Investigation on the effect of eclipta alba on animal models of learning and memory.

Short and long term memory loss may result from deteriorating cerebral mechanisms due to varied causes which could have a tremendous impact on the quality of life. Herbs are being constantly explored to resolve cognitive deficits. Eclipta alba (Ea) commonly called as the trailing Eclipta is being examined for its memory enhancing quality as it is traditionally used for this purpose. The shade dried leaves of Eclipta alba was extracted with distilled water. The suspension of Ea containing 100 and 200 mg/kg was administered to rats to evaluate Transfer Latency (TL) on an elevated plus maze. TL was a measure of acquisition and retrieval learning. Mice were placed at the center of open field apparatus to assess spatial habitual learning, observed for 20 minutes for rearing and time spent during rearing using varied doses for 30 minutes, 24 hours and 96 hours and 144 hrs. The results revealed significant improvement of retrieval memory.

Sildenafil improves acquisition and retention of memory in mice.

Sildenafil (Viagra) has been introduced recently in market to correct male impotency and has gained immense popularity for its dramatic effects all over the world. The present study was designed to investigate the effect of sildenafil on learning and memory in mice using elevated plus maze. A total of XV groups of animals were employed in the present study. Central cholinergic pathways play a crucial role in learning and memory processes. Physostigmine, an anticholinesterase agent (0.5 mg, 1.0 mg kg(-1), i.p) was employed for its memory enhancing property and alprazolam a benzodiazepine receptor agonist served as a memory-impairing agent. In the present study, alprazolam produced anterograde amnesia (at 0.5 mg kg(-1), i.p) and retrograde amnesia (at 0.25 mg, 0.5 mg, 0.75 mg kg(-1), i.p.) in separate groups of animals. Caffeine at 5 mg, 10 mg and 20 mg kg(-1), i.p. (an established psychostimulant) did not show any significant change in learning and memory of mice. Sildenafil (at 8 mg kg(-1), i.p.) administered 30 minutes prior to training on first day produced a marginal decrease in transfer latency time on first day; whereas, sildenafil (at 2 mg, 4 mg, 8 mg kg(-1), i.p.) administered immediately after training on first day produced a dose-dependent improvement of memory in mice. However, further studies need to be carried out to elucidate the underlying mechanism of sildenafil as a memory enhancer.