Posttraining norepinephrine infusion into the central amygdala differentially enhances later retention in Roman high-avoidance and low-avoidance rats.
Memory-enhancement effects of norepinephrine (NE) were investigated by infusing NE into the central amygdala (CEA) of Roman high-avoidance (RHA) and low-avoidance (RLA) rats after training on active and passive behaviors in the defensive-burying paradigm. During acquisition, both lines spent comparable time in burying behavior. RLA rats, but not RHA rats, also displayed substantial immobility. During retention, the cerebrospinal-fluid-treated RLA rats mostly displayed immobility to the nonelectrified probe, whereas the RHA rats showed neither burying nor immobility. In the RLA rats, high-dose (200 ng), but not low-dose (20 ng), NE infusion enhanced the duration of the passive response (immobility) without affecting the active response. NE given into the CEA of RHA rats caused a selective dose-dependent appearance of the active behavioral component. The results suggest a phenotype-dependent effect of intra-amygdaloid NE on memory processes in the rat.
Roozendaal
B
B
Department of Animal Physiology, University of Groningen, Haren, The Netherlands.
Koolhaas
J M
JM
Bohus
B
B
D000679:Amygdala / Q000187:drug effects*; D000818:Animals; D001143:Arousal / Q000187:drug effects; D001362:Avoidance Learning / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004597:Electroshock; D008297:Male; D011939:Mental Recall / Q000187:drug effects; D009638:Norepinephrine / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012153:Retention, Psychology / Q000187:drug effects*; D013045:Species Specificity
D009638:Norepinephrine