Sustained aftereffect of the amnestic action of scopolamine in rats and its elimination by piracetam

Abstract

Experiments were carried out on male Wistar rats to assess (1) the effect of chronically administered (for 20 days) scopolamine on their learning capacity and memory 10 days after its last administration and (2) the influence of the nootropic piracetam, given for 10 days after scopolamine and before leaming a conditioned passive avoidance response, on cognitive functions of the brain altered as a result of the M-cholinergic receptors being blocked by scopolamine. Scopolamine-dosed rats showed poor reproduction of the conditioned passive avoidance response when tested for this response at 24 h and 30 days after learning it, whereas those treated with piracetam after scopolamine retained the response well both at 24 h and at 30 days. Piracetam also restored the scopolanaine-impaired acute extinction of orienting/exploratory activity in the rats.

The cannabinoid-memory and the Angiotensin-memory paradoxes: Another penrose triangle?

“…The paradoxical effects could be partially explained by U-shaped dose response relationship that is inherent of most of the toxicological compounds like scopolamine. 11,12,13,14 Valsartan could follow similar effect relationship the peaks might be mediated by AT1 and later by AT4 receptors, the trough by AT2 receptors, owing probably to differential affinities of valsartan to these receptors.…”