Volume 17, Number 11,
Issue of June 1, 1997
pp. 4441-4447
Copyright ©1997 Society for Neuroscience
An Escalating Dose/Multiple High-Dose Binge Pattern of
Amphetamine Administration Results in Differential Changes in the
Extracellular Dopamine Response Profiles in Caudate-Putamen and Nucleus
Accumbens
Received Jan. 24, 1997; revised March 11, 1997; accepted March 20, 1997.
Ronald Kuczenski and
David S. Segal
Psychiatry Department, School of Medicine, University of California
San Diego, La Jolla, California 92093
Amphetamine (AMPH)-induced psychosis is most frequently associated
with a chronic high-dose "binge" or "run" pattern of stimulant abuse, generally preceded by a period of gradually escalating doses of
the drug. We showed previously that animals subjected to such a regimen
of AMPH administration developed, over multiple daily binges, a unique
pattern of behavioral response that included a decrease in stereotypy
and a pronounced increase in locomotion. Because of the involvement of
mesolimbic and mesostriatal dopamine (DA) pathways in locomotion and
stereotypy, respectively, we hypothesized that a persistent shift in
the relative magnitude of caudate-putamen (CP) and nucleus accumbens
(NAC) DA transmission may contribute to this altered behavioral
profile. To test this hypothesis, we examined CP and NAC extracellular
DA in response to multiple high-dose AMPH binges. Our results revealed
that with multiple binges the CP DA response but not the NAC response
developed a profound tolerance/tachyphylaxis to the drug-induced
increase in extracellular transmitter. These differential regional
response alterations seem to correspond to the shift in the relative
expression of stereotypy and locomotion. We hypothesize that changes in
DA synthesis, perhaps mediated by regionally specific adaptations in DA
autoreceptor function, contribute to the differential extracellular
transmitter response profiles, and suggest that these neurochemical
changes may have important implications for the mechanisms underlying
the addictive and psychotogenic properties of AMPH.
Key words:
amphetamine;
binge;
psychosis;
microdialysis;
dopamine;
caudate-putamen;
nucleus accumbens;
stereotypy;
locomotion