Substance P enhancement of inhibitory avoidance learning: mediation by the N-terminal sequence.
Experiments were performed to investigate the effects of intraperitoneally administered undecapeptide substance P (SP), its N-terminal fragment SP(1-7) (SPN) and the C-terminal analog [pGlu6]-SP(6-11) (SPC) on inhibitory avoidance learning, using a one-trial up-hill avoidance task. In Experiment 1 rats were injected with either SP (50 micrograms/kg), SPN (3.3, 33, 167, 333 micrograms/kg) or SPC (2.7, 27, 134, 268 micrograms/kg) immediately after the training trial. Controls received the diluent vehicles. When tested 24 hr later, rats injected with 50 micrograms/kg SP (37 nmol/kg) and 167 micrograms/kg SPN (185 nmol/kg) exhibited longer step-up latencies than vehicle-treated controls. None of the other doses of SPN nor of the C-terminal fragment influenced performance. In Experiment 2, 167 micrograms/kg SPN or vehicle was injected posttrial either immediately or 5 hr after the training trial. Retention latencies 24 hr later were longer for rats treated with 167 micrograms/kg SPN immediately after the training trial. Performance of the SPN 5-hr delay group did not differ from that of the vehicle-injected controls, ruling out proactive effects of SPN on recall.
Institute of Physiological Psychology, University of Düsseldorf, F.R.G.
R U
RU
Hasenöhrl
P
P
Gerhardt
J P
JP
Huston
D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects*; D008297:Male; D010446:Peptide Fragments / Q000494:pharmacology*; D011761:Pyrrolidonecarboxylic Acid / Q000031:analogs & derivatives; D051381:Rats; D011919:Rats, Inbred Strains; D013329:Structure-Activity Relationship; D013373:Substance P / Q000031:analogs & derivatives* / Q000494:pharmacology*
D010446:Peptide Fragments; D013373:Substance P; C026238:substance P (6-11), pGlu(6)-; C036877:substance P (1-7); D011761:Pyrrolidonecarboxylic Acid