Involvement of medullary GABAergic system in extraterritorial neuropathic pain mechanisms associated with inferior alveolar nerve transection.

Involvement of medullary GABAergic system in extraterritorial neuropathic pain mechanisms associated with inferior alveolar nerve transection.
Exp Neurol. 2015 Feb 28;
Authors: Okada-Ogawa A, Nakaya Y, Imamura Y, Kobayashi M, Shinoda M, Kita K, Sessle BJ, Iwata K
Abstract
In order to determine if the functional changes in the GABAergic system in the trigeminal spinal subnucleus caudalis (Vc) are involved in the mechanisms underlying extraterritorial neuropathic pain in the orofacial region following inferior alveolar nerve transection (IANX), mechanical noxious behavior, phosphorylated extracellular signal-regulated kinase (pERK) immunohistochemistry and single neuronal activity were analyzed in vesicular GABA transporter (VGAT)-VenusA rats expressing fluorescent protein and the VGAT in Vc neurons. The number of VGAT-VenusA positive neurons was significantly reduced in IANX rats than naïve and sham rats at 7days after nerve transection. The number of VGAT-VenusA positive pERK-immunoreactive (IR) cells was significantly increased in IANX rats at 21days after IAN transection compared with naïve and sham rats. The background activity and mechanical-evoked responses of Vc nociceptive neurons were significantly depressed after intrathecal application of the GABA receptor agonist muscimol in sham rats but not in IANX rats. Furthermore, the expression of potassium-chloride co-transporter 2 (KCC2) in the Vc was significantly reduced in IAN...

Source: Experimental Neurology - February 28, 2015 Category: Neurology Authors: Okada-Ogawa A, Nakaya Y, Imamura Y, Kobayashi M, Shinoda M, Kita K, Sessle BJ, Iwata K Tags: Exp Neurol Source Type: research