I certainly like the idea that this season might go down in the Alzheimer research history as the summer of calcium, with four major studies recently forging new links between calcium problems in neurons and Alzheimer disease (AD). However, a major issue is how AD-related, deranged calcium signals lead to neuron dysfunction and death.

We have shown a few days ago (Sanz-Blasco et al., 2008) that Aβ oligomers (but not fibrils) promote Ca2+ influx into primary neurons (but not glia). This influx is followed by mitochondrial calcium overload as monitored by photon counting imaging of low-affinity aequorin targeted to mitochondria. The relevance of this finding is that prevention of mitochondrial calcium overload using low concentrations of mitochondrial uncoupler protects neurons against Aβ-induced ROS production, permeability transition, cytochrome c release, and apoptosis and cell death.

Moreover, we found that a series of carboxylic, non-steroidal anti-inflammatory drugs including R-flurbiprofen prevent the mitochondrial calcium overload, acting as mitochondrial...  Read more

I certainly like the idea that this season might go down in the Alzheimer research history as the summer of calcium, with four major studies recently forging new links between calcium problems in neurons and Alzheimer disease (AD). However, a major issue is how AD-related, deranged calcium signals lead to neuron dysfunction and death.

We have shown a few days ago (Sanz-Blasco et al., 2008) that Aβ oligomers (but not fibrils) promote Ca2+ influx into primary neurons (but not glia). This influx is followed by mitochondrial calcium overload as monitored by photon counting imaging of low-affinity aequorin targeted to mitochondria. The relevance of this finding is that prevention of mitochondrial calcium overload using low concentrations of mitochondrial uncoupler protects neurons against Aβ-induced ROS production, permeability transition, cytochrome c release, and apoptosis and cell death.

Moreover, we found that a series of carboxylic, non-steroidal anti-inflammatory drugs including R-flurbiprofen prevent the mitochondrial calcium overload, acting as mitochondrial uncouplers and protecting against cell death. These effects are achieved at NSAID concentrations in the low microM range, well below the range required for targeting γ-secretase. Therefore, mitochondrial calcium overload contributes to cell death induced by Aβ oligomers.

In addition, the long-debated mechanism of neuroprotection by NSAIDs could be related to the calcium hypothesis of Alzheimer disease rather than to their ability to target inflammation or secretases. Whether mitochondrial calcium overload is also involved in cell death induced by excess calcium release promoted by either loss of ER calcium leak or IP3 receptor modulation remains to be established.

References:
Sanz-Blasco S, Valero RA, Rodríguez-Crespo I, Villalobos C, Núñez L. Mitochondrial Ca2+ overload underlies Abeta oligomers neurotoxicity providing an unexpected mechanism of neuroprotection by NSAIDs. PLoS ONE. 2008 Jul 23;3(7):e2718. Abstract

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