Modulation of glutamatergic and GABAergic neurotransmission in glutaryl-CoA dehydrogenase deficiency

Although the precise mechanisms underlying the CNS degeneration of patients with glutaryl-CoA dehydrogenase (GCDH) deficiency are still the subject of intense debate, many studies have highlighted that excitotoxicity plays a fundamental role in the neuropathology of this disease, particularly involving the N-methyl-D-aspartate receptor subtype of ionotropic glutamate receptors. Modulation of the glutamatergic system by these compounds involves an inhibition of glutamate uptake into synaptosomes and synaptic vesicles, and a decrease in glutamate binding. Furthermore, glutaric and 3-hydroxyglutaric acids inhibit glutamate decarboxylase, the key enzyme of GABA synthesis, and striatal GABAergic medium-spiny neurons are highly vulnerable to 3-hydroxyglutaric acid-induced neurotoxicity. In conclusion, glutaric acid and 3-hydroxyglutaric acid induce an imbalance in glutamatergic and GABAergic neurotransmission.