Abstract
The bilateral administration of 10 micrograms of (+)MK-801, but not (-)MK-801, into either the VTA or the N.Ac. stimulated locomotor activity. The stimulation induced by (+)MK-801 at both sites was inhibited by reserpine (5 mg/kg, SC) and the D1 antagonist, SCH 23390 (0.1 mg/kg, SC). Eticlopride (0.03 mg/kg, SC), a D2 antagonist, inhibited the stimulation produced by MK-801 in the VTA but not in the N.Ac. Baclofen (32 ng), a GABAB receptor agonist, injected into the VTA inhibited the stimulatory response to MK-801 injected systemically, into the VTA, or into the N.Ac., but did not significantly inhibit spontaneous locomotion or the stimulatory response to apomorphine (5 mg/kg, SC). These observations suggest that the stimulatory effects of MK-801 in the VTA and the N.Ac. are dependent on endogenous dopamine. In addition, the effects produced by MK-801 injected into the VTA closely resemble those produced by the systemic administration of low doses of MK-801, suggesting that this is the primary site of action of MK-801.
Publication types
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Adrenergic Uptake Inhibitors / pharmacology
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Animals
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Apomorphine / pharmacology
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Baclofen / pharmacology
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Benzazepines / pharmacology
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Dizocilpine Maleate / administration & dosage
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Dizocilpine Maleate / pharmacology*
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Dopamine / physiology*
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Dopamine Agonists / pharmacology
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Dopamine Antagonists / pharmacology
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Dopamine D2 Receptor Antagonists
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Excitatory Amino Acid Antagonists / administration & dosage
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Excitatory Amino Acid Antagonists / pharmacology*
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GABA Agonists / pharmacology
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Histocytochemistry
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Injections
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Male
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Motor Activity / drug effects
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Nucleus Accumbens / anatomy & histology
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Nucleus Accumbens / enzymology
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Nucleus Accumbens / physiology*
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Rats
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Rats, Sprague-Dawley
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Reserpine / pharmacology
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Salicylamides / pharmacology
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Stimulation, Chemical
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Tyrosine 3-Monooxygenase / metabolism
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Ventral Tegmental Area / anatomy & histology
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Ventral Tegmental Area / enzymology
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Ventral Tegmental Area / physiology*
Substances
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Adrenergic Uptake Inhibitors
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Benzazepines
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Dopamine Agonists
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Dopamine Antagonists
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Dopamine D2 Receptor Antagonists
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Excitatory Amino Acid Antagonists
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GABA Agonists
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Salicylamides
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Dizocilpine Maleate
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Reserpine
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Tyrosine 3-Monooxygenase
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Baclofen
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eticlopride
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Apomorphine
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Dopamine