Sodium salicylate reduces inhibitory postsynaptic currents in neurons of rat auditory cortex.
Sodium salicylate (SS) is a medicine for anti-inflammation and for chronic pain relief with a side effect of tinnitus. To understand the cellular mechanisms of tinnitus induced by SS in the central auditory system, we examined effects of SS on evoked and miniature inhibitory postsynaptic currents (eIPSCs and mIPSCs) recorded from layer II/III pyramidal neurons of rat auditory cortex in a brain slice preparation with whole-cell patch-clamp techniques. Both eIPSCs and mIPSCs recorded from the auditory cortex could be completely blocked by bicuculline, a selective GABA(A) receptor antagonist. SS did not change the input resistance of neurons but was found to reversibly depress eIPSCs in a concentration-dependent manner. SS reduced eIPSCs to 82.3% of the control level at 0.5 mM (n=7) and to 60.9% at 1.4 mM (n=12). In addition, SS at 1.4 mM significantly reduced the amplitude of mIPSCs from 24.12+/-1.44 pA to 19.92+/-1.31 pA and reduced the frequency of mIPSCs from 1.34+/-0.23 Hz to 0.89+/-0.13 Hz (n=6). Our results demonstrate that SS attenuates inhibitory postsynaptic currents in the auditory cortex, suggesting that the alteration of inhibitory neural circuits may be one of the cellular mechanisms for tinnitus induced by SS in the central auditory region.
Wang
Hai-Tao
HT
Auditory Research Laboratory, School of Life Sciences, University of Science and Technology of China, 443 Yellow Mountain Road, Hefei 230027, China.
Luo
Bin
B
Zhou
Ke-Qing
KQ
Xu
Tian-Le
TL
Chen
Lin
L
D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000009:adverse effects*; D001303:Auditory Cortex / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D004195:Disease Models, Animal; D005260:Female; D008297:Male; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D012980:Sodium Salicylate / Q000009:adverse effects*; D009435:Synaptic Transmission / Q000187:drug effects*; D014012:Tinnitus / Q000139:chemically induced / Q000503:physiopathology*
D000894:Anti-Inflammatory Agents, Non-Steroidal; D012980:Sodium Salicylate