Diverse immunocytochemical expression of opioid receptors in electrophysiologically defined cells of rat dorsal root ganglia
| Autor: | Richard D. Johnson, Brian Y. Cooper, Kristofer K. Rau, Robert M. Caudle |
|---|---|
| Rok vydání: | 2005 |
| Předmět: |
Male
medicine.medical_specialty Cell type Patch-Clamp Techniques Receptors Opioid mu Pain Membrane Potentials Rats Sprague-Dawley Cellular and Molecular Neuroscience chemistry.chemical_compound Dorsal root ganglion Ganglia Spinal Receptors Opioid delta Internal medicine medicine Animals Neurons Afferent Patch clamp Receptor Cells Cultured Cell Size Afferent Pathways Chemistry Receptors Opioid kappa Nociceptors Immunohistochemistry Rats medicine.anatomical_structure Endocrinology Nociception Opioid Capsaicin Receptors Opioid Nociceptor Neuroscience medicine.drug |
| Zdroj: | Journal of Chemical Neuroanatomy. 29:255-264 |
| ISSN: | 0891-0618 |
| DOI: | 10.1016/j.jchemneu.2005.02.002 |
| Popis: | The development of opiate analgesics that do not produce adverse side effects is hampered by the difficulty in developing drugs that are tissue/sensory cell-specific. Previously, our laboratory has demonstrated that small- and medium-diameter dorsal root ganglia (DRG) cells can be subclassified into at least nine distinct cell types based upon their patterns of voltage activated currents [Petruska, J.C., Napaporn, J., Johnson, R.D., Gu, J.G., Cooper, B.Y., 2000. Subclassified acutely dissociated cells of rat DRG: histochemistry and patterns of capsaicin-, proton-, and ATP-activated currents. J. Neurophysiol. 84 (5), 2365-2379; Petruska, J.C., Napaporn, J., Johnson, R.D., Cooper, B.Y., 2002. Chemical responsiveness and histochemical phenotype of electrophysiologically classified cells of the adult rat dorsal root ganglion. Neuroscience 115 (1), 15-30.] Based on their responses to algesic compounds and histochemical phenotype, eight of the nine subtypes are likely nociceptors. In the present study, we examined the immunoreactivity (IR) of delta-, kappa- and mu-opioid receptors (DOR, KOR and MOR, respectively), in 164 electrophysiologically subclassified DRG neurons. The expression of opioid receptors in the DRG cell types was diverse. Type 1 (25-30 microm cell diameter) and type 9 (35-45 microm) expressed MOR-IR, but were negative for DOR-IR and KOR-IR. Type 2 (25-30 microm) co-expressed DOR-IR and MOR-IR, but did not express KOR-IR. Type 3 (15-20 microm), the non-nociceptive cell type, was not immunoreactive. Type 4 (35-45 microm), type 6 (35-45 microm), and type 7 (15-20 microm) expressed all three opioid receptors. Type 5 (35-45 microm) and type 8 (35-45 microm), co-expressed KOR-IR and MOR-IR, but did not express DOR-IR. The co-expression of opioid receptors in some of the cell types suggests that these sensory afferents might contain heteromeric opioid receptors. Additionally, the diverse expression patterns of opioid receptors between cell types and the consistency of these patterns maintained within each cell type provides further evidence of distinct functional properties of DRG nociceptors. |
| Databáze: | OpenAIRE |
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