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The noradrenergic projection from the locus coeruleus to the cochlear root neurons in rats

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Abstract

The cochlear root neurons (CRNs) are key components of the primary acoustic startle circuit; mediating auditory alert and escape behaviors in rats. They receive a great variety of inputs which serve to elicit and modulate the acoustic startle reflex (ASR). Recently, our group has suggested that CRNs receive inputs from the locus coeruleus (LC), a noradrenergic nucleus which participates in attention and alertness. Here, we map the efferent projection patterns of LC neurons and confirm the existence of the LC-CRN projection using both anterograde and retrograde tract tracers. Our results show that each LC projects to the CRNs of both sides with a clear ipsilateral predominance. The LC axons terminate as small endings distributed preferentially on the cell body and primary dendrites of CRNs. Using light and confocal microscopy, we show a strong immunoreactivity for tyrosine hydroxylase and dopamine β-hydroxylase in these terminals, indicating noradrenaline release. We further studied the noradrenergic system using gene expression analysis (RT-qPCR) and immunohistochemistry to detect specific noradrenergic receptor subunits in the cochlear nerve root. Our results indicate that CRNs contain a noradrenergic receptor profile sufficient to modulate the ASR, and also show important gender-specific differences in their gene expression. 3D reconstruction analysis confirms the presence of sexual dimorphism in the density and distribution of LC neurons. Our study describes a coerulean noradrenergic projection to the CRNs that might contribute to neural processes underlying sensory gating of the ASR, and also provides an explanation for the gender differences observed in the behavioral paradigm.

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References

  1. Aasen I, Kolli L, Kumari V (2005) Sex effects in prepulse inhibition and facilitation of the acoustic startle response: implications for pharmacological and treatment studies. J Psychopharmacol 19(1):39–45

  2. Adams LM, Geyer MA (1981) Effects of 6-hydroxydopamine lesions of locus coeruleus on startle in rats. Psychopharmacology 73(4):394–398

  3. Aitkin L (1996) The anatomy of the cochlear nuclei and superior olivary complex of arboreal Australian marsupials. Brain Behav Evol 48:103–114

  4. Alsene KM, Bakshi VP (2011) Pharmacological stimulation of locus coeruleus reveals a new antipsychotic-responsive pathway for deficient sensorimotor gating. Neuropsychopharmacology 36(8):1656–1667

  5. Alsene KM, Fallace K, Bakshi VP (2010) Ventral striatal noradrenergic mechanisms contribute to sensorimotor gating deficits induced by amphetamine. Neuropsychopharmacology 35(12):2346–2356

  6. Amaral DG, Sinnamon HM (1977) The locus coeruleus: neurobiology of a central noradrenergic nucleus. Prog Neurobiol 9:147–196

  7. Aston-Jones G, Cohen JD (2005) Adaptive gain and the role of the locus coeruleus-norepinephrine system in optimal performance. J Comp Neurol 493:99–110

  8. Aston-Jones G, Rajkowski J, Cohen J (1999) Role of the locus coeruleus in attention and behavioural flexibility. Biol Psychiatry 46:1309–1320

  9. Bakshi VP, Geyer MA (1997) Phencyclidine-induced deficits in prepulse inhibition of startle are blocked by prazosin, an alpha-1 noradrenergic antagonist. J Pharmacol Exp Ther 283(2):666–674

  10. Bakshi VP, Geyer MA (1999) Alpha-1-adrenergic receptors mediate sensorimotor gating deficits produced by intracerebral dizocilpine administration in rats. Neuroscience 92(1):113–121

  11. Bangasser DA, Curtis A, Reyes BA, Bethea TT, Parastatidis I, Ischiropoulos H, Van Bockstaele EJ, Valentino RJ (2010) Sex differences in corticotropin-releasing factor receptor signaling and trafficking: potential role in female vulnerability to stress-related psychopathology. Mol Psychiatry 15(9):877, 896–904

  12. Berridge CW, Abercrombie ED (1999) Relationship between locus coeruleus discharge rates and rates of norepinephrine release within neocortex as assessed by in vivo microdialysis. Neuroscience 93:1263–1270

  13. Berridge CW, Waterhouse BD (2003) The locus coeruleus noradrenergic system: modulation of behavioral state and state dependent cognitive processes. Brain Res Rev 42:33–84

  14. Braff DL, Geyer MA (1990) Sensorimotor gating and schizophrenia. Human and animal model studies. Arch Gen Psychiatry 47(2):181–188

  15. Braff DL, Geyer MA, Swerdlow NR (2001) Human studies of prepulse inhibition of startle: normal subjects, patient groups, and pharmacological studies. Psychopharmacology 156(2–3):234–258

  16. Cai J, Li J, Mao Y, Bai X, Xu L, Wang H (2013) Immunohistochemical localization of α2-adrenergic receptors in the neonatal rat cochlea and the vestibular labyrinth. J Mol Neurosci (Published online)

  17. Carasso BS, Bakshi VP, Geyer MA (1998) Disruption in prepulse inhibition after alpha-1 adrenoceptor stimulation in rats. Neuropharmacology 37:401–404

  18. Curtis AL, Bethea T, Valentino RJ (2006) Sexually dimorphic responses of the brain norepinephrine system to stress and corticotropin-releasing factor. Neuropsychopharmacology 31:544–554

  19. Davis M, Cedarbaum JM, Aghajanian GK, Gendelman DS (1977) Effects of clonidine on habituation and sensitization of acoustic startle in normal, decerebrate and locus coeruleus lesioned rats. Psychopharmacology (Berl) 51(3):243–253

  20. Ebert U (1996) Noradrenalin enhances the activity of cochlear nucleus neurons in the rat. Eur J Neurosci 8:1306–1314

  21. Fendt M, Li L, Yeomans JS (2001) Brain stem circuits mediating prepulse inhibition of the startle reflex. Psychopharmacology 156:216–224

  22. Foote SL, Bloom FE, Aston-Jones G (1983) Nucleus locus coeruleus: new evidence of anatomical and physiological specificity. Physiol Rev 63:844–914

  23. Foote SL, Berridge CW, Adams LM, Pineda JA (1991) Electrophysiological evidence for the involvement of the locus coeruleus in alerting, orienting, and attending. Prog Brain Res 88:521–532

  24. Fritschy JM, Grzanna R (1990) Distribution of locus coeruleus axons within the rat brain stem demonstrated by Phaseolus vulgaris leucoagglutinin anterograde tracing in combination with dopamine-beta-hydroxylase immuno-fluorescence. J Comp Neurol 293:616–631

  25. Gómez-Nieto R, Rubio ME, López DE (2008a) Cholinergic input from the ventral nucleus of the trapezoid body to cochlear root neurons in rats. J Comp Neurol 506:452–468

  26. Gómez-Nieto R, Horta-Júnior JA, Castellano O, Herrero-Turrión MJ, Rubio ME, López DE (2008b) Neurochemistry of the afferents to the rat cochlear root nucleus: possible synaptic modulation of the acoustic startle. Neuroscience 154:51–64

  27. Gómez-Nieto R, Horta-Júnior JA, Castellano O, Sinex DG, López DE (2010) Auditory prepulse inhibition of neuronal activity in the rat cochlear root nucleus. In: Palmer AR, Meddis R, López Poveda EA (eds) The neurophysiological bases of auditory perception. Springer, New York, pp 79–90

  28. Gómez-Nieto R, Sinex DG, C Horta-Júnior JD, Castellano O, Herrero-Turrión JM, López DE (2013) A fast cholinergic modulation of the primary acoustic startle circuit in rats. Brain Struct Funct. Published online

  29. Groves PM, Thompson RF (1970) Habituation. A dual process theory. Psycholo Rev 77(5):419–450

  30. Guillamon A, de Blas MR, Segovia S (1988) Effects of sex steroids on the development of the locus coeruleus in the rat. Brain Res 468:306–310

  31. Gupta A, Décaillot FM, Gomes I, Tkalych O, Heimann AS, Ferro ES, Devi LA (2007) Conformation state-sensitive antibodies to G-protein-coupled receptors. J Biol Chem 282(8):5116–5124

  32. Harrison JM, Warr WB, Irving R (1962) Second order neurons in the acoustic nerve. Science 138:893–895

  33. Hoffman HS, Ison JR (1980) Reflex modification in the domain of startle: I. Some empirical findings and their implications for how the nervous system processes sensory input. Psychol Rev 87:175–189

  34. Hormigo S, Horta Júnior Jde A, Gómez-Nieto R, López DE (2012) The selective neurotoxin DSP-4 impairs the noradrenergic projections from the locus coeruleus to the inferior colliculus in rats. Front Neural Circuits 6:41

  35. Horta-Júnior Jde A, López DE, Alvarez-Morujo AJ, Bittencourt JC (2008) Direct and indirect connections between cochlear root neurons and facial motor neurons: pathways underlying the acoustic pinna reflex in the albino rat. J Comp Neurol 507:1763–1779

  36. Jones BE (1991) Noradrenergic locus coeruleus neurons: their distant connections and their relationship to neighboring (including cholinergic and GABAergic) neurons of the central gray and reticular formation. Prog Brain Res 88:15–30

  37. Jones BE, Yang TZ (1985) The efferent projections from the reticular formation and the locus coeruleus studied by anterograde and retrograde axonal transport in the rat. J Comp Neurol 242(1):56–92

  38. Klepper A, Herbert H (1991) Distribution and origin of noradrenergic and serotonergic fibers in the cochlear nucleus and inferior colliculus of the rat. Brain Res 557:190–201

  39. Kritzer MF (2003) Long-term gonadectomy affects the density of tyrosine hydroxylase- but not dopamine-beta-hydroxylase-, choline acetyltransferase- or serotonin-immunoreactive axons in the medial prefrontal cortices of adult male rats. Cereb Cortex 13:282–296

  40. Kromer LF, Moore RY (1976) Cochlear nucleus innervation by central norepinephrine neurons in the rat. Brain Res 118:531–537

  41. Kromer LF, Moore RY (1980) A study of the organization of the locus coeruleus projections to the lateral geniculate nuclei in the albino rat. Neuroscience 5:255–271

  42. Landis C, Hunt WA (1939) The startle pattern. Ferrar and Rinehart, New York

  43. Larrauri JA, Levin ED (2012) The α2-adrenergic antagonist idazoxan counteracts prepulse inhibition deficits caused by amphetamine or dizocilpine in rats. Psychopharmacology 219(1):99–108

  44. Lee Y, López DE, Meloni EG, Davis M (1996) A primary acoustic startle pathway: obligatory role of cochlear root neurons and the nucleus reticularis pontis caudalis. J Neurosci 16:3775–3789

  45. Lehmann J, Pryce CR, Feldon J (1999) Sex differences in the acoustic startle response and prepulse inhibition in Wistar rats. Behav Brain Res 104(1–2):113–117

  46. Li L, Du Y, Li N, Wu X, Wu Y (2009) Top-down modulation of prepulse inhibition of the startle reflex in humans and rats. Neurosci Biobehav Rev 33(8):1157–1167

  47. Livak KJ, Schmittgen TD (2001) Analysis of relative gene expression data using real-time quantitative PCR and the 2(-Delta Delta C(T)). Methods 25:402–408

  48. López DE, Merchán MA, Bajo VM, Saldaña E (1993) The cochlear root neurons in the rat, mouse and gerbil. In: Merchán MA, Juiz JM, Godfrey DA, Mugnaini E (eds) The mammalian cochlear nuclei: organization and function. Plenum Press, New York, pp 291–301

  49. López DE, Saldaña E, Nodal FR, Merchán MA, Warr WB (1999) Projections of cochlear root neurons, sentinels of the auditory pathway in the rat. J Comp Neurol 415:160–174

  50. Loughlin SE, Foote SL, Bloom FE (1986a) Efferent projections of nucleus locus coeruleus: topographic organization of cells of origin demonstrated by three-dimensional reconstruction. Neuroscience 18:291–306

  51. Loughlin SE, Foote SL, Grzanna R (1986b) Efferent projections of nucleus locus coeruleus: morphologic subpopulations have different efferent targets. Neuroscience 18:307–319

  52. Luque JM, de Blas MR, Segovia S, Guillamon A (1992) Sexual dimorphism of the dopamine-beta-hydroxylase-immunoreactive neurons in the rat locus ceruleus. Brain Res Dev Brain Res 67:211–215

  53. Merchán MA, Collía F, López DE, Saldana E (1988) Morphology of cochlear root neurons in the rat. J Neurocytol 17:711–725

  54. Molina V, Montes C, Tamayo P, Villa R, Isabel Osuna M, Pérez J, Sancho C, López-Albuquerque T, Cardoso A, Castellano O, López DE (2009) Correlation between prepulse inhibition and cortical perfusion during an attentional test in schizophrenia. A pilot study. Prog Neuropsychopharmacol Biol Psychiatry 33(1):53–61

  55. Mulders WH, Robertson D (2001) Origin of the noradrenergic innervation of the superior olivary complex in the rat. J Chem Neuroanat 21:313–322

  56. Nitecka L, Amerski L, Panek-Mikuła J, Narkiewicz O (1980) Tegmental afferents of the amygdaloid body in the rat. Acta Neurobiol Exp (Wars) 40(3):609–624

  57. Nodal FR, López DE (2003) Direct input from cochlear root neurons to pontine reticulospinal neurons in albino rat. J Comp Neurol 460:80–93

  58. Osen KK, López DE, Slyngstad TA, Ottersen OP, Storm-Mathisen J (1991) GABA-like and glycine-like immunoreactivities of the cochlear root nucleus in rat. J Neurocytol 20:17–25

  59. Saitoh K, Shaw S, Tilson HA (1986) Noradrenergic influence on the prepulse inhibition of acoustic startle. Toxicol Lett 34:209–216

  60. Samuels ER, Szabadi E (2008) Functional neuroanatomy of the noradrenergic locus coeruleus: its roles in the regulation of arousal and autonomic function part I: principles of functional organisation. Curr Neuropharmacol 6:235–253

  61. Schmittgen TD, Livak KJ (2008) Analyzing real-time PCR data by the comparative C(T) method. Nat Protoc 3:1101–1108

  62. Simpson KL, Altman DW, Wang L, Kirifides ML, Lin RC, Waterhouse BD (1997) Lateralization and functional organization of the locus coeruleus projection to the trigeminal somatosensory pathway in rat. J Comp Neurol 385(1):135–147

  63. Sinex DG, López DE, Warr WB (2001) Electrophysiological responses of cochlear root neurons. Hear Res 158:28–38

  64. Swerdlow NR, Geyer MA (1998) Using an animal model of deficient sensorimotor gating to study the pathophysiology and new treatments of schizophrenia. Schizophr Bull 24:285–301

  65. Swerdlow NR, Geyer MA, Braff DL (2001) Neural circuit regulation of prepulse inhibition of startle in the rat: current knowledge and future challenges. Psychopharmacol 156:194–215

  66. Szabadi E (2012) Modulation of physiological reflexes by pain: role of the locus coeruleus. Front Integr Neurosci 6:94

  67. Szabadi E (2013) Functional neuroanatomy of the central noradrenergic system. J Psychopharmacol 27(8):659–693

  68. Unnerstall JR, Kopajtic TA, Kuhar MJ (1984) Distribution of alpha 2 agonist binding sites in the rat and human central nervous system: analysis of some functional, anatomic correlates of the pharmacologic effects of clonidine and related adrenergic agents. Brain Res 319(1):69–101

  69. Vicentic A, Robeva A, Rogge G, Uberti M, Minneman KP (2002) Biochemistry and pharmacology of epitope-tagged alpha(1)-adrenergic receptor subtypes. J Pharmacol Exp Ther 302(1):58–65

  70. Yeomans JS, Lee J, Yeomans MH, Steidl S, Li L (2006) Midbrain pathways for prepulse inhibition and startle activation in rat. Neuroscience 142:921–929

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Acknowledgments

We thank the two anonymous reviewers for their constructive comments, which helped us to improve the manuscript. This research was supported by grants from the Spanish Ministry of Science and Innovation (MICINN, #BFU2010-17754) to Dr. Dolores E. López and the São Paulo State Research Foundation (FAPESP, #2008/02771-6) to Dr. José de Anchieta de Castro e Horta-Júnior.

Conflict of interest

The authors declare no competing financial interests.

Author information

Correspondence to Dolores E. López or José de Anchieta de Castro e Horta-Júnior.

Additional information

S. Hormigo and R. Gómez-Nieto contributed equally to this work.

Electronic supplementary material

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3D reconstruction with dynamic rotation of the locus coeruleus in a female and male rat. Each coerulean neuron is showed as a dot. Notice the gender-specific differences in distribution of LC neuronal density. This video corresponds to Fig. 10. 3D scale bars = 500 μm (WMV 13189 kb)

PCR primers of noradrenergic receptors (ADR α1A-C, ADR α2A-C, ADR β1-3). Primer location in the corresponding GenBank* sequences of rat origin is indicated (TIFF 10291 kb)

Retrogradely labeled neurons in the locus coeruleus (LC) after FluoroGold (FG) injections in the cochlear root nucleus. A and B, Micrographs of Nissl-counterstained coronal sections show FG-retrogradely labeled neurons in the ipsilateral (A) and contralateral (C) LC. This case corresponds to the injection site shown in Fig 3A. C and D, High magnification micrographs (corresponding to the frame in A and B) shows details of FG-labeled neurons in the LC. The number of FG-labeled neurons on the ipsilateral was considerably higher than on the contralateral side. The insets (positions denoted with arrows) are a higher magnification of the LC neurons retrogradely labeled with FG. PDTg, posterodorsal tegmental nucleus; scp, superior cerebellar peduncle; 4V, fourth ventricle. Scale bars = 300 μm in A and B; 100 μm in C and D (25 μm in the insets) (TIFF 17636 kb)

Tyrosine hydroxylase (TH) and dopamine beta-hydroxylase (DBH) immunoreactivity in the cochlear root nucleus. A-B, High magnification micrographs show TH-immunolabeled endings on the cell bodies (arrowheads in A) and dendrites (arrows in B) of cochlear root neurons immunolabeled for CaBP. C-D, High magnification micrographs show DBH-immunolabeled endings on the cell body (arrowheads in C) and dendrites (arrows in D) of cochlear root neurons immunolabeled for CaBP. Scale bars = 25 μm in A, B, C and D (TIFF 15947 kb)

Tyrosine hydroxylase (TH) and dopamine beta-hydroxylase (DBH) enzymes overlap in the cochlear root nucleus. A, Confocal image shows double immunolabeling for TH and DBH endings (in blue, Cy5, and in green, Cy2, respectively) in the cochlear root nucleus. B–C, Confocal images show TH (B) and DBH (C) immunolabeled endings corresponding to the merge in A. D-F, Colocalization of TH and DBH endings is confirmed by the 1 μm confocal image (D) and the orthogonal view (F). The arrow and arrowhead indicate the endings that were analyzed in the 1 μm confocal image and the orthogonal view, respectively. Scale bars = 20 μm in A, B, C, D and E (TIFF 19097 kb)

3D reconstruction of the locus coeruleus in a female rat. Each coerulean neuron is showed as a dot. The adobe PDF document contains an embedded 3D model of brainstem sections that were reconstructed using Neurolucida (Version 10). 3D scale bars = 500 μm (PDF 300 kb)

3D reconstruction of the locus coeruleus in a male rat. Each coerulean neuron is showed as a dot. The adobe PDF document contains an embedded 3D model of brainstem sections that were reconstructed using Neurolucida (Version 10). 3D scale bars = 500 μm (PDF 381 kb)

3D reconstruction with dynamic rotation of the locus coeruleus in a female and male rat. Each coerulean neuron is showed as a dot. Notice the gender-specific differences in distribution of LC neuronal density. This video corresponds to Fig. 10. 3D scale bars = 500 μm (WMV 13189 kb)

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Hormigo, S., Gómez-Nieto, R., Castellano, O. et al. The noradrenergic projection from the locus coeruleus to the cochlear root neurons in rats. Brain Struct Funct 220, 1477–1496 (2015). https://doi.org/10.1007/s00429-014-0739-3

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Keywords

  • Acoustic startle reflex
  • Gender differences
  • Neuronal tracers
  • Noradrenergic receptors
  • Sensory gating
  • 3D reconstruction