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Oxytocin actions on afferent evoked spinal cord neuronal activities in neuropathic but not in normal rats.
Brain Res. 2005 May 31; 1045(1-2):124-33.BR

Abstract

A hypothalamic oxytocinergic-descending pathway that reaches the dorsal horn of the spinal cord has been well documented and recently related to states of pain and analgesia. In order to study the action of the neuropeptide oxytocin (OT) on pain-related responses, we compared dorsal horn neuronal responses to electrical and mechanical stimulation of receptive fields in normal and neuropathic rats. Spinal nerve (L5 and L6) ligation (Chung rats) was used to produce experimental neuropathy. Single unit activity was recorded at the L4-L5 level from neurons identified as wide dynamic range presenting latency responses corresponding to A-beta, A-delta, C fibers and also exhibiting post-discharge, and wind-up. We tested intrathecally applied doses of 0.05, 0.1, 1, 2, 5, 10 I.U. of OT. Minor effects on responses to electrical stimulation were present in normal rats. Mechanical responses evoked by von Frey filaments were slightly reduced in normal animals. In neuropathic rats a dose of 1 I.U. produced a significant reduction in C-fibers and post-discharge activities, and doses of 2 I.U. caused a further, pronounced reduction in post-discharge, wind-up, and input values. However, the most marked change was the post-discharge reduction at 10 and 20 min after OT administration. Mechanical responses were significantly reduced in terms of their discharge rate response in neuropathic rats. The contrasting results obtained in normal and neuropathic rats revealed an important distinction between these animals and indicate that plastic changes occur as a consequence of nerve damage. In neuropathic rats, mechanisms involving ascending noxious information to the paraventricular nuclei and descending OT activities could be altered so sensitizing the OT receptors of the spinal dorsal horn cells and could explain our observations. Our results point out an anti-algesic OT effect in neuropathic rats.

Authors+Show Affiliations

Departamento de Neurofisiología, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus UNAM-Juriquilla, México. condes@servidor.unam.mxNo affiliation info availableNo affiliation info available

Pub Type(s)

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

Language

eng

PubMed ID

15910770

Citation

Condés-Lara, Miguel, et al. "Oxytocin Actions On Afferent Evoked Spinal Cord Neuronal Activities in Neuropathic but Not in Normal Rats." Brain Research, vol. 1045, no. 1-2, 2005, pp. 124-33.
Condés-Lara M, Maie IA, Dickenson AH. Oxytocin actions on afferent evoked spinal cord neuronal activities in neuropathic but not in normal rats. Brain Res. 2005;1045(1-2):124-33.
Condés-Lara, M., Maie, I. A., & Dickenson, A. H. (2005). Oxytocin actions on afferent evoked spinal cord neuronal activities in neuropathic but not in normal rats. Brain Research, 1045(1-2), 124-33.
Condés-Lara M, Maie IA, Dickenson AH. Oxytocin Actions On Afferent Evoked Spinal Cord Neuronal Activities in Neuropathic but Not in Normal Rats. Brain Res. 2005 May 31;1045(1-2):124-33. PubMed PMID: 15910770.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Oxytocin actions on afferent evoked spinal cord neuronal activities in neuropathic but not in normal rats. AU - Condés-Lara,Miguel, AU - Maie,Idil Ahmed Sh, AU - Dickenson,Anthony H, Y1 - 2005/04/21/ PY - 2004/08/30/received PY - 2005/03/04/revised PY - 2005/03/15/accepted PY - 2005/5/25/pubmed PY - 2005/8/19/medline PY - 2005/5/25/entrez SP - 124 EP - 33 JF - Brain research JO - Brain Res VL - 1045 IS - 1-2 N2 - A hypothalamic oxytocinergic-descending pathway that reaches the dorsal horn of the spinal cord has been well documented and recently related to states of pain and analgesia. In order to study the action of the neuropeptide oxytocin (OT) on pain-related responses, we compared dorsal horn neuronal responses to electrical and mechanical stimulation of receptive fields in normal and neuropathic rats. Spinal nerve (L5 and L6) ligation (Chung rats) was used to produce experimental neuropathy. Single unit activity was recorded at the L4-L5 level from neurons identified as wide dynamic range presenting latency responses corresponding to A-beta, A-delta, C fibers and also exhibiting post-discharge, and wind-up. We tested intrathecally applied doses of 0.05, 0.1, 1, 2, 5, 10 I.U. of OT. Minor effects on responses to electrical stimulation were present in normal rats. Mechanical responses evoked by von Frey filaments were slightly reduced in normal animals. In neuropathic rats a dose of 1 I.U. produced a significant reduction in C-fibers and post-discharge activities, and doses of 2 I.U. caused a further, pronounced reduction in post-discharge, wind-up, and input values. However, the most marked change was the post-discharge reduction at 10 and 20 min after OT administration. Mechanical responses were significantly reduced in terms of their discharge rate response in neuropathic rats. The contrasting results obtained in normal and neuropathic rats revealed an important distinction between these animals and indicate that plastic changes occur as a consequence of nerve damage. In neuropathic rats, mechanisms involving ascending noxious information to the paraventricular nuclei and descending OT activities could be altered so sensitizing the OT receptors of the spinal dorsal horn cells and could explain our observations. Our results point out an anti-algesic OT effect in neuropathic rats. SN - 0006-8993 UR - https://www.unboundmedicine.com/medline/citation/15910770/Oxytocin_actions_on_afferent_evoked_spinal_cord_neuronal_activities_in_neuropathic_but_not_in_normal_rats_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0006-8993(05)00442-7 DB - PRIME DP - Unbound Medicine ER -