Intracerebroventricular effects of angiotensin II on a step-through passive avoidance task in rats.
A wealth of evidence indicates that angiotensin II (Ang II) is involved in learning and memory. However, the precise role of this peptide in these cognitive processes is still controversial, with data indicating either an inhibitory or an enhancing action. The present study was designed to further investigate the effects of intracerebroventricular injections of Ang II (0.5, 1 or 3nmol/5microl) on a step-through passive avoidance task in male adult Wistar rats. When administered pretraining, Ang II did not affect the acquisition of passive avoidance, but markedly improved avoidance performance when given before the retrieval test. The latter effect was observed in retest sessions performed up to 72h after training. Administration of the peptide five minutes after training impaired retention of inhibitory avoidance. Therefore, Ang II may exert opposite effects on passive avoidance memory according to its interference with brain mechanisms leading to the storage or retrieval of this aversively motivated task.
de Souza
F A M
FA
Laboratório de Farmacologia, Faculdade de Ciências Farmacêuticas de Ribeirão Preto-USP, Brazil.
Sanchis-Segura
C
C
Fukada
S Y
SY
de Bortoli
V C
VC
Zangrossi
H
H
de Oliveira
A M
AM
D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D001245:Association Learning / Q000187:drug effects*; D001362:Avoidance Learning / Q000187:drug effects*; D001921:Brain / Q000187:drug effects; D003214:Conditioning, Classical / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D005239:Fear / Q000187:drug effects; D007276:Injections, Intraventricular; D008297:Male; D011939:Mental Recall / Q000187:drug effects*; D009042:Motivation; D009043:Motor Activity / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D011930:Reaction Time / Q000187:drug effects; D012153:Retention, Psychology / Q000187:drug effects*
D000804:Angiotensin II