Mnemogenic effects of injecting RA-octil, a CE-inhibitor derivate, systemically or into the basal forebrain.
The aim of this study was to investigate the effects of systemically or intracerebrally administered RA-octil, a derivative of the angiotensin converting enzyme (CE)-inhibitor ramipril, on memory and reinforcement and to compare its effectiveness with that of the neurokinin substance P (SP). In the first experiment systemic post-trial application of RA-octil and SP in the rat enhanced habituation, a learning task which does not require motivational treatments. Unlike SP, injection of RA-octil did not have reinforcing effects as measured with a conditioned place preference task. In the second experiment, a facilitation of inhibitory avoidance learning was obtained by injection of RA-octil or SP unilaterally into the basal forebrain immediately after the learning trial. In contrast, a 5 h delayed injection of RA-octil had no effects on learning. The results demonstrate memory-enhancing effects of RA-octil after systemic application as well as after injection into the basal forebrain. Furthermore, the mnemogenic effects of SP after central and peripheral administration were confirmed. Since RA-octil, although being structurally closely related to CE-inhibitors, does not affect plasma CE, yet exhibits mnemogenic effects, it is possible that "cognition-enhancing" actions of CE-inhibitors are dissociable from their action within the renin-angiotensin system.
Gerhardt
P
P
Institute of Physiological Psychology I, University of Düsseldorf, Germany.
Hasenöhrl
R U
RU
Hock
F J
FJ
Huston
J P
JP
D000806:Angiotensin-Converting Enzyme Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects; D001643:Bridged Bicyclo Compounds / Q000008:administration & dosage / Q000494:pharmacology*; D003216:Conditioning, Operant / Q000187:drug effects; D006185:Habituation, Psychophysiologic; D007267:Injections; D008297:Male; D008568:Memory / Q000187:drug effects*; D016548:Prosencephalon / Q000033:anatomy & histology / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D013373:Substance P / Q000494:pharmacology
D000806:Angiotensin-Converting Enzyme Inhibitors; D001643:Bridged Bicyclo Compounds; C061541:HOE 065; D013373:Substance P