Evaluation of potential antiamnesic activities of aqueous extract of Vitex trifolia leaves against scopolamine induced amnesia and in normal rats.

BACKGROUND

The goal of this study was to evaluate the cerebroprotective and cognition-enhancing activities of the aqueous Vitex trifolia (Vt) L. (Verbenaceae) leaf extract against scopolamine-induced amnesia and in normal rats.

METHODS

Reference or working memory and long-term memory in rodents were tested by experimental paradigms like passive avoidance (PA) and T-maze (TM), respectively. TM and Morris water maze (MWM) were used to screen putative spatial or localization task and the navigation memory-enhancing activities of Vt extract, respectively. In both the PA and TM models, scopolamine (0.5 mg/kg, intraperitoneal, 30 min prior to the trial) was used to induce amnesia, and donepezil (3 mg/kg/day for 15 days) was used as a standard antiamnesic drug. In MWM, two doses of Vt extract were tested against normal control rats. The aqueous Vt extract was prepared as a suspension in 0.5% carboxymethyl cellulose and administered orally at two doses (10 and 20 mg/kg/day) for 15 days to the respective group of rats.

RESULTS

The higher dose (20 mg/kg) of plant extract exhibited significant (p<0.01) antiamnesic activity in the PA and TM models vs. the control. In the MWM test, at probe trial, Vt extract 20 mg/kg showed the least escape latency time, which was statistically significant (p<0.01) and exhibited maximum percentage of time spent in the probe quadrant by 60.75%.

CONCLUSIONS

These results partly substantiate the traditional use of Vt leaves for improvement of cognition, indicating that daily administration of Vt leaves differentially could modulate short- and long-term learning and memory in rats probably through its battery of anticholinesterase, procholinergic, anti-inflammatory, antioxidant, and neuroprotective activities.