• Hyeong Cheol Moon, Youn Joo Lee, Chul Bum Cho, and Young Seok Park.
• Department of Medical Neuroscience and Neurosurgery, College of Medicine, Chungbuk National University, Cheongju, Republic of Korea.
• Neurosci. Lett. 2016 Oct 6; 632: 55-61.

ObjectiveSuppression of the gamma-aminobutyric acid (GABA)ergic activity of the zona incerta (ZI) reportedly plays a role in neuropathic pain after spinal cord injury (SCI). A reduction in GABAergic signaling in the ZI of a thoracic hemisection-SCI rat model has been suggested, but not clearly demonstrated. Accordingly, our objective was to investigate whether GABAergic signals influence SCI-induced neuropathic pain.MethodsIn vivo, we recorded and compared single-unit, neuronal activity between hemisection-SCI and sham-operated rat models. Furthermore, we analyzed neuronal activity in both models following treatment with either a GABAA receptor agonist (muscimol) or antagonist (bicuculline).ResultsRats that underwent hemisection SCI exhibited reduced hindpaw withdrawal thresholds, latencies, and decreased ZI neuronal activity compared with sham-operated controls. Importantly, muscimol treatment increased, whereas bicuculline decreased, the firing rates of the ZI neurons. The muscimol treated, hemisection-SCI rats also exhibited increased hindpaw withdrawal thresholds and latencies.ConclusionsThese data provide evidence that neuropathic pain after SCI is caused by decreased GABAergic signaling in the ZI. Furthermore, our data demonstrate that infusion of a GABAergic drug into the ZI could restore its inhibitory action and improve neuropathic pain behaviors.Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

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