chapter 4: psychopharmacology
TRANSCRIPT
Chapter 4
Psychopharmacology
Psychopharmacology• Drug
– Medication?– Heroin or cocaine?– An exogenous chemical not necessary for normal
cellular functioning that significantly alters the function of certain cells of the body when taken in relatively low doses
• Drug effect– Changes of physiological process and behavior
• Site of action– May only have effect on certain neurons at certain
locations
Routes of administration• Intravenous (IV), vein• Intraperitoneal (IP) injection, abdominal wall• Intramuscular (IM) injection• Subcutaneous (SC) injection, beneath the skin• Oral administration• Sublingual administration, beneath the tongue• Intrarectal administration• Inhalation, lung• Topical administration, absorbed by skin• Intracerebral administration• Intracerebroventricular (ICV) administration
• Depot binding– Binding of a drug
with various tissues of the body or with protein in the blood
• Albumin– A protein found in
the blood; serves to transport free fatty acids and can bind with some lipid-soluble drugs
• Dose-response curve• Affinity
– The readiness with which two molecules join together (compare)
• Tolerance– A decrease in the effectiveness of a drug that is
administered repeatedly• Withdrawal symptoms
• Sensitization– An increase in the effectiveness of a drug that is
administered repeatedly• Placebo effects
– An inerr substance that is given to an organism lieu of a physiologically active drug; used experimentally to control for the effects of more administration of a drug
• Antagonists– A drug that opposes or inhibits the effects of a
particular neurotransmitter on the postsynaptic cell
• Agonists– A drug that facilitates the effects of a
particular neurotransmitter on the postsynaptic cell
• Competitive binding: binding of a drug to a site on a receptor interferes with the site for the principal ligand
– Direct agonist• A drug that binds with and
activates a receptor– Direct antagonist / receptor
blocker• A drug binds with a receptor
but does not activate it; prevents the natural ligand from binding with the receptor
• Noncompetitive binding: Binding of a drug to a site on a receptor; does not interfere with the binding site for the principal ligand
• Indirect antagonist– A drug that attaches to a
binding site on a receptor and facilitates the action of the receptor; does not interfere with the binding site for the principal ligand
• Presynapticheteroreceptor– A receptor located in
the membrane of a terminal button that receives input from another reminalbutton by means of an axoaxonicsynapse; binds with the neurotransmitter released by the presynaptic terminal button
Acetylcholine
• Choline acetyltransferase (ChAT)
Functions and sites of effects• A. Muscular
movements and autonomic nervous system
• B. In the brain– 1. Dorsolateral
pons—REM sleep– 2. Basal forebrain—
activating the cerebral cortex and facilitating perceptual learning
– 3. Medial septum—electrical rhythms of the hippocampus and modulate its function
• Acetycholinesterase (AChE)
Two types of ACh receptors
• Nicotinic receptor– Ionotropic, fast, muscle fibers
• Muscarinic receptor– Metabotropic, slow, dominant in CNS
Related Drugs of ACh
+MuscarineStimulate muscarinicreceptors
Muscle paralysis
atropine
curare
nicotine
neostigmine
hemicholinium
Black widow spider venom
Botulinum toxin -preventRelease
+stimulate
Receptor
Deconstruction enzyme (AChE)
Reuptake of choline
-block
-Block muscarinicreceptors
-Block nicotinic receptors
+Stimulate nicotinic receptors
+deactivate
Monoamine• Classification
– Catecholamine• Dopamine, Norepinephrine,
Epinephrine• Catecholamine Synthesis
– L-DOPA---Dopamine---Norepinephrine (NE)
– Indolamines• Serotonin
Dopamine• Both excitatory and
inhibitory– 1. Nigrostriatal system—
substantia nigra to caudate nucleus and putamen—control of movement (Parkinson’s disease)
– 2. Mesolimbic system—ventral tegmental area to limbic system (amygdalaand hippocampus)—reinforcing and rewarding (drug addiction)
– 3. Mesocortical system—ventral tegmental area to prefrontal cortex—short-term memory, planning and strategy.
• Receptors, D1 and D2
Related Drugs of Dopamine
+Stimulate releaseAmphetamine, cocaine, methylphenidate
inhibitReuptake
Alleviate schizophrenia
Alleviate Parkinson’s disease
deprenyl
chlorpromazine
High dose of apomorphine
Low dose of apomorphine
reserpine
AMPT
L-DOPA +facilitateSynthesis
-inhibit
Deconstruction enzyme (MAO)
Post-synaptic receptor
Autoreceptor
Storage in vesicles
-inhibit
+destroy
-inhibit
+activate
-activate
Norepinephrine (NE)• Autonomic nervous
system• Final step of
synthesis: Domapine—norepinephrineoccurs inside the vesicles
• Release through axonal varicosities rather than terminal buttons
• Originating site: Locus coeruleus in dorsal pons—increase in vigilance
• All adrenergic receptors are metabotropic, α1, α2, β1, β2
• Both excitatory and inhibitory effects.
Related Drugs of Norepinephrine
-Same with DopaminereserpineinhibitStorage in vesicles
Stimulate release, same as Dopamine
AmphetamineMDMA
idazoxan
moclobemide
Fusaric acid -inhibitsynthesis
+blockDeconstruction enzyme (MAO-A)
Reuptake
Autoreceptor +block
+inhibit
Serotonin• Mood, eating,
sleep, arousal, pain, dreaming
• Originated from Raphe nuclei and projects to basal ganglia and hippocampalformation
• Released from varicosities rather than terminal buttons
• At least 9 types of receptors
Related Drugs of Serotonin
+LSDstimulateReceptor
-Same with DopaminereserpineinhibitStorage in vesicles
-PCPAinhibitsynthesis
Stimulate releasing
Treatment of obesity
Treatment of depression, anxiety disorder and OCD
MDMA
fenfluramine
Fluoxetine (Prozac) +inhibitReuptake
+inhibit
+inhibit
Amino Acids• The most common
neurotransmitters in CNS– Glutamate (direct excitatory
in brain and spinal cord)– Gamma-aminobutyric acid
(GABA) (direct inhibitory in the brain)
– Glycine (direct inhibitory in spinal cord)
• Direct excitatory/inhibitory role– Independent of receptors,
suggesting a general modulating role before the evolution of receptor molecules.
Glutamate
• Four major receptors• Ionotropic
– NMDA receptor– AMPA receptor– Kainate receptor
• Metabotropic receptor– Metabotropic glutamate receptor
NMDA receptor of Glutamate• 6 binding sites,
sodium and calcium channels—EPSP and second messenger
• Required conditions– Glutamate– Glycine– Removal of
magnesium--depolarization
• Modulations– Zinc ion (-)– Polyamine (+)– PCP (-)
• Both voltage and neurotransmitter-dependent ion channel
Related Drugs of Glutamate
+NMDAStimulate NMDA receptor
+Kainate acidStimulate kainatereceptor
AP5
AMPA +Stimulate AMPA receptor
receptor
-Blocks NMDA receptor
GABA receptor• 5 binding sites• Stimulating:
– barbiturate, – Steroid site, – Benzodiazopine
• Inhibiting: – Picrotoxin
• Ionotropic receptor or metabotropic?
• Voltage or neutrotransmittordependent Chloride channel?
• Excitatory or inhibitory?
Related Drugs of GABA
+calming effectbarbituratestimulate
-allylglycineinhibitsynthesis
+Tranquilizing drugs, reduce anxiety, sleep medication
BenzodiazepineDiazepam (Valium)Chlordiazepoxide(Librium)
stimulate
-directbicucullineblock
direct
Picrotoxin
muscimol +stimulatereceptor
-inhibit
Glycine
• Inhibitory neurotransmitter in the spinal cord• Ionotropic receptor controlling a chloride
channel• Strychnine blocks glycine receptor (-)
-StychnineblockReceptor
Neuropeptides and meuromodulators
• General characteristics of neuropeptides and neuromodulators
• 1. Larger molecular weight
• 2. Slower-acting (minutes, hours)
• 3. Can act in concert with a neurotransmitter
• 4. Like neurotransmitters, there is more than one receptor subtype, and the response is tissue-specific
Peptides• Neurotransmitter: Endogenous opiods• Receptor: Opiate receptor• Effects
– Analgesia– Inhibits defensive response such as fleeing and hiding– Reinforcement (addiction)
-Naloxoneinhibit
+Opiates (morphine, heroin, etc)
stimulateReceptor
Lipids• Neurotransmitter: anandamide• Metabotropic receptors• Effects
– Analgesia and sedation, stimulate appetite, reduce nausea, reduce symptom of motor disorder
– Interferes with concentration and memory, alter visual and auditory perception and perception of the passage of time
+MAFPinhibitDeconstruction enzyme (FAAH)
+AM1172blockreuptake
+THCstimulate
-Rimonabantblockreceptor
Nucleosides• Sugar molecule bound with a
purine or pyrimidine base• Neuromodulator: adenosine• Metabotropic receptors with
potassium channels • Effects:
– Dilate blood vessel and bring oxygen to cells
– Inhibitory, control of sleep, increase during wakefulness and decrease during sleep
• Caffeine, block receptor (-), excitatory effects
-CaffeineblockReceptor
Soluble gases• Nitric oxide (NO) one nitrogen and one oxygen atom• Control of muscle of intestine wall; Dilate blood vessel
to become metabolically active• Produced in several regions of a nerve cell, including
dendrites, release as soon as produced, no vesicles/impulse involved
• L-NAME deactivate the enzyme that involves in the synthesis of NO, (-)
-L-NAMEinhibitSynthesis
brainExcitatoryamino acid
Glutamate
Spinal cordInhibitoryamino acid
Glycine
CaffeinesleepNucleosides
adenosine
Analgesia and sedation, perception distortion
Lipidsanandamide
Addiction to opiates
Painkiller, inhibit defense, reinforcement
peptidesEnkephalins(Opioids)
Inhibitory
Excitatory & Inhibitory
Excitatory & Inhibitory
Excitatory & Inhibitory
Excitatory & Inhibitory
Postsynaptic effect
Related diseasesFunctionsOriginated locationType
Paralysismuscle movement, REM sleep, Memory, learning
Dorsal lateral ponsBasal forebrainMedial septum
Acetic acid
Acetylcholine (ACh)
Parkinson’s disease, schizophrenia, depression
Motorreward, planning
Substantia nigraVentral tegmental
AmineDopamine
Dilate blood vesselGasNitric oxide (NO)
Anxiety disorderAnxiety levelbrainamino acid
GABA
Depression, OCD, anxiety, obesity
Mood, sleep, pain, appetite
Raphe nucleiAmineSerotonin
DepressionIncrease vigilance, heighten mood
Locus coeruleusAmineNorepinephrine