Mitochondrial free radical production induced by glucose deprivation in cerebellar granule neurons

Abstract

Using a fluorescent probe for superoxide, hydroethidine, we have demonstrated that glucose deprivation (GD) activates production of reactive oxygen species (ROS) in cultured cerebellar granule neurons. ROS production was insensitive to the blockade of ionotropic glutamate channels by MK-801 (10 microM) and NBQX (10 microM). Inhibitors of mitochondrial electron transport, i.e. rotenone (complex I), antimycin A (complex III), or sodium azide (complex IV), an inhibitor of mitochondrial ATP synthase--oligomycin, an uncoupler of oxidative phosphorylation--CCCP, a chelator of intracellular Ca2+--BAPTA, an inhibitor of electrogenic mitochondrial Ca2+ transport--ruthenium red, as well as pyruvate significantly decreased neuronal ROS production induced by GD. GD was accompanied by a progressive decrease in the mitochondrial membrane potential and an increase in free cytosolic calcium ions, [Ca2+](i). Pyruvate, BAPTA, and ruthenium red lowered the GD-induced calcium overload, while pyruvate and ruthenium red also prevented mitochondrial membrane potential changes induced by GD. We conclude that GD-induced ROS production in neurons is related to potential-dependent mitochondrial Ca2+ overload. GD-induced mitochondrial Ca2+ overload in neurons in combination with depletion of energy substrates may result in the decrease of the membrane potential in these organelles.

Exposure to hypoglycemia and risk of stroke

“…Selective increase in lipo‐peroxidation due to hypoglycemia leads to oxidative stress that has been confirmed in animal studies . Animal studies have also confirmed increased mitochondrial ROS production during both hypoglycemia and in cultured neurons during glucose deprivation . ROS are also known to activate several intermediates of thrombosis, including platelets .…”

The role of reactive oxygen species and autophagy in safingol-induced cell death

“…Previously, sphingolipids have been shown to inhibit glucose uptake, 32, 33 which could in turn induce oxidative stress. 34 These reports provided the basis for us to hypothesize that safingol, a synthetic sphingolipid, might be able to inhibit glucose uptake. Using a fluorescent derivative of glucose, 2-( N -(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-2-deoxyglucose (2-NBDG), the uptake was probed in MDA-MB-231 and HT-29 cells.…”

“…39 Similarly, glucose deprivation was shown to initiate oxidative stress and increase mitochondria production of ROS, as demonstrated in lung cancer cells A549, brain cells, retina cells and adrenal cells. 34 Although several in vivo studies supported the upstream role of ROS in activating AMPK, 40 this remains to be determined in safingol-treated cells. AMPK is not only known as an energy sensor, but also reported to have a role in inducing autophagy through the suppression of mTOR.…”

The causes of cancer revisited: “Mitochondrial malignancy” and ROS-induced oncogenic transformation – Why mitochondria are targets for cancer therapy

“…Prolonged hypoxia and glucose deprivation are key components of ischemia in bodily tissues as a significant driver of elevated mitochondrial ROS production and this has been well described in the context of myocardial disease (Valko et al, 2007;Chen et al, 2008). Although studies of primary cultured cells specifically examining the effects of low glucose or glucose deprivation (hypoglycaemic conditions) on the induction of mitochondrial ROS production have not been extensively reported, it has been shown to occur, inducing cytotoxicity in neuronal cells Liu, 2006, 2007;Isaev et al, 2008) and in pancreatic beta islet cells (Martens et al, 2005). A more definitive study addressed the differential susceptibility of cancer cells versus normal cells to glucose deprivation .…”