title: A D2-like receptor family agonist produces analgesia in mechanonociception but not in thermonociception at the spinal cord level in rats.
abstract: The administration of dopaminergic drugs produces analgesia in individuals experiencing different types of pain. Analgesia induced by these drugs at the spinal cord level is mediated by D2-like agonists, which specifically inhibit the detection of nociceptive stimuli by sensory afferents. The extent of the analgesia provided by spinal dopamine agonists remains controversial, and the cellular mechanism of this analgesic process is poorly understood. The objective of this study was to evaluate the analgesic effect of quinpirole, a D2-like agonist, based on two nociceptive tests and at various doses that were selected to specifically activate dopamine receptors. We found that intrathecal quinpirole administration produces analgesia of mechanical but not thermal nociception and that the analgesic effect of quinpirole is reversed by a mix of D2, D3, and D4 receptor-specific antagonists, suggesting that the activation of all D2-like receptors is involved in the analgesia produced by intrathecal quinpirole. The differential effect on thermal and mechanical nociception was also tested upon the activation of μ-opioid receptors. As reported previously, low doses of the μ-opioid receptor agonist DAMGO produced analgesia of only thermonociception. This evidence shows that a D2-like receptor agonist administered at the spinal cord level produces analgesia specific to mechanonociception but not thermonociception.
authors: Laboratorio de Fisiología Celular, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Calzada México-Xochimilco 101, Col. San Lorenzo Huipulco, Del. Tlalpan, C.P. 14370 México D.F., Mexico.
authors: Angélica
authors: A
authors: Almanza
authors: Laboratorio de Neurofisiología Integrativa, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Calzada México-Xochimilco 101, Col. San Lorenzo Huipulco, Del. Tlalpan, C.P. 14370 México D.F., Mexico.
authors: Karina
authors: K
authors: Simón-Arceo
authors: Laboratorio de Neurofisiología Integrativa, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Calzada México-Xochimilco 101, Col. San Lorenzo Huipulco, Del. Tlalpan, C.P. 14370 México D.F., Mexico.
authors: Ulises
authors: U
authors: Coffeen
authors: Departamento de Matemáticas, Facultad de Ciencias, Universidad Nacional Autónoma de México, Av. Universidad 3000, Circuito Exterior s/n, Ciudad Universitaria, C.P. 04510 México D.F., Mexico.
authors: Ruth
authors: R
authors: Fuentes-García
authors: Laboratorio de Neurofisiología Integrativa, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Calzada México-Xochimilco 101, Col. San Lorenzo Huipulco, Del. Tlalpan, C.P. 14370 México D.F., Mexico.
authors: Bernardo
authors: B
authors: Contreras
authors: Laboratorio de Neurofisiología Integrativa, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Calzada México-Xochimilco 101, Col. San Lorenzo Huipulco, Del. Tlalpan, C.P. 14370 México D.F., Mexico. Electronic address: pellicer@imp.edu.mx.
authors: Francisco
authors: F
authors: Pellicer
authors: Laboratorio de Fisiología Celular, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Calzada México-Xochimilco 101, Col. San Lorenzo Huipulco, Del. Tlalpan, C.P. 14370 México D.F., Mexico. Electronic address: fmercado@imp.edu.mx.
authors: Francisco
authors: F
authors: Mercado
mesh_terms: D000698:Analgesia / Q000379:methods*; D000818:Animals; D018491:Dopamine Agonists / Q000008:administration & dosage*; D006358:Hot Temperature / Q000009:adverse effects*; D007278:Injections, Spinal; D008297:Male; D010146:Pain / Q000188:drug therapy* / Q000378:metabolism; D010812:Physical Stimulation / Q000009:adverse effects; D019257:Quinpirole / Q000008:administration & dosage; D051381:Rats; D017448:Receptors, Dopamine D2 / Q000819:agonists* / Q000378:metabolism; D013116:Spinal Cord / Q000187:drug effects* / Q000378:metabolism
chemical_list: D018491:Dopamine Agonists; D017448:Receptors, Dopamine D2; D019257:Quinpirole
keywords: Analgesia; D2-like dopamine receptor; Mechanonociception; Modulation; Thermonociception