Selective enhancement of emotional, but not motor, learning in monoamine oxidase A-deficient mice.
Mice deficient in monoamine oxidase A (MAOA), an enzyme that metabolizes monoamines such as norepinephrine and serotonin, have elevated norepinephrine and serotonin levels in the frontal cortex, hippocampus, and cerebellum, compared with normal wild-type mice. Since monoamines in these areas are critically involved in a variety of behaviors, we examined learning and memory (using emotional and motor tasks) in MAOA mutant mice. The MAOA-deficient mice exhibited significantly enhanced classical fear conditioning (freezing to both tone and contextual stimuli) and step-down inhibitory avoidance learning. In contrast, eyeblink conditioning was normal in these mutant mice. The female MAOA-deficient mice also displayed normal species-typical maternal behaviors (nesting, nursing, and pup retrieval). These results suggest that chronic elevations of monoamines, due to a deletion of the gene encoding MAOA, lead to selective alterations in emotional behavior.
Kim
J J
JJ
Neuroscience Program, University of Southern California, Los Angeles, CA 90089-2520, USA. jeansok.kim@yale.edu
Shih
J C
JC
Chen
K
K
Chen
L
L
Bao
S
S
Maren
S
S
Anagnostaras
S G
SG
Fanselow
M S
MS
De Maeyer
E
E
Seif
I
I
Thompson
R F
RF
D000818:Animals; D001362:Avoidance Learning; D001767:Blinking; D001921:Brain / Q000378:metabolism*; D002531:Cerebellum / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism; D004644:Emotions; D005239:Fear; D005260:Female; D005625:Frontal Lobe / Q000378:metabolism; D006624:Hippocampus / Q000378:metabolism; D007858:Learning; D008297:Male; D008425:Maternal Behavior; D008568:Memory; D051379:Mice; D008809:Mice, Inbred C3H; D008817:Mice, Mutant Strains; D008995:Monoamine Oxidase / Q000172:deficiency*; D009043:Motor Activity; D009638:Norepinephrine / Q000378:metabolism; D012016:Reference Values; D012701:Serotonin / Q000378:metabolism
D012701:Serotonin; D008995:Monoamine Oxidase; D004298:Dopamine; D009638:Norepinephrine