NSAIDs modulate GABA-activated currents via Ca2+-activated Cl− channels in rat dorsal root ganglion neurons

• Published in: Experimental and therapeutic medicine 2016-05, Vol.11 (5), p.1755-1761
• Main Authors: ZHAO, LEI, LI, LI, MA, KE-TAO, WANG, YANG, LI, JING, SHI, WEN-YAN, ZHU, HE, ZHANG, ZHONG-SHUANG, SI, JUN-QIANG
• Format: Article
• Language: English
• Subjects: Ca2+-activated Cl− channels; Chloride; dorsal root ganglion; Drugs; Laboratory animals; Ligands; Microscopy; modulatory; Nervous system; Neurons; niflumic acid; non-steroidal anti-inflammatory drugs; Polyclonal antibodies; Regulation; Rodents; Studies; γ-aminobutyrate-induced inward current
• ISSN: 1792-0981; 1792-1015
• DOI: 10.3892/etm.2016.3158

The ability of non-steroidal anti-inflammatory drugs (NSAIDs) to modulate γ-aminobutyrate (GABA)-activated currents via Ca2+-activated Cl− channels in rat dorsal root ganglion neurons (DRG), was examined in the present study. During the preparation of DRG neurons harvested from Sprague-Dawley rats, the whole-cell recording technique was used to record the effect of NSAIDs on GABA-activated inward currents, and the expression levels of the TMEM16A and TMEM16B subunits were revealed. In the event that DRG neurons were pre-incubated for 20 sec with niflumic acid (NFA) and 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB) prior to the administration of GABA, the GABA-induced inward currents were diminished markedly in the majority of neurons examined (96.3%). The inward currents induced by 100 µmol/l GABA were attenuated by (0±0.09%; neurons = 4), (5.32±3.51%; neurons = 6), (21.3±4.00%; neurons = 5), (33.8±5.20%; neurons = 17), (52.2±5.10%; neurons = 4) and (61.1±4.12%; neurons = 12) by 0.1, 1, 3, 10, 30 and 100 µmol/l NFA, respectively. The inward currents induced by 100 µmol/l GABA were attenuated by (13.8±6%; neurons = 6), (23.2±14.7%; neurons = 6) and (29.7±9.1%; neurons = 9) by 3, 10 and 30 µmol/l NPPB, respectively. NFA and NPPB dose-dependently inhibited GABA-activated currents with half maximal inhibitory concentration (IC50) values of 6.7 and 11 µmol/l, respectively. The inhibitory effect of 100 µmol/l NFA on the GABA-evoked inward current were also strongly inhibited by nitrendipine (NTDP; an L-type calcium channel blocker), 1,2-bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid tetrakis (a highly selective calcium chelating reagent), caffeine (a widely available Ca2+ consuming drug) and calcium-free extracellular fluid, in a concentration-dependent manner. Immunofluorescent staining indicated that TMEM16A and TMEM16B expression was widely distributed in DRG neurons. The results suggest that NSAIDs may be able to regulate Ca2+-activated chloride channels to reduce GABAA receptor-mediated inward currents in DRGs.