Taurine Activates Strychnine-Sensitive Glycine Receptors in Neurons Freshly Isolated From Nucleus Accumbens of Young Rats

Abstract

. Although functional glycine receptors (GlyRs) are present in the mature nucleus accumbens (NAcc), an important area of the mesolimbic dopamine system involved in drug addiction, their role has been unclear because the NAcc contains little glycine. However, taurine, an agonist of GlyRs, is abundant throughout the brain, especially during early development. In the present study on freshly dissociated NAcc neurons from young Sprague-Dawley rats (12-to 21-day old), we found that both glycine and taurine can strongly depolarize NAcc neurons and modulate their excitability. In voltage-clamped NAcc neurons, glycine and taurine elicited chloride currents (I Gly and I Tau ) with an EC 50 of 0.12 and 1.25 mM, respectively. The reversal potential of I Gly or I Tau was 0 mV in conventional whole cell mode and -30 mV in gramicidin-perforated mode. At concentrations Ͻ1 mM, both glycine and taurine were very effectively antagonized by strychnine and by picrotoxin (with an IC 50 of 60 nM and 36.5 M for I Gly , and 40 nM and 42.2 M for I Tau ) but were insensitive to 10 M bicuculline. The currents elicited by taurine (Յ1 mM) showed complete cross-desensitization with I Gly , but none with ␥-aminobutyric acid (GABA)-induced currents (I GABA ). However, I Tau elicited by very concentrated taurine (10 mM) showed partial cross-desensitization with I GABA , and it was substantially antagonized by 10 M bicuculline. These results indicate that taurine binds mainly to GlyRs in NAcc, but it could be a partial agonist of GABA A receptors. By activating GlyRs, taurine may play an important physiological role in the control of NAcc function, especially during development.

Intracisternal or intrathecal glycine, taurine, or muscimol inhibit bicuculline-induced allodynia and thermal hyperalgesia in mice

“…Although not directly comparable, the results of the present study are consistent with the results obtained by Jiang et al, namely, that taurine (300 µmol) binds primarily to the glycine receptor; however, at high concentrations, taurine (10 mmol) can also activate GABA A receptors in vitro [7] . In fact, Idrissi and Trenkner reported that taurine interacts directly with GABA A receptor in vitro [17] .…”

“…GABA and glycine are colocalized in interneurons in spinal laminae I-III [4,5] and are coreleased from the same interneurons [6] . However, taurine binds to glycine receptors in the CNS and functions as a partial agonist of GABA A receptors [7] , inhibiting behaviors evoked by intrathecal N-methyl-D-aspartate (NMDA) or kainate injection [8,9] . If GABA and glycine are coreleased from the same interneurons, and glycine-related amino acids act at GABA and glycine receptors to modulate low-threshold transmission via distinct but complementary mechanisms, then glycine or its related amino acids might inhibit bicuculline-induced allodynia.…”

Taurine Is a Potent Activator of Extrasynaptic GABAAReceptors in the Thalamus

“…Taurine is a structural analog of the inhibitory neurotransmitters glycine and GABA, and activates both glycine and GABA A receptors. For example, low to moderate concentrations (200 M to 1 mM) of taurine have been shown to activate glycine receptors in the basolateral amygdala (McCool and Botting, 2000), hippocampus (Wu and Xu, 2003), nucleus accumbens (Jiang et al, 2004), supraoptic nucleus (Hussy et al, 1997), and inferior colliculus (Xu et al, 2004), whereas high concentrations of taurine (1-10 mM) activate GABA A receptors in these brain regions.…”

The Effect of Subacute Supplementation of Taurine on Spatial Learning and Memory

“…The roles of endogenous taurine in the liver and heart are to increase bile acid secretion by forming bile acid conjugate [2] and regulate Ca 2+ kinetics to protect and improve the heart function [17], respectively. In the brain, taurine is also abundant, especially in the hippocampus, and modulates synaptic transmission as an inhibitory neuromodulator interacting with g-aminobutyric acid type A (GABA A ) or glycine receptors [9,22]. Recent electrophysiological studies using rat brain preparations, however, have shown that taurine application induced long-lasting synaptic potentiation [3,6].…”