Neuroscience 2003 Abstract
| Presentation Number: | 174.13 |
|---|---|
| Abstract Title: | Morphine inhibition of CGRP release from DRG neurons is mediated by Delta opioid receptors. |
| Authors: |
Khasabova, I. A.*1
; Harding-Rose, C.1
; Simone, D. A.1
; Seybold, V. S.2
1Oral Sci., Univ. of Minnesota, Minneapolis, MN 2Neurosci., Univ. of Minnesota, Minneapolis, MN |
| Primary Theme and Topics |
Sensory Systems - Pain -- Spinal cord processing: phamacology |
| Session: |
174. Dorsal Horn Circuitry & Pharmacology Poster |
| Presentation Time: | Sunday, November 9, 2003 8:00 AM-9:00 AM |
| Location: | Morial Convention Center - Hall F-I, Board # G106 |
| Keywords: | ANALGESIA, OPIATE, SPINAL CORD |
Morphine modulates nociceptive transmission at the level of the spinal cord through opioid receptors localized pre-and post-synaptically on primary afferent fibers and dorsal horn neurons, respectively. We determined previously that morphine inhibited the depolarization-evoked increase in intracellular Ca2+ in the cell body of dissociated, adult dorsal root ganglion (DRG) neurons, and that this effect was mediated by µ- (MOR) and δ- (DOR) opioid receptors (Khasabova et al., SFN abstract #453.2, 2002). The present study used the same model to address which opioid receptors modulate K+-evoked release of calcitonin gene-related peptide (CGRP) from DRG neurons in vitro. Pretreatment of DRG neurons with morphine (1 mM) decreased K+- evoked CGRP release by 40%. The inhibitory effect of morphine was blocked by naltrindole (100 nM), a selective DOR antagonist, and was insensitive to CTAP (3nM – 100nM), a selective MOR antagonist. Naltrindole and CTAP alone had no effect. Examination of immunostained spinal cord sections with a confocal microscope showed a high density of MOR-, DOR- and CGRP-immunoreactive processes within the superficial laminae of the dorsal horn of the spinal cord. There was a high level of co-localization of CGRP-immunoreactivity (ir) with DOR-ir but little co-existence of CGRP-ir with MOR-ir. Therefore, DOR but not MOR mediates morphine inhibition of K+-evoked release of CGRP from DRG neurons. Considered together with earlier results on modulation of K+-evoked increase in intracellular Ca2+, the data indicate a differential distribution of MOR between cell bodies and terminals of primary afferent neurons.
Supported by DA11471 (DS)
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2003 Neuroscience Meeting Planner. New Orleans, LA: Society for Neuroscience, 2003. Online.
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