Protective effect of α-terpineol against impairment of hippocampal synaptic plasticity and spatial memory following transient cerebral ischemia in rats

Abstract

<strong><em>Objective(s)</em></strong>: Cerebral ischemia is often associated with cognitive impairment. Oxidative stress has a crucial role in the memory deficit following ischemia/reperfusion injury. α-Terpineol is a monoterpenoid with anti-inflammatory and antioxidant effects. This study was carried out to investigate the effect of α-terpineol against memory impairment following cerebral ischemia in rats. <br/><strong><em>Materials and Methods: </em></strong>Cerebral ischemia was induced by transient bilateral common carotid artery occlusion in male Wistar rats. The rats were allocated to sham, ischemia, and α-terpineol-treated groups. α-Terpineol was given at doses of 50, 100, and 200 mg/kg, IP once daily for 7 days post ischemia. Morris water maze (MWM) test was used to assess spatial memory and in vivo extracellular recording of long-term potentiation (LTP) in the hippocampal dentate gyrus was carried out to evaluate synaptic plasticity. Malondialdehyde (MDA) was measured to assess the extent of lipid peroxidation in the hippocampus. <br/><strong><em>Results:</em></strong> In MWM test, α-terpineol (100 mg/kg, IP) significantly decreased the escape latency during training trials (<em>P</em><0.01). In addition, α-terpineol increased the number of crossings over the platform location and decreased average proximity to the target in probe trial (<em>P</em><0.05). In electrophysiological recording, α-terpineol (100 mg/kg) facilitated the induction of LTP in the hippocampus which was persistent over 2 hr. α-Terpineol (100 and 200 mg/kg) also significantly lowered hippocampal MDA levels in rats subjected to cerebral ischemia. <br/><strong><em>Conclusion:</em></strong> These findings indicate that α-terpineol improves cerebral ischemia-related memory impairment in rats through the facilitation of LTP and suppression of lipid peroxidation in the hippocampus.