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Co-localization of endomorphin-2 and substance P in primary afferent nociceptors and effects of injury: a light and electron microscopic study in the rat.
Eur J Neurosci. 2004 Apr; 19(7):1789-99.EJ

Abstract

Endomorphin-2 (EM2) is a tetrapeptide with remarkable affinity and selectivity for the mu-opioid receptor. In the present study, we used double-fluorescence and electron microscopic immunocytochemistry to identify subsets of EM2-expressing neurons in dorsal root ganglia and spinal cord dorsal horn of adult rats. Within the lumbar dorsal root ganglia, we found EM2 immunoreactivity mainly in small-to-medium size neurons, most of which co-expressed the neuropeptide substance P (SP). In adult rat L4 dorsal root ganglia, 23.9% of neuronal profiles contained EM2 immunoreactivity and ranged in size from 15 to 36 microM in diameter (mean 24.3 +/- 4.3 microM). Double-labelling experiments with cytochemical markers of dorsal root ganglia neurons showed that approximately 95% of EM2-immunoreactive cell bodies also label with SP antisera, 83% co-express vanilloid receptor subtype 1/capsaicin receptor, and 17% label with isolectin B4, a marker of non-peptide nociceptors. Importantly, EM2 immunostaining persisted in mice with a deletion of the preprotachykinin-A gene that encodes SP. In the lumbar spinal cord dorsal horn, EM2 expression was concentrated in presumptive primary afferent terminals in laminae I and outer II. At the ultrastructural level, electron microscopic double-labelling showed co-localization of EM2 and SP in dense core vesicles of lumbar superficial dorsal horn synaptic terminals. Finally, 2 weeks after sciatic nerve axotomy we observed a greater than 50% reduction in EM2 immunoreactivity in the superficial dorsal horn. We suggest that the very strong anatomical relationship between primary afferent nociceptors that express SP and EM2 underlies an EM2 regulation of SP release via mu-opioid autoreceptors.

Authors+Show Affiliations

Department of Anatomy, University of California San Francisco, San Francisco, CA 94143, USA.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

15078552

Citation

Sanderson Nydahl, Katarina, et al. "Co-localization of Endomorphin-2 and Substance P in Primary Afferent Nociceptors and Effects of Injury: a Light and Electron Microscopic Study in the Rat." The European Journal of Neuroscience, vol. 19, no. 7, 2004, pp. 1789-99.
Sanderson Nydahl K, Skinner K, Julius D, et al. Co-localization of endomorphin-2 and substance P in primary afferent nociceptors and effects of injury: a light and electron microscopic study in the rat. Eur J Neurosci. 2004;19(7):1789-99.
Sanderson Nydahl, K., Skinner, K., Julius, D., & Basbaum, A. I. (2004). Co-localization of endomorphin-2 and substance P in primary afferent nociceptors and effects of injury: a light and electron microscopic study in the rat. The European Journal of Neuroscience, 19(7), 1789-99.
Sanderson Nydahl K, et al. Co-localization of Endomorphin-2 and Substance P in Primary Afferent Nociceptors and Effects of Injury: a Light and Electron Microscopic Study in the Rat. Eur J Neurosci. 2004;19(7):1789-99. PubMed PMID: 15078552.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Co-localization of endomorphin-2 and substance P in primary afferent nociceptors and effects of injury: a light and electron microscopic study in the rat. AU - Sanderson Nydahl,Katarina, AU - Skinner,Kate, AU - Julius,David, AU - Basbaum,Allan I, PY - 2004/4/14/pubmed PY - 2004/5/25/medline PY - 2004/4/14/entrez SP - 1789 EP - 99 JF - The European journal of neuroscience JO - Eur. J. Neurosci. VL - 19 IS - 7 N2 - Endomorphin-2 (EM2) is a tetrapeptide with remarkable affinity and selectivity for the mu-opioid receptor. In the present study, we used double-fluorescence and electron microscopic immunocytochemistry to identify subsets of EM2-expressing neurons in dorsal root ganglia and spinal cord dorsal horn of adult rats. Within the lumbar dorsal root ganglia, we found EM2 immunoreactivity mainly in small-to-medium size neurons, most of which co-expressed the neuropeptide substance P (SP). In adult rat L4 dorsal root ganglia, 23.9% of neuronal profiles contained EM2 immunoreactivity and ranged in size from 15 to 36 microM in diameter (mean 24.3 +/- 4.3 microM). Double-labelling experiments with cytochemical markers of dorsal root ganglia neurons showed that approximately 95% of EM2-immunoreactive cell bodies also label with SP antisera, 83% co-express vanilloid receptor subtype 1/capsaicin receptor, and 17% label with isolectin B4, a marker of non-peptide nociceptors. Importantly, EM2 immunostaining persisted in mice with a deletion of the preprotachykinin-A gene that encodes SP. In the lumbar spinal cord dorsal horn, EM2 expression was concentrated in presumptive primary afferent terminals in laminae I and outer II. At the ultrastructural level, electron microscopic double-labelling showed co-localization of EM2 and SP in dense core vesicles of lumbar superficial dorsal horn synaptic terminals. Finally, 2 weeks after sciatic nerve axotomy we observed a greater than 50% reduction in EM2 immunoreactivity in the superficial dorsal horn. We suggest that the very strong anatomical relationship between primary afferent nociceptors that express SP and EM2 underlies an EM2 regulation of SP release via mu-opioid autoreceptors. SN - 0953-816X UR - https://www.unboundmedicine.com/medline/citation/15078552/Co_localization_of_endomorphin_2_and_substance_P_in_primary_afferent_nociceptors_and_effects_of_injury:_a_light_and_electron_microscopic_study_in_the_rat_ L2 - https://onlinelibrary.wiley.com/resolve/openurl?genre=article&sid=nlm:pubmed&issn=0953-816X&date=2004&volume=19&issue=7&spage=1789 DB - PRIME DP - Unbound Medicine ER -