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Clinical Neurochemistry PowerPoint Presentation

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Description : Check out this medical PowerPoint presentation titled "Clinical Neurochemistry”.

This medical PowerPoint presentation is about Clinical neurochemistry is a branch of medical science that deals with the study of chemical processes and abnormalities in the nervous system. It involves the analysis of various biochemical markers in body fluids such as blood, cerebrospinal fluid (CSF), and urine, to diagnose and monitor neurological disorders.

The central nervous system (CNS) and peripheral nervous system (PNS) rely on a complex network of neurotransmitters, neuromodulators, and other signaling molecules to communicate between cells and control bodily functions. Any disturbance in these chemical processes can result in a range of neurological disorders such as Alzheimers disease, Parkinsons disease, multiple sclerosis, epilepsy, and depression.

Clinical neurochemistry aims to identify and measure biomarkers that can help in the diagnosis, prognosis, and treatment of these disorders. Some of the commonly measured biomarkers in clinical neurochemistry include neurotransmitters such as dopamine, serotonin, and acetylcholine, as well as proteins such as tau, amyloid beta, and alpha-synuclein.

Various techniques such as chromatography, electrophoresis, immunoassays, and mass spectrometry are used to measure these biomarkers accurately. The results obtained from these tests help doctors to diagnose and monitor neurological disorders, and also to evaluate the effectiveness of treatments.

In summary, clinical neurochemistry plays a crucial role in understanding the chemical processes that underlie neurological disorders, and in developing effective diagnostic and treatment strategies to improve patient outcomes.

Tags : Clinical neurochemistry, nervous system, biochemical markers in body fluids, blood, cerebrospinal fluid, urine, monitor neurological disorders, central nervous system, peripheral nervous system, neurotransmitters, neuromodulators, Neurology, Neurology PowerPoint presentation

Published on : Jun 20, 2023 | Views : 1664 | Downloads : 1

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Slide 1-

Clinical Neurochemistry “The Soup”
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A good working knowledge of clinical neurochemistry is essential for understanding and treating neurological and psychiatric disorders. It is important to learn the basics now so you can update your clinical management as new information becomes available.
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What You Should Know Primary cell bodies, sites of action and metabolic pathways for dopamine, norepinepherine, serotonin, acetylcholine, GABA and glutamate Know the main mechanism of action and termination of action of the most common neurotransmitters Be aware of the most common receptor subtypes for each neurotransmitter Be familiar with examples of the mechanism of action of commonly used drugs for each neurotransmitter and the diseases they treat
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Advances in Neurochemistry Slow neurotransmitters include the monoamines and work through G proteins and second messengers Fast neurotransmitters include GABA and glutamate and bind directly on ion-gated channels
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Clinical Neurochemistry Monoamines Dopamine Norepinephrine Serotonin Others Acetylcholine GABA Glutamate
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Catecholamines Dopamine Norepinephrine Epinephrine
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Dopamine (Main Cell Bodies) Long tracts Substantia nigra  primarily to striatum Ventral tegmental area  striatum plus the mesolimbic and mesocortical systems Intermediate Hypothalamic—pituitary (DA inhibits prolactin) Short Olfactory Retina
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Dopamine cell bodies and tracts SN VTA DR Weigert stain of the midbrain SN=substantia nigra, VTA= ventral tegmental area, DR= dorsal raphe
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Phenylalanine Phenylalanine hydroxylase
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Rate-Limiting Step and Termination of Action of Dopamine Action of tyrosine hydroxylase is the rate-limiting step The main termination of action for the monoamines is presynaptic reuptake Monoamine oxidase (MAOB), catechol-O-methyltransferase (COMT)
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Monoaminergic Receptors Formed by 7 membrane spanning regions with an intracellular carboxy tail and an intracellular amino region The structure of the receptors are highly conserved with small changes in amino acid sequence leading to changes in receptor affinity Monoaminergic receptors exert their effect through G-proteins and other 2nd, 3rd and 4th messengers that often cause protein phosphorylation and regulation of an ion channel
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Dopamine Receptors D1 is the most common and thought to involve stimulation of adenylate cyclase and increased production of cyclic AMP D1 receptors are found in the striatum but also abundantly in cortical and limbic regions D2 receptors are located primarily in the striatum and inhibit adenylate cyclase The D3, D4 and D5 receptors occur primarily in cortical and limbic regions
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Drugs that affect the dopaminergic system Neuroleptics are classified as typical or typical based on their degree of blockade of the D2 receptor Haloperidol is a potent D2 blocker and typical antipsychotic. It is an effective antipsychotic but can cause Parkinsonism, tardive dyskinesia (TD) and cognitive slowing. Clozapine is an atypical antipsychotic with weak antagonism at D1 and D2 receptors and blocks 5HT2 serotonin receptors. It may exert its antipsychotic effect by blocking D4 receptors, thereby sparing the striatum. Clozapine does not normally cause extrapyramidal symptoms, TD, or increased prolactin.
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Too much dopamine can cause euphoria, confusion and psychosis. Too little produces Parkinsonism Dopamine does not cross the blood-brain barrier. Replace dopamine in Parkinson’s disease with L-dopa. Cocaine blocks reuptake. Amantadine and amphetamine promote presynaptic release. MAO-B inhibitors such as deprenyl are specific for blocking dopamine breakdown at the usual doses of 5 mg/bid. Clinical Significance
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NE cell bodies are in the locus ceruleus at the upper dorsal pons.
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Noradrenergic Cell Bodies in the Dorsal Pons LC LC AS Weigert myelin stain of pons. LC=locus ceruleus, AS=aqueduct of Sylvius
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Metabolism—Termination Reuptake—main route of termination COMT  Normetanephrine + MAO  VMA (3 methoxy 4 hydroxy-mandelic acid) MAO  MHPG (3 methoxy-4 hydroxy-phenylglycol)
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Alpha and beta receptors in a noradrenergic synapse
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Noradrenergic Receptors Phenoxybenzamine and phentolamine are A1 blockers and are used in the treatment of hypertension Clonidine is an alpha2 presynaptic autoreceptor agonist and causes a decrease in sympathetic tone. It is useful in the treatment of hypertension and opiate withdrawal Yohimbine is primarily an alpha2 presynaptic antagonist and causes an increase in sympathetic tone which may lead to increased arousal, panic anxiety and sexual potency. The beta receptors are thought to activate cyclic AMP
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The amygdala is richly innervated by nonadrenergic neurons in the locus ceruleus. Norepinephrine plays an important role in panic disorder, maintenance of attention and transmission of pleasurable stimuli via the brainstem reticular activating system and medial forebrain bundle. NE enhances emotional memories and beta blockers can inhibit the formation of emotional memories There is a dropout of noradrenergic neurons in the locus ceruleus in patients with Parkinson’s disease which may contribute to the high incidence of depression and anxiety in PD Clinical Significance
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Serotonin Cell bodies Main cell bodies are in the dorsal raphe nuclei surrounding the cerebral aqueduct in the midbrain. They project diffusely to the striatum, limbic system, cortex and cerebellum. Caudal raphe nuclei in the pons and medulla project to the spinal cord and probably play a role in the mediation of pain in the dorsal horn of the cord
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Synthesis Availability of tryptophan is the rate limiting step in serotonin synthesis
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Metabolism Reuptake—primary method of inactivation MAO 5-HIAA Clinical significance Serotonin has effects on: Sleep induction Mood Pain/headache Nausea Anxiety Extrapyramidal system Pleasure Vasomotor tone Psychosis
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Availability of tryptophan is the rate-limiting step, Activity of Tryptophan hydroxylase is also important Reserpine depletes vesicular stores and may exacerbate depression Fenfluramine promotes presynaptic release MAOI pre- and postsynaptically slows metabolism Tricyclic antidepressants such as amitriptyline, and fluoxetine inhibit reuptake Clinical Significance
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Serotonergic Receptors A very active area of research. 5-HT1-7 receptors have been described; subtypes of each group have been identified 5-HT1 works primarily  or  adenylate cyclase, Imitrex, used to treat acute migraine, is a 1D agonist 5-HT receptors affect phosphatidylinositol systems methysergide, LSD Ondansetron a 5-HT3 antagonist is a potent antiemetic
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Serotonin Syndrome MS—confusion, agitation, restlessness Motor—myoclonus, rigidity, hyperreflexia Autonomic-shivering, flushing, fever, diaphoresis GI—nausea, diarrhea
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Acetylcholine Primary cell bodies Found in the patchy forebrain nuclei of the nucleus basalis of Mynert and septal nuclei Rich connections to the hippocampus and amygdala Ach is the main neurotransmitter at the neuromuscular jct and in the autonomic nervous system Termination of action by both: Enzymatic cholinesterase- choline plus acetate By reuptake of choline
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NBM NBM=nucleus basalis of Meynert
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Acetylcholine Involved in: Memory and attention Induction of REM sleep Regulation of behavior Motor function Autonomic nervous system
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Clinical Significance Choline acetyltransferase (CAT) is the enzyme involved in the synthesis of Ach, CAT decreases in AD Botulinum toxin inhibits release of acetylcholine and is useful for the treatment of focal dystonia. Lambert-Eaton syndrome, a paraneoplastic disorder, leads to decreased release of Ach Acetylcholinesterase inhibitors such as Aricept, Exelon and Reminyl are approved for the Rx of mild-mod AD. Reminyl also modulates presynaptic nicotinic receptors. Exelon also inhibits butyrylcholinesterase Mestinon, a peripheral cholinesterase inhibitor, improves motor symptoms in myasthenia gravis
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Cholinergic Receptors Nicotinic at NMJ and ANS. Antibodies formed against nicotinic cholinergic receptors at the neuromuscular junction cause myasthenia gravis M1-5 muscarinic receptors in the brain. Nicotinic receptors also in brain. M2 and 4 decrease cAMP and M1,3,5 work via PI Atropine and scopolamine block muscarinic receptors. Atropine increases heart rate, slows GI motility and dilates the pupils. Scopolamine can cause memory disturbance. Urecholine, an autonomic agonist, promotes bladder emptying. Ditropan, an autonomic antagonist, promotes retention of urine
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GABA Distribution The major inhibitory neurotransmitter in the brain Ubiquitously distributed High concentrations in the striatum, hypothalamus, spinal cord, colliculi and medial temporal lobe Synthesis Glutamate (amino acid precursor)  Glutamic acid decarboxylase (GAD) GABA
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GABA Receptors GABA A-chloride channel GABA binding opens the chloride channel Benzodiazepines enhance GABA affinity and activity Bicuculline is a receptor antagonist and induces seizures Barbiturates and alcohol help open the chloride channel at another site in the receptor Picrotoxin inhibits the chloride channel and produces seizures GABA is found to be decreased in the striatum in Huntington’s disease GABA B-Baclofen
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GABA Neuron
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GABA Function Benzodiazepines are used to treat anxiety, seizures, and muscle spasms GABA transaminase inhibitor vigabatrin used in Europe for epilepsy The anticonvulsant tiagabine (Gabatril) blocks reuptake of GABA Topiramate (Topamax), divalproex (Depakote), gabapentin (Neurontin) and other AC’s modulate GABA
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Glutamate The most common excitatory neurotransmitter in the CNS. Amino acid involved in excitotoxic injury, seizures, learning, memory, anxiety, depression, psychosis Blockade of glutamate receptors may have a protective role for tissue at risk in acute stroke and for TBI. MK801 and PCP are NMDA antagonists and both cause psychotic symptoms Riduzole and lamotrigine medication for ALS and epilepsy decrease glutamatergic transmission. Memanatine an NMDA antagonist is being tried for advanced AD
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Glutamate Receptor Function Glutamate, at NMDA receptors, leads to opening of an ion channel and influx of Ca and Na The block of Mg is removed by activation of an AMPA receptor Glycine must also bind to its receptor to allow Ca and Na influx Some glutamate receptors are metabotropic and use 2nd messengers Glutamate reuptake is tightly regulated
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Feeling stuck? Check out the Neurotransmitter Table on p. 73
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Questions 1. Why does cocaine chorea? a. It is a dopamine agonist b. It reduces GABA levels c. It enhances serotonin d. It increases endogenous dopamine 2. Which glutamate reactions are neurotoxic? a. Glutamate-ACh c. Glutamate-NMDA b. Glutamate-dopamine d. Glutamate-serotonin 3. Stimulation of which dopamine receptor(s) increases adenyl cyclase activity? a. D1 receptors c. Both D1 and D2 b. D2 receptors d. Neither
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Questions 4. The primary cell bodies for dopamine are located in the nucleus accumbens? a. True b. False Matching Type: 5. Dopamine a. Locus ceruleus 6. Serotonin b. Nucleus basalis of Meynert 7. Acetylcholine c. Substantia nigra 8. Norepinepherine d. Dorsal raphe 9. Dopamine a. Pons 10. Serotonin b. Midbrain 11. Acetylcholine c. Basal forebrain 12. Norepinepherine d. Cerebellum
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Questions 13. What is the rate-limiting step in norepinepherine synthesis? a. Phenylalanine to tyrosine d. Tyrosine to dopa b. Tyrosine to tyrosine e. Dopa to norepinephine hydroxylase 14. Clozapine does not increase prolactin. a. True b. False 15. The activity of the monoamines is primarily terminated by: a. breakdown by MAO d. phosphorylation b. reuptake into the e. Ion channel inactivation presynaptic neuron c. Conversion to choline and acetate
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Answers 1. D 2. C 3. A 4. B 5. C 6. D 7. B 8. A 9. B 10. B 11. C 12. A 13. D 14. A 15. B
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People and Pills and the Art of Medicine
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Surgical Treatment- Cavernous Hemangioma
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9/29/2003
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9/29/2003