Using Genetically Encoded Calcium Indicators to Study Astrocyte Physiology: A Field Guide.

Ca imaging is the most frequently used technique to study glial cell physiology. While chemical Ca indicators served to visualize and measure changes in glial cell cytosolic Ca concentration for several decades, genetically encoded Ca indicators (GECIs) have become state of the art in recent years. Great improvements have been made since the development of the first GECI and a large number of GECIs with different physical properties exist, rendering it difficult to select the optimal Ca indicator.

Norepinephrine-Induced Calcium Signaling and Store-Operated Calcium Entry in Olfactory Bulb Astrocytes.

It is well-established that astrocytes respond to norepinephrine with cytosolic calcium rises in various brain areas, such as hippocampus or neocortex. However, less is known about the effect of norepinephrine on olfactory bulb astrocytes. In the present study, we used confocal calcium imaging and immunohistochemistry in mouse brain slices of the olfactory bulb, a brain region with a dense innervation of noradrenergic fibers, to investigate the calcium signaling evoked by norepinephrine in astrocytes.

Purinergic Signaling in the Vertebrate Olfactory System.

Adenosine 5'-triphosphate (ATP) is an ubiquitous co-transmitter in the vertebrate brain. ATP itself, as well as its breakdown products ADP and adenosine are involved in synaptic transmission and plasticity, neuron-glia communication and neural development. Although purinoceptors have been demonstrated in the vertebrate olfactory system by means of histological techniques for many years, detailed insights into physiological properties and functional significance of purinergic signaling in olfaction have been published only recently.

Adenosine A Receptor-Mediated Attenuation of Reciprocal Dendro-Dendritic Inhibition in the Mouse Olfactory Bulb.

It is well described that A adenosine receptors inhibit synaptic transmission at excitatory synapses in the brain, but the effect of adenosine on reciprocal synapses has not been studied so far. In the olfactory bulb, the majority of synapses are reciprocal dendro-dendritic synapses mediating recurrent inhibition. We studied the effect of A receptor activation on recurrent dendro-dendritic inhibition in mitral cells using whole-cell patch-clamp recordings.

Adenosine A receptor activates background potassium channels and modulates information processing in olfactory bulb mitral cells.

Key Points: Adenosine is a widespread neuromodulator in the mammalian brain, but whether it affects information processing in sensory system(s) remains largely unknown. Here we show that adenosine A receptors hyperpolarize mitral cells, one class of principal neurons that propagate odour information from the olfactory bulb to higher brain areas, by activation of background K channels. The adenosine-modulated background K channels belong to the family of two-pore domain K channels.

Parkin cooperates with GDNF/RET signaling to prevent dopaminergic neuron degeneration.

Parkin and the glial cell line-derived neurotrophic factor (GDNF) receptor RET have both been independently linked to the dopaminergic neuron degeneration that underlies Parkinson's disease (PD). In the present study, we demonstrate that there is genetic crosstalk between parkin and the receptor tyrosine kinase RET in two different mouse models of PD. Mice lacking both parkin and RET exhibited accelerated dopaminergic cell and axonal loss compared with parkin-deficient animals, which showed none, and RET-deficient mice, in which we found moderate degeneration.

P2Y1 receptor activation by photolysis of caged ATP enhances neuronal network activity in the developing olfactory bulb.

It has recently been shown that adenosine-5'-triphosphate (ATP) is released together with glutamate from sensory axons in the olfactory bulb, where it stimulates calcium signaling in glial cells, while responses in identified neurons to ATP have not been recorded in the olfactory bulb yet. We used photolysis of caged ATP to elicit a rapid rise in ATP and measured whole-cell current responses in mitral cells, the output neurons of the olfactory bulb, in acute mouse brain slices. Wide-field photolysis of caged ATP evoked an increase in synaptic inputs in mitral cells, indicating an ATP-dependent increase in network activity.