Protective effects of Centella asiatica extract on spatial memory and learning deficits in animal model of systemic inflammation induced by lipopolysaccharide

BACKGROUND AND AIM: Centella asiatica (L.) Urb. (Apiaceae) is a renowned medicinal plant being used in the Ayurvedic system for its pharmacological effects on the central nervous system such as rejuvenating, sedative, anxiolytic and memory-enhancing properties. The present study was designed to investigate the effect of Centella asiatica (CA) extract on inflammatory responses induced by lipopolysaccharide (LPS) and resulting changes in cognitive behavior. MATERIALS AND METHODS: Adult male Sprague-Dawley rats were divided into 4 groups as control, LPS, CA and LPS + CA. The treatments with LPS (5 mg/kg) were intraperitoneally (i.p) injected on day 4 and CA ethanol extract (200 mg/kg) were given orally for 14 days. Morris Water Maze (MWM) test was performed to assess spatial learning and memory performance. Acute oral toxicity of the extract at the highest dose of 5000 mg/kg was also conducted. RESULTS: Single administration of LPS was able to significantly elicit learning and memory impairment (p < .05) when compared to the control groups. Treatment with CA significantly improved the impaired learning ability in which the LPS + CA rats took the shortest time and route to find the hidden platform (15.85 ± 2.68 s (p < .001); 352.43 ± 88.10 cm (p < .001) on day 5) and induced differential cytokine responses in the blood. No mortality and no significant variation in the body and organ weights between the control and the treated group was observed after 14 days of acute toxicity study. Hematological analysis and biochemical parameters revealed no toxic effects of the extract. Pathologically, neither gross abnormalities nor histopathological changes were observed. DISCUSSION AND CONCLUSION: Centella asiatica KEY MESSAGE: 1. A single dose of lipopolysaccharide (LPS) (5 mg/kg) administered systemically to mimic the consequences of LPS-induced inflammatory responses was able to affect some behavioral modification of spatial memory at the time point of study. 2. The study showed that the learning capability during the training trial was restored or ameliorated with the pre-emptive treatment of Centella asiatica extract (200 mg/kg). 3. Centella asiatica extract improves spatial memory, learning deficits and regulates proinflammatory responses in systemic LPS-treated rats.