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Nerve growth factor selectively decreases activity-dependent conduction slowing in mechano-insensitive C-nociceptors.
Pain. 2011 Sep; 152(9):2138-2146.PAIN

Abstract

Nerve growth factor (NGF) induces acute sensitization of nociceptive sensory endings and long-lasting hyperalgesia. NGF modulation of sodium channel expression might contribute to neurotrophin-induced hyperalgesia. Here, we investigated NGF-evoked changes of the activity-dependent slowing of conduction in porcine C-fibers. Animals received intradermal injections of NGF (2 μg or 8 μg) or saline in both hind limbs. Extracellular recordings from the saphenous nerves were performed 1 week later. Based on sensory thresholds and electrically induced activity-dependent slowing (ADS) of axonal conduction, C-fibers were classified as mechano-sensitive afferents, mechano-insensitive afferents, cold nociceptors, and sympathetic efferents. NGF (2 μg) increased conduction velocity in C-fibers from 1.0±0.05 m/s to 1.2±0.07 m/s. In mechano-insensitive afferents, NGF (8 μg) reduced activity-dependent slowing of conduction, from 5.3±0.2% to 3.2±0.5% (0.125-0.5 Hz stimulation) and from 28.5±1.3% to 20.9±1.9% (2 Hz stimulation), such that ADS no longer differentiated between mechano-sensitive and mechano-insensitive fibers. Accordingly, the number of fibers with pronounced ADS decreased but more units with pronounced ADS were mechano-sensitive. Spontaneously active C-fibers were increased above the control level (1%) by NGF 8 μg (8%). The results demonstrate that NGF changes the functional axonal characteristics of mechano-insensitive C-fibers and enhances spontaneous activity thereby possibly contributing to hyperalgesia.

Authors+Show Affiliations

Department of Anesthesiology Mannheim, Heidelberg University, Mannheim, Germany Department of Neurosurgery, Johns Hopkins University, Baltimore, MD, USA Department of Mathematics and Computer Science, Bethel University, St. Paul, MN, USA.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

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

Language

eng

PubMed ID

21763072

Citation

Obreja, Otilia, et al. "Nerve Growth Factor Selectively Decreases Activity-dependent Conduction Slowing in Mechano-insensitive C-nociceptors." Pain, vol. 152, no. 9, 2011, pp. 2138-2146.
Obreja O, Ringkamp M, Turnquist B, et al. Nerve growth factor selectively decreases activity-dependent conduction slowing in mechano-insensitive C-nociceptors. Pain. 2011;152(9):2138-2146.
Obreja, O., Ringkamp, M., Turnquist, B., Hirth, M., Forsch, E., Rukwied, R., Petersen, M., & Schmelz, M. (2011). Nerve growth factor selectively decreases activity-dependent conduction slowing in mechano-insensitive C-nociceptors. Pain, 152(9), 2138-2146. https://doi.org/10.1016/j.pain.2011.05.021
Obreja O, et al. Nerve Growth Factor Selectively Decreases Activity-dependent Conduction Slowing in Mechano-insensitive C-nociceptors. Pain. 2011;152(9):2138-2146. PubMed PMID: 21763072.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Nerve growth factor selectively decreases activity-dependent conduction slowing in mechano-insensitive C-nociceptors. AU - Obreja,Otilia, AU - Ringkamp,Matthias, AU - Turnquist,Brian, AU - Hirth,Michael, AU - Forsch,Elmar, AU - Rukwied,Roman, AU - Petersen,Marlen, AU - Schmelz,Martin, Y1 - 2011/07/18/ PY - 2011/02/07/received PY - 2011/04/27/revised PY - 2011/05/18/accepted PY - 2011/7/19/entrez PY - 2011/7/19/pubmed PY - 2012/6/5/medline SP - 2138 EP - 2146 JF - Pain JO - Pain VL - 152 IS - 9 N2 - Nerve growth factor (NGF) induces acute sensitization of nociceptive sensory endings and long-lasting hyperalgesia. NGF modulation of sodium channel expression might contribute to neurotrophin-induced hyperalgesia. Here, we investigated NGF-evoked changes of the activity-dependent slowing of conduction in porcine C-fibers. Animals received intradermal injections of NGF (2 μg or 8 μg) or saline in both hind limbs. Extracellular recordings from the saphenous nerves were performed 1 week later. Based on sensory thresholds and electrically induced activity-dependent slowing (ADS) of axonal conduction, C-fibers were classified as mechano-sensitive afferents, mechano-insensitive afferents, cold nociceptors, and sympathetic efferents. NGF (2 μg) increased conduction velocity in C-fibers from 1.0±0.05 m/s to 1.2±0.07 m/s. In mechano-insensitive afferents, NGF (8 μg) reduced activity-dependent slowing of conduction, from 5.3±0.2% to 3.2±0.5% (0.125-0.5 Hz stimulation) and from 28.5±1.3% to 20.9±1.9% (2 Hz stimulation), such that ADS no longer differentiated between mechano-sensitive and mechano-insensitive fibers. Accordingly, the number of fibers with pronounced ADS decreased but more units with pronounced ADS were mechano-sensitive. Spontaneously active C-fibers were increased above the control level (1%) by NGF 8 μg (8%). The results demonstrate that NGF changes the functional axonal characteristics of mechano-insensitive C-fibers and enhances spontaneous activity thereby possibly contributing to hyperalgesia. SN - 1872-6623 UR - https://www.unboundmedicine.com/medline/citation/21763072/Nerve_growth_factor_selectively_decreases_activity_dependent_conduction_slowing_in_mechano_insensitive_C_nociceptors_ L2 - https://linkinghub.elsevier.com/retrieve/pii/00006396-201109000-00029 DB - PRIME DP - Unbound Medicine ER -