Abstract
Field recordings were used to determine the influence of delta-opioid receptor activation on corticostriatal synaptic transmission. Application of the selective delta-opioid receptor agonist, [Tyr-D-Pen-Gly-Phe-D-Pen]-enkephalin (DPDPE, 1 microM), decreased the amplitude of the field-excitatory synaptic potential and at the same time increased the paired pulse ratio (PPR) suggesting a presynaptic site of action. This response reversed rapidly when DPDPE was washed and blocked by 1 nM of the selective delta-receptor antagonist naltrindole. Neither omega-conotoxin GVIA (1 microM) nor omega-agatoxin TK (400 nM), blockers of N- and P/Q-type Ca2+-channels, respectively, nor TEA (1 mM), blocker of some classes of K+-channels, occluded the effects of DPDPE. Instead, 1 mM 4-AP or 400 microM Ba2+ occluded completely the effects of DPDPE. Therefore, the results suggest that the modulation by delta opioids at corticostriatal terminals is mediated by transient (KV4) K+-conductances.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Analgesics, Opioid / pharmacology
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Animals
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Calcium Channel Blockers / pharmacology
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Cerebral Cortex / drug effects
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Cerebral Cortex / metabolism*
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Corpus Striatum / drug effects
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Corpus Striatum / metabolism*
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Electric Stimulation
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Enkephalin, D-Penicillamine (2,5)- / pharmacology*
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Excitatory Postsynaptic Potentials / drug effects
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Excitatory Postsynaptic Potentials / physiology
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Male
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Narcotic Antagonists / pharmacology
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Neural Pathways / drug effects
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Neural Pathways / metabolism*
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Neurotransmitter Agents / metabolism*
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Opioid Peptides / metabolism
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Organ Culture Techniques
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Potassium Channel Blockers / pharmacology
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Presynaptic Terminals / drug effects
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Presynaptic Terminals / metabolism
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Rats
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Rats, Wistar
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Receptors, Opioid, delta / agonists*
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Receptors, Opioid, delta / antagonists & inhibitors
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Receptors, Opioid, delta / metabolism
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Shal Potassium Channels / agonists*
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Shal Potassium Channels / antagonists & inhibitors
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Shal Potassium Channels / metabolism
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Synaptic Transmission / drug effects
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Synaptic Transmission / physiology
Substances
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Analgesics, Opioid
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Calcium Channel Blockers
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Narcotic Antagonists
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Neurotransmitter Agents
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Opioid Peptides
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Potassium Channel Blockers
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Receptors, Opioid, delta
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Shal Potassium Channels
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Enkephalin, D-Penicillamine (2,5)-