Posted by disney4 on April 4, 2003, at 11:40:49
In reply to Re: Magnesium--HELP anyone, posted by jemma on April 4, 2003, at 11:22:21
Hi Larry,
Could you help me to interpret this article on glycine? I am considering switching to the magnesium glycinate from the magnesium l-lactate (mag-tab slow release) for added help with bipolar disorder and medication withdrawl induced benign myoclonic jerks.
GLYCINE: SYNTHESIS AND UPTAKE
Glycine is the major inhibitory neurotransmitter in the brainstem and spinal cord, where it participates in a variety of motor and sensory functions. Glycine is also present in the forebrain, where it has recently been shown to function as a coagonist at the N-methyl-D-aspartate (NMDA) subtype of glutamate receptor. In the latter, context glycine promotes the actions of glutamate, the major excitatory neurotransmitter (for a discussion of glycine's role as a coagonist of the NMDA receptor, see Excitatory Amino Acid Neurotransmission). Thus, glycine subserves both inhibitory and excitatory functions within the CNS.Glycine is formed from serine by the enzyme serine hydroxymethyltransferase (SHMT). Glycine, like GABA, is released from nerve endings in a Ca2+-dependent fashion. The actions of glycine are terminated primarily by reuptake via Na+/Cl--dependent, high-affinity glycine transporters. The specific uptake of glycine has been demonstrated in the brainstem and spinal cord in regions where there are also high densities of inhibitory glycine receptors.
Recently, two glycine transporters have been cloned and shown to be expressed in the CNS as well as in various peripheral tissues (11, 19). These glycine transporters are members of the large family of Na+/Cl--dependent neurotransmitter transporters, and both share approximately 50% sequence identity with the GABA transporters discussed above. The deduced amino acid sequence of both cDNAs predicts the typical 12 transmembrane domains characteristic of these transporters. The two glycine cloned transporters have been named GLYT-1 and GLYT-2 in the order that they were reported (11). These transporter cDNAs are transcribed from the same gene and are quite similar in their 3¢ nucleotide sequences. They differ in their 5¢ noncoding regions as well as in the first 44 nucleotides of their coding sequence. Expression of GLYT-1 and GLYT-2 yield transporters with similar kinetic and pharmacological properties. Interestingly, however, the distribution of GLYT-1 and GLYT-2 transcripts measured by in situ hybridization are different. GLYT-1 mRNA also closely parallels the distribution of the glycine receptor. These data suggest that GLYT-1 is primarily a glial glycine transporter whereas GLYT-2 is primarily a neuronal transporter. The mapping of both glycine transporter mRNAs, as well as the glycine receptor subunit mRNAs, confirm the importance of this neurotransmitter in the brainstem and spinal cord, but support a more widespread distribution in supraspinal brain regions than was previously suspected.
poster:disney4
thread:214008
URL: http://www.dr-bob.org/babble/20030402/msgs/216189.html