GABAergic synaptic response and its opioidergic modulation in periaqueductal gray neurons of rats with neuropathic pain

BMC Neuroscience

Research Article

Jong-Ju Lee¹  Younghoon Kim²  Young-Wuk Cho²  Eu-Teum Hahm³ 

[1] Department of Dental Pharmacology, School of Dentistry, Kyungpook National University, 700-412, Daegu, South Korea;Department of Physiology, Biomedical Science Institute, Kyung Hee University School of Medicine, 130-701, Seoul, South Korea;Department of Physiology, Biomedical Science Institute, Kyung Hee University School of Medicine, 130-701, Seoul, South Korea;Department of Physiology and Biophysics, University of Colorado Denver, Anschutz Medical Campus, 80045, Aurora, CO, USA;

关键词: Neuropathic pain;    Endogenous pain control system;    Opioid analgesia;    GABAergic synaptic transmission;    Periaqueductal gray;   

DOI  :  10.1186/1471-2202-12-41

 received in 2011-03-01, accepted in 2011-05-12,  发布年份 2011

来源: Springer

【 摘 要 】

BackgroundNeuropathic pain is a chronic and intractable symptom associated with nerve injury. The periaqueductal gray (PAG) is important in the endogenous pain control system and is the main site of the opioidergic analgesia. To investigate whether neuropathic pain affects the endogenous pain control system, we examined the effect of neuropathic pain induced by sacral nerve transection on presynaptic GABA release, the kinetics of postsynaptic GABA-activated Cl- currents, and the modulatory effect of μ-opioid receptor (MOR) activation in mechanically isolated PAG neurons with functioning synaptic boutons.ResultsIn normal rats, MOR activation inhibited the frequency of GABAergic miniature inhibitory postsynaptic currents (mIPSCs) to 81.3% of the control without any alteration in their amplitude. In neuropathic rats, the inhibition of mIPSC frequency by MOR activation was 82.4%. The frequency of GABAergic mIPSCs in neuropathic rats was 151.8% of normal rats without any difference in the mIPSC amplitude. Analysis of mIPSC kinetics showed that the fast decay time constant and synaptic charge transfer of mIPSCs in neuropathic rats were 76.0% and 73.2% of normal rats, respectively.ConclusionsThese results indicate that although the inhibitory effect of MOR activation on presynaptic GABA release is similar in both neuropathic and normal rats, neuropathic pain may inhibit endogenous analgesia in the PAG through an increase in presynaptic GABA release.

【 授权许可】

Unknown   
© Hahm et al; licensee BioMed Central Ltd. 2011. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.