HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Hussy, N Articles by Moos, F Search for Related Content PubMed PubMed Citation Articles by Hussy, N Articles by Moos, F

CNRS-UPR 9055, Montpellier, France. hussy@bacchus.montp.inserm.fr

1. To evaluate the implication of taurine in the physiology of supraoptic neurones, we (i) investigated the agonist properties of taurine on glycine and GABAA receptors of supraoptic magnocellular neurones acutely dissociated from adult rats, using whole-cell voltage clamp, (ii) studied the effects of taurine and strychnine in vivo by extracellular recordings of supraoptic vasopressin neurones in anaesthetized rats, and (iii) measured the osmolarity-dependent release of endogenous taurine from isolated supraoptic nuclei by HPLC. 2. GABA, glycine and taurine evoked rapidly activating currents that all reversed close to the equilibrium potential for Cl-, indicating activation of Cl(-)-selective channels. Glycine-activated currents were reversibly blocked by strychnine (IC50 of 35 nM with 100 microM glycine), but were unaffected by the GABAA antagonist gabazine (1-3 microM). GABA-activated currents were reversibly antagonized by 3 microM gabazine, but not by strychnine (up to 1 microM). 3. Responses to 1 mM taurine were blocked by strychnine but not by gabazine and showed no additivity with glycine-induced currents, indicating selective activation of glycine receptors. Responses to 10 mM taurine were partially antagonized by gabazine, the residual current being blocked by strychnine. Thus, taurine is also a weak agonist of GABAA receptors. 4. In the presence of gabazine, taurine activated glycine receptors with an EC50 of 406 microM. Taurine activated at most 70% of maximal glycine currents, suggesting that it is a partial agonist of glycine receptors. 5. In vivo, locally applied strychnine (300 nM) increased and taurine (1 mM) decreased the basal electrical activity of vasopressin neurones in normally hydrated rats. The effect of strychnine was markedly more pronounced in water-loaded rats. 6. Taurine, which is concentrated in supraoptic glial cells, could be released from isolated supraoptic nuclei upon hyposmotic stimulation. Decreases in osmolarity of 15 and 30% specifically enhanced basal release of taurine by 42 and 124%, respectively. 7. We conclude that supraoptic neurones express high amounts of glycine receptors, of which taurine may be regarded as a major natural agonist. We postulate that taurine, which can be released in hyposmotic situations, acts on glycine receptors to exert an inhibitory control on magnocellular neurones during alterations of body fluid homeostasis, implicating an active participation of glial cells in this neuroendocrine regulatory loop.

This article has been cited by other articles:

				D. T. Theodosis, D. A. Poulain, and S. H. R. Oliet Activity-Dependent Structural and Functional Plasticity of Astrocyte-Neuron Interactions Physiol Rev, July 1, 2008; 88(3): 983 - 1008. [Abstract] [Full Text] [PDF]

				F. Jia, M. Yue, D. Chandra, A. Keramidas, P. A. Goldstein, G. E. Homanics, and N. L. Harrison Taurine Is a Potent Activator of Extrasynaptic GABAA Receptors in the Thalamus J. Neurosci., January 2, 2008; 28(1): 106 - 115. [Abstract] [Full Text] [PDF]

				S. N. Orlov and A. A. Mongin Salt-sensing mechanisms in blood pressure regulation and hypertension Am J Physiol Heart Circ Physiol, October 1, 2007; 293(4): H2039 - H2053. [Abstract] [Full Text] [PDF]

				F. Wang, C. Xiao, and J. H. Ye Taurine activates excitatory non-synaptic glycine receptors on dopamine neurones in ventral tegmental area of young rats J. Physiol., June 1, 2005; 565(2): 503 - 516. [Abstract] [Full Text] [PDF]

				A. A. Mongin and H. K. Kimelberg ATP regulates anion channel-mediated organic osmolyte release from cultured rat astrocytes via multiple Ca2+-sensitive mechanisms Am J Physiol Cell Physiol, January 1, 2005; 288(1): C204 - C213. [Abstract] [Full Text] [PDF]

				Z. Jiang, K. Krnjevic, F. Wang, and J. H. Ye Taurine Activates Strychnine-Sensitive Glycine Receptors in Neurons Freshly Isolated From Nucleus Accumbens of Young Rats J Neurophysiol, January 1, 2004; 91(1): 248 - 257. [Abstract] [Full Text]

				A. A. Mongin and H. K. Kimelberg ATP potently modulates anion channel-mediated excitatory amino acid release from cultured astrocytes Am J Physiol Cell Physiol, August 1, 2002; 283(2): C569 - C578. [Abstract] [Full Text] [PDF]