Retrograde optogenetic characterization of the pontospinal module of the locus coeruleus with a canine adenoviral vector

Brain Res. 2016 Jun 15;1641(Pt B):274-90. doi: 10.1016/j.brainres.2016.02.023. Epub 2016 Feb 19.


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.

Keywords: Locus coeruleus; Noradrenaline; Optogenetics; Pontospinal; Retrograde vector.

MeSH terms

  • Adenoviruses, Canine / genetics
  • Animals
  • Cerebellum / cytology
  • Cerebellum / physiology
  • Genetic Vectors
  • Gyrus Cinguli / cytology
  • Gyrus Cinguli / physiology
  • Locus Coeruleus / cytology*
  • Locus Coeruleus / physiology*
  • Male
  • Membrane Potentials / physiology
  • Neural Pathways / cytology
  • Neural Pathways / physiology
  • Neuroanatomical Tract-Tracing Techniques
  • Neurons / cytology*
  • Neurons / physiology*
  • Norepinephrine / metabolism
  • Optogenetics* / methods
  • Periaqueductal Gray / cytology
  • Periaqueductal Gray / physiology
  • Rats, Long-Evans
  • Rats, Wistar
  • Sleep / physiology
  • Spinal Cord / cytology
  • Spinal Cord / physiology
  • Tissue Culture Techniques
  • Wakefulness / physiology


  • Norepinephrine