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.