α-KETO-ß-METHYL-n-VALERIC ACID DIMINISHES REACTIVE OXYGEN SPECIES AND ALTERS ENDOPLASMIC RETICULUM Ca2+ STORES

Mitochondrial dysfunction and oxidative stress occur in neurodegenerative diseases. Other results show that bombesin-releasable calcium stores (BRCS) from the endoplasmic reticulum (ER) are exaggerated in fibroblasts from patients with Alzheimer’s disease (AD) compared with controls and in fibroblasts from a young control treated with H2O2. We hypothesize that alterations in oxidative stress underlie the exaggeration in BRCS in AD, and that appropriate antioxidants may be useful in treating this abnormality. Two indicators of different oxidant species were used to determine the effects of select oxidants on cellular oxidation status: carboxydichlorofluorescein (c-DCF) to detect reactive oxygen species (ROS), and 4-amino-5-methylamino-2′,7′-difluorofluorescein (DAF) to detect nitric oxide (NO ). Various conditions that induce ROS, including H2O2, oxygen/glucose deprivation, and 3-morpholinosyndnonimine (SIN-1), were used to test the ability of α-keto-ß-methyl-n-valeric acid (KMV) to scavenge ROS. KMV diminished c-DCF-detectable ROS that were induced by H2O2, oxygen/glucose deprivation, or SIN-1 in PC12 cells, primary neuronal cultures, or fibroblasts. Furthermore, KMV reduced the H2O2–induced increase in BRCS and diminished the elevation in BRCS in cells from AD patients to control levels. On the other hand, DAF-detectable NO induced by SIN-1 was not scavenged by KMV and did not exaggerate BRCS. The results indicate that KMV is an effective antioxidant of c-DCF-detectable ROS. The effects of KMV are not cell type specific, but are ROS specific. The same H2O2-induced ROS that reacts with KMV may also underlie the changes in BRCS related to AD. Thus, KMV ameliorates the effects of ROS on calcium homeostasis related to oxidative stress and to AD.