Intra-amygdala administration of polyamines modulates fear conditioning in rats.
Amygdalar NMDA receptor activation has been implicated in the acquisition of fear memories in rats. However, little is known about the role of endogenous modulators of the NMDA receptor, such as polyamines, in pavlovian fear-conditioning learning. Therefore, in the present study we investigated whether the immediate pretraining or post-training bilateral infusion of arcaine, an antagonist of the NMDA receptor polyamine-binding site, or spermidine, an agonist of the NMDA receptor polyamine-binding site, into the amygdala affected classical fear conditioning in rats. Bilateral microinjections of arcaine (0.0002-0.2 nmol) decreased, whereas spermidine (0.002-20 nmol) increased, contextual and auditory fear conditioning. Arcaine coadministration, at a dose that had no effect per se, reversed the facilitatory effect of spermidine. These results provide evidence that endogenous and exogenous polyamines modulate the acquisition or early consolidation (or both) of the fear-conditioning task in the amygdala.
Department of Chemistry, Center of Exact and Natural Sciences, Federal University of Santa Maria, 97105-900, Santa Maria, Rio Grande do Sul, Brazil. marubin@smail.ufsm.br
Maribel A
MA
Rubin
Daiane B
DB
Berlese
Juliano A
JA
Stiegemeier
Márcio A
MA
Volkweis
Denise M
DM
Oliveira
Telma L B
TL
dos Santos
Ana C
AC
Fenili
Carlos F
CF
Mello
D000679:Amygdala / Q000187:drug effects* / Q000502:physiology*; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D001645:Biguanides / Q000494:pharmacology; D015317:Biogenic Polyamines / Q000008:administration & dosage / Q000494:pharmacology*; D002404:Catheterization; D003214:Conditioning, Classical / Q000187:drug effects*; D004333:Drug Administration Routes; D005239:Fear / Q000187:drug effects* / Q000502:physiology; D008297:Male; D018782:Maze Learning / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism; D013037:Spatial Behavior / Q000187:drug effects; D013095:Spermidine / Q000008:administration & dosage / Q000494:pharmacology
D001645:Biguanides; D015317:Biogenic Polyamines; D016194:Receptors, N-Methyl-D-Aspartate; C006624:arcaine; D013095:Spermidine