FRET Measurements of Aβ-Induced Glutamate Release from Astrocytes

SANZ BLASCO S; PIÑA-CRESPO JC; TALANTOVA M; LIPTON SA

San Diego

Congreso; 136th Annual Meeting of the American Neurological Association; 2011

American Neurological Association

Recent failures of clinical trials for Alzheimer?s disease (AD) using anti-amyloid β-peptide (Aβ) approaches suggest that it may be necessary to attack downstream targets in the Aβ cascade. To elucidate such targets, we studied the effect of Aβ on astrocytes. Astrocytes are known to modulate neuronal excitability and synaptic transmission. Here, we used the glutamate sensing fluorescent reporter (SuperGluSnFR) developed by Roger Tsien's laboratory to perform sensitive optical measurements of glutamate release in response to Aβ. This probe provides both a temporal and quantitative fluorescent readout of glutamate concentration by imaging FRET-dependent changes. We transfected HEK-293T cells with SuperGluSnFr, and then co-cultured these 'glutamate-sensing cells' with astrocytes. Nanomolar concentrations of oligomerized (but not non-oligomerized) Aβ induced release of several hundred-micromolar glutamate from astrocytes. These levels of glutamate can cause synaptic loss and excitotoxic damage to neurons. Taken together with prior studies, our work suggests that the neurotoxic effects of Aβ may be mediated at least in part by local release of glutamate from astrocytes. Additionally, we found that newer congeners of memantine (called NitroMemantines) are able to prevent toxic glutamatergic effects of Aβ to a greater degree than memantine itself.