Pannexin-1 opening in neuronal edema causes cell death but also leads to protection via increased microglia contacts.

Neuronal swelling during cytotoxic edema is triggered by Na and Cl entry and is Ca independent. However, the causes of neuronal death during swelling are unknown. Here, we investigate the role of large-conductance Pannexin-1 (Panx1) channels in neuronal death during cytotoxic edema.

KCC2 drives chloride microdomain formation in dendritic blebbing.

Intracellular chloride ion concentration ([Cl]) homeostasis is critical for excitatory/inhibitory balance and volume regulation in neurons. We quantitatively map spatiotemporal dendritic [Cl] dynamics during N-methyl-d-aspartate (NMDA) excitotoxicity to determine how Cl changes contribute to localized dendritic swelling (blebbing) in stroke-like conditions. Whole-cell patch clamp electrophysiology combined with simultaneous fluorescence lifetime imaging (FLIM) of the Cl dye N-(ethoxycarbonylmethyl)-6-methoxyquinolinium bromide (MQAE; MQAE-FLIM) reliably report resting and dynamic [Cl] shifts in dendrites.

Mitochondrial Ca uptake by the MCU facilitates pyramidal neuron excitability and metabolism during action potential firing.

Neuronal activation is fundamental to information processing by the brain and requires mitochondrial energy metabolism. Mitochondrial Ca uptake by the mitochondrial Ca uniporter (MCU) has long been implicated in the control of energy metabolism and intracellular Ca signalling, but its importance to neuronal function in the brain remains unclear. Here, we used in situ electrophysiology and two-photon imaging of mitochondrial Ca, cytosolic Ca, and NAD(P)H to test the relevance of MCU activation to pyramidal neuron Ca signalling and energy metabolism during action potential firing.

Simultaneous imaging of redox states in dystrophic neurites and microglia at Aβ plaques indicate lysosome accumulation not microglia correlate with increased oxidative stress.

The inter-relationship between microglia dynamics and oxidative stress (Ox-stress) in dystrophic neurites (DNs) at Alzheimer's Disease (AD) plaques may contribute to the pathological changes in neurons. We developed new in vivo imaging strategies to combine EGFP expression in microglia with neuronal expression of genetically encoded ratiometric redox sensors (rogRFP2 or roGFP1), and immunohistochemistry to investigate how microglia influence Ox-stress at amyloid plaques in 5xFAD AD mice. By simultaneously imaging microglia morphology and neuronal Ox-stress over time in vivo and in fixed brains we found that microglia preferentially enwrapped DNs exhibiting the greatest degree of Ox-stress.

Ca transients in astrocyte fine processes occur via Ca influx in the adult mouse hippocampus.

Astrocytes display complex morphologies with an array of fine extensions extending from the soma and the primary thick processes. Until the use of genetically encoded calcium indicators (GECIs) selectively expressed in astrocytes, Ca signaling was only examined in soma and thick primary processes of astrocytes where Ca -sensitive fluorescent dyes could be imaged. GECI imaging in astrocytes revealed a previously unsuspected pattern of spontaneous Ca transients in fine processes that has not been observed without chronic expression of GECIs, raising potential concerns about the effects of GECI expression.