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Peripheral formalin injury induces 2 stages of microglial activation in the spinal cord.
J Pain. 2010 Nov; 11(11):1056-65.JP

Abstract

The formalin test produces 2 well-known acute phases of nociceptive behavior. Recently, we have shown that this same formalin test produces a third phase of nociceptive behavior consisting of prolonged thermal and mechanical hyperalgesia beginning days after formalin injection and lasting for at least 3 weeks. Here we investigated the activity of 3 MAPKs (p38, ERK and JNK) in the spinal dorsal horn following 5% formalin injection into rat hind paw. The p38 MAPK was rapidly activated in the spinal microglia minutes after injection and the activation persisted for 1 hour. In addition, this same injury induced a secondary increase of phospho-p38 expression in spinal microglia that was maximal 3 to 7 days postinjection. Intrathecal administration of p38 inhibitor SB203580 not only inhibited the early acute spontaneous nociceptive behaviors, but also inhibited the long-term formalin injury-induced mechanical hyperalgesia. Our results suggest that peripheral formalin injection induces 2 stages of microglial activation, and p38 activation in spinal microglia plays key roles in central pain modulation in formalin test respectively for the early acute phases and the late secondary long-term pain state as well.

PERSPECTIVE

This article presents unique properties of spinal microglial activation in a pain animal model. This finding could potentially help clinicians to further understand the contributions of spinal microglia to acute and chronic pain state.

Authors+Show Affiliations

Center for TMD & Orofacial Pain, Peking University School & Hospital of Stomatology, Beijing 100081, P R China.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

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

Language

eng

PubMed ID

20488758

Citation

Li, Kai, et al. "Peripheral Formalin Injury Induces 2 Stages of Microglial Activation in the Spinal Cord." The Journal of Pain : Official Journal of the American Pain Society, vol. 11, no. 11, 2010, pp. 1056-65.
Li K, Lin T, Cao Y, et al. Peripheral formalin injury induces 2 stages of microglial activation in the spinal cord. J Pain. 2010;11(11):1056-65.
Li, K., Lin, T., Cao, Y., Light, A. R., & Fu, K. Y. (2010). Peripheral formalin injury induces 2 stages of microglial activation in the spinal cord. The Journal of Pain : Official Journal of the American Pain Society, 11(11), 1056-65. https://doi.org/10.1016/j.jpain.2010.01.268
Li K, et al. Peripheral Formalin Injury Induces 2 Stages of Microglial Activation in the Spinal Cord. J Pain. 2010;11(11):1056-65. PubMed PMID: 20488758.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Peripheral formalin injury induces 2 stages of microglial activation in the spinal cord. AU - Li,Kai, AU - Lin,Ting, AU - Cao,Ye, AU - Light,Alan R, AU - Fu,Kai-Yuan, Y1 - 2010/05/20/ PY - 2009/12/17/received PY - 2010/01/15/revised PY - 2010/01/26/accepted PY - 2010/5/22/entrez PY - 2010/5/22/pubmed PY - 2011/9/29/medline SP - 1056 EP - 65 JF - The journal of pain : official journal of the American Pain Society JO - J Pain VL - 11 IS - 11 N2 - UNLABELLED: The formalin test produces 2 well-known acute phases of nociceptive behavior. Recently, we have shown that this same formalin test produces a third phase of nociceptive behavior consisting of prolonged thermal and mechanical hyperalgesia beginning days after formalin injection and lasting for at least 3 weeks. Here we investigated the activity of 3 MAPKs (p38, ERK and JNK) in the spinal dorsal horn following 5% formalin injection into rat hind paw. The p38 MAPK was rapidly activated in the spinal microglia minutes after injection and the activation persisted for 1 hour. In addition, this same injury induced a secondary increase of phospho-p38 expression in spinal microglia that was maximal 3 to 7 days postinjection. Intrathecal administration of p38 inhibitor SB203580 not only inhibited the early acute spontaneous nociceptive behaviors, but also inhibited the long-term formalin injury-induced mechanical hyperalgesia. Our results suggest that peripheral formalin injection induces 2 stages of microglial activation, and p38 activation in spinal microglia plays key roles in central pain modulation in formalin test respectively for the early acute phases and the late secondary long-term pain state as well. PERSPECTIVE: This article presents unique properties of spinal microglial activation in a pain animal model. This finding could potentially help clinicians to further understand the contributions of spinal microglia to acute and chronic pain state. SN - 1528-8447 UR - https://www.unboundmedicine.com/medline/citation/20488758/Peripheral_formalin_injury_induces_2_stages_of_microglial_activation_in_the_spinal_cord_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S1526-5900(10)00288-9 DB - PRIME DP - Unbound Medicine ER -