Chemical Communication in the Nervous System: Glycine

Background and Location of Glycine

Glycine is located in the central nervous system. It is considered a “inhibitory neurotransmitter,” meaning it works to decrease a neuron's action potential (Werman et al., 1967). Glycine is most commonly found in the spinal cord, retina, and brain stem (Werman et al., 1967). It is the simplest amino acid, its main function is to build protein molecules in the body (Werman et al., 1967). While glycine is considered a non-essential amino acid because it can be created from other chemicals in the body, it’s also the second most commonly found amino acid in proteins (McIntire et al., 1997).

Primary Role and Function of Glycine

Glycine processes “motor and sensory information that allows movement, vision, and sound” to be signaled from the brain (Lopez-Corcuera et al., 2001). It’s mostly responsible for transmitting chemical signals in the brain. Glycine is often co-released into the post-synaptic terminal with GABA (gamma-amino butyric acid), which is the prime inhibitory amino acid neurotransmitter (as illustrated in the diagram below) (McIntire et al., 1997). When glycine is released into the synapse (the space between nerve cells), glycine binds to a receptor and makes the post-synaptic membrane (the receiving end across the synapse) more absorbent of chlorine-ion (Lopez-Corcuera et al., 2001). Hyperpolarization then occurs in the membrane, meaning there’s an increase in electrical charge on both sides of the cell membrane which also increases the membrane electric potential (Lopez-Corcuera et al., 2001). Glycine can also sometimes be used as treatment of cognitive disorders or behavioral problems such as schizophrenia, manic depression, alcohol addiction, and hyperactivity (Harvey &Yee, 2013). 

Glycine Video

The video discusses the three prominent amino acids Glutamate, GABA and Glycine. Even though the whole clip is beneficial in understanding the amino acids and how they function in central nervous system, the speaker specifically discusses the function of glycine starting at 4:32.

References

Harvey, R. J., & Yee, B. K. (2013). Glycine transporters as novel therapeutic targets in 

          

          schizophrenia,alcohol dependence and pain. Nature Reviews Drug Discovery, 12(11), 866-885.

Lopez-Corcuera, B., Geerlings, A., & Aragon, C. (2001). Glycine neurotransmitter transporters: an

           

          update. Molecular membrane biology, 18(1), 13-20.

McIntire, S. L., Reimer, R. J., Schuske, K., Edwards, R. H. and Jorgensen, E. M. (1997). 

            

           Identificationand characterization of the vesicular GABA transporter. Nature, 389, 870-876.

Werman, R., Davidoff, R. A. & Aprison, M. H. (1967). Inhibition of motoneurons by iontophoresis 

            of glycine. Nature, 214, 681-683.