Adenosine Monophosphate–activated Protein Kinase Regulates Interleukin-1β Expression and Glial Glutamate Transporter Function in Rodents with Neuropathic Pain. (June 2015)

• Record Type: Journal Article
• Authors: Maixner, Dylan W.; Yan, Xisheng; Gao, Mei; Yadav, Ruchi; Weng, Han-Rong
• Is Part Of: Anesthesiology. Volume 122:Number 6(2015)
• Publication Date: 2015-06
• Subjects: Anesthesiology -- Periodicals; Anesthetics -- Periodicals; Anesthesia -- Periodicals; 617.9605
• DOI: 10.1097/ALN.0000000000000619
• Languages: English
• ISSNs: 0003-3022

Abstract

Abstract : Background: Neuroinflammation and dysfunctional glial glutamate transporters (GTs) in the spinal dorsal horn are implicated in the genesis of neuropathic pain. The authors determined whether adenosine monophosphate–activated protein kinase (AMPK) in the spinal dorsal horn regulates these processes in rodents with neuropathic pain. Methods: Hind paw withdrawal responses to radiant heat and mechanical stimuli were used to assess nociceptive behaviors. Spinal markers related to neuroinflammation and glial GTs were determined by Western blotting. AMPK activities were manipulated pharmacologically and genetically. Regulation of glial GTs was determined by measuring protein expression and activities of glial GTs. Results: AMPK activities were reduced in the spinal dorsal horn of rats (n = 5) with thermal hyperalgesia induced by nerve injury, which were accompanied with the activation of astrocytes, increased production of interleukin-1β and activities of glycogen synthase kinase 3β, and suppressed protein expression of glial glutamate transporter-1. Thermal hyperalgesia was reversed by spinal activation of AMPK in neuropathic rats (n = 10) and induced by inhibiting spinal AMPK in naive rats (n = 7 to 8). Spinal AMPKα knockdown (n = 6) and AMPKα1 conditional knockout (n = 6) induced thermal hyperalgesia and mechanical allodynia. These genetic alterations mimicked the changes of molecular markers induced by nerve injury. Pharmacological activation of AMPK enhanced glial GT activity in mice with neuropathic pain (n = 8) and attenuated glial glutamate transporter-1 internalization induced by interleukin-1β (n = 4). Conclusions: These findings suggest that enhancing spinal AMPK activities could be an effective approach for the treatment of neuropathic pain. Abstract : Nerve injury reduced adenosine monophosphate–activated protein kinase (AMPK) activity, increased inflammation, reduced glutamate transporter expression in the spinal cord, and induced thermal hyperalgesia. Activation of AMPK increased glutamate transporter activity and reduced neuropathic pain; by contrast, knockdown of AMPK induced allodynia. These data indicate that AMPK plays an important role in nociceptive processing in the spinal cord and extend the novel possibility of manipulation of AMPK activity as a therapeutic target in experimental models of pain.