The Journal of Neuroscience, December 15, 2000, 20(24):9320-9325
Aggressive Behavior, Increased Accumbal Dopamine, and Decreased
Cortical Serotonin in Rats
Annemoon M. M.
van Erp1 and
Klaus A.
Miczek1, 2
1 Department of Psychology, Tufts University, Medford,
Massachusetts 02155, and 2 Departments of Psychiatry,
Pharmacology, and Neuroscience, Tufts University, Boston, Massachusetts
02111
Dopamine (DA) and serotonin have been implicated in the
regulation of aggressive behavior, but it has remained challenging to
assess the dynamic changes in these neurotransmitters while aggressive
behavior is in progress. The objective of this study was to
learn about ongoing monoamine activity in corticolimbic areas during
aggressive confrontations in rats. Male Long-Evans rats were implanted
with a microdialysis probe aimed at the nucleus accumbens (NAC) or
medial prefrontal cortex (PFC); next, 10 min samples were collected
before, during, and after a 10 min confrontation. Rats continued to
display aggressive behavior while being sampled, and they performed two
to six attack bites as well as 140 sec of aggressive acts and postures.
Dopamine levels in NAC were significantly increased up to 60 min after
the confrontation. Peak levels of 140% were achieved ~20-30 min
after the confrontation. No concurrent changes in accumbal serotonin
levels were seen during or after the confrontation. Dopamine and
serotonin levels in PFC changed in the opposite direction, with a
sustained decrease in serotonin to 80% of baseline levels during and
after the confrontation and an increase in dopamine to 120% after the
confrontation. The temporal pattern of monoamine changes, which
followed rather than preceded the confrontation, points to a
significant role of accumbal and cortical DA and 5-hydroxytryptamine in
the consequences as opposed to the triggering of aggressive acts. The
increase in accumbal DA in aggressive animals supports the hypothesis
that this neural system is linked to the execution of biologically
salient and demanding behavior.
Key words:
aggression; dopamine; serotonin; nucleus accumbens; prefrontal cortex; rats; microdialysis; behavior
Copyright © 2000 Society for Neuroscience 0270-6474/00/20249320-06$05.00/0
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