NMDA receptor antagonist-induced dopamine release in the ventral pallidum does not correlate with motor activation

• Published in: Brain research Vol. 859; no. 1; pp. 147 - 156
• Main Author: Kretschmer, Beate D.
• Format: Journal Article
• Language: English
• Published: London Elsevier B.V 17.03.2000; Amsterdam Elsevier; New York, NY
• Subjects: Animals; Behavior, Animal - drug effects; Behavior, Animal - physiology; Biological and medical sciences; Central nervous system; Central neurotransmission. Neuromudulation. Pathways and receptors; Dizocilpine (MK-801); Dizocilpine Maleate - pharmacology; Dopamine - metabolism; Dopamine release; Excitatory Amino Acid Antagonists - pharmacology; Fundamental and applied biological sciences. Psychology; Globus Pallidus - cytology; Globus Pallidus - drug effects; Globus Pallidus - metabolism; Male; Microdialysis; Motor Activity - drug effects; Motor Activity - physiology; Motor behavior; Nucleus Accumbens - cytology; Nucleus Accumbens - drug effects; Nucleus Accumbens - metabolism; Rats; Rats, Sprague-Dawley; Receptors, N-Methyl-D-Aspartate - antagonists & inhibitors; Ventral pallidum; Ventral tegmental area; Vertebrates: nervous system and sense organs; Dopamine release; Microdialysis; Motor behavior; Ventral pallidum; Dizocilpine (MK-801); Ventral tegmental area; Dopamine; Rat; Rodentia; Central nervous system; Basal ganglion; Glutamate receptor; Pallidum; Locomotion; Vertebrata; Mammalia; Antagonist; NMDA receptor; Release; Brain (vertebrata)
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/S0006-8993(00)01989-2

The ventral pallidum is the output structure of the nucleus accumbens in the ventral corticostriato-thalamocortical loop. Information processing in this loop is critically involved in motor behavior and reinforcement. The ventral pallidum receives a direct dopaminergic input from the ventral tegmental area, but also glutamatergic input from cortical and limbic areas. It has been assumed that dopamine release in the VP is indeed modulated by glutamate. 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 pallidum and were systemically injected or locally perfused via the microdialysis probe with dizocilpine (0.32 mg/kg, 10 and 100 μM, respectively). Effects on dopamine and on locomotion were simultaneously monitored. In a second experiment, ventral pallidum was lesioned by quinolinic acid and the effects of systemic dizocilpine (0.08 and 0.16 mg/kg) on locomotion and stereotyped sniffing behavior were determined. It was found that systemic and local dizocilpine administration increased dopamine release in the ventral pallidum to a similar extent whereas only systemic treatment was accompanied by locomotor stimulation. Lesion of the ventral pallidum did not affect locomotion and stereotyped sniffing behavior induced by systemic dizocilpine treatment. Thus, DA release in the ventral pallidum that is elevated by blockade of NMDA receptors is not relevant for activation of motor behavior.