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Systemic and site-specific effects of A-425619, a selective TRPV1 receptor antagonist, on wide dynamic range neurons in CFA-treated and uninjured rats.
J Neurophysiol. 2006 Jan; 95(1):18-25.JN

Abstract

Systemic administration of A-425619, a potent and selective TRPV1 receptor antagonist that does not readily enter the CNS, produces antinociception in several rat models of pathological nociception, including complete Freund's adjuvant (CFA)-induced thermal hyperalgesia. To further understand the peripheral mechanisms of TRPV1-related antinociception, we examined the effects of systemic and site-specific injections of A-425619 on evoked and spontaneous firing of spinal wide dynamic range (WDR) neurons in uninjured rats and rats with peripheral inflammation (CFA; 48 h). In uninjured rats, capsaicin-evoked (1 microg) WDR activity was completely blocked by intraplantar administration of A-425619 (3-100 nmol). Systemic injection of A-425619 (3-30 micromol/kg, iv) reduced WDR responses to thermal stimulation in both CFA-inflamed (47 degrees C) and uninjured (52 degrees C) rats. However, the efficacy of A-425619 to attenuate thermal-evoked WDR activity was significantly greater (P < 0.01) in CFA-treated rats. Both intradorsal root ganglion (DRG; L5; 20 nmol) and intraplantar (30-300 nmol) injection of A-425619 reduced WDR responses to thermal stimulation. While the effectiveness of A-425619 was similar between CFA-inflamed and uninjured rats after intraplantar injection, the effects of A-425619 after intra-DRG injection were enhanced in the inflamed rats (compared with the uninjured rats). Spontaneous WDR discharges were unaltered by systemic or site-specific injections of A-425619. Thus noxious thermal stimulation triggers the transmission of TRPV1-related signals to spinal WDR neurons in both inflamed and uninjured animals. The apparent increase in TRPV1 signaling to WDR neurons after injury may be the result of changes to the distribution/sensitization of peripheral TRPV1 receptors.

Authors+Show Affiliations

Neuroscience Res., Abbott Laboratories, R4PM, AP9-1, 100 Abbott Park Rd., Abbott Park, IL 60064-6118, USA. Steve.P.McGaraughty@abbott.comNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article

Language

eng

PubMed ID

16162831

Citation

McGaraughty, Steve, et al. "Systemic and Site-specific Effects of A-425619, a Selective TRPV1 Receptor Antagonist, On Wide Dynamic Range Neurons in CFA-treated and Uninjured Rats." Journal of Neurophysiology, vol. 95, no. 1, 2006, pp. 18-25.
McGaraughty S, Chu KL, Faltynek CR, et al. Systemic and site-specific effects of A-425619, a selective TRPV1 receptor antagonist, on wide dynamic range neurons in CFA-treated and uninjured rats. J Neurophysiol. 2006;95(1):18-25.
McGaraughty, S., Chu, K. L., Faltynek, C. R., & Jarvis, M. F. (2006). Systemic and site-specific effects of A-425619, a selective TRPV1 receptor antagonist, on wide dynamic range neurons in CFA-treated and uninjured rats. Journal of Neurophysiology, 95(1), 18-25.
McGaraughty S, et al. Systemic and Site-specific Effects of A-425619, a Selective TRPV1 Receptor Antagonist, On Wide Dynamic Range Neurons in CFA-treated and Uninjured Rats. J Neurophysiol. 2006;95(1):18-25. PubMed PMID: 16162831.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Systemic and site-specific effects of A-425619, a selective TRPV1 receptor antagonist, on wide dynamic range neurons in CFA-treated and uninjured rats. AU - McGaraughty,Steve, AU - Chu,Katharine L, AU - Faltynek,Connie R, AU - Jarvis,Michael F, Y1 - 2005/09/14/ PY - 2005/9/16/pubmed PY - 2006/1/21/medline PY - 2005/9/16/entrez SP - 18 EP - 25 JF - Journal of neurophysiology JO - J Neurophysiol VL - 95 IS - 1 N2 - Systemic administration of A-425619, a potent and selective TRPV1 receptor antagonist that does not readily enter the CNS, produces antinociception in several rat models of pathological nociception, including complete Freund's adjuvant (CFA)-induced thermal hyperalgesia. To further understand the peripheral mechanisms of TRPV1-related antinociception, we examined the effects of systemic and site-specific injections of A-425619 on evoked and spontaneous firing of spinal wide dynamic range (WDR) neurons in uninjured rats and rats with peripheral inflammation (CFA; 48 h). In uninjured rats, capsaicin-evoked (1 microg) WDR activity was completely blocked by intraplantar administration of A-425619 (3-100 nmol). Systemic injection of A-425619 (3-30 micromol/kg, iv) reduced WDR responses to thermal stimulation in both CFA-inflamed (47 degrees C) and uninjured (52 degrees C) rats. However, the efficacy of A-425619 to attenuate thermal-evoked WDR activity was significantly greater (P < 0.01) in CFA-treated rats. Both intradorsal root ganglion (DRG; L5; 20 nmol) and intraplantar (30-300 nmol) injection of A-425619 reduced WDR responses to thermal stimulation. While the effectiveness of A-425619 was similar between CFA-inflamed and uninjured rats after intraplantar injection, the effects of A-425619 after intra-DRG injection were enhanced in the inflamed rats (compared with the uninjured rats). Spontaneous WDR discharges were unaltered by systemic or site-specific injections of A-425619. Thus noxious thermal stimulation triggers the transmission of TRPV1-related signals to spinal WDR neurons in both inflamed and uninjured animals. The apparent increase in TRPV1 signaling to WDR neurons after injury may be the result of changes to the distribution/sensitization of peripheral TRPV1 receptors. SN - 0022-3077 UR - https://www.unboundmedicine.com/medline/citation/16162831/Systemic_and_site_specific_effects_of_A_425619_a_selective_TRPV1_receptor_antagonist_on_wide_dynamic_range_neurons_in_CFA_treated_and_uninjured_rats_ L2 - https://journals.physiology.org/doi/10.1152/jn.00560.2005?url_ver=Z39.88-2003&amp;rfr_id=ori:rid:crossref.org&amp;rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -