title: Retrograde optogenetic characterization of the pontospinal module of the locus coeruleus with a canine adenoviral vector.
abstract: Noradrenergic neurons of the brainstem extend projections throughout the neuraxis to modulate a wide range of processes including attention, arousal, autonomic control and sensory processing. A spinal projection from the locus coeruleus (LC) is thought to regulate nociceptive processing. To characterize and selectively manipulate the pontospinal noradrenergic neurons in rats, we implemented a retrograde targeting strategy using a canine adenoviral vector to express channelrhodopsin2 (CAV2-PRS-ChR2-mCherry). LC microinjection of CAV2-PRS-ChR2-mCherry produced selective, stable, transduction of noradrenergic neurons allowing reliable opto-activation in vitro. The ChR2-transduced LC neurons were opto-identifiable in vivo and functional control was demonstrated for >6 months by evoked sleep-wake transitions. Spinal injection of CAV2-PRS-ChR2-mCherry retrogradely transduced pontine noradrenergic neurons, predominantly in the LC but also in A5 and A7. A pontospinal LC (ps:LC) module was identifiable, with somata located more ventrally within the nucleus and with a discrete subset of projection targets. These ps:LC neurons had distinct electrophysiological properties with shorter action potentials and smaller afterhyperpolarizations compared to neurons located in the core of the LC. In vivo recordings of ps:LC neurons showed a lower spontaneous firing frequency than those in the core and they were all excited by noxious stimuli. Using this CAV2-based approach we have demonstrated the ability to retrogradely target, characterise and optogenetically manipulate a central noradrenergic circuit and show that the ps:LC module forms a discrete unit. This article is part of a Special Issue entitled SI: Noradrenergic System.
authors.affiliation: School of Physiology & Pharmacology, University of Bristol, Bristol BS8 1TD, UK.
authors.forename: Yong
authors.initials: Y
authors.lastname: Li
authors.affiliation: School of Physiology & Pharmacology, University of Bristol, Bristol BS8 1TD, UK.
authors.forename: Louise
authors.initials: L
authors.lastname: Hickey
authors.affiliation: School of Physiology & Pharmacology, University of Bristol, Bristol BS8 1TD, UK.
authors.forename: Ray
authors.initials: R
authors.lastname: Perrins
authors.affiliation: School of Physiology & Pharmacology, University of Bristol, Bristol BS8 1TD, UK.
authors.forename: Emilie
authors.initials: E
authors.lastname: Werlen
authors.affiliation: School of Physiology & Pharmacology, University of Bristol, Bristol BS8 1TD, UK.
authors.forename: Amisha A
authors.initials: AA
authors.lastname: Patel
authors.affiliation: School of Physiology & Pharmacology, University of Bristol, Bristol BS8 1TD, UK.
authors.forename: Stefan
authors.initials: S
authors.lastname: Hirschberg
authors.affiliation: School of Physiology & Pharmacology, University of Bristol, Bristol BS8 1TD, UK.
authors.forename: Matt W
authors.initials: MW
authors.lastname: Jones
authors.affiliation: Institut de Génétique Moléculaire de Montpellier, CNRS UMR 5535, Montpellier, France; Université de Montpellier, Montpellier, France.
authors.forename: Sara
authors.initials: S
authors.lastname: Salinas
authors.affiliation: Institut de Génétique Moléculaire de Montpellier, CNRS UMR 5535, Montpellier, France; Université de Montpellier, Montpellier, France.
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Kremer
authors.affiliation: School of Physiology & Pharmacology, University of Bristol, Bristol BS8 1TD, UK; Department of Anaesthesia, University Hospitals Bristol, Bristol BS2 8HW, UK. Electronic address: Tony.Pickering@bristol.ac.uk.
authors.forename: Anthony E
authors.initials: AE
authors.lastname: Pickering
mesh_terms: D006516:Adenoviruses, Canine / Q000235:genetics; D000818:Animals; D002531:Cerebellum / Q000166:cytology / Q000502:physiology; D005822:Genetic Vectors; D006179:Gyrus Cinguli / Q000166:cytology / Q000502:physiology; D008125:Locus Coeruleus / Q000166:cytology* / Q000502:physiology*; D008297:Male; D008564:Membrane Potentials / Q000502:physiology; D009434:Neural Pathways / Q000166:cytology / Q000502:physiology; D056347:Neuroanatomical Tract-Tracing Techniques; D009474:Neurons / Q000166:cytology* / Q000502:physiology*; D009638:Norepinephrine / Q000378:metabolism; D062308:Optogenetics / Q000379:methods; D010487:Periaqueductal Gray / Q000166:cytology / Q000502:physiology; D020318:Rats, Long-Evans; D017208:Rats, Wistar; D012890:Sleep / Q000502:physiology; D013116:Spinal Cord / Q000166:cytology / Q000502:physiology; D046509:Tissue Culture Techniques; D014851:Wakefulness / Q000502:physiology
chemical_list: D009638:Norepinephrine
keywords: Locus coeruleus; Noradrenaline; Optogenetics; Pontospinal; Retrograde vector