Functional properties of dopamine neurons and co-expression of vasoactive intestinal polypeptide in the dorsal raphe nucleus and ventro-lateral periaqueductal grey

Authors

  • Antonios G. Dougalis,

    1. Medical Research Council Clinical Sciences Centre, Imperial College London, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK
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    • A.G.D. and G.A.C.M contributed equally to this work.

  • Gillian A. C. Matthews,

    1. Medical Research Council Clinical Sciences Centre, Imperial College London, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK
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    • A.G.D. and G.A.C.M contributed equally to this work.

  • Matthew W. Bishop,

    1. Medical Research Council Clinical Sciences Centre, Imperial College London, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK
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  • Frédéric Brischoux,

    1. Medical Research Council Clinical Sciences Centre, Imperial College London, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK
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    • Present address: ‘Physiopathology of the Neuronal Network Responsible for the Sleep-Waking Cycle’ Team, CNRS UMR5292; INSERM U1028; Lyon Neuroscience Research Center, Lyon, F-69372, France.

  • Kazuto Kobayashi,

    1. Department of Molecular Genetics, Institute of Biomedical Sciences, Fukushima Medical University School of Medicine, Fukushima 960-1295, Japan
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  • Mark A. Ungless

    1. Medical Research Council Clinical Sciences Centre, Imperial College London, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK
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Dr M. A. Ungless, as above.
E-mail: mark.ungless@imperial.ac.uk

Abstract

The dorsal raphe nucleus (DRN) and ventrolateral periaqueductal grey (vlPAG) regions contain populations of dopamine neurons, often considered to be a dorsal caudal extension of the A10 group [mostly found in the ventral tegmental area (VTA)]. Recent studies suggest they are involved in promoting wakefulness and mediate some of the antinociceptive and rewarding properties of opiates. However, little is known about their electrophysiological properties. To address this, we used Pitx3-GFP and tyrosine hydroxylase (TH)-GFP mice to carry out targeted whole-cell recordings from this population in acute brain slices. We found that DRN/vlPAG dopamine neurons have characteristics similar to most VTA dopamine neurons, but distinct from dorsal raphe serotonin neurons. They fire broad action potentials at a relatively slow, regular rate, exhibit a hyperpolarization-activated inward current and delayed repolarization, and show spike-frequency adaptation in response to prolonged depolarization. In addition, they receive fast excitatory and inhibitory synaptic inputs. Moreover, we found co-expression of vasoactive intestinal polypeptide in small, periaqueductal dopamine neurons, but generally not in larger, more ventral dopamine neurons.

Ancillary