Bd. Kretschmer, NMDA receptor antagonist-induced dopamine release in the ventral pallidum does not correlate with motor activation, BRAIN RES, 859(1), 2000, pp. 147-156
The ventral pallidum is the output structure of the nucleus accumbens in th
e ventral corticostriato-thalamocortical loop. Information processing in th
is loop is critically involved in motor behavior and reinforcement. The ven
tral pallidum receives a direct dopaminergic input from the ventral tegment
al area, but also glutamatergic input from cortical and limbic areas. It ha
s been assumed that dopamine release in the VP is indeed modulated by gluta
mate. The present study investigated the effects of NMDA receptor blockade
on motor behavior and dopamine release in the ventral pallidum. In a first
experiment, rats were implanted with microdialysis probes in the ventral pa
llidum and were systemically injected or locally perfused via the microdial
ysis probe with dizocilpine (0.32 mg/kg, 10 and 100 mu M, respectively). Ef
fects on dopamine and on locomotion were simultaneously monitored. In a sec
ond experiment, ventral pallidum was lesioned by quinolinic acid and the ef
fects of systemic dizocilpine (0.08 and 0.16 mg/kg) on locomotion and stere
otyped sniffing behavior were determined. It was found that systemic and lo
cal dizocilpine administration increased dopamine release in the ventral pa
llidum to a similar extent whereas only systemic treatment was accompanied
by locomotor stimulation. Lesion of the ventral pallidum did not affect loc
omotion and stereotyped sniffing behavior induced by systemic dizocilpine t
reatment. Thus, DA release in the ventral pallidum that is elevated by bloc
kade of NMDA receptors is not relevant for activation of motor behavior. (C
) 2000 Elsevier Science B.V. All rights reserved.