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Published byRobert McCarthy Modified over 8 years ago
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some controversy……..
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Muscarinic agonists – Muscarine
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some controversy…….. Muscarinic agonists – Muscarine Muscarinic antagonists Synthetic and natural-
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DA – dopamine NE – norepinephrine 5HT - serotonin monoamines
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NE and E are synthesized from their precursor DA with the appropriate enzymes present catecholamines
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tyrosine hydroxylase- rate limiting step
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tyrosine hydroxylase DA decarboxylase
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tyrosine hydroxylase DA decarboxylase DA β hydroxylase PNMT
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CNS - reward, movement, motivated behaviors, executive function? numerous DA pathways in CNS of importance for psychotropics….. DA (dopamine)
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DA receptor subtypes – 2 major families – D1 and D2 families DA receptor subtypes
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In CNS- arousal; role in depression, possible role in spinal analgesia, possible motivated behaviors such as hunger, thirst, sex, anxiety, drug reward? NE is in both the CNS and PNS NE (norepinephrine)
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receptor subtypes – alpha 1 and 2; β 1 – 3 NE receptor subtypes
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Catecholamines removed by reuptake: – DAT – DA transporter – NET – NE transporter How are catecholamines taken removed from the synapse?
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metabolism – – far slower than ACh by AChE metabolism
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metabolism – – far slower than ACh by AChE – MAO enzymes (monoamine oxidase) metabolism
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metabolism – – far slower than ACh by AChE – MAO enzymes (monoamine oxidase) MAOA AND MAOB enzymes MAO A – more selective for NE and 5HT metabolism
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metabolism – – far slower than ACh by AChE – MAO enzymes (monoamine oxidase) MAOA AND MAOB enzymes MAO A – more selective for NE and 5HT MAO B- more selective for DA metabolism
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Major metabolites: – Important when trying to study potential differences – DA - dopac and HVA – NE - MHPG -(3-methoxy-4-hydroxy- phenethyleneglycol)
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Tyrosine Tyrosine hydroxylase (rate limiting step) TH DOPA DA- β -hydroxylase Dopamine (DA) Norepinephrine (NE) Epinephrine (E) Aromatic acid decarboxylase mao homovanillic acid (HVA) pnmt catecholamines MHPG mao
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more recent in our history of studying NT similarity to LSD found early in high concentrations in the gut found in many non neuronal cells (only ~ 1 – 2% of 5HT in whole body is in brain) cannot cross bbb so…… 5HT
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behavioral role (CNS): sleep, aggressive behavior abnormal function implicated in: – schizophrenia, depression, phobic disorders, OCD, eating disorders, migraine, etc 5HT
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synthesis – amino acid precursor – tryptophan 5HT
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synthesis – amino acid precursor – tryptophan – elimination of dietary tryptophan can significantly lower brain 5HT levels 5HT
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synthesis – amino acid precursor – tryptophan – elimination of dietary tryptophan can significantly lower brain 5HT levels – foods high in tryptophan; nuts (ie walnuts, almonds), tofu, milk, eggs, certain cheeses, turkey, seafood, seeds 5HT
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receptor subtypes- many – at least 18 subtypes have been identified - probably best way to group 5HT1 and 5HT2 families; - some are metabotropic; some ionotropic 5HT
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reuptake main mechanism for terminating – SSRIs breakdown – major metabolite 5HIAA 5HT
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pervasive throughout the brain classified into 2 general categories – excitatory (glutamate, aspartate) – inhibitory (GABA, glycine) amino acids are more difficult to classify as nt amino acid neurotransmitters
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first identified in leg of lobster causes hyperpolarization of neurons highest concentrations in brain and spinal cord and virtually absent in peripheral nerve or other organs does not cross bbb easily GABA
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stored in synaptic vesicles (like other nt) usually removed from synapse via transporter (GAT) GABA also found in glia receptor subtypes: – GABA A – ionotropic – clinically important – GABA B - metabotropic GABA
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mediates anxiolytic, sedative, anticonvulsant, muscle-relaxant and amnesic activity subunit compositions appear to vary from one brain region to another and even between neurons within a given region linked to chloride channel GABA A
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modulatory effects
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found in high concentrations in brain serves many functions GAD (enzyme – can convert glutamate to GABA) glutamate
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found in high concentrations in brain serves many functions GAD (enzyme – can convert glutamate to GABA) receptor subtypes: – tremendous work done in recent years glutamate
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receptor subtypes: – NMDA, ionotropic, various other receptors including metabotropic GLU R (mGLUR) – families within these – role of neuromodulators current potential interests – reducing neurotoxicity, psychiatric disorders, substance use disorders, Alzhemiers Disease? glutamate
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memantine 2005 – first non AChE inhibitor for treating AD Only approved for advanced (not early stage) uncompetitive low-to-moderate affinity NMDA receptor antagonist Multiple other uses possible
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– acts as a neurotransmitter; also released during immune response; also found in gut – antihistaminergic effects: drowsiness, dry mouth, dizziness, sleepiness, upset stomach, decreased coordination, fatigue, weight gain, dry mouth and throat, upset stomach, fluttery heartbeat, loss of appetite, hives, sleepiness, vision problems More about histamine
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Overview of nervous system
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PNS - peripheral nervous system 2 components- autonomic and somatic 1. autonomic nervous system -“involuntary” - role in emotion and stress - controls smooth muscles, cardiac muscles and glands
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1. Sympathetic NS “fight or flight” activated during emergencies, stress and/or arousal Autonomic NS has two components
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Maintain homeostasis, energy restoration – physiological changes: 2. Parasympathetic nervous system
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voluntary nervous system – sensory and motor nerves – connection between all motor nerves and muscle (NMJ – neuromuscular junction) are nicotinic ACh synapses 2 nd part of the PNS is the somatic nervous system
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CNS – Central Nervous System – brain, spinal cord PNS – Peripheral Nervous System – Somatic, autonomic 2 divisions of the nervous system
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3 main divisions of brain – hindbrain; midbrain; forebrain brain
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hindbrain Medulla
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medulla – Contains part of the reticular formation – (nuclei involved in integration of information from senses, attention, arousal, and control of sleep and wakefulness)hindbrain
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medulla – Contains part of the reticular formation – (nuclei involved in integration of information from senses, attention, arousal, and control of sleep and wakefulness) as well as – Nuclei important for vital functionshindbrain
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medulla – Contains part of the reticular formation – (nuclei involved in integration of information from senses, attention, arousal, and control of sleep and wakefulness) as well as – Nuclei important for vital functions – Various ascending and descending pathwayshindbrain
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medulla hindbrain
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pons – Contains part of the reticular formation Nuclei important for sleep and arousalhindbrain
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pons – Contains part of the reticular formation Nuclei important for sleep and arousal – Specific nuclei include Raphe (5HT) – sleep and dreaming Locus coerulus (NE) - arousalhindbrain
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pons – Contains part of the reticular formation Nuclei important for sleep and arousal – Specific nuclei include Raphe (5HT) – sleep and dreaming Locus coerulus (NE) - arousal Cerebellumhindbrain
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Sensory information – reticular formation movement – substantia nigra - midbrain
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cortical and subcortical structures forebrain
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frontal parietal temporal occipital
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4 lobes of cerebral cortex Frontal – Motor function – Prefrontal – higher “executive function”
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4 lobes of cerebral cortex Frontal – Motor function Prefrontal – higher “executive function” Parietal – Somatosensory function Temporal – Audition – emotion Occipital – vision
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Prefrontal cortex
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thalamus Some subcortical structures
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The thalamus communicates with much of the cerebral cortex - serving as a sensory and motor information relay.
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thalamus hypothalamus Some subcortical structures
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thalamus hypothalamus limbic system Some subcortical structures
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thalamus hypothalamus limbic system basal ganglia Some subcortical structures
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S ome major nt pathways
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Mesolimbic/cortical – – Involved in reward, possible role in schizophrenia Projects to nucleus accumbens and parts of the limbic system nigrostriatal – – Important in initiation of movement; system that degenerates in Parkinsons disease projections from the substantia nigra to the basal ganglia tuberofundibular – – Important for hormonal release via hypothalamus and pituitary gland 3 major DA fiber tracts
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Peptides Opioids – Mu – Delta – Kappa – Endorphins and enkephalins are opioids Substance P Neurotransmitters and Receptors
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