Taurine prevents ammonia-induced accumulation of cyclic GMP in rat striatum by interaction with GABAA and glycine receptors

Previously, we had shown that ammonium chloride (ammonia)-induced accumulation of cyclic GMP in the microdialysates of rat striatum is blocked by taurine. In this study, coinfusion with taurine of a GABAA receptor antagonist bicuculline or a glycine receptor antagonist strychnine (100 mu M each), separately, restored ammonia-induced release of cGMP to the extracellular fluid to similar to 29% and 18% of the level measured in the absence of taurine, respectively. Simultaneous coinfusion of both antagonists or of 100 mu M picrotoxin, which is an antagonist of both GABAA and Gly receptors, offsets most of the taurine block. Ammonia-induced accumulation of cyclic GMP was attenuated by similar to 12% upon coinfusion of a GABAA receptor agonist muscimol (100 mu M). The results suggest that stimulation of both GABAA and glycine receptors is involved in the mechanism by which taurine limits the activation of the NMDA/NO/cGMP pathway by ammonia in the striatum. (c) 2005 Elsevier B.V. All rights reserved.