Abstract
In the present experiments the influence of NMDA receptor antagonist (+/-)-CPP on morphine- and amphetamine-conditioned activation of locomotor activity was studied in rats chronically implanted with bilateral cannulas in the nucleus accumbens septi. Animals were conditioned by pairing subcutaneous injections of morphine (3.0 mg/kg), amphetamine (1.5 mg/kg), or saline with a distinctive environment. Following the five drug-environment pairings, rats displayed significant increase in locomotion when exposed to the drug-paired environment. The expression of this conditioned response was completely prevented by the bilateral intraaccumbens pretreatment with (+/-)-CPP (1.0, but not 0.1 or 0.3 microgram/ microliter/side). These findings suggest that the locomotor hyperactivity conditioned by morphine and amphetamine involves the activation of NMDA receptors within the nucleus accumbens.
MeSH terms
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Amphetamine / antagonists & inhibitors
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Amphetamine / pharmacology
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Analgesics, Opioid / antagonists & inhibitors
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Analgesics, Opioid / pharmacology
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Animals
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Central Nervous System Stimulants / antagonists & inhibitors
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Central Nervous System Stimulants / pharmacology
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Conditioning, Psychological / drug effects
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Excitatory Amino Acid Antagonists / administration & dosage
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Excitatory Amino Acid Antagonists / pharmacology*
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Injections
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Male
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Morphine / antagonists & inhibitors
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Morphine / pharmacology
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Motor Activity / drug effects*
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Nucleus Accumbens / anatomy & histology
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Nucleus Accumbens / physiology*
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Piperazines / administration & dosage
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Piperazines / pharmacology*
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Rats
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Rats, Wistar
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Receptors, N-Methyl-D-Aspartate / antagonists & inhibitors*
Substances
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Analgesics, Opioid
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Central Nervous System Stimulants
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Excitatory Amino Acid Antagonists
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Piperazines
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Receptors, N-Methyl-D-Aspartate
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Morphine
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3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid
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Amphetamine