α-Lipoic Acid Derivatives as Allosteric Modulators for Targeting AMPA-Type Glutamate Receptors' Gating Modules

The ionotropic glutamate receptor subtype α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) is responsible for most excitatory transmission in the brain. AMPA receptor function is altered in numerous neurological illnesses, making AMPA receptors appealing therapeutic targets for clinical intervention. Alpha-Lipoic acid (α-LA) is a naturally occurring compound, which functions as a co-factor in metabolism and energy production. α-LA is an antioxidant with various benefits in treating diabetes, including managing symptomatic diabetic neuropathy. This study will test a novel and innovative strategy to synthesize a new isomer of lipoic acid (R-LA) derivatives (bifunctional NO-donor/antioxidant) in one chemical on homomeric and heteromeric AMPA receptor subunits. We used patch-clamp electrophysiology to examine LA derivatives expressed in human embryonic kidney 293 cells (HEK293) for inhibition and changes in desensitization or deactivation rates. LA derivatives were shown to be potent antagonists of AMPA receptors, with an 8-11-fold reduction in AMPA receptor currents seen following the delivery of the compounds. Furthermore, the LA derivatives influenced the rates of desensitization and deactivation of AMPA receptors. Based on our results, especially given that α-LA is closely connected to the nervous system, we may better understand using AMPA receptors and innovative drugs to treat neurological diseases associated with excessive activation of AMPA receptors.