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CHAPTER 4
Psychopharmacology
Basic Lecture Outline with notes
Principles of Psychopharmacology
Definition of drug
Exogenous
Endogenous
Pharmacokinetics
Routes of administration (seven ways drugs can be administered)
Drug Effectiveness
Dose-response curve
Margin of safety/therapeutic index
Effects of Repeated Administration
Tolerance
Sensitization
Placebo Effects
Sites of Drug Action
Effects on Production of Neurotransmitters
Agonist (example: L-Dopa precursor of dopamine and norepinephrine)
Antagonist (example: PCPA blocks tryptophan from becoming 5-HT)
Effects on Storage and Release of Neurotransmitters
Filling of neurotransmitter into vesicle
Antagonist –Blocks filling of neurotransmitter into vesicle (example:
reserpine)
Release of neurotransmitter from terminal button
Antagonist – Prevents release of neurotransmitter (example: Botulinum
toxin)
Agonist – triggers release of neurotransmitter (example: Black widow spider
venom)
Effects on Receptors
Autoreceptor
Antagonists - stimulates autoreceptor- thus inhibits synthesis and release of
neurotransmitter (example: apomorphine)
Agonists – blocks autoreceptors – drug increases synthesis and release of
nuerotransmitter (example: clonadine)
Binding sites
Agonist – masquerades as the neurotransmitter by binding with the same
site – (example: muscarine/nicotine)
Antagonists-masquerades as neurotransmitter, but blocks the site –
(example: atropine/curare)
Effects on Reuptake or Destruction of Neurotransmitters
Agonist - Leaves more neurotransmitter in synaptic cleft where it can
stimulate postsynaptic receptors (example: SSRI’s Prozac, Paxil, Zoloft)
Agonist – Destroys the enzyme which would deactivate the neurotransmitter
Acetylcholine (example: AchE)
Neurotransmitters and Neuromodulators
Acetylcholine - primary neurotransmitter – generally excitatory - all muscle movement
due to release of Ach
Dorsolateral pons – REM sleep
Basal forebrain – activates cerebral cortex and facilitates learning
Medial septum – controls the electrical rhythms of hippocampus and includes the
formation of particular kinds of memories
The Monoamines (neurons serve to modulate the function of widespread regions of
brain)
Catecholamine
Epinephrine – hormone secreted by adrenal medulla – can also serve as
neurotransmitter in brain
Norepinephrine – increases vigilance – attentiveness to environment
Dopamine (can generate excitatory and inhibitory postsynaptic potentials
depending on postsynaptic receptors.)
Nigrostriatal system – substantial nigra – neostriatum the caudate
nucleus and putamen (control of movement)
Mesolimpic system – ventral tegmental area – nucleus accumbens,
amygdale, hippocampus – (addiction)
Mesocortical system – ventral tegmental – prefrontal cortex –
(short-term memory, planning problem solving)
Indolamines
Serotonin (5-HT) – regulates mood, controls eating, sleep and arousal and
also used in regulation of pain.
Amino Acids
Most synaptic communication is accomplished by two neurotransmitters;
EPSP effects
Glutamate the principal excitatory neurotransmitter in brain and spinal cord
Glutamate receptors
Ionotropic
NMDA receptor
Permits sodium and calcium to enter cell. Generates
ESPS. Calcium serves as second messenger, very
important in forming memory.
AMPA receptor
Most common glutamate receptor controls sodium
channel products ESPS
Kainate receptor
Similar to AMPA receptor controls kainic acid
Metobotropic glutamate receptor
IPSP effects
GABA generally inhibitory
GABA (a) is ionotropic
Five binding sites
GABA
Benodiazephine (tranquilizers)
Barbiturates and alcohol
Picrotoxin (opposite of benzodiazepine and barbiturate)
GABA (b) is metabotropic opens potassium channels hyperpolarizing IPSP’s (
Glycine (found in spinal cord and lower brain stem)
Peptides
Endogenous opiads “like opium” found in midbrain (tectum, tegmentum,
periaquductal gray)
Produces analgesia
Inhibits fleeing and hiding
Produces “reward” or reinforcement
Lipids
Cannabinoids
THC (analgesia and sedation, stimulates appetite, reduces nausea, reduces
symptoms of certain motor disorders.)
Nucleosides
Adenosine (ribose and adenine) release by glial cells and neurons when cells are
short of fuel or oxygen. Adenosine opens potassium channels producing IPSP’s.
Caffeine blocks adenosine receptors.
Soluble Gases
Nitric oxide – soluable gas produced by activity of an enzyme found in certain
neurons. Dilates blood vessels in regions of the brain that become metabolically active.