The Peripheral Nervous System

The Peripheral Nervous System The Peripheral Nervous System Bởi: OpenStaxCollege The peripheral nervous system (PNS) is the connection between the central nervous system and the rest of the body The CNS is like the power plant of the nervous system It creates the signals that control the functions of the body The PNS is like the wires that go to individual houses Without those “wires,” the signals produced by the CNS could not control the body (and the CNS would not be able to receive sensory information from the body either) The PNS can be broken down into the autonomic nervous system, which controls bodily functions without conscious control, and the sensory-somatic nervous system, which transmits sensory information from the skin, muscles, and sensory organs to the CNS and sends motor commands from the CNS to the muscles Autonomic Nervous System Art Connection 1/8 The Peripheral Nervous System In the autonomic nervous system, a preganglionic neuron of the CNS synapses with a postganglionic neuron of the PNS The postganglionic neuron, in turn, acts on a target organ Autonomic responses are mediated by the sympathetic and the parasympathetic systems, which are antagonistic to one another The sympathetic system activates the “fight or flight” response, while the parasympathetic system activates the “rest and digest” response Which of the following statements is false? The parasympathetic pathway is responsible for resting the body, while the sympathetic pathway is responsible for preparing for an emergency Most preganglionic neurons in the sympathetic pathway originate in the spinal cord Slowing of the heartbeat is a parasympathetic response Parasympathetic neurons are responsible for releasing norepinephrine on the target organ, while sympathetic neurons are responsible for releasing acetylcholine 2/8 The Peripheral Nervous System The autonomic nervous system serves as the relay between the CNS and the internal organs It controls the lungs, the heart, smooth muscle, and exocrine and endocrine glands The autonomic nervous system controls these organs largely without conscious control; it can continuously monitor the conditions of these different systems and implement changes as needed Signaling to the target tissue usually involves two synapses: a preganglionic neuron (originating in the CNS) synapses to a neuron in a ganglion that, in turn, synapses on the target organ, as illustrated in [link] There are two divisions of the autonomic nervous system that often have opposing effects: the sympathetic nervous system and the parasympathetic nervous system Sympathetic Nervous System The sympathetic nervous system is responsible for the “fight or flight” response that occurs when an animal encounters a dangerous situation One way to remember this is to think of the surprise a person feels when encountering a snake (“snake” and “sympathetic” both begin with “s”) Examples of functions controlled by the sympathetic nervous system include an accelerated heart rate and inhibited digestion These functions help prepare an organism’s body for the physical strain required to escape a potentially dangerous situation or to fend off a predator 3/8 The Peripheral Nervous System The sympathetic and parasympathetic nervous systems often have opposing effects on target organs Most preganglionic neurons in the sympathetic nervous system originate in the spinal cord, as illustrated in [link] The axons of these neurons release acetylcholine on postganglionic neurons within sympathetic ganglia (the sympathetic ganglia form a chain that extends alongside the spinal cord) The acetylcholine activates the postganglionic neurons Postganglionic neurons then release norepinephrine onto target organs As anyone who has ever felt a rush before a big test, speech, or athletic event can attest, the effects of the sympathetic nervous system are quite pervasive This is both because one preganglionic neuron synapses on multiple postganglionic neurons, amplifying the effect of the original synapse, and because the adrenal gland also releases norepinephrine (and the closely related hormone epinephrine) into the blood stream The physiological effects of this norepinephrine release include dilating the trachea and bronchi (making it easier for the animal to breathe), increasing heart rate, and moving blood from the skin to the heart, muscles, and brain (so the animal can think and run) 4/8 The Peripheral Nervous System The strength and speed of the sympathetic response helps an organism avoid danger, and scientists have found evidence that it may also increase LTP—allowing the animal to remember the dangerous situation and avoid it in the future Parasympathetic Nervous System While the sympathetic nervous system is activated in stressful situations, the parasympathetic nervous system allows an animal to “rest and digest.” One way to remember this is to think that during a restful situation like a picnic, the parasympathetic nervous system is in ...Planarian peptidylglycine-hydroxylating monooxygenase, a neuropeptide processing enzyme, colocalizes with cytochrome b 561 along the central nervous system Akikazu Asada 1 , Hidefumi Orii 1 , Kenji Watanabe 1 and Motonari Tsubaki 1,2,3 1 Department of Life Science, Graduate School of Life Science, University of Hyogo (formerly Himeji Institute of Technology), Hyogo, Japan 2 CREST, Japan Science and Technology Agency (JST), Saitama, Japan 3 Department of Molecular Science and Material Engineering, Graduate School of Science and Technology, Kobe University, Hyogo, Japan Neuropeptides in the brain, in the nervous system, and in various endocrine cells are synthesized in the rough endoplasmic reticulum as large precursor proteins. After transit to vesicles and during axonal transportation along axons, several processing enzymes residing in the vesicles process the peptides to convert them to mature forms. C-terminal a-amidation of the peptides occurs in the late stage [1] and is probably a rate-limiting step in many instances [2]. Over half of peptide hormones or neuropeptides are amidated in vertebrates; in insects, greater than 90% of such peptides show the presence of a C-terminal amide moiety [3]. This C-terminal amide is very important in their functions, as its absence often disrupts the activity or receptor-binding properties of the peptide ligands [4]. Indeed, most neurotransmitters thus far identified are amidated peptides in cnidarians Keywords peptidylglycine a-hydroxylating monooxygenase; cytochrome b 561 ; planarian; neuroendocrine vesicle; neuropeptide amidation Correspondence M. Tsubaki, Department of Molecular Science and Material Engineering, Graduate School of Science and Technology, Kobe University, Rokkodai-cho, Nada-ku, Kobe, Hyogo 657-8501, Japan Fax: +81 78 803 6582 Tel: +81 78 803 6582 E-mail: mtsubaki@kobe-u.ac.jp Note The nucleotide sequence of planarian PHM in this article has been submitted to the DDBJ ⁄ EMBL ⁄ GenBank databases with accession number AB195502. (Received 27 September 2004, revised 2 December 2004, accepted 14 December 2004) doi:10.1111/j.1742-4658.2004.04528.x Planarians are one of the simplest animal groups with a central nervous system. Their primitive central nervous system produces large quantities of a variety of neuropeptides, of which many are amidated at their C terminus. In vertebrates, peptide amidation is catalyzed by two enzymes [peptidylglycine a-hydroxylating monooxygenase (PHM) and peptidyl-a- hydroxylglycine a-amidating lyase] acting sequentially. In mammals, both enzymatic activities are contained within a single protein that is encoded by a single gene. By utilizing PCR with degenerate oligonucleotides derived from conserved regions of PHM, we succeeded in cloning a full-length cDNA encoding planarian PHM. The deduced amino acid sequence showed full conservation of five His residues and one Met residue, which bind two Cu atoms that are essential for the activity of PHM. Northern blot analysis confirmed the expression of a PHM mRNA of the expected size. Distribution of the mRNA was analyzed by in situ hybridization, showing specific expression in neurons with two morphologically distinct structures, a pair of the ventral nerve cords and the brain. The distribution of PHM was very similar to that of cytochrome b 561 . This indicates that the ascorbate-related electron transfer system operates in the planarian cen- tral nervous system to support the PHM activity and that it predates the emergence of Plathelminthes in the evolutionary history. Abbreviations AsA, ascorbic acid; CNS, central nervous BioMed Central Page 1 of 13 (page number not for citation purposes) Journal of Neuroinflammation Open Access Research Temporal expression and cellular origin of CC chemokine receptors CCR1, CCR2 and CCR5 in the central nervous system: insight into mechanisms of MOG-induced EAE Sana Eltayeb 1 , Anna-Lena Berg* 2 , Hans Lassmann 3 , Erik Wallström 1 , Maria Nilsson 4 , Tomas Olsson 1 , Anders Ericsson-Dahlstrand 4 and Dan Sunnemark 4 Address: 1 Department of Clinical Neuroscience, Center for Molecular Medicine, Neuroimmunology Unit, Karolinska Institute, S-171 76 Stockholm, Sweden, 2 Department of Pathology, Safety Assessment, AstraZeneca R&D Södertälje, S-15185 Södertälje, Sweden, 3 Brain Research Institute, University of Vienna, Vienna, Austria and 4 Department of Disease Biology, Local Discovery Research Area CNS and Pain Control, AstraZeneca R&D Södertälje, S-151 85 Södertälje, Sweden Email: Sana Eltayeb - Sana.Eltayeb@ki.se; Anna-Lena Berg* - Anna-Lena.Berg@astrazeneca.com; Hans Lassmann - Hans.Lassmann@meduniwien.ac.at; Erik Wallström - Erik.Wallstrom@ki.se; Maria Nilsson - Maria.Nilsson@astrazeneca.com; Tomas Olsson - Tomas.Olsson@ki.se; Anders Ericsson-Dahlstrand - Anders.Ericsson-Dahlstrand@astrazeneca.com; Dan Sunnemark - Dan.Sunnemark@astrazeneca.com * Corresponding author Abstract Background: The CC chemokine receptors CCR1, CCR2 and CCR5 are critical for the recruitment of mononuclear phagocytes to the central nervous system (CNS) in multiple sclerosis (MS) and other neuroinflammatory diseases. Mononuclear phagocytes are effector cells capable of phagocytosing myelin and damaging axons. In this study, we characterize the regional, temporal and cellular expression of CCR1, CCR2 and CCR5 mRNA in the spinal cord of rats with myelin oligodendrocyte glycoprotein-induced experimental autoimmune encephalomyelitis (MOG-EAE). While resembling human MS, this animal model allows unique access to CNS-tissue from various time-points of relapsing neuroinflammation and from various lesional stages: early active, late active, and inactive completely demyelinated lesions. Methods: The expression of CCR1, CCR2 and CCR5 mRNA was studied with in situ hybridization using radio labelled cRNA probes in combination with immunohistochemical staining for phenotypic cell markers. Spinal cord sections from healthy rats and rats with MOG-EAE (acute phase, remission phase, relapse phase) were analysed. In defined lesion stages, the number of cells expressing CCR1, CCR2 and CCR5 mRNA was determined. Data were statistically analysed by the nonparametric Mann-Whitney U test. Results: In MOG-EAE rats, extensive up-regulation of CCR1 and CCR5 mRNA, and moderate up-regulation of CCR2 mRNA, was found in the spinal cord during episodes of active inflammation and demyelination. Double staining with phenotypic cell markers identified the chemokine receptor mRNA-expressing cells as macrophages/microglia. Expression of all three receptors was substantially reduced during clinical remission, coinciding with diminished inflammation and demyelination in the spinal cord. Healthy control rats did not show any detectable expression of CCR1, CCR2 or CCR5 mRNA in the spinal cord. Section III. Drugs Acting on the Central Nervous System Chapter 12. Neurotransmission and the Central Nervous System Overview Drugs that act upon the central nervous system (CNS) influence the lives of everyone, every day. These agents are invaluable therapeutically because they can produce specific physiological and psychological effects. Without general anesthetics, modern surgery would be impossible. Drugs that affect the CNS can selectively relieve pain, reduce fever, suppress disordered movement, induce sleep or arousal, reduce the desire to eat, or allay the tendency to vomit. Selectively acting drugs can be used to treat anxiety, mania, depression, or schizophrenia and do so without altering consciousness (see Chapters 19: Drugs and the Treatment of Psychiatric Disorders: Depression and Anxiety Disorders and 20: Drugs and the Treatment of Psychiatric Disorders: Psychosis and Mania). The nonmedical self-administration of CNS-active drugs is a widespread practice. Socially acceptable stimulants and antianxiety agents produce stability, relief, and even pleasure for many. However, the excessive use of these and other drugs also can affect lives adversely when their uncontrolled, compulsive use leads to physical dependence on the drug or to toxic side effects, which may include lethal overdosage (see Chapter 24: Drug Addiction and Drug Abuse). The unique quality of drugs that affect the nervous system and behavior places investigators who study the CNS in the midst of an extraordinary scientific challenge—the attempt to understand the cellular and molecular basis for the enormously complex and varied functions of the human brain. In this effort, pharmacologists have two major goals: to use drugs to elucidate the mechanisms that operate in the normal CNS and to develop appropriate drugs to correct pathophysiological events in the abnormal CNS. Approaches to the elucidation of the sites and mechanisms of action of CNS drugs demand an understanding of the cellular and molecular biology of the brain. Although knowledge of the anatomy, physiology, and chemistry of the nervous system is far from complete, the acceleration of interdisciplinary research on the CNS has led to remarkable progress. This chapter introduces guidelines and fundamental principles for the comprehensive analysis of drugs that affect the CNS. Specific therapeutic approaches to neurological and psychiatric disorders are discussed in the chapters that follow in this section (see Chapters 13: History and Principles of Anesthesiology, 14: General Anesthetics, 15: Local Anesthetics, 16: Therapeutic Gases: Oxygen, Carbon Dioxide, Nitric Oxide, and Helium, 17: Hypnotics and Sedatives, 18: Ethanol, 19: Drugs and the Treatment of Psychiatric Disorders: Depression and Anxiety Disorders, 20: Drugs and the Treatment of Psychiatric Disorders: Psychosis and Mania, 21: Drugs Effective in the Therapy of the Epilepsies, 22: Treatment of Central Nervous System Degenerative Disorders, 23: Opioid Analgesics, and 24: Drug Addiction and Drug Abuse). Organizational Principles of the Brain The brain is an assembly of interrelated neural systems that regulate their own and each other's activity in a dynamic, complex fashion. Macrofunctions of Brain Regions The large anatomical divisions provide a superficial classification of the distribution of Minireview The long term effects of chemotherapy on the central nervous system Patricia K Duffner Address: Department of Neurology, Women and Children’s Hospital of Buffalo, University of Buffalo School of Medicine, 219 Bryant St., Buffalo, NY 14222, USA. Email: PatriciaDuffner@aol.com Although the long-term effects of irradiation on the central nervous system (CNS) are now well-known and accepted, the long term consequences of most chemotherapeutic agents have rarely been considered, either in the develop- ment of multi-institutional cancer group studies or in the follow-up of survivors. In this issue of Journal of Biology, Mark Noble and colleagues [1] describe an interesting and important series of experiments that helps define the cellular basis for cognitive decline and white matter diseases (leukoencephalopathy) in patients treated with chemotherapy. Noble and colleagues [1] have now shown that standard chemotherapeutic agents, given in dosages comparable to those used in the clinical arena, are even more toxic to CNS progenitor cells and oligodendrocytes than they are to cancer cell lines, causing both decreased cell division and cell death. The authors conducted four groups of experiments. In the first, DNA cross-linking agents - 1,3-bis(2-chlorethyl)-1-nitrosourea (BCNU) and cisplatin (CDDP) - were applied in vitro to purified populations of neuroepthelial stem cells, neural-restricted precursor cells, glial-restricted precursor cells, and oligodendrocyte precursor cells (O-2A/OPCs) as well as to a variety of human cancer cell lines. They found that clinically relevant concentrations of BCNU or CDDP were more toxic to lineage-committed precursor cells and neuroepithelial stem cells than to cancer cells. These effects were seen even at very low levels of exposure. Moreover, the vulnerability was not restricted to dividing cells, as non-dividing oligodendrocytes were as much at risk as the rapidly dividing neural progenitor cells. In the second in vitro experiment, O-2A/OPCs exposed to sublethal concentrations of CDDP and BCNU were found to have both reduced cell division and increased differen- tiation into oligodendrocytes. Thus, the chemotherapy compromised the ability of the O-2A/OPCs to continue cell division and form new precursor cells. In the third experiment, mice were treated systemically with BCNU and CDDP and then examined for evidence of cell death and cell division in the CNS. As with the in vitro experiments, neuronal and glial progenitor cells and oligodendrocytes were adversely affected, particularly in the subventricular zone, the corpus callosum and the dentate gyrus of the hippocampus. By examining incorporation of bromodeoxyuridine (BrdU) in adult animals, the authors found that cell proliferation in putative germinal zones was Abstract Cranial radiotherapy is known to have adverse effects on intelligence. A new study shows that chemotherapy is also toxic to the central nervous system, especially to neural progenitor cells and oligodendrocytes. By identifying the cell populations at risk, these results may help explain the neurological problems previously seen after chemotherapy. BioMed Central Journal of Biology Journal of Biology 2005, 5:21 Published: 30 November 2006 Journal of Biology 2006, 5:21 The electronic version of this article is the complete one and can be found online at http://jbiol.com/content/5/7/21 © 2006 BioMed Central Ltd reduced for at least 6 weeks following repeated injections of BCNU. Overall, the effects of CDDP were more transient than those produced by BCNU. In the fourth experiment, AraC (an antimetabolite) was found to be highly toxic in vitro for neural progenitor cells in concentrations equivalent to those used in clinical trials. As with BCNU and CDDP, O-2A/OPCs were more sensitive to adverse effects than were the leukemia and lymphoma cell lines. In addition, sublethal concentrations of the drug were associated with suppression of cell division in clonal assays. ... mediated by the sympathetic and the parasympathetic systems, which are antagonistic to one another The sympathetic system activates the “fight or flight” response, while the parasympathetic system. .. sensory-somatic nervous systems The autonomic nervous system provides unconscious control over visceral functions and has two divisions: the sympathetic and parasympathetic nervous systems The sympathetic nervous. .. are the main differences between the sympathetic and parasympathetic branches of the autonomic nervous system? The sympathetic nervous system prepares the body for “fight or flight,” whereas the