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Abstract
Presynaptic receptors for four families of neuropeptides will be discussed: opioids, neuropeptide Y, adrenocorticotropic hormone (ACTH), and orexins. Presynaptic receptors for the opioids (micro, delta, kappa, and ORL(1)) and neuropeptide Y (Y(2)) inhibit transmitter release from a variety of neurones, both in the peripheral and central nervous systems. These receptors, which were also identified in human tissue, are coupled to G(i/o) proteins and block voltage-dependent Ca(2+) channels, activate voltage-dependent K(+) channels, and/or interfere with the vesicle release machinery. Presynaptic receptors for ACTH (MC(2) receptors) have so far been identified almost exclusively in cardiovascular tissues from rabbits, where they facilitate noradrenaline release; they are coupled to G(s) protein and act via stimulation of adenylyl cyclase. Presynaptic receptors for orexins (most probably OX(2) receptors) have so far almost exclusively been identified in the rat and mouse brain, where they facilitate the release of glutamate and gamma-aminobutyric acid (GABA); they are most probably linked to G(q) and directly activate the vesicle release machinery or act via a transduction mechanism upstream of the release process. Agonists and antagonists at opioid receptors owe at least part of their therapeutic effects to actions on presynaptic receptors. Therapeutic drugs targeting neuropeptide Y and orexin receptors and presynaptic ACTH receptors so far are not available.
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MESH Headings
- Animals
- Humans
- Neuropeptides/metabolism
- Orexin Receptors
- Receptors, Corticotropin/drug effects
- Receptors, Corticotropin/metabolism
- Receptors, G-Protein-Coupled/drug effects
- Receptors, G-Protein-Coupled/metabolism
- Receptors, Neuropeptide/drug effects
- Receptors, Neuropeptide/metabolism
- Receptors, Neuropeptide Y/drug effects
- Receptors, Neuropeptide Y/metabolism
- Receptors, Opioid/drug effects
- Receptors, Opioid/metabolism
- Receptors, Presynaptic/drug effects
- Receptors, Presynaptic/metabolism
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Affiliation(s)
- E Schlicker
- Institut für Pharmakologie und Toxikologie, Rheinische Friedrich-Wilhelms-Universität, Reuterstrasse 2b, 53113 Bonn, Germany.
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Larsson TA, Larson ET, Fredriksson R, Conlon JM, Larhammar D. Characterization of NPY receptor subtypes Y2 and Y7 in rainbow trout Oncorhynchus mykiss. Peptides 2006; 27:1320-7. [PMID: 16359756 DOI: 10.1016/j.peptides.2005.10.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2005] [Revised: 10/09/2005] [Accepted: 10/10/2005] [Indexed: 01/03/2023]
Abstract
We report the cloning and pharmacological characterization of two neuropeptide Y (NPY) receptor subtypes, Y2 and Y7, in rainbow trout (Oncorhynchus mykiss). These subtypes are approximately 50% identical to each other and belong to the Y2 subfamily of NPY receptors. The binding properties of the receptors were investigated after expression in human HEK-293 EBNA cells. Both receptors bound the three zebrafish peptides NPY, PYYa, and PYYb, as well as porcine NPY and PYY, with affinities in the nanomolar range that are similar to mammalian Y2. The affinity of the truncated porcine NPY fragments, NPY 13-36 and NPY 18-36 was markedly lower compared to mammalian and chicken Y2. This suggests that mammalian and chicken Y2 are unique among NPY receptors in their ability to bind truncated peptide fragments. The antagonist BIIE0246, developed for mammalian Y2, did not bind either of the two rainbow trout receptors. Our results support the proposed expansion of this gene family by duplications before the gnathostome radiation. They also reveal appreciable differences in the repertoire and characteristics of NPY receptors between fish and tetrapods stressing the importance of lineage-specific gene loss as well as sequence divergence after duplication.
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Affiliation(s)
- Tomas A Larsson
- Department of Neuroscience, Uppsala University, Box 593, SE-75124, Uppsala, Sweden.
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Canning B, Mazzone S. Reflexes Initiated by Activation of the Vagal Afferent Nerves Innervating the Airways and Lungs. ADVANCES IN VAGAL AFFERENT NEUROBIOLOGY 2005. [DOI: 10.1201/9780203492314.ch15] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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Abstract
The skeleton is an efficient 'servo' (feedback-controlled/steady-state) system that continuously integrates signals and responses which sustain its functions of delivering calcium while maintaining strength. In many individuals, bone mass homeostasis starts failing in midlife, leading to bone loss, osteoporosis and debilitating fractures. Recent advances, spearheaded by genetic information, offer the opportunity to stop or reverse this downhill course.
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Affiliation(s)
- Shun-ichi Harada
- Department of Bone Biology & Osteoporosis Research, Merck Research Laboratories, West Point, Pennsylvania 19002, USA
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Matsuda H, Brumovsky PR, Kopp J, Pedrazzini T, Hökfelt T. Distribution of neuropeptide Y Y1 receptors in rodent peripheral tissues. J Comp Neurol 2002; 449:390-404. [PMID: 12115674 DOI: 10.1002/cne.10303] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Using a sensitive immunohistochemical technique, the localization of neuropeptide Y (NPY) Y1-receptor (Y1R)-like immunoreactivity (LI) was studied in various peripheral tissues of rat. Wild-type (WT) and Y1R-knockout (KO) mice were also analyzed. Y1R-LI was found in small arteries and arterioles in many tissues, with particularly high levels in the thyroid and parathyroid glands. In the thyroid gland, Y1R-LI was seen in blood vessel walls lacking alpha-smooth muscle actin, i.e., perhaps in endothelial cells of capillaries. Larger arteries lacked detectable Y1R-LI. A distinct Y1R-immunoreactive (IR) reticulum was seen in the WT mouse spleen, but not in Y1R-KO mouse or rat. In the gastrointestinal tract, Y1R-positive neurons were observed in the myenteric plexus, and a few enteroendocrine cells were Y1R-IR. Some cells in islets of Langerhans in the pancreas were Y1R-positive, and double immunostaining showed coexistence with somatostatin in D-cells. In the urogenital tract, Y1R-LI was observed in the collecting tubule cells of the renal papillae and in some epithelial cells of the seminal vesicle. Some chromaffin cells of adrenal medulla were positive for Y1R. The problem of the specificity of the Y1R-LI is evaluated using adsorption tests as well as comparisons among rat, WT mouse, and mouse with deleted Y1R. Our findings support many earlier studies based on other methodologies, showing that Y1Rs on smooth muscle cells of blood vessels mediate NPY-induced vasoconstriction in various organs. In addition, Y1Rs in other cells in parenchymal tissues of several organs suggest nonvascular effects of NPY via the Y1R.
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MESH Headings
- Animals
- Cardiovascular System/metabolism
- Cardiovascular System/ultrastructure
- Digestive System/blood supply
- Digestive System/metabolism
- Digestive System/ultrastructure
- Endocrine System/blood supply
- Endocrine System/metabolism
- Endocrine System/ultrastructure
- Female
- Ganglia, Autonomic/blood supply
- Ganglia, Autonomic/metabolism
- Ganglia, Autonomic/ultrastructure
- Lymphatic System/blood supply
- Lymphatic System/metabolism
- Lymphatic System/ultrastructure
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Muscle, Smooth, Vascular/metabolism
- Muscle, Smooth, Vascular/ultrastructure
- Neurons/chemistry
- Neurons/ultrastructure
- Organ Specificity/physiology
- Rats
- Rats, Sprague-Dawley
- Receptors, Neuropeptide Y/deficiency
- Receptors, Neuropeptide Y/genetics
- Receptors, Neuropeptide Y/metabolism
- Receptors, Neuropeptide Y/ultrastructure
- Skin/blood supply
- Skin/metabolism
- Skin/ultrastructure
- Trachea/blood supply
- Trachea/metabolism
- Trachea/ultrastructure
- Urogenital System/blood supply
- Urogenital System/metabolism
- Urogenital System/ultrastructure
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Affiliation(s)
- Hideki Matsuda
- Department of Neuroscience, Karolinska Institutet, Retzius Laboratory, Retzius Väg 8, S-171 77 Stockholm, Sweden
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Baldock PA, Sainsbury A, Couzens M, Enriquez RF, Thomas GP, Gardiner EM, Herzog H. Hypothalamic Y2 receptors regulate bone formation. J Clin Invest 2002; 109:915-21. [PMID: 11927618 PMCID: PMC150931 DOI: 10.1172/jci14588] [Citation(s) in RCA: 125] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Neuropeptide Y (NPY) is a downstream modulator of leptin action, possibly at the level of the arcuate nucleus where NPY neurons are known to express both leptin receptors and Y2 receptors. In addition to the well-described role of NPY and leptin in energy balance and obesity, intracerebroventricular administration of NPY or leptin also causes bone loss. Here we show that Y2 receptor-deficient mice have a twofold increase in trabecular bone volume as well as greater trabecular number and thickness compared with control mice. We also demonstrate that central Y2 receptors are crucial for this process, since selective deletion of hypothalamic Y2 receptors in mature conditional Y2 knockout mice results in an identical increase in trabecular bone volume within 5 weeks. This hypothalamus-specific Y2 receptor deletion stimulates osteoblast activity and increases the rate of bone mineralization and formation, with no effect on osteoblast or osteoclast surface measurements. The lack of any changes in plasma total calcium, leptinemia, or hypothalamo-pituitary-corticotropic, -thyrotropic, -somatotropic, or -gonadotropic output suggests that Y2 receptors do not modulate bone formation by humoral mechanisms, and that alteration of autonomic function through hypothalamic Y2 receptors may play a key role in a major central regulatory circuit of bone formation.
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Affiliation(s)
- Paul A Baldock
- Bone and Mineral Program, Garvan Institute of Medical Research, St. Vincent's Hospital, Sydney, Australia
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Baldock PA, Sainsbury A, Couzens M, Enriquez RF, Thomas GP, Gardiner EM, Herzog H. Hypothalamic Y2 receptors regulate bone formation. J Clin Invest 2002. [DOI: 10.1172/jci0214588] [Citation(s) in RCA: 313] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Smith-White MA, Hardy TA, Brock JA, Potter EK. Effects of a selective neuropeptide Y Y2 receptor antagonist, BIIE0246, on Y2 receptors at peripheral neuroeffector junctions. Br J Pharmacol 2001; 132:861-8. [PMID: 11181427 PMCID: PMC1572619 DOI: 10.1038/sj.bjp.0703879] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2000] [Revised: 11/09/2000] [Accepted: 11/30/2000] [Indexed: 11/09/2022] Open
Abstract
1. This study investigated the effects of BIIE0246, a novel neuropeptide Y (NPY) Y2 receptor antagonist, on the inhibition of cholinergic neuroeffector transmission in rat heart and guinea-pig trachea and purinergic neuroeffector transmission in guinea-pig vas deferens produced by the NPY Y2 receptor agonist, N-acetyl [Leu28,31] NPY 24-36. 2. In pentobarbitone anaesthetized rats, supramaximal stimulation every 30 s, of the vagus nerve innervating the heart, increased pulse interval by approximately 100 ms. This response was attenuated by intravenous administration of N-acetyl [Leu28,31] NPY 24-36 (10 nmol x kg(-1)). 3. Transmural stimulation of segments of guinea-pig trachea at 1 min intervals with 5 s trains of stimuli at 0.5, 5, 10, 20 and 40 Hz evoked contractions which were reduced in force by N-acetyl [Leu28,31] NPY 24-36 (2 microM). 4. In guinea-pig vasa deferentia, the amplitude of excitatory junction potentials evoked by trains of 20 stimuli at 1 Hz was reduced in the presence of N-acetyl [Leu28,31] NPY 24-36 (1 microM). 5. In all preparations BIIE0246 attenuated the inhibitory effect of N-acetyl [Leu28,31] NPY 24-36 but had no effect when applied alone. 6. The findings support the view that the nerve terminals of postganglionic parasympathetic and sympathetic neurones possess neuropeptide Y Y2 receptors which, when activated, reduce neurotransmitter release.
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Affiliation(s)
- Margaret A Smith-White
- Prince of Wales Medical Research Institute, Prince of Wales Hospital, Barker St., Randwick 2031, Sydney, Australia
| | - Todd A Hardy
- Prince of Wales Medical Research Institute, Prince of Wales Hospital, Barker St., Randwick 2031, Sydney, Australia
| | - James A Brock
- Prince of Wales Medical Research Institute, Prince of Wales Hospital, Barker St., Randwick 2031, Sydney, Australia
| | - Erica K Potter
- Prince of Wales Medical Research Institute, Prince of Wales Hospital, Barker St., Randwick 2031, Sydney, Australia
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Zimmerman MP, Pisarri TE. Bronchial vasodilation evoked by increased lower airway osmolarity in dogs. J Appl Physiol (1985) 2000; 88:425-32. [PMID: 10658007 DOI: 10.1152/jappl.2000.88.2.425] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Hyperosmotic saline solutions stimulate lower airway sensory nerves. To determine whether airway hyperosmolarity evokes neurally mediated changes in bronchial artery blood flow (Qbr), we measured the effect of injection of small volumes (1 ml) of hyperosmotic saline into a right lobar bronchus on Qbr of anesthetized, artificially ventilated dogs. In 14 dogs, hyperosmotic saline (1,200 and 2,400 mmol/l) increased Qbr by 58 +/- 12 (SE) and 118 +/- 12%, respectively, from a baseline of 8 +/- 2 ml/min. Qbr increased within 6-8 s of the injections, peaked at 20 s, and returned to control over 2-3 min. Isosmotic saline had minimal effects. In contrast, hyperosmotic saline decreased flow in an intercostal artery that did not supply the airways. The bronchial vasodilation was decreased by 72 +/- 11% after combined blockade of alpha-adrenoceptors and muscarinic cholinergic receptors and by 66 +/- 6% when the cervical vagus nerves were cooled to 0 degrees C. Blockade of H(1) and H(2) histamine receptors did not reduce the nonvagal response. We conclude that hyperosmolarity of the lower airways evokes bronchial vasodilation by both a centrally mediated reflex that includes cholinergic and adrenergic efferent pathways and by unidentified local mechanisms.
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Affiliation(s)
- M P Zimmerman
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, Nebraska 68178-0405, USA
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