Journal article
Inhibitory actions of delta 1-, delta 2-, and mu-opioid receptor agonists on excitatory transmission in lamina II neurons of adult rat spinal cord
The Journal of neuroscience, Vol.14(8), pp.4965-4971
08/01/1994
DOI: 10.1523/JNEUROSCI.14-08-04965.1994
PMCID: PMC6577194
PMID: 8046463
Abstract
This study examined the electrophysiological consequences of selective activation of delta 1-, delta 2-, or mu-opioid receptors using whole- cell recordings made from visually identified lamina II neurons in thin transverse slices of young adult rat lumbar spinal cord. Excitatory postsynaptic currents (EPSCs) or potentials (EPSPs) were evoked electrically at the ipsilateral dorsal root entry zone after blocking inhibitory inputs with bicuculline and strychnine, and NMDA receptors with D-2-amino-5-phosphonopentanoic acid. Bath application of the mu receptor agonist [D-Ala2, N-MePhe4, Gly5-ol]enkephalin (DAMGO) or the delta 1 receptor agonist [D-Pen2, D-Pen5]enkephalin (DPDPE) produced a long-linear, concentration-dependent reduction in the amplitude of the evoked EPSP/EPSC. By comparison, the delta 2 receptor agonist [D- Ala2,Glu4]deltorphin (DELT) was unable to reduce the evoked EPSP/EPSC by more than 50% at 100 microM, the highest concentration tested. At concentrations that reduced evoked EPSP/EPSCs by 40–60%, neither DAMGO, DPDPE, nor DELT decreased the amplitude of the postsynaptic current produced by brief pressure ejection of (S)-alpha-amino-3-hydroxy-5- methyl-4-isoxazole-propionic acid, suggesting a presynaptic site of action of these opioid receptor agonists. Bath application of 200 nM naltriben (NTB), a delta 2 receptor antagonist, competitively increased the EC75 of DELT by 15.3-fold, but did not antagonize either DPDPE or DAMGO. The EC75 of DELT was further increased by 169.7-fold in the presence of 1 microM NTB. However, this high concentration of NTB also increased the EC50 of DPDPE by about threefold in a noncompetitive manner and antagonized DAMGO in a noncompetitive manner.
Details
- Title: Subtitle
- Inhibitory actions of delta 1-, delta 2-, and mu-opioid receptor agonists on excitatory transmission in lamina II neurons of adult rat spinal cord
- Creators
- Steven R GlaumRichard J MillerDonna L Hammond
- Resource Type
- Journal article
- Publication Details
- The Journal of neuroscience, Vol.14(8), pp.4965-4971
- Publisher
- Society for Neuroscience
- DOI
- 10.1523/JNEUROSCI.14-08-04965.1994
- PMID
- 8046463
- PMCID
- PMC6577194
- ISSN
- 0270-6474
- eISSN
- 1529-2401
- Language
- English
- Date published
- 08/01/1994
- Academic Unit
- Iowa Neuroscience Institute; Nursing; Anesthesia; Neuroscience and Pharmacology
- Record Identifier
- 9984006331102771
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