Ubiquinone protects cultured neurons against spontaneous and excitotoxin-induced degeneration

Ubiquinone is an endogenous quinone with pharmacological actions mainly related to its antioxidant properties. Here we report that ubiquinone protects cultured cerebellar granule cells against glutamate-induced neurotoxicity. In control cultures at 9 days of maturation in vitro (DIV), a 30-min exposure to 100 μM glutamate induced neuronal degeneration, as reflected by the great percentage (>90%) of cells labeled with propidium iodide 24 h after the exposure. Glutamate-induced neuronal death was dramatically reduced in cultures treated daily with ubiquinone since the second DIV. In these cultures, glutamate failed to induce a "delayed" increase in the flux of ⁴⁵Ca²⁺, an established parameter of excitotoxicity. Similarly, repeated addition of ubiquinone attenuated in a concentration-dependent manner the agedependent degeneration of granule cells that is due to the toxic action of the endogenous glutamate progressively released into the medium. These results suggest that ubiquinone may be a useful drug in the therapy of acute and chronic neurodegenerative diseases related to hyperactivity of excitatory amino acid neurotransmission.