Dataset Information

Dopamine-induced calcium signaling in olfactory bulb astrocytes.

ABSTRACT: It is well established that astrocytes respond to the major neurotransmitters glutamate and GABA with cytosolic calcium rises, whereas less is known about the effect of dopamine on astroglial cells. In the present study, we used confocal calcium imaging in mouse brain slices of the olfactory bulb, a brain region with a large population of dopaminergic neurons, to investigate calcium signaling evoked by dopamine in astrocytes. Our results show that application of dopamine leads to a dose-dependent cytosolic calcium rise in astrocytes (EC50?=?76?µM) which is independent of neuronal activity and mainly mediated by PLC/IP3-dependent internal calcium release. Antagonists of both D1- and D2-class dopamine receptors partly reduce the dopaminergic calcium response, indicating that both receptor classes contribute to dopamine-induced calcium transients in olfactory bulb astrocytes.

SUBMITTER: Fischer T

PROVIDER: S-EPMC6971274 | biostudies-literature | 2020 Jan

REPOSITORIES: biostudies-literature

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Dopamine-induced calcium signaling in olfactory bulb astrocytes.

Fischer Timo T Scheffler Paula P Lohr Christian C

Scientific reports 20200120 1

It is well established that astrocytes respond to the major neurotransmitters glutamate and GABA with cytosolic calcium rises, whereas less is known about the effect of dopamine on astroglial cells. In the present study, we used confocal calcium imaging in mouse brain slices of the olfactory bulb, a brain region with a large population of dopaminergic neurons, to investigate calcium signaling evoked by dopamine in astrocytes. Our results show that application of dopamine leads to a dose-dependen ...[more]

PMID: 31959788

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Project description:The mammalian olfactory bulb (OB) has a vast population of dopamine (DA) neurons, whose function is to increase odor discrimination through mostly inhibitory synaptic mechanisms. However, it is not well understood whether there is more than one neuronal type of OB DA neuron, how these neurons respond to different stimuli, and the ionic mechanisms behind those responses. In this study, we used a transgenic rat line (hTH-GFP) to identify fluorescent OB DA neurons for recording via whole-cell electrophysiology. These neurons were grouped based on their localization in the glomerular layer ("Top" vs. "Bottom") with these largest and smallest neurons grouped by neuronal area ("Large" vs. "Small," in μm2). We found that some membrane properties could be distinguished based on a neuron's area, but not by its glomerular localization. All OB DA neurons produced a single action potential when receiving a sufficiently depolarizing stimulus, while some could also spike multiple times when receiving weaker stimuli, an activity that was more likely in Large than Small neurons. This single spiking activity is likely driven by the Na+ current, which showed a sensitivity to inactivation by depolarization and a relatively long time constant for the removal of inactivation. These recordings showed that Small neurons were more sensitive to inactivation of Na+ current at membrane potentials of -70 and -60 mV than Large neurons. The hyperpolarization-activated H-current (identified by voltage sags) was more pronounced in Small than Large DA neurons across hyperpolarized membrane potentials. Lastly, to mimic a more physiological stimulus, these neurons received ramp stimuli of various durations and current amplitudes. When stimulated with weaker/shallow ramps, the neurons needed less current to begin and end firing and they produced more action potentials at a slower frequency. These spiking properties were further analyzed between the four groups of neurons, and these analyses support the difference in spiking induced with current step stimuli. Thus, there may be more than one type of OB DA neuron, and these neurons' activities may support a possible role of being high-pass filters in the OB by allowing the transmission of stronger odor signals while inhibiting weaker ones.

Dataset Information

Dopamine-induced calcium signaling in olfactory bulb astrocytes.

Publications

Dopamine-induced calcium signaling in olfactory bulb astrocytes.

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