Acetylcholine & Glutamate PDF

Acetylcholine & Glutamate @Arturas Volianskis EOAD Wells, Jennie L.; Pasternak, Stephen H., Alzheimer Disease & Associated Disorders33(2):166-169, April-June 2019. doi: 10.1097/WAD.0000000...

Acetylcholine & Glutamate @Arturas Volianskis EOAD Wells, Jennie L.; Pasternak, Stephen H., Alzheimer Disease & Associated Disorders33(2):166-169, April-June 2019. doi: 10.1097/WAD.0000000000000269 Acetylcholine & Glutamate Learning outcomes: 1. Introduce Myasthenia Gravis, its symptoms and causes. 2. Discuss synthesis of ACh, distribution of its nuclei in the brain, ACh pathways, receptors, some of the agonists and antagonists. 3. Introduce Alzheimer’s disease, its symptoms, treatment and diagnosis. 4. Introduce and discuss glutamate, its synthesis and termination of action; and glutamate receptor types. 5. Discuss NMDA receptors, their subunit expression and function. BI2432: Fundamental neuropharmacology Acetylcholine Amanita muscaria Case story - Myasthenia Gravis Working as a librarian at a high school, in December 2017 the patient noticed her eyelids were drooping while she was taking off her makeup before bed. Over the Christmas break she began to notice double vision and arm weakness while reading which became progressively worse. She visited her in early January 2018 who referred her to a local neurologist after having concerns. During her appointment with the neurologist, he ran a blood test and found high levels of acetylcholine receptor antibodies. After her blood test results and a physical exam, he diagnosed her with Myasthenia Gravis. She was prescribed a cholinesterase inhibitor medication and took time off work to help with her symptoms. Over the summer break, the patient continued to take her medication and took time to Most people with myasthenia gravis rest and relax. She noticed improvements in her condition have weakness in the muscles of the and was eager to return to work in late August to prepare eyes, eyelids and face. for the upcoming school year. Symptoms might include:droopy eyelids (1 or both eyes), double vision, difficulty making facial expressions, etc. https://www.physio-pedia.com/ Myasthenia_Gravis_Case_Study https://www.nhs.uk/conditions/myasthenia-gravis/symptoms/ BI2432: Fundamental neuropharmacology ACh is synthesised from choline & acetyl coenzyme A Choline is found in high concentrations in the presynaptic terminal. It primarily comes from fat in our diet, but can also be produced in small amounts by the liver. Choline acetyltransferase is the enzyme required to combine acetyl coenzyme A and choline into acetylcholine. Choline acetyltransferase is present only in the cholinergic neurones. Acetylcholine is used at the NMJ to elicit muscle contractions and acts as a neuromodulator in the brain regulating many functions, including memory and sleep. BI2432: Fundamental neuropharmacology Anatomy of cholinergic pathways BI2432: Fundamental neuropharmacology Anatomy of cholinergic pathways BI2432: Fundamental neuropharmacology Synthesis and degradation of ACh 1. Acetylcholine is synthesised from acetyl CoA and choline. 2. The newly synthesised transmitter is pumped into vesicles. 3. The neurotransmitter is released upon the arrival of an action potential. 4. ACh acts for a short time on postsynaptic receptors before it is degraded by AChE. 5. Choline is recycled and pumped back into the presynaptic terminal by the choline transporter. BI2432: Fundamental neuropharmacology Nicotinic and muscarinic ACh receptors Cholinergic receptors are named after the selective agonists which mimic the effects of the endogenous ligand (ACh). Agonist Antagonist nicotine curare 1 muscarine atropine 1 2 2 BI2432: Fundamental neuropharmacology Nomenclature of ACh receptors and their subunits (α1)2(β1)(γ)(δ or ε) (α4)2(β2)3 (α7)5 Each nicotinic receptor consists of five subunits (α, β, γ, δ, ε). There are ten α subunits and four β subunits. Receptors in muscle cells have a different composition than receptors in neurones. Nicotinic receptors are permeable Na+ and K+, with some subunit combinations also permeable to Ca2+. BI2432: Fundamental neuropharmacology Case story - Myasthenia gravis, an autoimmune disease 1. Antibody testing 2. Electromyography 3. Neostagmine (edrophonium) test https://www.nhs.uk/conditions/myasthenia-gravis/diagnosis/ BI2432: Fundamental neuropharmacology Inhibition of ACh release reverses ageing? Botox is an injectable form of botulinum toxin. Before Treatment: Note the presence of “unsightly” wrinkles above the brow. Wrinkles occur when muscles in the face are chronically After Treatment: activated. Botox The muscles are now “erases” these paralysed and remain wrinkles by paralysing relaxed. the wrinkle-causing muscles. BI2432: Fundamental neuropharmacology Muscarinic ACh receptors Prototypical muscarinic antagonists include atropine and scopolamine. Neither of these is subtype selective. Atropine is a derivative of belladonna, whose name (beautiful woman) reflects its historical cosmetic use as a pupillary dilator. Belladonna is produced by the deadly nightshade plant, named because ingestion of excessive amounts are dangerous. Indeed, any excess use of antimuscarinic drugs produces cognitive impairment, and at higher doses delirium, along with tachycardia and other dangerous autonomic symptoms. BI2432: Fundamental neuropharmacology Ligands affecting cholinergic transmission BI2432: Fundamental neuropharmacology Ligands affecting cholinergic transmission BI2432: Fundamental neuropharmacology  Glutamate Glutamate Case story - Early Onset Alzheimer’s Disease The patient was referred to our specialty memory clinic at the age of 58 with a 2-year history of repetitiveness, memory loss, and executive function loss. Magnetic resonance imaging scan at age 58 revealed mild generalized cortical atrophy. She is white with 2 years of postsecondary education. Retirement at age 48 from employment as a manager in telecommunications company was because family finances allowed and not because of cognitive challenges with work. Progressive cognitive decline was evident by the report of deficits in instrumental activities of daily living performance over the past 9 months before her initial consultation in the memory clinic. Word finding and literacy skills were noted to have deteriorated in the preceding 6 months according to her spouse. Examples of functional losses were being slower in processing and carrying out instructions, not knowing how to turn off the stove, and becoming unable to assist in boat docking which was the couple’s pastime. She stopped driving a motor vehicle about 6 months before her memory clinic consultation. Her past medical history was relevant for hypercholesterolemia and vitamin D deficiency. She had no surgical history. She had no history of smoking, alcohol, or other drug misuse. Laboratory screening was normal. There was no first-degree family history of presenile dementia. Neurocognitive assessment at the first clinic visit revealed a Mini Mental State Examination (MMSE) score of 14/30; poor verbal fluency (patient was able to produce only 5 animal names and 1 F-word in 1 min) as well as poor visuospatial and executive skills. She had fluent speech without semantic deficits. Her neurological examination was pertinent for normal muscle tone and power, mild ideomotor apraxia on performing commands for motor tasks with no suggestion of cerebellar dysfunction, normal gait, no frontal release signs. Her speech was fluent with obvious word finding difficulties but with no phonemic or semantic paraphrasic errors. Her general physical examination was unremarkable without evidence of presenile cataracts. She had normal hearing. There was no evidence of depression or psychotic symptoms. Wells, Jennie L.; Pasternak, Stephen H., Alzheimer Disease & Associated Disorders33(2):166-169, April-June 2019. doi: 10.1097/WAD.0000000000000269 BI2432: Fundamental neuropharmacology Case story - Early Onset Alzheimer’s Disease Because of her young age and clinical presentation with no personality changes, language or motor change, nor fluctuations, EOAD was the most likely clinical diagnosis. As visuospatial challenges were marked at her first visit and poor depth perception developing over time, posterior cortical variant of AD was also on the differential as was atypical presentation of frontotemporal dementias. Without fluctuations, Parkinsonism, falls, hallucinations, or altered attention, Lewy Body dementia was deemed unlikely. After treatment with a cholinesterase inhibitor, her MMSE improved to 18/30, tested 15 months later with stability in function. Verbal fluency improved marginally with 7 animals and 3 F-words. After an additional 18 months, function and cognition declined (MMSE=13/30) so memantine was added. The stabilizing response to the cholinesterase inhibitor added some degree of confidence to the EOAD diagnosis. In the subsequent 4 years, she continued to decline in cognition and function such that admission to a care facility was required with associated total dependence for basic activities of daily living. Noted by family before transfer to the long-term care facility were episodic possible hallucinations. It was challenging to know if what was described was misinterpretation of objects in view or a true hallucination. During this time, she developed muscle rigidity, motor apraxias, worsening perceptual, and language skills and became dependent for all activities of daily livings. At the fourth year of treatment, occasional myoclonus was noted. She was a 1 person assist for walking because of increased risk of falls. After 1 year in the care home, she was admitted to the acute care hospital in respiratory distress. CT brain imaging during that admission revealed marked generalized global cortical atrophy and marked hippocampal atrophy. She died at age 63 of pneumonia. An autopsy was performed confirming the cause of death and her diagnosis of AD, showing numerous plaques and tangles with congophilic amyloid angiopathy. In addition, there was prominent Lewy Body pathology noted in the amygdala. Wells, Jennie L.; Pasternak, Stephen H., Alzheimer Disease & Associated Disorders33(2):166-169, April- June 2019. doi: 10.1097/WAD.0000000000000269 BI2432: Fundamental neuropharmacology Glutamate synthesis and inactivation BI2432: Fundamental neuropharmacology Glutamate synthesis and inactivation BI2432: Fundamental neuropharmacology Glutamatergic transmission Jeff Watkins BI2432: Fundamental neuropharmacology iGluR subunits BI2432: Fundamental neuropharmacology Activation by NMDAR, AMPAR (Quis) and Kainate R BI2432: Fundamental neuropharmacology Ketamine; an antagonist of NMDA receptors QK QK QK N N N Q = Quisqualate (AMPAR agonist) Lodge D and Mercier MS British Journal of K = Kainate Pharmacology 2015 (review) N = NMDA BI2432: Fundamental neuropharmacology Types of NMDA receptors Conventional NMDA receptors contain 2 GluN1 subunits and 2 GluN2 subunits Unconventional NMDARs incorporate GluN3 subunits in addition to either GluN1 or also GluN2 and less is known about them NMDARs can be either di-heteromeric (incorporating up to 2 types of different sub-units) or tri-heteromeric (3 types). BI2432: Fundamental neuropharmacology Conventional NMDARs Channel blockers Agonists Coagonists Glutamate Glycine M Memantine NMDA D-serine Na +/ Ca 2+ + Mg2+ Antagonists SH Modulators D-AP5 Polyamines 5,7-DCKA Ifenprodil Zn 2+ GluN2B GluN1 M Histamine + SH Redox N N Pregnenolone N2A N1 N1 N2B K+ Parsons CG, Stöffler A & Danysz W (2007). Memantine: a NMDA receptor antagonist that improves memory by restoration of homeostasis in the glutamatergic system - too little activation is bad, too much is even worse. Neuropharmacology 53, 699–723. BI2432: Fundamental neuropharmacology  Glu and gly sensitivity of GluN1/N2 receptors GluN1/2A GluN1/2C (Gly present) (Gly present) GluN1/2A GluN1/2C (Glu present) (Glu present) Monyer H, Sprengel R, Schoepfer R, Herb A, Higuchi M, Lomeli H, Burnashev N, Sakmann B & Seeburg PH (1992). Heteromeric NMDA receptors: molecular and functional distinction of subtypes. Science 256, 1217–1221. Differences in evoked currents Gly present GluN1/2A GluN1/2B GluN1/2C GluN1/2D 100 μM Glu / 30 μM Gly Monyer H, Burnashev N, Laurie DJ, Sakmann B & Seeburg PH (1994). (300 ms) Developmental and regional expression in the rat brain and functional properties of four NMDA receptors. Neuron 12, 529–540. BI2432: Fundamental neuropharmacology Mg2+ dependence of NMDA receptor-opening Nowak L, Bregestovski P, Ascher P, Herbet A & Prochiantz A (1984). Magnesium gates glutamate-activated channels in mouse central neurones. Nature 307, 462–465. BI2432: Fundamental neuropharmacology  Differential Mg2+ sensitivity GluN1/2A GluN1/2B GluN1/2C GluN1/2D Monyer H, Burnashev N, Laurie DJ, Sakmann B & Seeburg PH (1994). Developmental and regional expression in the rat brain and functional properties of four NMDA receptors. Neuron 12, 529–540.  Expression of GluN2 subunits in adults GluN1 GluN2A GluN2B GluN2C Monyer H, Sprengel R, Schoepfer R, Herb A, Higuchi M, Lomeli H, Burnashev N, Sakmann B & Seeburg PH (1992). Heteromeric NMDA receptors: molecular and functional distinction of subtypes. Science 256, 1217–1221.  Developmental regulation of GluN2 subunits N1 N1 N1 N1 N2A N2A N2A N2A Monyer H, Burnashev N, Laurie DJ, Sakmann B & Seeburg PH (1994). Developmental and regional expression in the rat brain and functional properties of four NMDA receptors. Neuron 12, 529–540.  Developmental regulation of GluN2 subunits N1 N1 N1 N1 N2B N2B N2B N2B Monyer H, Burnashev N, Laurie DJ, Sakmann B & Seeburg PH (1994). Developmental and regional expression in the rat brain and functional properties of four NMDA receptors. Neuron 12, 529–540.  Developmental regulation of GluN2 subunits N2C N2C N2C N2C N2D N2D N2D N2D Monyer H, Burnashev N, Laurie DJ, Sakmann B & Seeburg PH (1994). Developmental and regional expression in the rat brain and functional properties of four NMDA receptors. Neuron 12, 529–540.  Conventional vs nonconventional NMDARs Kehoe LA, Bernardinelli Y & Muller D (2013). GluN3A: An NMDA Receptor Subunit with Exquisite Properties and Functions. Neural Plast 2013, 1–12 Matsuda K, Kamiya Y, Matsuda S & Yuzaki M (2002). Cloning and characterization of a novel NMDA receptor subunit NR3B: a dominant subunit that reduces calcium permeability. Brain Res Mol Brain Res 100, 43–52. Assembly of NMDARs GluN1 GluN1 GluN3 GluN3 GluN3 GluN1 GluN3 GluN3 GluN1 or GluN1 or GluN2 GluN2 GluN3 or GluN1 GluN2 Schüler T, Mesic I, Madry C, Bartholomäus I & Laube B (2008). Formation of NR1/NR2 and NR1/NR3 heterodimers constitutes the initial step in N-methyl-D-aspartate receptor assembly. J Biol Chem 283, 37–46. BI2432: Fundamental neuropharmacology GluN1/N3 excitatory glycine receptors (NMDARs) GluN1/3A/3B GluN1/3A/3B GluN1/3A GluN1/3B 250 pA 500 pA 5 s 5 s Smothers CT & Woodward JJ (2007). Pharmacological Characterization of Glycine-Activated Currents in HEK 293 Cells Expressing N-Methyl-D-aspartate NR1 and NR3 Subunits. J Pharmacol Exp Ther 322, 739–748. BI2432: Fundamental neuropharmacology GluN1/N3 excitatory glycine receptors (NMDARs) GluN3A + GluN1-1a GluN1-2a GluN1-3a GluN1-4a 100 μM Glycine 100 μM Glycine 100 μM Glycine 100 μM Glycine Similar for GluN3B 100 pA 5 s Smothers CT & Woodward JJ (2009). Expression of glycine-activated diheteromeric NR1/NR3 receptors in human embryonic kidney 293 cells Is NR1 splice variant-dependent. Journal of Pharmacology and Experimental Therapeutics 331, 975–984. BI2432: Fundamental neuropharmacology GluN1/N3 excitatory glycine receptors (NMDARs) Grand T, Gerges SA, David M, Diana MA & Paoletti P (2018). Unmasking GluN1/GluN3A excitatory glycine NMDA receptors. Nat Commun1–12. BI2432: Fundamental neuropharmacology GluN1/N3 excitatory glycine receptors (NMDARs) Grand T, Gerges SA, David M, Diana MA & Paoletti P (2018). Unmasking GluN1/GluN3A excitatory glycine NMDA receptors. Nat Commun1–12. BI2432: Fundamental neuropharmacology  GluN1/N3 excitatory glycine receptors (NMDARs) Pachernegg S, Strutz-Seebohm N & Hollmann M (2012). GluN3 subunit-containing NMDA receptors: not just one-trick ponies. Trends Neurosci 35, 240–249. BI2432: Fundamental neuropharmacology Pharmacological targeting NMDARs Lodge D and Mercier MS British Journal of Pharmacology 2015 (review) Collingridge GL, Volianskis A et al. Neuropharmacology 64 (2013) NMDARs are in: epilepsy, stroke, pain, schizophrenia, psychosis, depression, autism, et al, Neurotoxicity Research, Vol. 2. (2000) Alzheimer’s… BI2432: Fundamental neuropharmacology Example questions L5: Q1: Which compound is a nicotinic receptor agonist? (A) Atropine (B) Curare (C) D-AP5 (D) Pilocarpine (E) Varenicline BI2432: Fundamental neuropharmacology Example questions L5: Q2: Which area of the adult brain shows the highest expression of GluN2C subunits? (A) Hippocampus (B) Thalamus (C) Cerebellum (D) Cortex (E) Hypothalamus BI2432: Fundamental neuropharmacology Study materials: BI2432: Fundamental neuropharmacology Weekly schedule of the fundamental neuropharmacology Friday 29.11.2024 (13:10-14:00 & 14:10-15:00); C/-1.04 Meyer & Quenzer Psychopharmacology, Nestler, Hyman & Malenka’s Molecular Neuropharmacology L1. Introduction to fundamental neuropharmacology Rang & Dale’s Pharmacology, L2. Basic principles of neuropharmacology I & lecture materials Friday 06.12.2024 (13:10-14:00 & 14:10-15:00); C/-1.04 Meyer & Quenzer Psychopharmacology, Nestler, Hyman & Malenka’s Molecular Neuropharmacology L3. Basic principles of neuropharmacology II Rang & Dale’s Pharmacology L4. Techniques in neuropharmacology & lecture materials Friday 10.12.2024 (13:10-14:00 & 14:10-15:00); C/-1.04 Meyer & Quenzer Psychopharmacology, Nestler, Hyman & Malenka’s Molecular Neuropharmacology L5. Acetylcholine and Glutamate (and a bit of Glycine) Rang & Dale’s Pharmacology L6. Pharmacological dissection of field responses The Hippocampus Book pages 27-30 & lecture materials Tuesday 07.01.2025 (13:10-14:00);C/-1.04 Meyer & Quenzer Psychopharmacology, Nestler, Hyman & Malenka’s Molecular Neuropharmacology L7. GABA and Glycine Rang & Dale’s Pharmacology & lecture materials Friday 10.01.2025 (13:10-14:00 & 14:10-15:00); C/-1.04 Meyer & Quenzer Psychopharmacology, Nestler, Hyman & Malenka’s Molecular Neuropharmacology L8. Catecholamines Rang & Dale’s Pharmacology L9. Serotonin & lecture materials Friday 27.01.2025 (13:00-13:45 & 14:00-14:45); C/-1.04 Meyer & Quenzer Psychopharmacology, Nestler, Hyman & Malenka’s Molecular Neuropharmacology L10. Neuropharmacology of drug dependence and addiction I Rang & Dale’s Pharmacology L11. Neuropharmacology of drug dependence and addiction II & lecture materials Tuesday 21.01.2025 (13:10-14:00); C/-1.04 Tuesday 23.01.2025 Neuroanatomy L12. Exam preparation 2 and Neuropharmacology ICA BI2432: Fundamental neuropharmacology