Pretraining but not preexposure to the task apparatus prevents the memory impairment induced by blockade of protein synthesis, PKA or MAP kinase in rats.
Adult male Wistar rats were trained and tested in a step-down inhibitory avoidance task (0.4 mA footshock, 24 h training-test interval). Fifteen minutes before or 0, 1.5 or 3 hours after training, animals received a 0.8 microl intrahippocampal infusion of the protein synthesis inhibitor anisomycin (80 microg), the PKA inhibitor Rp-cAMP (0.05 microg), the MAPK kinase inhibitor PD 098059 (50 microM solution) or vehicle (phosphate buffer in saline, pH 7.4). Anisomycin, Rp-cAMP and PD 098059 impaired retention test performance in animals injected at different times, prior and after training. Pretraining with a low footshock intensity (0.2 mA) 24 h before training prevented the amnestic effect of all drugs studied. However, simple preexposure to the inhibitory avoidance apparatus did not alter the amnestic effects of all drugs. The results suggest that memory processing requires hippocampal mechanisms dependent on protein synthesis, PKA and MAPK kinase at different times after training. These findings suggest that weak training must be sufficient to produce some lasting cellular expression of the experience so that the enhancement of consolidation of a previously acquired memory is not dependent on protein synthesis, PKA or MAPK.
Quevedo
João
J
Laboratório de Neurociências, Universidade do Extremo Sul Catarinense, 88806-000 Criciúma, SC, Brazil. quevedo1@terra.com.br
Vianna
Monica R M
MR
Roesler
Rafael
R
Martins
Marcio Rodrigo
MR
de-Paris
Fernanda
F
Medina
Jorge H
JH
Izquierdo
Ivan
I
D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects* / Q000502:physiology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D008297:Male; D008569:Memory Disorders / Q000139:chemically induced / Q000517:prevention & control*; D047428:Protein Kinase Inhibitors / Q000633:toxicity*; D011500:Protein Synthesis Inhibitors / Q000633:toxicity*; D051381:Rats; D017208:Rats, Wistar; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D013997:Time Factors
D047428:Protein Kinase Inhibitors; D011500:Protein Synthesis Inhibitors; D017868:Cyclic AMP-Dependent Protein Kinases; D048049:Extracellular Signal-Regulated MAP Kinases