Intrahippocampal, but not intra-amygdala, infusion of an inhibitor of heme oxygenase causes retrograde amnesia in the rat.
Zinc protoporhyrin-9 (ZnPP) is an inhibitor of heme oxygenase, the enzyme involved in the biosynthesis of carbon monoxide (CO). CO regulates the activity of glutamatergic synapses and has been proposed to play a role in the early phases of long-term potentiation. The present paper reports on the effect of ZnPP on memory of inhibitory avoidance and of habituation to a novel environment. The bilateral infusion of ZnPP (2 micrograms/side) into the dorsal hippocampus caused amnesia for the inhibitory avoidance task when given before training or 0 or 30 min, but not 60 or 100 min, after training. The immediate post-training intrahippocampal infusion of ZnPP also caused amnesia for the habituation task. The immediate post-training intra-amygdala infusion of ZnPP had no effect on retention of the avoidance task. The data are consistent with the hypotheses that memory involves long-term potentiation initiated at the time of training in the hippocampus, and that hippocampal but not amygdala long-term potentiation may be regulated by CO.
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Departamento de Bioquímica, UFRGS (Centro), Porto Alegre, RS, Brazil.
Schmitz
P K
PK
Da Silva
R C
RC
Bernabeu
R
R
Medina
J H
JH
Izquierdo
I
I
D000648:Amnesia, Retrograde / Q000139:chemically induced* / Q000523:psychology; D000679:Amygdala / Q000502:physiology*; D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects; D006185:Habituation, Psychophysiologic / Q000187:drug effects; D006419:Heme Oxygenase (Decyclizing) / Q000037:antagonists & inhibitors*; D006624:Hippocampus / Q000502:physiology*; D007267:Injections; D017774:Long-Term Potentiation / Q000187:drug effects; D008297:Male; D011524:Protoporphyrins / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar
D011524:Protoporphyrins; C017803:zinc protoporphyrin; D006419:Heme Oxygenase (Decyclizing)