Amnestic effect of cocaine after the termination of its stimulant action.
The effects of cocaine on memory are controversial. Furthermore, the psychostimulant action of cocaine can be a critical issue in the interpretation of its effects on learning/memory models. The effects of a single administration of cocaine on memory were investigated during the presence of its motor stimulating effect or just after its termination. The plus-maze discriminative avoidance task (PM-DAT) was used because it provides simultaneous information about memory, anxiety and motor activity. In Experiment I, mice received saline, 7.5, 10, 15 or 30 mg/kg cocaine 5 min before the training session. In Experiment II, mice were trained 30 min after the injection of saline, 7.5, 10, 15 or 30 mg/kg cocaine. In Experiment III, mice received 30 mg/kg cocaine 30 min pre-training and pre-test. In Experiment IV, mice received 30 mg/kg cocaine immediately post-training. Tests were always conducted 24 h following the training session. Given 5 min before training, cocaine promoted a motor stimulant effect at the highest dose during the training session but did not impair memory. When cocaine was injected 30 min pre-training, the drug did not modify motor activity, but produced marked amnestic effects at all doses tested. This amnesia induced by cocaine given 30 min pre-training was not related to a state-dependent learning because it was not abolished by pre-test administration of the drug. Post-training cocaine administration did not induce memory deficits either. Our results suggest that the post-stimulant phase is the critical moment for cocaine-induced memory deficit in a discriminative task in mice.
Niigaki
S T
ST
Department of Pharmacology, Universidade Federal de São Paulo, R. Botucatu, 862, Ed. Leal Prado, 1 andar, 04023062, São Paulo, SP, Brazil.
Silva
R H
RH
Patti
C L
CL
Cunha
J L S
JL
Kameda
S R
SR
Correia-Pinto
J C
JC
Takatsu-Coleman
A L
AL
Levin
R
R
Abílio
V C
VC
Frussa-Filho
R
R
D000647:Amnesia / Q000139:chemically induced* / Q000503:physiopathology*; D000704:Analysis of Variance; D000818:Animals; D001007:Anxiety / Q000139:chemically induced; D001362:Avoidance Learning / Q000187:drug effects; D003042:Cocaine / Q000009:adverse effects* / Q000494:pharmacology*; D004192:Discrimination, Psychological / Q000187:drug effects; D004195:Disease Models, Animal; D018765:Dopamine Uptake Inhibitors / Q000009:adverse effects* / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D008297:Male; D018782:Maze Learning / Q000187:drug effects; D051379:Mice; D009043:Motor Activity / Q000187:drug effects; D013997:Time Factors
D018765:Dopamine Uptake Inhibitors; D003042:Cocaine