Glycine protection of PC-12 cells against injury by ATP-depletion.

A distinctive mechanism of cell injury during ATP depletion involves the loss of cellular glycine. The current study examined whether provision of glycine during ATP depletion can prevent injury in PC-12 cells, a cell line with neuronal property. In addition, we have examined the role played by glycine receptors in cytoprotective effects of the amino acid. It was shown that ATP depletion led to plasma membrane damage in PC-12 cells, which was ameliorated by 0.25-5 mM glycine. Cytoprotective activity of glycine was shared by alanine, but not by glutamate or gamma-aminobutyric acid (GABA). Of interest, strychnine, an antagonist of glycine receptor, was also protective. The results, while suggesting the involvement of glycine receptor in cytoprotection, indicate that chloride channel activity of the receptor is dispensable. Such a scenario is further supported by the observation that removal of extracellular chloride did not affect ATP depletion-induced cell injury or its prevention by glycine. In short, this study has provided the first evidence for glycine protection of cells with neuronal properties. Cytoprotection may involve the glycine receptor; however, it can be dissociated from its channel activity.