[Significance of the time of administering substance P on learning and memory in rats].

We studied the influence of time and period of application of substance P (SP) on type and size of the effects on learning in Wistar rats. Treatment with SP before acquisition training had a fascillitating effect on learning. If SP was applied from the 1st or 3rd d of acquisition training there was no effect; if given from the 2nd d an inhibition was found; if given from the 4th d the consolidation of memory became finished. We found during the inhibition of exploration if SP was given acquisition training only (and no longer during the retention test). Some possible explanations of these differing effects of SP are discussed.