title: Characterization of the nociceptive effect of carrageenan: Masseter versus gastrocnemius.
abstract: BACKGROUND
  To better understand the pathophysiology of chronic muscle pain, there are multiple animal models that mimic different acute/chronic pain conditions, such as carrageenan injection. Our previous studies demonstrated differences between muscles of different innervation in acute pain. In this study we characterized the effect of carrageenan in 2 muscles: masseter (trigeminal innervation) and gastrocnemius (spinal innervation).
  
  
  METHODS
  Carrageenan (3%, 6%, and 9%) was injected into the masseter and gastrocnemius of rats. Mechanical, heat, and chemical nociceptive thresholds were measured for 14 days.
  
  
  RESULTS
  Carrageenan did not induce mechanical allodynia or thermal hypersensitivity in either muscle. Instead, it induced a short-lasting mechanical hyperalgesia, greater in the masseter than in the gastrocnemius.
  
  
  CONCLUSIONS
  Carrageenan injected into the masseter and gastrocnemius induces a short-lasting hyperalgesia. These results could indicate a higher susceptibility of orofacial muscles to this type of insult and, consequently, a difference between trigeminal and spinal innervation. Muscle Nerve 56: 804-813, 2017.
authors.affiliation: Área de Farmacología y Nutrición, Unidad asociada I+D+i al Instituto de Química Médica, Grupo de excelencia investigadora URJC-Banco de Santander-Grupo Multidisciplinar de Investigación y Tratamiento del Dolor (i+DOL), Alcorcón, Madrid, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Bagüés
authors.affiliation: Área de Farmacología y Nutrición, Unidad asociada I+D+i al Instituto de Química Médica, Grupo de excelencia investigadora URJC-Banco de Santander-Grupo Multidisciplinar de Investigación y Tratamiento del Dolor (i+DOL), Alcorcón, Madrid, Spain.
authors.forename: M Isabel
authors.initials: MI
authors.lastname: Martín-Fontelles
authors.affiliation: Área de Medicina Preventiva y Salud Pública, Facultad de Ciencias de la Salud. Universidad Rey Juan Carlos, Alcorcón, Madrid, Spain.
authors.forename: Jesús
authors.initials: J
authors.lastname: Esteban-Hernández
authors.affiliation: Área de Farmacología y Nutrición, Unidad asociada I+D+i al Instituto de Química Médica, Grupo de excelencia investigadora URJC-Banco de Santander-Grupo Multidisciplinar de Investigación y Tratamiento del Dolor (i+DOL), Alcorcón, Madrid, Spain.
authors.forename: Eva M
authors.initials: EM
authors.lastname: Sánchez-Robles
mesh_terms: D000818:Animals; D002351:Carrageenan / Q000008:administration & dosage / Q000633:toxicity*; D006930:Hyperalgesia / Q000139:chemically induced* / Q000473:pathology; D007273:Injections, Intramuscular; D008297:Male; D008406:Masseter Muscle / Q000187:drug effects* / Q000473:pathology; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000473:pathology; D010147:Pain Measurement / Q000187:drug effects* / Q000379:methods; D051381:Rats; D017208:Rats, Wistar; D016896:Treatment Outcome
chemical_list: D002351:Carrageenan
keywords: carrageenan; gastrocnemius; masseter; muscle pain; rat