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Bhave VM, Nectow AR. The dorsal raphe nucleus in the control of energy balance. Trends Neurosci 2021; 44:946-960. [PMID: 34663507 DOI: 10.1016/j.tins.2021.09.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 09/04/2021] [Accepted: 09/23/2021] [Indexed: 01/07/2023]
Abstract
Energy balance is orchestrated by an extended network of highly interconnected nuclei across the central nervous system. While much is known about the hypothalamic circuits regulating energy homeostasis, the 'extra-hypothalamic' circuits involved are relatively poorly understood. In this review, we focus on the brainstem's dorsal raphe nucleus (DRN), integrating decades of research linking this structure to the physiologic and behavioral responses that maintain proper energy stores. DRN neurons sense and respond to interoceptive and exteroceptive cues related to energy imbalance and in turn induce appropriate alterations in energy intake and expenditure. The DRN is also molecularly differentiable, with different populations playing distinct and often opposing roles in controlling energy balance. These populations are integrated into the extended circuit known to regulate energy balance. Overall, this review summarizes the key evidence demonstrating an important role for the DRN in regulating energy balance.
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Affiliation(s)
- Varun M Bhave
- Department of Medicine, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA; Harvard Medical School, Boston, MA 02115, USA
| | - Alexander R Nectow
- Department of Medicine, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA.
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2
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Belmer A, Beecher K, Jacques A, Patkar OL, Sicherre F, Bartlett SE. Axonal Non-segregation of the Vesicular Glutamate Transporter VGLUT3 Within Serotonergic Projections in the Mouse Forebrain. Front Cell Neurosci 2019; 13:193. [PMID: 31133811 PMCID: PMC6523995 DOI: 10.3389/fncel.2019.00193] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 04/17/2019] [Indexed: 11/13/2022] Open
Abstract
A subpopulation of raphe 5-HT neurons expresses the vesicular glutamate transporter VGLUT3 with the co-release of glutamate and serotonin proposed to play a pivotal role in encoding reward- and anxiety-related behaviors. Serotonin axons are identifiable by immunolabeling of either serotonin (5-HT) or the plasma membrane 5-HT transporter (SERT), with SERT labeling demonstrated to be only partially overlapping with 5-HT staining. Studies investigating the colocalization or segregation of VGLUT3 within SERT or 5-HT immunolabeled boutons have led to inconsistent results. Therefore, we combined immunohistochemistry, high resolution confocal imaging, and 3D-reconstruction techniques to map and quantify the distribution of VGLUT3 immunoreactive boutons within 5-HT vs. SERT-positive axons in various regions of the mouse forebrain, including the prefrontal cortex, nucleus accumbens core and shell, bed nucleus of the stria terminalis, dorsal striatum, lateral septum, basolateral and central amygdala, and hippocampus. Our results demonstrate that about 90% of 5-HT boutons are colocalized with SERT in almost all the brain regions studied, which therefore reveals that VGLUT3 and SERT do not segregate. However, in the posterior part of the NAC shell, we confirmed the presence of a subtype of 5-HT immunoreactive axons that lack the SERT. Interestingly, about 90% of the 5-HT/VGLUT3 boutons were labeled for the SERT in this region, suggesting that VGLUT3 is preferentially located in SERT immunoreactive 5-HT boutons. This work demonstrates that VGLUT3 and SERT cannot be used as specific markers to classify the different subtypes of 5-HT axons.
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Affiliation(s)
- Arnauld Belmer
- Translational Research Institute, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia
| | - Kate Beecher
- Translational Research Institute, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia
| | - Angela Jacques
- Translational Research Institute, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia
| | - Omkar L Patkar
- QIMR Berghofer Medical Research Institute, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia
| | - Florian Sicherre
- Biologie Integrative et Physiologie, Université Pierre et Marie Curie, Paris, France
| | - Selena E Bartlett
- Translational Research Institute, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia
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Nyman M, Eskola O, Kajander J, Jokinen R, Penttinen J, Karjalainen T, Nummenmaa L, Hirvonen J, Burns D, Hargreaves R, Solin O, Hietala J. Brain neurokinin-1 receptor availability in never-medicated patients with major depression - A pilot study. J Affect Disord 2019; 242:188-194. [PMID: 30193189 DOI: 10.1016/j.jad.2018.08.084] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 08/16/2018] [Accepted: 08/20/2018] [Indexed: 10/28/2022]
Abstract
BACKGROUND Neurotransmitter substance P (SP) and its preferred neurokinin-1 receptor (NK1R) have been implicated in the treatment of affective and addiction disorders. Despite promising preclinical data on antidepressant action, the clinical trials of NK1R antagonists in major depression have been disappointing. There are no direct in vivo imaging studies on NK1R characteristics in patients with a major depressive disorder (MDD). METHODS In this cross-sectional case-control study, we recruited nine never-medicated patients with moderate to severe MDD and nine matched healthy controls. NK1R availability (NK1R binding potential, BPND) was measured with in vivo 3-D positron emission tomography and a specific NK1 receptor tracer [18F]SPA-RQ. Clinical symptoms were assessed with the 17-item Hamilton Rating Scale for Depression (HAM-D17). RESULTS NK1R-BPND did not differ statistically significantly between patients with MDD and healthy controls. HAM-D17 total scores (range 21-32) correlated positively with NK1R-BPND in cortical and limbic areas. HAM-D17 subscale score for anxiety symptoms correlated positively with NK1R-BPND in specific brain areas implicated in fear and anxiety. LIMITATIONS Small sample size. Low variability in the clinical HAM-D subscale ratings may affect the observed correlations. CONCLUSIONS Our preliminary results do not support a different baseline expression of NK1Rs in a representative sample of never-medicated patients with MDD during a current moderate/severe depressive episode. The modulatory effect of NK1Rs on affective symptoms is in line with early positive results on antidepressant action of NK1 antagonists. However, the effect is likely to be too weak for treatment of MDD with NK1R antagonists alone in clinical practice.
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Affiliation(s)
- Mikko Nyman
- Turku PET Centre, Neuropsychiatric Imaging, Turku, Finland; Department of Radiology, University of Turku and Turku University Hospital, Turku, Finland
| | - Olli Eskola
- Turku PET Centre, Radiopharmaceutical Chemistry Laboratory, Turku, Finland
| | - Jaana Kajander
- Turku PET Centre, Neuropsychiatric Imaging, Turku, Finland
| | - Riitta Jokinen
- Department of Psychiatry, University of Turku and Turku University Hospital, Turku, Finland
| | - Jukka Penttinen
- Department of Psychiatry, University of Turku and Turku University Hospital, Turku, Finland
| | | | | | - Jussi Hirvonen
- Turku PET Centre, Neuropsychiatric Imaging, Turku, Finland; Department of Radiology, University of Turku and Turku University Hospital, Turku, Finland
| | - Donald Burns
- Imaging Research, Merck Research Laboratories, West Point, PA, USA
| | | | - Olof Solin
- Turku PET Centre, Radiopharmaceutical Chemistry Laboratory, Turku, Finland; Department of Chemistry, University of Turku, Turku, Finland
| | - Jarmo Hietala
- Turku PET Centre, Neuropsychiatric Imaging, Turku, Finland; Department of Psychiatry, University of Turku and Turku University Hospital, Turku, Finland.
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4
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Bright FM, Vink R, Byard RW. The potential role of substance P in brainstem homeostatic control in the pathogenesis of sudden infant death syndrome (SIDS). Neuropeptides 2018; 70:1-8. [PMID: 29908886 DOI: 10.1016/j.npep.2018.02.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 02/25/2018] [Accepted: 02/25/2018] [Indexed: 12/30/2022]
Abstract
Victims of sudden infant death syndrome (SIDS) are believed to have an underlying dysfunction in medullary homeostatic control that impairs critical responses to life threatening challenges such as hypoxia, hypercarbia and asphyxia, often during a sleep period. This failure is thought to result from abnormalities in a network of neural pathways in the medulla oblongata that control respiration, chemosensitivity, autonomic function and arousal. Studies have mainly focused on the role of serotonin, 5-hydroxytyptamine (5HT), although the neuropeptide substance P (SP) has also been shown to play an integral role in the modulation of medullary homeostatic function, often in conjunction with 5-HT. Actions of SP include regulation of respiratory rhythm generation, integration of cardiovascular control, modulation of the baroreceptor reflex and mediation of the chemoreceptor reflex in response to hypoxia. Abnormalities in SP neurotransmission may, therefore, also play a significant role in homeostatic dysfunction of the neurotransmitter network in SIDS. This review focuses on the pathways within the medulla involving SP and its tachykinin NK1 receptor, their potential relationship with the medullary 5-HT system, and possible involvement in the pathogenesis of SIDS.
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Affiliation(s)
- Fiona M Bright
- Discipline of Anatomy and Pathology, Adelaide Medical School, University of Adelaide, SA, Australia.
| | - Robert Vink
- Sansom Institute for Health Research, University of South Australia, Adelaide, SA, Australia
| | - Roger W Byard
- Discipline of Anatomy and Pathology, Adelaide Medical School, University of Adelaide, SA, Australia
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5
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Culman J, Mühlenhoff S, Blume A, Hedderich J, Lützen U, Hunt SP, Rupniak NMJ, Zhao Y. The Hypothalamic-Pituitary-Adrenal Axis and Serotonin Metabolism in Individual Brain Nuclei of Mice with Genetic Disruption of the NK1 Receptor Exposed to Acute Stress. Cell Mol Neurobiol 2018; 38:1271-1281. [PMID: 29948553 DOI: 10.1007/s10571-018-0594-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 05/23/2018] [Indexed: 12/12/2022]
Abstract
Mice lacking the substance P (SP) neurokinin-1 (NK1) receptor (NK1R-/-mice) were used to investigate whether SP affects serotonin (5-HT) function in the brain and to assess the effects of acute immobilisation stress on the hypothalamic-pituitary-adrenocortical (HPA) axis and 5-HT turnover in individual brain nuclei. Basal HPA activity and the expression of hypothalamic corticotropin-releasing hormone (CRH) in wild-type (WT)- and NK1R-/- mice were identical. Stress-induced increases in plasma ACTH concentration were considerably higher in NK1R-/- mice than in WT mice while corticosterone concentrations were equally elevated in both mouse lines. Acute stress did not alter the expression of CRH. In the dorsal raphe nucleus (DRN), basal 5-HT turnover was increased in NK1R-/- mice and a 15 min stress further magnified 5-HT utilisation in this region. In the frontoparietal cortex, medial prefrontal cortex, central nucleus of amygdala, and the hippocampal CA1 region, stress increased 5-HT and/or 5-hydroxyindoleacetic acid (5-HIAA) concentrations to a similar extent in WT and NK1R-/- mice. 5-HT turnover in the hypothalamic paraventricular nucleus was not affected by stress, but stress induced similar increases in 5-HT and 5-HIAA in the ventromedial and dorsomedial hypothalamic nuclei in WT and NK1R-/- mice. Our findings indicate that NK1 receptor activation suppresses ACTH release during acute stress but does not exert sustained inhibition of the HPA axis. Genetic deletion of the NK1 receptor accelerates 5-HT turnover in DRN under basal and stress conditions. No differences between the responses of serotonergic system to acute stress in WT and NK1R-/- mice occur in forebrain nuclei linked to the regulation of anxiety and neuroendocrine stress responses.
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Affiliation(s)
- Juraj Culman
- Institute of Experimental and Clinical Pharmacology, University Hospital of Schleswig-Holstein, Campus Kiel, Arnold-Heller-Strasse 3, 24105, Kiel, Germany. .,Department of Nuclear Medicine, Molecular Imaging, Diagnostics and Therapy, University Hospital of Schleswig-Holstein, Campus Kiel, Arnold-Heller-Strasse 3, 24105, Kiel, Germany.
| | - Stephan Mühlenhoff
- Institute of Experimental and Clinical Pharmacology, University Hospital of Schleswig-Holstein, Campus Kiel, Arnold-Heller-Strasse 3, 24105, Kiel, Germany
| | - Annegret Blume
- Institute of Experimental and Clinical Pharmacology, University Hospital of Schleswig-Holstein, Campus Kiel, Arnold-Heller-Strasse 3, 24105, Kiel, Germany
| | - Jürgen Hedderich
- Institute of Medical Informatics and Statistics, University Hospital of Schleswig-Holstein, Campus Kiel, Brunswiker Strasse 10, 24105, Kiel, Germany
| | - Ulf Lützen
- Department of Nuclear Medicine, Molecular Imaging, Diagnostics and Therapy, University Hospital of Schleswig-Holstein, Campus Kiel, Arnold-Heller-Strasse 3, 24105, Kiel, Germany
| | - Stephen P Hunt
- Department of Cell and Developmental Biology, University College London, Gower Street, London, WC1E 6BT, UK
| | | | - Yi Zhao
- Department of Nuclear Medicine, Molecular Imaging, Diagnostics and Therapy, University Hospital of Schleswig-Holstein, Campus Kiel, Arnold-Heller-Strasse 3, 24105, Kiel, Germany
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6
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Schank JR, Heilig M. Substance P and the Neurokinin-1 Receptor: The New CRF. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2017; 136:151-175. [DOI: 10.1016/bs.irn.2017.06.008] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Fernandez SP, Cauli B, Cabezas C, Muzerelle A, Poncer JC, Gaspar P. Multiscale single-cell analysis reveals unique phenotypes of raphe 5-HT neurons projecting to the forebrain. Brain Struct Funct 2015; 221:4007-4025. [PMID: 26608830 DOI: 10.1007/s00429-015-1142-4] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 11/02/2015] [Indexed: 11/28/2022]
Abstract
Serotonergic neurons of the raphe nuclei exhibit anatomical, neurochemical and elecrophysiological heterogeneity that likely underpins their specific role in multiple behaviors. However, the precise organization of serotonin (5-HT) neurons to orchestrate 5-HT release patterns throughout the brain is not well understood. We compared the electrophysiological and neurochemical properties of dorsal and median raphe 5-HT neurons projecting to the medial prefrontal cortex (mPFC), amygdala (BLA) and dorsal hippocampus (dHP), combining retrograde tract tracing with brain slice electrophysiology and single-cell RT-PCR in Pet1-EGFP mice. Our results show that 5-HT neurons projecting to the dHP and the mPFC and the BLA form largely non-overlapping populations and that BLA-projecting neurons have characteristic excitability and membrane properties. In addition, using an unbiased clustering method that correlates anatomical, molecular and electrophysiological phenotypes, we find that 5-HT neurons with projections to the mPFC and the dHP segregate from those projecting to the BLA. Single-cell gene profiling showed a restricted expression of the peptide galanin in the population of 5-HT neurons projecting to the mPFC. Finally, cluster analysis allowed identifying an atypical subtype of 5-HT neuron with low excitability, long firing delays and preferential expression of the vesicular glutamate transporter type 3. Overall, these findings allow to define correlated anatomical and physiological identities of serotonin raphe neurons that help understanding how discrete raphe cells subpopulations account for the heterogeneous activities of the midbrain serotonergic system.
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Affiliation(s)
- Sebastian Pablo Fernandez
- Institut du Fer à Moulin, INSERM U839, 17 rue du Fer à Moulin, 75005, Paris, France. .,Université Pierre et Marie Curie, Paris, France. .,Institut du Fer a Moulin, Paris, France.
| | - Bruno Cauli
- Université Pierre et Marie Curie, Paris, France.,CNRS, UMR 8246, Neuroscience Paris Seine, 75005, Paris, France.,Inserm UMR-S 1130, Neuroscience Paris Seine, 75005, Paris, France
| | - Carolina Cabezas
- Institut du Fer à Moulin, INSERM U839, 17 rue du Fer à Moulin, 75005, Paris, France.,Université Pierre et Marie Curie, Paris, France.,Institut du Fer a Moulin, Paris, France
| | - Aude Muzerelle
- Institut du Fer à Moulin, INSERM U839, 17 rue du Fer à Moulin, 75005, Paris, France.,Université Pierre et Marie Curie, Paris, France.,Institut du Fer a Moulin, Paris, France
| | - Jean-Christophe Poncer
- Institut du Fer à Moulin, INSERM U839, 17 rue du Fer à Moulin, 75005, Paris, France.,Université Pierre et Marie Curie, Paris, France.,Institut du Fer a Moulin, Paris, France
| | - Patricia Gaspar
- Institut du Fer à Moulin, INSERM U839, 17 rue du Fer à Moulin, 75005, Paris, France. .,Université Pierre et Marie Curie, Paris, France. .,Institut du Fer a Moulin, Paris, France.
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8
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Hamity MV, Walder RY, Hammond DL. Increased neuronal expression of neurokinin-1 receptor and stimulus-evoked internalization of the receptor in the rostral ventromedial medulla of the rat after peripheral inflammatory injury. J Comp Neurol 2015; 522:3037-51. [PMID: 24639151 DOI: 10.1002/cne.23564] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Revised: 01/31/2014] [Accepted: 02/18/2014] [Indexed: 12/28/2022]
Abstract
This study examined possible mechanisms by which Substance P (Sub P) assumes a pronociceptive role in the rostral ventromedial medulla (RVM) under conditions of peripheral inflammatory injury, in this case produced by intraplantar (ipl) injection of complete Freund's adjuvant (CFA). In saline- and CFA-treated rats, neurokinin-1 receptor (NK1R) immunoreactivity was localized to neurons in the RVM. Four days after ipl injection of CFA, the number of NK1R-immunoreactive neurons in the RVM was increased by 30%, and there was a concomitant increase in NK1R-immunoreactive processes in CFA-treated rats. Although NK1R immunoreactivity was increased, tachykinin-1 receptor (Tacr1) mRNA was not increased in the RVM of CFA-treated rats. To assess changes in Sub P release, the number of RVM neurons that exhibited NK1R internalization was examined in saline- and CFA-treated rats following noxious heat stimulation of the hind paws. Only CFA-treated rats that experienced noxious heat stimulation exhibited a significant increase in the number of neurons showing NK1R internalization. These data suggest that tonic Sub P release is not increased as a simple consequence of peripheral inflammation, but that phasic or evoked release of Sub P in the RVM is increased in response to noxious peripheral stimulation in a persistent inflammatory state. These data support the proposal that an upregulation of the NK1R in the RVM, as well as enhanced release of Sub P following noxious stimulation, underlie the pronociceptive role of Sub P under conditions of persistent inflammatory injury.
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Affiliation(s)
- Marta V Hamity
- Department of Anesthesia, University of Iowa, Iowa City, Iowa, 52242
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9
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Lacoste B, Angeloni D, Dominguez-Lopez S, Calderoni S, Mauro A, Fraschini F, Descarries L, Gobbi G. Anatomical and cellular localization of melatonin MT1 and MT2 receptors in the adult rat brain. J Pineal Res 2015; 58:397-417. [PMID: 25726952 DOI: 10.1111/jpi.12224] [Citation(s) in RCA: 132] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2015] [Accepted: 02/26/2015] [Indexed: 12/12/2022]
Abstract
The involvement of melatonin in mammalian brain pathophysiology has received growing interest, but information about the anatomical distribution of its two G-protein-coupled receptors, MT1 and MT2 , remains elusive. In this study, using specific antibodies, we examined the precise distribution of both melatonin receptors immunoreactivity across the adult rat brain using light, confocal, and electron microscopy. Our results demonstrate a selective MT1 and MT2 localization on neuronal cell bodies and dendrites in numerous regions of the rat telencephalon, diencephalon, and mesencephalon. Confocal and ultrastructural examination confirmed the somatodendritic nature of MT1 and MT2 receptors, both being localized on neuronal membranes. Overall, striking differences were observed in the anatomical distribution pattern of MT1 and MT2 proteins, and the labeling often appeared complementary in regions displaying both receptors. Somadendrites labeled for MT1 were observed for instance in the retrosplenial cortex, the dentate gyrus of the hippocampus, the islands of Calleja, the medial habenula, the suprachiasmatic nucleus, the superior colliculus, the substantia nigra pars compacta, the dorsal raphe nucleus, and the pars tuberalis of the pituitary gland. Somadendrites endowed with MT2 receptors were mostly observed in the CA3 field of the hippocampus, the reticular thalamic nucleus, the supraoptic nucleus, the inferior colliculus, the substantia nigra pars reticulata, and the ventrolateral periaqueductal gray. Together, these data provide the first detailed neurocytological mapping of melatonin receptors in the adult rat brain, an essential prerequisite for a better understanding of melatonin distinct receptor function and neurophysiology.
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Affiliation(s)
- Baptiste Lacoste
- Neurobiological Psychiatry Unit, Department of Psychiatry, McGill University Health Center, McGill University, Montreal, QC, Canada
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10
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Porter AJ, Pillidge K, Tsai YC, Dudley JA, Hunt SP, Peirson SN, Brown LA, Stanford SC. A lack of functional NK1 receptors explains most, but not all, abnormal behaviours of NK1R-/- mice(1). GENES BRAIN AND BEHAVIOR 2015; 14:189-99. [PMID: 25558794 PMCID: PMC4415486 DOI: 10.1111/gbb.12195] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 12/04/2014] [Accepted: 12/11/2014] [Indexed: 01/16/2023]
Abstract
Mice lacking functional neurokinin-1 receptors (NK1R-/-) display abnormal behaviours seen in Attention Deficit Hyperactivity Disorder (hyperactivity, impulsivity and inattentiveness). These abnormalities were evident when comparing the behaviour of separate (inbred: 'Hom') wildtype and NK1R-/- mouse strains. Here, we investigated whether the inbreeding protocol could influence their phenotype by comparing the behaviour of these mice with that of wildtype (NK1R+/+) and NK1R-/- progeny of heterozygous parents ('Het', derived from the same inbred strains). First, we recorded the spontaneous motor activity of the two colonies/genotypes, over 7 days. This continuous monitoring also enabled us to investigate whether the diurnal rhythm in motor activity differs in the two colonies/genotypes. NK1R-/- mice from both colonies were hyperactive compared with their wildtypes and their diurnal rhythm was also disrupted. Next, we evaluated the performance of the four groups of mice in the 5-Choice Serial Reaction-Time Task (5-CSRTT). During training, NK1R-/- mice from both colonies expressed more impulsive and perseverative behaviour than their wildtypes. During testing, only NK1R-/- mice from the Hom colony were more impulsive than their wildtypes, but NK1R-/- mice from both colonies were more perseverative. There were no colony differences in inattentiveness. Moreover, a genotype difference in this measure depended on time of day. We conclude that the hyperactivity, perseveration and, possibly, inattentiveness of NK1R-/- mice is a direct consequence of a lack of functional NK1R. However, the greater impulsivity of NK1R-/- mice depended on an interaction between a functional deficit of NK1R and other (possibly environmental and/or epigenetic) factors.
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Affiliation(s)
- A J Porter
- Department of Neuroscience, Physiology and Pharmacology
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11
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Thornton E, Hassall MM, Corrigan F, Vink R. The NK1 receptor antagonist N-acetyl-L-tryptophan reduces dyskinesia in a hemi-parkinsonian rodent model. Parkinsonism Relat Disord 2014; 20:508-13. [PMID: 24637127 DOI: 10.1016/j.parkreldis.2014.02.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Revised: 01/07/2014] [Accepted: 02/08/2014] [Indexed: 01/06/2023]
Abstract
BACKGROUND Dyskinesia or abnormal involuntary movements (AIMs) are a disabling effect of chronic L-DOPA administration and consequent pulsatile stimulation of dopamine receptors. This abnormal activation causes maladaptive changes including upregulation of FosB expression in dynorphin containing striatal cells. Substance P (SP) is co-localized within dynorphin positive cells and is increased within the substantia nigra by L-DOPA (L-3,4-dihydroxyphenylalanine) treatment. Accordingly, we determined if treatment with a SP NK1 receptor antagonist reduced the onset of L-DOPA induced dyskinesia (LID) in the hemi-parkinsonian rodent model. METHODS Adult male Sprague-Dawley rats underwent unilateral 6-OHDA (6-hydroxydopamine-hydrobromide) lesions of the medial forebrain bundle. At day 21, daily administration commenced of either L-DOPA (6 mg/kg plus 15 mg/kg of benseraside), L-DOPA with the NK1 antagonist N-acetyl-L-tryptophan (NAT) or equal volume of saline. Animals were tested with the rodent AIM scale assessing axial, contralateral forelimb and orolingual AIMs. Assessment of L-DOPA induced turning was undertaken, and motor function determined using the accelerating rotarod and adjusting step test. Dopaminergic neuronal counts and immunoreactivity for SP and FosB were undertaken. RESULTS All animals treated with L-DOPA alone developed dyskinesia, whereas combined administration of NAT with L-DOPA significantly reduced onset of AIMs and prevented mild to moderate dyskinesia. In non-dyskinetic NAT treated animals, similar numbers of FosB+ striatal cells were recorded as in saline treated animals. Importantly NAT treatment did not interfere with the anti-parkinsonian effect of L-DOPA. CONCLUSION Daily administration of a SP NK1 receptor antagonist may represent a novel treatment regime that reduces the onset of LID whilst conserving motor function.
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Affiliation(s)
- Emma Thornton
- The Adelaide Centre for Neuroscience Research, School of Medical Sciences, The University of Adelaide, South Australia, Australia.
| | - Mark Macquarie Hassall
- The Adelaide Centre for Neuroscience Research, School of Medical Sciences, The University of Adelaide, South Australia, Australia
| | - Frances Corrigan
- The Adelaide Centre for Neuroscience Research, School of Medical Sciences, The University of Adelaide, South Australia, Australia
| | - Robert Vink
- The Adelaide Centre for Neuroscience Research, School of Medical Sciences, The University of Adelaide, South Australia, Australia
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12
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Chen T, Wang XL, Qu J, Wang W, Zhang T, Yanagawa Y, Wu SX, Li YQ. Neurokinin-1 Receptor-Expressing Neurons That Contain Serotonin and Gamma-Aminobutyric Acid in the Rat Rostroventromedial Medulla Are Involved in Pain Processing. THE JOURNAL OF PAIN 2013; 14:778-92. [DOI: 10.1016/j.jpain.2013.02.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Revised: 11/24/2012] [Accepted: 02/06/2013] [Indexed: 01/22/2023]
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13
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Maejima T, Masseck OA, Mark MD, Herlitze S. Modulation of firing and synaptic transmission of serotonergic neurons by intrinsic G protein-coupled receptors and ion channels. Front Integr Neurosci 2013; 7:40. [PMID: 23734105 PMCID: PMC3661940 DOI: 10.3389/fnint.2013.00040] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Accepted: 05/03/2013] [Indexed: 11/13/2022] Open
Abstract
Serotonergic neurons project to virtually all regions of the central nervous system and are consequently involved in many critical physiological functions such as mood, sexual behavior, feeding, sleep/wake cycle, memory, cognition, blood pressure regulation, breathing, and reproductive success. Therefore, serotonin release and serotonergic neuronal activity have to be precisely controlled and modulated by interacting brain circuits to adapt to specific emotional and environmental states. We will review the current knowledge about G protein-coupled receptors and ion channels involved in the regulation of serotonergic system, how their regulation is modulating the intrinsic activity of serotonergic neurons and its transmitter release and will discuss the latest methods for controlling the modulation of serotonin release and intracellular signaling in serotonergic neurons in vitro and in vivo.
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Affiliation(s)
- Takashi Maejima
- Department of Zoology and Neurobiology, Ruhr-University Bochum Bochum, Germany
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Ju H, Liu XS, Wei LZ, Liu H, Yin JP. Effect of infection on cytokine expression in the colon mucosa of patients with irritable bowel syndrome. Shijie Huaren Xiaohua Zazhi 2012; 20:1574-1578. [DOI: 10.11569/wcjd.v20.i17.1574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To explore the impact of infection on the immune-nervous-endocrine network in patients with irritable bowel syndrome (IBS).
METHODS: Forty-five patients with postinfectious IBS (PI-IBS), 60 patients with non-postinfectious IBS (non-PI-PBS), and 30 healthy controls were included. Immunohistochemical staining was performed to analyze the expression of substance P (SP), interleukin (IL)-2, 5-hydroxytryptamine (5-HT), interferon (IFN)-γ, substance P receptor (SPR) in the colon mucosa of these subjects. Mast cells (MCs) were stained with toluidine blue.
RESULTS: The expression of SP, MCs, 5-HT, SP-R, IFN-γ, and IL-2 in PI-IBS patients was higher than that in non-PI-IBS patients and controls (t = 2.5, 2.8, both P < 0.01; t = 11.5, 12.1, both P < 0.01; t = 13.6, 14.1, both P < 0.01; t = 3.8, 6.1, both P < 0.05; t = 13.8, 15.2, both P < 0.05; t = 12.6, 14.7, both P < 0.05). The expression of ileocecal mucosal MCs was positively correlated with that of SP in PI-IBS patients (r = 0.71, P < 0.01). The expression of ileocecal mucosal 5-HT was closely associated with that of SPR in PI-IBS patients (r = 0.18, P < 0.05). SP expression in PI-IBS patients who were positive for IFN-γ or IL-2 was higher than that in non-PI-IBS patients (t = 2.22, 2.3, P < 0.05) and controls (t = 2.3, 2.4, P < 0.05).
CONCLUSION: Nerve fibers are critical for the immune-nervous-endocrine network in IBS patients after intestinal infection.
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Dittrich L, Heiss JE, Warrier DR, Perez XA, Quik M, Kilduff TS. Cortical nNOS neurons co-express the NK1 receptor and are depolarized by Substance P in multiple mammalian species. Front Neural Circuits 2012; 6:31. [PMID: 22679419 PMCID: PMC3367498 DOI: 10.3389/fncir.2012.00031] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Accepted: 05/06/2012] [Indexed: 11/17/2022] Open
Abstract
We have previously demonstrated that Type I neuronal nitric oxide synthase (nNOS)-expressing neurons are sleep-active in the cortex of mice, rats, and hamsters. These neurons are known to be GABAergic, to express Neuropeptide Y (NPY) and, in rats, to co-express the Substance P (SP) receptor NK1, suggesting a possible role for SP in sleep/wake regulation. To evaluate the degree of co-expression of nNOS and NK1 in the cortex among mammals, we used double immunofluorescence for nNOS and NK1 and determined the anatomical distribution in mouse, rat, and squirrel monkey cortex. Type I nNOS neurons co-expressed NK1 in all three species although the anatomical distribution within the cortex was species-specific. We then performed in vitro patch clamp recordings in cortical neurons in mouse and rat slices using the SP conjugate tetramethylrhodamine-SP (TMR-SP) to identify NK1-expressing cells and evaluated the effects of SP on these neurons. Bath application of SP (0.03–1 μM) resulted in a sustained increase in firing rate of these neurons; depolarization persisted in the presence of tetrodotoxin. These results suggest a conserved role for SP in the regulation of cortical sleep-active neurons in mammals.
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Affiliation(s)
- Lars Dittrich
- Biosciences Division, Center for Neuroscience, SRI International, Menlo Park CA, USA
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16
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Hafizi S, Serres F, Pei Q, Totterdell S, Sharp T. Evidence for the differential co-localization of neurokinin-1 receptors with 5-HT receptor subtypes in rat forebrain. J Psychopharmacol 2012; 26:505-15. [PMID: 22057017 DOI: 10.1177/0269881111425969] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Studies suggest that like selective 5-hydroxytryptamine (5-HT; serotonin) reuptake inhibitors, antagonists at neurokinin-1 receptors (NK(1)Rs) may have antidepressant and anxiolytic properties. NK(1)Rs are present in 5-HT innervated forebrain regions which may provide a common point of interaction between these two transmitter systems. This study aimed to investigate for cellular co-localization between NK(1)Rs and 5-HT receptor subtypes in mood-related brain regions in the rat forebrain. With experiments using fluorescence immunocytochemistry, double-labelling methods demonstrated a high degree of co-localization between NK(1)Rs and 5-HT(1A) receptors in most regions examined. Co-localization was highest in the medial septum (88% NK(1)R expressing cells were 5-HT(1A) receptor-positive) and hippocampal regions (e.g. dentate gyrus, 65%), followed by the lateral/basolateral amygdala (35%) and medial prefrontal cortex (31%). In contrast, co-localization between NK(1)Rs and 5-HT(2A) receptors was infrequent (< 8%) in most areas examined except for the hippocampus (e.g. CA3, 43%). Overall co-localization between NK(1)Rs and 5-HT(1A) receptors was much greater than that between NK(1)Rs and 5-HT(2A) receptors. Thus, these experiments demonstrate a high degree of co-localization between NK(1)Rs and 5-HT(1A) receptors in cortical and limbic regions of the rat forebrain. These findings suggest a novel site of interaction between NK(1)R antagonists and the 5-HT system.
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Affiliation(s)
- Sepehr Hafizi
- Department of Pharmacology, University of Oxford, Oxford, UK.
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17
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Misono K, Lessard A. Apomorphine-evoked redistribution of neurokinin-3 receptors in dopaminergic dendrites and neuronal nuclei of the rat ventral tegmental area. Neuroscience 2012; 203:27-38. [DOI: 10.1016/j.neuroscience.2011.12.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Revised: 12/06/2011] [Accepted: 12/08/2011] [Indexed: 12/16/2022]
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18
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A genetically defined morphologically and functionally unique subset of 5-HT neurons in the mouse raphe nuclei. J Neurosci 2011; 31:2756-68. [PMID: 21414898 DOI: 10.1523/jneurosci.4080-10.2011] [Citation(s) in RCA: 110] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Heterogeneity of central serotonin (5-HT) raphe neurons is suggested by numerous lines of evidence, but its genetic basis remains elusive. The transcription factor Pet1 is required for the acquisition of serotonergic identity in a majority of neurons in the raphe nuclei. Nevertheless, a subset of 5-HT neurons differentiates in Pet1 knock-out mice. We show here that these residual 5-HT neurons outline a unique subpopulation of raphe neurons with highly selective anatomical targets and characteristic synaptic differentiations. In Pet1 knock-out mice, 5-HT innervation strikingly outlines the brain areas involved in stress responses with dense innervation to the basolateral amygdala, the paraventricular nucleus of the hypothalamus, and the intralaminar thalamic nuclei. In these regions, 5-HT terminals establish asymmetric synaptic junctions. This target selectivity could not be related to altered growth of the remaining 5-HT neurons, as indicated by axon tracing and cell culture analyses. The residual 5-HT axon terminals are functional with maintained release properties in vitro and in vivo. The functional consequence of this uneven distribution of 5-HT innervation on behavior was characterized. Pet1 knock-out mice showed decreased anxiety behavior in novelty exploration and increased fear responses to conditioned aversive cues. Overall, our findings lead us to propose the existence of Pet1-dependent and Pet1-resistant 5-HT neurons targeting different brain centers that might delineate the anatomical basis for a dual serotonergic control on stress responses.
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19
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Lillesaar C. The serotonergic system in fish. J Chem Neuroanat 2011; 41:294-308. [PMID: 21635948 DOI: 10.1016/j.jchemneu.2011.05.009] [Citation(s) in RCA: 214] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2011] [Revised: 05/07/2011] [Accepted: 05/16/2011] [Indexed: 01/20/2023]
Abstract
Neurons using serotonin (5-HT) as neurotransmitter and/or modulator have been identified in the central nervous system in representatives from all vertebrate clades, including jawless, cartilaginous and ray-finned fishes. The aim of this review is to summarize our current knowledge about the anatomical organization of the central serotonergic system in fishes. Furthermore, selected key functions of 5-HT will be described. The main focus will be the adult brain of teleosts, in particular zebrafish, which is increasingly used as a model organism. It is used to answer not only genetic and developmental biology questions, but also issues concerning physiology, behavior and the underlying neuronal networks. The many evolutionary conserved features of zebrafish combined with the ever increasing number of genetic tools and its practical advantages promise great possibilities to increase our understanding of the serotonergic system. Further, comparative studies including several vertebrate species will provide us with interesting insights into the evolution of this important neurotransmitter system.
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Affiliation(s)
- Christina Lillesaar
- Zebrafish Neurogenetics Group, Laboratory of Neurobiology and Development (NED), Institute of Neurobiology Albert Fessard, Gif-sur-Yvette, France.
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20
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Soiza-Reilly M, Commons KG. Glutamatergic drive of the dorsal raphe nucleus. J Chem Neuroanat 2011; 41:247-55. [PMID: 21550397 DOI: 10.1016/j.jchemneu.2011.04.004] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2011] [Accepted: 04/15/2011] [Indexed: 11/24/2022]
Abstract
The dorsal raphe nucleus (DR) contains the majority of serotonin (5-hydroxytryptamine, 5-HT) neurons in the brain that regulate neural activity in forebrain regions through their widespread projections. DR function is linked to stress and emotional processing, and is implicated in the pathophysiology of affective disorders. Glutamatergic drive of the DR arises from many different brain areas with the capacity to inform the nucleus of sensory, autonomic, endocrine and metabolic state as well as higher order neural function. Imbalance of glutamatergic neurotransmission could contribute to maladaptive 5-HT neurotransmission and represents a potential target for pharmacotherapy. Within the DR, glutamate-containing axon terminals can be identified by their content of one of three types of vesicular glutamate transporter, VGLUT1, 2 or 3. Each of these transporters is heavily expressed in particular brain areas such that their content within axons correlates with the afferent's source. Cortical sources of innervation to the DR including the medial prefrontal cortex heavily express VGLUT1 whereas subcortical sources primarily express VGLUT2. Within the DR, many local neurons responsive to substance P contain VGLUT3, and these provide a third source of excitatory drive to 5-HT cells. Moreover VGLUT3 is present, with or without 5-HT, in output pathways from the DR. 5-HT and non-5-HT neurons receive and integrate glutamatergic neurotransmission through multiple subtypes of glutamate receptors that have different patterns of expression within the DR. Interestingly, excitatory drive provided by glutamatergic neurotransmission is closely opposed by feedback inhibition mediated by 5-HT1A receptors or local GABAergic circuits. Understanding the intricacies of these local networks and their checks and balances, may help identify how potential imbalances could cause psychopathology and illuminate strategies for therapeutic manipulation.
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Affiliation(s)
- Mariano Soiza-Reilly
- Department of Anesthesiology, Perioperative and Pain Medicine, Children's Hospital, Boston, United States
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21
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Fu W, Le Maître E, Fabre V, Bernard JF, David Xu ZQ, Hökfelt T. Chemical neuroanatomy of the dorsal raphe nucleus and adjacent structures of the mouse brain. J Comp Neurol 2010; 518:3464-94. [PMID: 20589909 DOI: 10.1002/cne.22407] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Serotonin neurons play a major role in many normal and pathological brain functions. In the rat these neurons have a varying number of cotransmitters, including neuropeptides. Here we studied, with histochemical techniques, the relation between serotonin, some other small-molecule transmitters, and a number of neuropeptides in the dorsal raphe nucleus (DRN) and the adjacent ventral periaqueductal gray (vPAG) of mouse, an important question being to establish possible differences from rat. Even if similarly distributed, the serotonin neurons in mouse lacked the extensive coexpression of nitric oxide synthase and galanin seen in rat. Although partly overlapping in the vPAG, no evidence was obtained for the coexistence of serotonin with dopamine, substance P, cholecystokinin, enkephalin, somatostatin, neurotensin, dynorphin, thyrotropin-releasing hormone, or corticotropin-releasing hormone. However, some serotonin neurons expressed the gamma-aminobutyric acid (GABA)-synthesizing enzyme glutamic acid decarboxylase (GAD). Work in other laboratories suggests that, as in rat, serotonin neurons in the mouse midline DRN express the vesicular glutamate transporter 3, presumably releasing glutamate. Our study also shows that many of the neuropeptides studied (substance P, galanin, neurotensin, dynorphin, and corticotropin-releasing factor) are present in nerve terminal networks of varying densities close to the serotonin neurons, and therefore may directly or indirectly influence these cells. The apparently low numbers of coexisting messengers in mouse serotonin neurons, compared to rat, indicate considerable species differences with regard to the chemical neuronatomy of the DRN. Thus, extrapolation of DRN physiology, and possibly pathology, from rat to mouse, and even human, should be made with caution.
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Affiliation(s)
- Wenyu Fu
- Department of Neuroscience, Karolinska Institutet, 17177 Stockholm, Sweden
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22
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Chronic intermittent hypoxia reduces neurokinin-1 (NK(1)) receptor density in small dendrites of non-catecholaminergic neurons in mouse nucleus tractus solitarius. Exp Neurol 2010; 223:634-44. [PMID: 20206166 DOI: 10.1016/j.expneurol.2010.02.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2009] [Revised: 02/18/2010] [Accepted: 02/21/2010] [Indexed: 12/16/2022]
Abstract
Chronic intermittent hypoxia (CIH) is a frequent concomitant of sleep apnea, which can increase sympathetic nerve activity through mechanisms involving chemoreceptor inputs to the commissural nucleus of the solitary tract (cNTS). These chemosensory inputs co-store glutamate and substance P (SP), an endogenous ligand for neurokinin-1 (NK(1)) receptors. Acute hypoxia results in internalization of NK(1) receptors, suggesting that CIH also may affect the subcellular distribution of NK(1) receptors in subpopulations of cNTS neurons, some of which may express tyrosine hydroxylase, the rate-limiting enzyme for catecholamine synthesis (TH). To test this hypothesis, we examined dual immunolabeling for the NK(1) receptor and TH in the cNTS of male mice subjected to 10days or 35days of CIH or intermittent air. Electron microscopy revealed that NK(1) receptors and TH were almost exclusively localized within separate somatodendritic profiles in cNTS of control mice. In dendrites, immunogold particles identifying NK(1) receptors were prevalent in the cytoplasm and on the plasmalemmal surface. Compared with controls, CIH produced a significant region-specific decrease in the cytoplasmic (10 and 35days, P<0.05, unpaired Student t-test) and extrasynaptic plasmalemmal (35days, P<0.01, unpaired Student t-test) density of NK(1) immunogold particles exclusively in small (<0.1microm) dendrites without TH immunoreactivity. These results suggest that CIH produces a duration-dependent reduction in the availability of NK(1) receptors preferentially in small dendrites of non-catecholaminergic neurons in the cNTS. The implications of our findings are discussed with respect to their potential involvement in the slowly developing hypertension seen in sleep apnea patients.
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23
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Monti JM. The structure of the dorsal raphe nucleus and its relevance to the regulation of sleep and wakefulness. Sleep Med Rev 2010; 14:307-17. [PMID: 20153669 DOI: 10.1016/j.smrv.2009.11.004] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2009] [Revised: 11/15/2009] [Accepted: 11/16/2009] [Indexed: 11/30/2022]
Abstract
Serotonergic (5-HT) cells in the rat dorsal raphe nucleus (DRN) appear in topographically organized groups. Based on cellular morphology, expression of other neurotransmitters, afferent and efferent connections and functional properties, 5-HT neurons of the DRN have been grouped into six cell clusters. The subdivisions comprise the rostral, ventral, dorsal, lateral, caudal and interfascicular parts of the DRN. In addition to 5-HT cells, neurons containing γ-aminobutyric acid (GABA), glutamate, dopamine, nitric oxide and the neuropeptides corticotropin-releasing factor, substance P, galanin, cholecystokinin, neurotensin, somatostatin, vasoactive intestinal peptide, neuropeptide Y, thyrotropin-releasing hormone, growth hormone, leu-enkephalin, met-enkephalin and gastrin have been characterized in the DRN. Moreover, numerous brain areas have neurons that project to the DRN and express monoamines (norepinephrine, histamine), amino acids (GABA, glutamate), acetylcholine or neuropeptides (orexin, melanin-concentrating hormone, corticotropin-releasing factor and substance P) that directly or indirectly, through local circuits, regulate the activity of 5-HT cells. The 5-HT cells predominate along the midline of the rostral, dorsal and ventral subdivisions of the DRN and outnumber the non-5-HT cells occurring in the raphe nucleus. The GABAergic and glutamatergic neurons are clustered mainly in the lateral and dorsal subdivisions of the DRN, respectively. The 5-HT(1A) receptor is located on the soma and the dendrites of 5-HT neurons and at postsynaptic sites (outside the DRN). It is expressed, in addition, by non-5-HT cells of the DRN. The 5-HT(1B) receptor is located at presynaptic and postsynaptic sites (outside the boundaries of the DRN). It has been described also in the ventromedial DRN where it is expressed by non-5-HT cells. The 5-HT(2A) and 5-HT(2C) receptors are located within postsynaptic structures. At the level of the DRN the 5-HT(2A) and 5-HT(2C) receptor-containing cells are predominantly GABAergic interneurons and projection neurons. Within the boundaries of the DRN the 5-HT(3) receptor is expressed by, among others, glutamatergic interneurons. 5-HT(7) receptors in the DRN are not localized to serotonergic neurons but, at least in part, to GABAergic cells and terminals. The complex structure of the DRN may have important implications for neural mechanisms underlying 5-HT modulation of wakefulness and REM sleep.
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Affiliation(s)
- Jaime M Monti
- Department of Pharmacology and Therapeutics, School of Medicine Clinics Hospital, Montevideo, Uruguay.
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24
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Abstract
The molecular architecture of developing serotonin (5HT) neurons is poorly understood, yet its determination is likely to be essential for elucidating functional heterogeneity of these cells and the contribution of serotonergic dysfunction to disease pathogenesis. Here, we describe the purification of postmitotic embryonic 5HT neurons by flow cytometry for whole-genome microarray expression profiling of this unitary monoaminergic neuron type. Our studies identified significantly enriched expression of hundreds of unique genes in 5HT neurons, thus providing an abundance of new serotonergic markers. Furthermore, we identified several hundred transcripts encoding homeodomain, axon guidance, cell adhesion, intracellular signaling, ion transport, and imprinted genes associated with various neurodevelopmental disorders that were differentially enriched in developing rostral and caudal 5HT neurons. These findings suggested a homeodomain code that distinguishes rostral and caudal 5HT neurons. Indeed, verification studies demonstrated that Hmx homeodomain and Hox gene expression defined an Hmx(+) rostral subtype and Hox(+) caudal subtype. Expression of engrailed genes in a subset of 5HT neurons in the rostral domain further distinguished two subtypes defined as Hmx(+)En(+) and Hmx(+)En(-). The differential enrichment of gene sets for different canonical pathways and gene ontology categories provided additional evidence for heterogeneity between rostral and caudal 5HT neurons. These findings demonstrate a deep transcriptome and biological pathway duality for neurons that give rise to the ascending and descending serotonergic subsystems. Our databases provide a rich, clinically relevant resource for definition of 5HT neuron subtypes and elucidation of the genetic networks required for serotonergic function.
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25
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Zhang L, Hammond DL. Substance P enhances excitatory synaptic transmission on spinally projecting neurons in the rostral ventromedial medulla after inflammatory injury. J Neurophysiol 2009; 102:1139-51. [PMID: 19494188 DOI: 10.1152/jn.91337.2008] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
It has been proposed, but not directly tested, that persistent inflammatory nociception enhances excitatory glutamatergic inputs to neurons in the rostral ventromedial medulla (RVM), altering the activity and function of these neurons. This study used whole cell patch-clamp methods to record evoked excitatory postsynaptic currents (eEPSCs) in spinally projecting RVM neurons from rats injected with saline or complete Freund's adjuvant (CFA) 3-4 days earlier and to examine the role of substance P (SP) in modulating excitatory synaptic transmission. Input-output relationships demonstrated that CFA treatment facilitated fast excitatory glutamatergic inputs to type 1 and type 2 nonserotonergic spinally projecting RVM neurons, but not to type 3 neurons. The facilitation in type 1 and 2 neurons was dependent on neurokinin-1 (NK1) and N-methyl-d-aspartate (NMDA) receptors and prevented by the PKC inhibitor GF109203X. In a subset of neurons from naïve rats, SP mimicked the effects of CFA and increased the potency and efficacy of glutamatergic synaptic transmission. The facilitation was prevented by 10 microM GF109203X, but not by 10 microM KN93, a CaMKII inhibitor. SP (0.3-3 microM) by itself produced concentration-dependent inward currents in most nonserotonergic, but not serotonergic neurons. The present study is the first demonstration, at the cellular level, that persistent inflammatory nociception leads to a sustained facilitation of fast excitatory glutamatergic inputs to RVM neurons by an NK1 and NMDA receptor-dependent mechanism that involves PKC. Further, it demonstrates that the facilitation is restricted to specific populations of RVM neurons that by inference may be pain facilitatory neurons.
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Affiliation(s)
- Liang Zhang
- Department of Anesthesia, The University of Iowa, Iowa City, Iowa 52242, USA.
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26
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Lessard A, Savard M, Gobeil F, Pierce JP, Pickel VM. The neurokinin-3 (NK3) and the neurokinin-1 (NK1) receptors are differentially targeted to mesocortical and mesolimbic projection neurons and to neuronal nuclei in the rat ventral tegmental area. Synapse 2009; 63:484-501. [PMID: 19224600 PMCID: PMC2742351 DOI: 10.1002/syn.20627] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Tonic activation of neurokinin-3 (NK(3)) receptors in dopamine neurons of the ventral tegmental area (VTA) has been implicated in the pathophysiology of schizophrenia. This psychiatric disorder is associated with a dysfunctional activity in VTA projection neurons that can affect cognitive function at the level of the medial prefrontal cortex (mPFC) as well as motor and motivational states controlled in part by mesolimbic output to the nucleus accumbens (Acb). To determine the relevant sites for NK(3) receptor activation within this neuronal network, we used confocal and electron microscopy to examine NK(3) receptors (Cy5; immunogold) and retrograde labeling of fluorogold (FG, FITC; immunoperoxidase) in the VTA of rats receiving either Acb or mPFC injections of FG. Comparison was made with neurokinin-1 (NK(1)) receptors, which are also present, but less abundant then NK(3) receptors, in dopaminergic and GABAergic VTA neurons. There were no observable differences between NK(3) and NK(1) receptors in their primary locations in the cytoplasm and on the plasma membrane of VTA somata and dendrites with or without FG. Dendrites labeled with FG retrogradely transported from mPFC, however, contained more NK(3) or less NK(1) immunogold particles (plasmalemmal + cytoplasmic) then those retrogradely labeled following FG injection in the Acb. Moreover, only the NK(3) receptors were detected in neuronal nuclei in the VTA and in the nuclei of human HEK-293T NK(3)-transfected cells. The enrichment of NK(3) receptors in mesocortical projection neurons and nuclear distribution of these receptors may provide insight for understanding the selective antipsychotic effectiveness of NK(3) antagonists.
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Affiliation(s)
- Andrée Lessard
- Dept. Neurology and Neuroscience, Weill Medical College of Cornell University, New York, NY 10021
| | - Martin Savard
- Dept. Pharmacology, Faculty of Medicine, Université de Sherbrooke, Sherbrooke, Québec, Canada J1H 5N4
| | - Fernand Gobeil
- Dept. Pharmacology, Faculty of Medicine, Université de Sherbrooke, Sherbrooke, Québec, Canada J1H 5N4
| | - Joseph P. Pierce
- Dept. Neurology and Neuroscience, Weill Medical College of Cornell University, New York, NY 10021
| | - Virginia M. Pickel
- Dept. Neurology and Neuroscience, Weill Medical College of Cornell University, New York, NY 10021
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27
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Lacoste B, Riad M, Ratté MO, Boye SM, Lévesque D, Descarries L. Trafficking of neurokinin-1 receptors in serotonin neurons is controlled by substance P within the rat dorsal raphe nucleus. Eur J Neurosci 2009; 29:2303-14. [DOI: 10.1111/j.1460-9568.2009.06775.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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28
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Almarestani L, Waters SM, Krause JE, Bennett GJ, Ribeiro-da-Silva A. De novo expression of the neurokinin 1 receptor in spinal lamina I pyramidal neurons in polyarthritis. J Comp Neurol 2009; 514:284-95. [PMID: 19296480 DOI: 10.1002/cne.22024] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Spinal lamina I (LI) neurons play a major role in the transmission and integration of pain-related information that is relayed to higher centers. Alterations in the excitability of these neurons influence chronic pain development, and expression of the neurokinin 1 receptor (NK-1r) is thought to play a major role in such changes. Novel expression of NK-1r may underlie hyperexcitability in new populations of LI neurons. LI projection neurons can be classified morphologically into fusiform, pyramidal, and multipolar cells, differing in their functional properties, with the pyramidal type being nonnociceptive. In agreement with this, we have shown that spinoparabrachial pyramidal neurons seldom express NK-1r, in contrast with the other two cell types. In this study we investigated in the rat the long-term changes in NK-1r expression by spinoparabrachial LI neurons following the unilateral injection in the hindpaw plantar surface of complete Freund's adjuvant (CFA). Cholera toxin subunit B (CTb) was injected unilaterally into the parabrachial nucleus. Our results revealed that, ipsilaterally, pyramidal neurons were seldom immunoreactive for NK-1r both in saline-injected and in CFA-injected rats, up to 10 days post-CFA. However, a considerable number of pyramidal cells were immunoreactive for NK-1r at 15, 21, and 30 days post-CFA. Our data raise the possibility -- which needs to be confirmed by electrophysiology -- that most LI projection neurons of the pyramidal type are likely nonnociceptive in naive animals but might become nociceptive following the development of arthritis.
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Affiliation(s)
- L Almarestani
- Department of Pharmacology & Therapeutics, McGill University, Montreal, Quebec, Canada
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29
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Gobert A, Brocco M, Dekeyne A, Di Cara B, Bouchez G, Lejeune F, Gannon RL, Millan MJ. Neurokinin1 antagonists potentiate antidepressant properties of serotonin reuptake inhibitors, yet blunt their anxiogenic actions: a neurochemical, electrophysiological, and behavioral characterization. Neuropsychopharmacology 2009; 34:1039-56. [PMID: 18830239 DOI: 10.1038/npp.2008.176] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Though neurokinin(1) (NK(1)) receptor antagonists are active in experimental models of depression, clinical efficacy has proven disappointing. This encourages interest in association of NK(1) receptor blockade with inhibition of serotonin (5-HT) reuptake. The selective NK(1) antagonist, GR205171, dose-dependently enhanced citalopram-induced elevations of extracellular levels of 5-HT in frontal cortex, an action expressed stereospecifically vs its less active distomer, GR226206. Further, increases in 5-HT levels in dorsal hippocampus, basolateral amygdala, nucleus accumbens, and striatum were likewise potentiated, and GR205171 similarly facilitated the influence of fluoxetine upon levels of 5-HT, as well as dopamine and noradrenaline. In parallel electrophysiological studies, the inhibitory influence of citalopram and fluoxetine upon raphe-localized serotonergic neurones was stereospecifically blunted by GR205171. Antidepressant actions of citalopram in a forced-swim test in mice were stereospecifically potentiated by GR205171, and it also enhanced attenuation by citalopram of stress-related ultrasonic vocalizations in rats. Further, GR205171 and citalopram additively abrogated the advance in circadian rhythms provoked by exposure to light in hamsters. By contrast, GR205171 stereospecifically blocked anxiogenic actions of citalopram in social interaction procedures in rats and gerbils, and stereospecifically abolished facilitation of fear-induced foot tapping by fluoxetine in gerbils. By analogy to GR205171, a further NK(1) antagonist, RP67580, enhanced the influence of citalopram upon frontocortical levels of 5-HT and potentiated its actions in the forced swim test. In conclusion, NK(1)receptor blockade differentially modulates functional actions of SSRIs: antidepressant properties are reinforced, whereas anxiogenic effects are attenuated. Combined NK(1) receptor antagonism/5-HT reuptake inhibition may offer advantages in the management of depressed and anxious states.
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Affiliation(s)
- Alain Gobert
- Psychopharmacology Department, Institut de Recherches Servier, Centre de Recherches de Croissy, Paris, France
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30
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Lillesaar C, Stigloher C, Tannhäuser B, Wullimann MF, Bally-Cuif L. Axonal projections originating from raphe serotonergic neurons in the developing and adult zebrafish, Danio rerio, using transgenics to visualize raphe-specific pet1 expression. J Comp Neurol 2009; 512:158-82. [PMID: 19003874 DOI: 10.1002/cne.21887] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Serotonin is a major central nervous modulator of physiology and behavior and plays fundamental roles during development and plasticity of the vertebrate central nervous system (CNS). Understanding the developmental control and functions of serotonergic neurons is therefore an important task. In all vertebrates, prominent serotonergic neurons are found in the superior and inferior raphe nuclei in the hindbrain innervating most CNS regions. In addition, all vertebrates except for mammals harbor other serotonergic centers, including several populations in the diencephalon. This, in combination with the intricate and wide distribution of serotonergic fibers, makes it difficult to sort out serotonergic innervation originating from the raphe from that of other serotonergic cell populations. To resolve this issue, we isolated the regulatory elements of the zebrafish raphe-specific gene pet1 and used them to drive expression of an eGFP transgene in the raphe population of serotonergic neurons. With this approach together with retrograde tracing we 1) describe in detail the development, anatomical organization, and projection pattern of zebrafish pet1-positive neurons compared with their mammalian counterparts, 2) identify a new serotonergic population in the ventrolateral zebrafish hindbrain, and 3) reveal some extent of functional subdivisions within the zebrafish superior raphe complex. Together, our results reveal for the first time the specific innervation pattern of the zebrafish raphe and, thus, provide a new model and various tools to investigate further the role of raphe serotonergic neurons in vertebrates.
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Affiliation(s)
- Christina Lillesaar
- HelmholtzZentrum München, German Research Center for Environmental Health, Department of Zebrafish Neurogenetics, Institute of Developmental Genetics, D-85764 Neuherberg, Germany
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31
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Berner J, Ringstedt T, Brodin E, Hökfelt T, Lagercrantz H, Wickström R. Prenatal exposure to nicotine affects substance p and preprotachykinin-A mRNA levels in newborn rat. Pediatr Res 2008; 64:621-4. [PMID: 18679163 DOI: 10.1203/pdr.0b013e318186e5f5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Prenatal nicotine exposure influences neuronal development including effects on several neurotransmitter systems. It also attenuates the ventilatory response to hypoxia, known to require a functional substance P-ergic system. Previous studies have shown that nicotine increases the risk for sudden infant death syndrome (SIDS) by 4-fold, and that SIDS-victims have elevated brainstem levels of substance P. We, therefore, studied the effect of prenatal nicotine exposure on the levels of substance P-like immunoreactivity by RIA in the brain in newborn rat pups. The expression of the substance P precursor preprotachykinin A mRNA was also determined by real-time reverse transcriptase-polymerase chain reaction in carotid body, in petrosal/jugular and trigeminal ganglia, in cervical and lumbar dorsal root ganglia, and in the brainstem. We found that prenatal nicotine exposure increased levels of substance P-like immunoreactivity in the brainstem without changing levels in other parts of the brain or in the adrenals. Furthermore, mRNA levels were increased in the carotid bodies and in the petrosal ganglia, in contrast to the decreased levels in the cervical dorsal root ganglia. We conclude that nicotine causes alterations in the substance P-ergic system in the brainstem, possibly linked to the increased risk for SIDS after prenatal nicotine exposure.
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Affiliation(s)
- Jonas Berner
- Department of Woman and Child Health, Karolinska Institutet, 171 77 Stockholm, Sweden.
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Haddjeri N, Blier P. Neurokinin-1 receptor antagonists modulate brain noradrenaline and serotonin interactions. Eur J Pharmacol 2008; 600:64-70. [PMID: 18930727 DOI: 10.1016/j.ejphar.2008.10.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2008] [Revised: 09/12/2008] [Accepted: 10/01/2008] [Indexed: 11/19/2022]
Abstract
Substance P (neurokinin-1; NK1) receptor antagonists represent a putative new class of antidepressant/anxiolytic drugs. Using in vivo electrophysiological paradigms in rats, this study examined the effects of acute, sub-acute and long-term administration of these drugs on the firing of rat noradrenaline and serotonin (5-HT) neurons. In the locus coeruleus, neither a 2-day treatment with the tachykinin NK1 receptor antagonists [(2S,3S)-cis-2-(diphenylmethyl)-N-[(2-methoxyphenyl) methyl]-1-azabicyclo[2.2.2]octan-3-amine (CP-96,345, 10 mg/kg/day, i.p.), CP-99,994 (10 mg/kg/day, i.p.), nor a 14-day of treatment with (+)-(2S,3S)-3-(2-methoxybenzylamino)-2-phenylpiperidine (CP-99,994, 10 mg/kg/day, s.c.) significantly modified the firing rate of noradrenaline neurons. However, all these treatments attenuated the inhibitory action of the alpha(2)-adrenoceptor agonist clonidine on noradrenaline neuronal firing. While acute administration of the tachykinin NK1 receptor antagonist CP-96,345 (10 mg/kg, i.p.) attenuated the responsiveness of dorsal raphe 5-HT(1A) autoreceptors, lesioning noradrenaline neurons with the neurotoxin N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4) prevented the enhancing action of a 2-day treatment with CP-96,345 on 5-HT neuronal firing, suggesting that tachykinin NK1 receptor antagonists influence 5-HT system via noradrenaline neurons independently of their firing rate.
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Holden JE, Pizzi JA. Lateral hypothalamic-induced antinociception may be mediated by a substance P connection with the rostral ventromedial medulla. Brain Res 2008; 1214:40-9. [PMID: 18457815 PMCID: PMC2483309 DOI: 10.1016/j.brainres.2008.03.051] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2007] [Revised: 03/13/2008] [Accepted: 03/14/2008] [Indexed: 11/17/2022]
Abstract
Stimulation of the lateral hypothalamus (LH) produces antinociception modified by intrathecal serotonergic receptor antagonists. Spinally-projecting serotonergic neurons in the LH have not been identified, suggesting that the LH innervates brainstem serotonergic neurons in the rostral ventromedial medulla (RVM), known to modify nociception in the spinal cord dorsal horn. To determine whether substance P (SP) plays a role in LH-induced antinociception mediated by the RVM, we conducted an anatomical experiment using retrograde tract tracing combined with double label immunocytochemistry and found that neuron profiles immunoreactive for SP in the LH project to the RVM. To further identify a functional connection between SP neurons in the LH and the RVM, the cholinergic agonist carbachol (125 nmol) was microinjected into the LH of female Sprague-Dawley rats (250-350 g) and antinociception was obtained on the tail flick or foot withdrawal tests. Cobalt chloride (100 nM) was then microinjected in the RVM to block synaptic activation of spinally-projecting RVM neurons. Within 5 min of the cobalt chloride injection, the antinociceptive effect of carbachol stimulation was blocked. In another set of experiments, the specific NK1 receptor antagonist L-703,606 (5 microg) was microinjected in the RVM following LH stimulation with carbachol and abolished LH-induced antinociception as well. Microinjection of cobalt chloride or L-703,606 in the absence of LH stimulation had no effect. These anatomical and behavioral experiments provide converging evidence to support the hypothesis that antinociception produced by activating neurons in the LH is mediated in part by the subsequent activation of spinally-projecting neurons in the RVM.
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Affiliation(s)
- Janean E Holden
- Department of Medical-Surgical Nursing, College of Nursing, University of Illinois at Chicago, 845 South Damen Avenue, Chicago, IL 60612-7350, USA.
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Ursavas A. Upregulating substance P levels to treat obstructive sleep apnea. Expert Opin Ther Targets 2008; 12:583-8. [DOI: 10.1517/14728222.12.5.583] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Mengual E, Chan J, Lane D, San Luciano Palenzuela M, Hara Y, Lessard A, Pickel VM. Neurokinin-1 receptors in cholinergic neurons of the rat ventral pallidum have a predominantly dendritic distribution that is affected by apomorphine when combined with startle-evoking auditory stimulation. Neuroscience 2007; 151:711-24. [PMID: 18178320 DOI: 10.1016/j.neuroscience.2007.08.039] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2007] [Revised: 07/11/2007] [Accepted: 11/28/2007] [Indexed: 12/29/2022]
Abstract
Cholinergic neurons of the basal forebrain are implicated in startle reflex inhibition by a prior weak stimulus often referred to as prepulse inhibition (PPI) and used as an index of sensorimotor gating deficits in schizophrenia. Gating deficits can be produced in rodent models by acute systemic administration of apomorphine, a non-selective dopamine D1 and D2 receptor agonist that also affects trafficking of neurokinin-1 (NK(1)) receptors induced by startle evoking auditory stimulation (AS) in midbrain neurons. We used electron microscopic immunolabeling of NK(1) receptors and the vesicular acetylcholine transporter (VAchT) to test the hypothesis that the subcellular distributions of these receptors in cholinergic neurons of the rat ventral pallidum are subject to a similar regulation. In vehicle controls, NK(1) immunogold was often seen near cytoplasmic endomembranes in somata and large dendrites, but was more equally distributed in cytoplasmic and plasmalemmal compartments of medium dendrites, and principally located on the plasma membrane of small dendrites. These labeling patterns appeared to be largely independent of whether the NK(1) receptor was co-expressed with VAchT, however only the medium and small VAchT-labeled dendrites showed significant treatment-specific differences in NK(1) immunogold distributions. The NK(1) receptor immunogold particle density on the plasma membrane of medium cholinergic dendrites was significantly enhanced by combined apomorphine and AS, while neither alone affected either the plasmalemmal density or the equality of the plasmalemmal and cytoplasmic distributions of NK(1) receptors in these dendrites. Small cholinergic dendrites showed a significant AS-induced increase in both the plasmalemmal and cytoplasmic density of NK(1) gold particles, and an apomorphine-induced disruption of the preferential plasmalemmal targeting of the NK(1) receptors. These results provide ultrastructural evidence that NK(1) receptors in cholinergic neurons of the ventral pallidum have subcellular locations and plasticity conducive to active involvement in dopamine-dependent sensorimotor processing.
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Affiliation(s)
- E Mengual
- Department of Neurology and Neuroscience, Division of Neurobiology, Weill Medical College of Cornell University, 411 East 69th Street, KB 410, New York, NY 10021, USA
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Almarestani L, Waters SM, Krause JE, Bennett GJ, Ribeiro-da-Silva A. Morphological characterization of spinal cord dorsal horn lamina I neurons projecting to the parabrachial nucleus in the rat. J Comp Neurol 2007; 504:287-97. [PMID: 17640051 DOI: 10.1002/cne.21410] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Many Rexed's lamina I neurons are nociceptive and project to the brain. Lamina I projection neurons can be classified as multipolar, fusiform, or pyramidal, based on cell body shape and characteristics of their proximal dendrites in the horizontal plane. There is also evidence that both multipolar and fusiform cells are nociceptive and pyramidal neurons nonnociceptive. In this investigation we identified which types of lamina I neurons belong to the spinoparabrachial tract in the rat and characterized them regarding the presence or absence of neurokinin-1 receptor (NK-1r) immunoreactivity. For this, cholera toxin subunit B (CTb), conjugated to a fluorescent marker was injected unilaterally into the parabrachial nucleus. Sections were additionally stained for the detection of NK-1r immunoreactivity and were examined using fluorescence and confocal microscopy. Serial confocal optical sections and 3D reconstructions were obtained for a considerable number of neurons per animal. Using immunofluorescence, we assessed the proportion of lamina I neurons belonging to the spinoparabrachial (SPB) tract and/or expressing NK-1r. The relative distribution of neurons belonging to the SPB tract was: 38.7% multipolar, 36.8% fusiform, 22.7% pyramidal, and 1.9% unclassified. Most of the SPB neurons expressing NK-1r were either multipolar or fusiform. Pyramidal SPB neurons were seldom immunoreactive for NK-1r, an observation that provides further support to the concept that most lamina I projection neurons of the pyramidal type are nonnociceptive. In addition, our study provides further evidence that these distinct morphological types of neurons differ in their phenotypic properties, but not in their projection patterns.
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Affiliation(s)
- L Almarestani
- Department of Pharmacology & Therapeutics, McGill University, Montreal, Quebec H3G 1Y6, Canada
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Boselli C, Barbone MS, Lucchelli A. Older versus newer antidepressants: Substance P or calcium antagonism? Can J Physiol Pharmacol 2007; 85:1004-11. [DOI: 10.1139/y07-089] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Substance P (SP) is possibly involved in the pathophysiology of depression and anxiety. We investigated interactions between antidepressants on SP-induced effects and their potential calcium-blocking activity in the isolated guinea pig ileum. All the antidepressants tested, except pargyline, moclobemide, mianserin, and reboxetine, were able to inhibit in a concentration-dependent manner the contraction induced by 100 nmol/L SP. Clomipramine, fluoxetine, maprotiline, and amitriptyline (all at 3 μmol/L) flattened the concentration–response curves to SP, resulting in a reduction of up to 59%, 63%, 32%, and 23%, respectively, of the maximum contractile effect. All the antidepressants tested (3 μmol/L), except pargyline, moclobemide, and mianserin, produced a rightward parallel shift of the concentration–response curve to CaCl2. The L-type selective calcium blocker nifedipine and the T-type selective mibefradil showed similar behaviour against both agonists used, SP and CaCl2. The relative order of potency was nifedipine (pA2, 7.6 ± 0.1) > clomipramine (pA2, 7.0 ± 0.1) > fluoxetine (pKB, 6.5 ± 0.1) = mibefradil (pKB, 6.6 ± 0.1) > amitriptyline (pKB, 6.3 ± 0.1) = maprotiline (pKB, 6.2 ± 0.1) > fluvoxamine (pKB, 5.9 ± 0.1). The data reported in the present study suggest that the antidepressants tested did not behave as competitive antagonists versus NK1-receptor subtypes, but their inhibitory action seems to be related to their calcium-blocking properties.
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Affiliation(s)
- C. Boselli
- Department of Experimental and Applied Pharmacology, School of Pharmacy, University of Pavia, Viale Taramelli,14, 27100 Pavia, Italy
| | - M. Santagostino Barbone
- Department of Experimental and Applied Pharmacology, School of Pharmacy, University of Pavia, Viale Taramelli,14, 27100 Pavia, Italy
| | - A. Lucchelli
- Department of Experimental and Applied Pharmacology, School of Pharmacy, University of Pavia, Viale Taramelli,14, 27100 Pavia, Italy
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Guiard BP, Guilloux JP, Reperant C, Hunt SP, Toth M, Gardier AM. Substance P Neurokinin 1 Receptor Activation within the Dorsal Raphe Nucleus Controls Serotonin Release in the Mouse Frontal Cortex. Mol Pharmacol 2007; 72:1411-8. [PMID: 17890358 DOI: 10.1124/mol.107.040113] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Preclinical studies suggest that substance P (SP) neurokinin 1 (NK1) receptor antagonists are efficient in the treatment of anxiety and depression. This therapeutic activity could be mediated via stimulation of serotonin (5-HT) neurons located in the dorsal raphe nucleus (DRN), which receive important SP-NK1 receptor immunoreactive innervations. The present study examined the effects of intraraphe injection of SP on extracellular 5-HT levels in the frontal cortex, ventral hippocampus, and DRN by using intracerebral microdialysis in conscious mice. Intraraphe SP injection dose dependently decreased cortical 5-HT release, whereas no effects were detected in the ventral hippocampus. Cortical effects were blocked by the selective NK1 receptor antagonist N-[[2-methoxy-5-[5-(trifluoromethyl)tetrazol-1-yl]phenyl]methyl]-2-phenylpiperidin-3-amine (GR205171) and completely dampened in mice lacking NK1 receptors. Furthermore, genetic (in knockout 5-HT1A(-/-) mice) or pharmacological inactivation of 5-HT1A autoreceptors blocked cortical responses to SP. Contrasting with its cortical effects, intraraphe SP injection increased 5-HT outflow in the DRN in wild-type mice; this effect was potentiated by a local perfusion of the selective 5-HT1A antagonist N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-2-pyridinylcyclohexanecarboxamide (WAY100635). Finally, SP-induced changes in frontal cortex and DRN dialysate 5-HT levels were blocked by the DRN perfusion of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)/kainate ionotropic receptor antagonist 6,7-dinitroquinoxaline-2,3-dione (DNQX). These data support the hypothesis that SP-induced over-activation of 5-HT1A autoreceptors within the DRN limits cortical 5-HT release. A better knowledge of the complex relationship between tachykininergic, serotonergic, and glutamatergic systems within the DRN might help better understand the pathophysiology and subsequent treatment of depression.
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Affiliation(s)
- Bruno P Guiard
- Univ Paris-Sud EA 3544, Fac. Pharmacie, Chatenay-Malabry cedex F92296, France
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Berner J, Shvarev Y, Lagercrantz H, Bilkei-Gorzo A, Hökfelt T, Wickström R. Altered respiratory pattern and hypoxic response in transgenic newborn mice lacking the tachykinin-1 gene. J Appl Physiol (1985) 2007; 103:552-9. [PMID: 17525292 DOI: 10.1152/japplphysiol.01389.2006] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Substance P is known to be involved in respiratory rhythm and central pattern-generating mechanisms, especially during early development. We therefore studied respiratory responses in transgenic newborn mice (Tac1(-/-)) lacking substance P and neurokinin A (NKA). In vivo, the effects of intermittent isocapnic hypoxia (IH) and hypercapnia were studied using whole body flow plethysmography at P2-3 and P8-10. In vitro, anoxic responses and the effects of hypocapnic and hypercapnic conditions were studied in brain stem-spinal cord preparations (C4 activity) at P2. Hypoxic challenge considerably modified the respiratory activity in transgenic mice displayed in vivo as an attenuated increase in tidal volume during IH. Transgenic mice also showed a more prominent posthypoxic frequency decline in vivo, and posthypoxic neuronal arrests appeared more often in vitro. We recognized two types of sigh activity: with or without a following pause. During IH, the amount of sighs with a pause decreased and those without increased, a redistribution that became stronger with age only in controls. Intermittent anoxia induced long-term facilitation effects in controls, but not in Tac1(-/-) animals, manifested as an increase in burst frequency in vitro and by an augmentation of ventilation during posthypoxic periods in vivo. Thus our data demonstrate that a functional substance P/NKA system is of great importance for the generation of an adequate respiratory response to hypoxic provocation in newborn mice and during early maturation. It also indicates that substance P (and/or NKA) is involved in the development of the plasticity of the respiratory system.
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Affiliation(s)
- J Berner
- Department of Woman and Child Health, Karolinska Institutet, Stockholm, Sweden.
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Fisher AS, Stewart RJ, Yan T, Hunt SP, Stanford SC. Disruption of noradrenergic transmission and the behavioural response to a novel environment in NK1R-/- mice. Eur J Neurosci 2007; 25:1195-204. [PMID: 17331215 DOI: 10.1111/j.1460-9568.2007.05369.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The behaviour of neurokinin-1-receptor gene knockout (NK1R-/-) mice, which lack functional, substance P-preferring receptors, resembles that of NK1R+/+ mice treated with an antidepressant. Because all antidepressants increase central monoamine transmission, we have investigated whether noradrenergic transmission is increased in NK1R-/- mice and, if so, whether this could influence their behaviour. In anaesthetized subjects, the concentration of extracellular noradrenaline in NK1R-/- mice was two-fourfold greater than in NK1R+/+ mice. Systemic administration of the alpha2-adrenoceptor antagonist, 2-(2,3-dihydro-2-methoxy-1,4-benzodioxan-2-yl)-4,5-dihydro-1H-imidazoline (RX 821002), in anaesthetized or freely moving animals increased extracellular noradrenaline in NK1R+/+ mice only. This suggests that the function of alpha2a-autoreceptors, which modulate noradrenergic transmission, is impaired in NK1R-/- mice. Consistent with this, [35S]GTPgammaS binding to activated alpha2a-adrenoceptors was lower (-70%) in the locus coeruleus, but not the frontal cortex, of NK1R-/- mice compared with their NK1R+/+ counterparts. RX 821002-pretreatment, followed by retrodialysis of the noradrenaline reuptake inhibitor, desipramine, into the frontal cortex of anaesthetized mice increased extracellular noradrenaline to the same extent in the two genotypes. Western blots confirmed that there was no difference in the amount of noradrenaline transporter protein in NK1R-/- and NK1R+/+ mice. Finally, the effects of RX 821002 on certain behaviours in a light/dark exploration box were blunted in NK1R-/- mice, but there was no consistent effect on anxiety-like behaviour in the two genotypes. It is concluded that the greater basal efflux of noradrenaline in NK1R-/- mice is explained by increased transmitter release, coupled with desensitization of somatodendritic alpha2a-adrenoceptors. These changes could contribute to the difference in the behavioural phenotypes.
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Affiliation(s)
- Amy S Fisher
- Department of Anatomy and Development Biology, University College London, Gower Street, London WC1E 6BT, UK
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