psychopharmacology
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Transcript psychopharmacology
Drugs of abuse
Psychopharmacology
Chemical Signals
Target tissue can respond
to chemical signal
Target cells (within target
tissue) must have sensors
(RECEPTORS) to be able
to respond
Types of chemical signals:
Hormone – goes through
blood
Neurotransmitter – from
neuron directly on cell
Paracrine – in area of
tissue
Neuron
Neurotransmitters
Neurotransmitters
Some Neurotransmitters
At muscle and brain
Acetylcholine (ACh)
Main inhibitory neurotransmitter
Gamma-aminobutyric acid (GABA)
Monoamines
Serotonin (5HT)
Dopamine (DA)
Purines
Adenosine
Peptides
Endorphins
Reward system
Most drugs of addiction influence the action of the
neurotransmitter dopamine (DA) in the nucleus accumbens
Directly- alter DA neurotransmission
Indirectly – alter another neurotransmitter which controls
DA neurons
http://www.drugabuse.gov/pubs/teaching/
2 Ways to alter DA neuron activity in
the nucleus accumbens
Directly- alter DA
neurotransmission
Indirectly – alter
another
neurotransmitter
which controls DA
neurons
Neurotransmitter Receptors
Bind neurotransmitter
Receptor causes effect in postsynaptic cell
Channel for ions
or
Second messenger effects
Acetylcholine (ACh) as
Neurotransmitter
Cholinergic neurons:
Use ACh as NT.
ACh is both an excitatory and inhibitory NT.
Different effects due to type of receptors present
on postsynaptic cell
Acetylcholine (ACh) as
Neurotransmitter
Receptors classified
by binding
pharmacology
Nicotinic: binds
nicotine
Muscarinic: bind
muscarine from
poisonous
mushrooms
Both bind ACh
Acetylcholinesterase
AChE:
Enzyme that
inactivates ACh.
Prevents
continued
stimulation.
Sarin blocks
GABA as inhibitory
neurotransmitter
Two receptors
GABAA – ion
channel
GABAB – second
messenger
Stimulating the GABAA receptor
Inhibits cell activity
Decreases anxiety
Muscle-relaxant
Sedative
Hypnotic
Amnestic
Stimulating the GABAA receptor
Drugs
Barbiturates
Alcohol
Benzodiazepines
Valium
Dictyostelium
Report -- Dicty has GABAA
receptor!
Monoamines
Monoamine neurotransmitters:
Epinephrine (adrenaline)
Norepinephrine (NE)(noradrenaline)
Serotonin (5HT)
Dopamine (DA)
Release of Monoamines
Released by
exocytosis from
presynaptic
vesicles.
Diffuse across the
synaptic cleft.
Interact with
specific receptors
in postsynaptic
membrane.
Inactivation of monoamines
Reuptake of
monoamines into
presynaptic
membrane.
Enzymatic
degradation in
presynaptic
membrane by
enzymes.
Monoamine receptor effects
Monoamine NT do not directly open ion channels.
Act through
second messenger, cAMP.
Adenylate cyclase, converting ATP to cAMP.
cAMP causes effect throughout cell
cAMP inactivated by phosphodiesterase
Inactivation of second messenger
cAMP Inactivated by phosphodiesterase
Caffeine and theobromine resemble cAMP
inhibit phosphodiesterase
Dicty uses cAMP for extracellular
signal
Cocaine action
http://www.cerebromente.org.br/n08/doencas/drugs/animrecap_i.htm
Serotonin as NT
Regulation of mood, behavior, appetite, and cerebral
circulation.
SSRIs:
Used as an antidepressant.
Selective serotonin reuptake inhibitors.
Inhibit reuptake and destruction of serotonin, prolonging
the action of NT.
MDMA Action
MDMA Action