolamine-induced memory decline by enhancing antioxidant systems, cholinergic transmission, and molybdenum-containing enzymes.