TY - JOUR
T1 - On the properties of identified dopaminergic neurons in the mouse substantia nigra and ventral tegmental area
AU - Krashia, Paraskevi
AU - Martini, Alessandro
AU - Nobili, Annalisa
AU - Aversa, Daniela
AU - D'Amelio, Marcello
AU - Berretta, Nicola
AU - Guatteo, Ezia
AU - Mercuri, Nicola Biagio
PY - 2016
Y1 - 2016
N2 - We studied the properties of dopaminergic neurons in the substantia nigra pars compacta (SNpc) and ventral tegmental area (VTA) in mice expressing the enhanced green fluorescent protein (eGFP) under the control of the tyrosine hydroxylase promoter (TH-GFP). By using a practical map of cell positioning in distinct SNpc and VTA subregions in horizontal midbrain slices we saw that the spontaneous firing, membrane properties, cell body size and magnitude of the hyperpolarization-activated current (Ih) in TH-GFP-positive neurons (TH-GFP+) vary significantly among subregions, following a mediolateral gradient. Block of Ih with Zd7288 inhibited firing in the most lateral subregions, but had little effect in the intermediate/medial VTA. In addition, TH-GFP+ cells were excited by Met5-Enkephalin. Extracellular recordings from a large neuron number showed that all TH-GFP+ cells were inhibited by dopamine, suggesting that this is a reliable approach for identifying dopaminergic neurons in vitro. Simultaneous recordings from dopamine-sensitive and dopamine-insensitive neurons showed that dopamine-insensitive cells (putative non-dopaminergic neurons) are unaffected by Zd7288 but inhibited by Met5-Enkephalin. Under patch-clamp, dopamine generated a quantitatively similar outward current in most TH-GFP+ neurons, although medial VTA cells showed reduced dopamine sensitivity. Pargyline prolonged the dopamine current, whereas cocaine enhanced dopamine-mediated responses in both the SNpc and the VTA. Our work provides new insights into the variability in mouse midbrain dopaminergic neurons along the medial-lateral axis and points to the necessity of a combination of different electrophysiological and pharmacological approaches for reliably identifying these cells to distinguish them from non-dopaminergic neurons in the midbrain.
AB - We studied the properties of dopaminergic neurons in the substantia nigra pars compacta (SNpc) and ventral tegmental area (VTA) in mice expressing the enhanced green fluorescent protein (eGFP) under the control of the tyrosine hydroxylase promoter (TH-GFP). By using a practical map of cell positioning in distinct SNpc and VTA subregions in horizontal midbrain slices we saw that the spontaneous firing, membrane properties, cell body size and magnitude of the hyperpolarization-activated current (Ih) in TH-GFP-positive neurons (TH-GFP+) vary significantly among subregions, following a mediolateral gradient. Block of Ih with Zd7288 inhibited firing in the most lateral subregions, but had little effect in the intermediate/medial VTA. In addition, TH-GFP+ cells were excited by Met5-Enkephalin. Extracellular recordings from a large neuron number showed that all TH-GFP+ cells were inhibited by dopamine, suggesting that this is a reliable approach for identifying dopaminergic neurons in vitro. Simultaneous recordings from dopamine-sensitive and dopamine-insensitive neurons showed that dopamine-insensitive cells (putative non-dopaminergic neurons) are unaffected by Zd7288 but inhibited by Met5-Enkephalin. Under patch-clamp, dopamine generated a quantitatively similar outward current in most TH-GFP+ neurons, although medial VTA cells showed reduced dopamine sensitivity. Pargyline prolonged the dopamine current, whereas cocaine enhanced dopamine-mediated responses in both the SNpc and the VTA. Our work provides new insights into the variability in mouse midbrain dopaminergic neurons along the medial-lateral axis and points to the necessity of a combination of different electrophysiological and pharmacological approaches for reliably identifying these cells to distinguish them from non-dopaminergic neurons in the midbrain.
KW - Dopamine transporter
KW - I current
KW - Midbrain
KW - Monoamine oxidase
KW - Tyrosine hydroxylase
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U2 - 10.1111/ejn.13364
DO - 10.1111/ejn.13364
M3 - Article
AN - SCOPUS:84987597417
JO - European Journal of Neuroscience
JF - European Journal of Neuroscience
SN - 0953-816X
ER -