Long-lasting mnemotropic effect of substance P and its N-terminal fragment (SP1-7) on avoidance learning.
We investigated the long-lasting effect of peripheral injection of the neuropeptide substance P (SP) and of some N- or C-terminal SP fragments (SPN and SPC, respectively) on retention test performance of avoidance learning. Male Wistar rats (220 to 280 g) were trained in an inhibitory step-down avoidance task and tested 24 h or 21 days later. Immediately after the training trial rats received an intraperitoneal injection of SP (50 micrograms/kg), SPN 1-7 (167 micrograms/kg) or SPC 7-11 (134 micrograms/kg). Control groups were injected with vehicle or SP 5 h after the training trial. The immediate post-training administration of SP and SPN, but not SPC, facilitated avoidance behavior in rats tested 24 h or 21 days later, i.e., the retention test latencies of the SP and SPN groups were significantly longer (P < 0.05, Mann-Whitney U-test) during both training-test intervals. These observations suggest that the memory-enhancing effect of SP is long-lasting and that the amino acid sequence responsible for this effect is encoded by its N-terminal part.
Tomaz
C
C
Laboratório de Psicobiologia, Faculdade de Filosofia, Ciências e Letras de Ribeiräo Preto, Universidade de Säo Paulo, Brasil. calstomaz@spider.usp.br
Silva
A C
AC
Nogueira
P J
PJ
D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects*; D008297:Male; D008568:Memory / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D013373:Substance P / Q000494:pharmacology*
D013373:Substance P