Download Psychopharmacology

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Study of the effect of drugs on the nervous
system and on behavior
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Drug Effects - changes a drug produces in
an organism’s physiological processes and
behavior
Sites of Action - location at which molecules
of drugs interact with molecules located on or
in cells of the body
Pharmacokinetics - “movement of drugs”,
process by which drugs are absorbed,
distributed within the body, metabolized and
excreted
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Intravenous Injection (IV) - Fastest route;
entire dose reaches the bloodstream at once
Intraperitoneal Injection (IP) - peritoneal
cavity ; space that surrounds the stomach,
intestines, live and other abdominal organs
Intramuscular Injection (IM)
Subcutaneous Injection (SC) - space
beneath the skin
Oral administration
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Sublingual Administration - substance by
placing it beneath the tongue
Intrarectal Administration - substance into
the rectum
Inhalation
Topical Administration - substance directly
onto the skin or muscle membrane
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Intracerebral Administration - To study the
effects of a drug in specific region of the
brain, a researcher will inject a very small
amount of a drug directly into the brain
Intracerebroventricular (ICV) Administration
- Drug is injected into a cerebral ventricle
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Sites of action - located on or in particular
cells in the central nervous system
One of the factors determining the rate at
which the drug that is present in the
bloodstream reaches sites of action within
the brain is lipid solubility
All are eventually excreted – primarily by the
kidneys
Enzymatic deactiviation
Occasionally, the transformed molecule is
even more active than the one that is
administered
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Different drugs may have different sites of
action
Affinity for the molecules to which they can
attach - readiness with which the two
molecules join together
◦ High affinity will produce effects at a relatively low
concentration
◦ Low affinity must be administered in relatively high
doses
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Tolerance
Sensitization
Withdrawal Symptoms
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Neurotransmitters are synthesized and
stored in synaptic vesicles
Synaptic vesicles travel to the presynaptic
membrane
When an axon fires, the neurotransmitters
are released into the synaptic cleft
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Molecules of the neurotransmitters bind
with the postsynaptic receptor, causing
receiving neurons’ particular ion channels
to open, which produces excitatory or
inhibitory postsynaptic potentials
The effects of the neurotransmitters are
relatively brief by their reuptake by
transporter molecule in the presynaptic
membrane or by their destruction by
enzymes
◦ Monoamine Oxidase (MAO)
Types of drugs that affects synaptic
transmission:
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Antagonist – Those that block or inhibit the
postsynaptic effects.
◦ Receptor Blocker (Direct Antagonist) – A drug that
binds with a receptor but does not activates it;
prevents the natural ligand from binding with a
receptor
Types of drugs that affects synaptic
transmission:
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Agonist – Those that facilitate the effects of a
particular neurotransmitter on the
postsynaptic cell.
◦ Direct Agonist – Drug that binds and activates a
receptor.
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Drug serves as a precursor
Drug stimulates release of
neurotransmitters (NT)
Drug stimulates postsynaptic receptors
(direct agonist)
Drug blocks autoreceptors; increase
synthesis/release of NT
Drug blocks reuptake
Drug inactivates enzymes that breakdown
NT
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Drug inactivates synthetic enzymes; inhibits
synthesis of NT
Drug prevents storage of NT
Drug Inhibits release of NT
Drug blocks postsynaptic receptor (direct
antagonist)
Drug stimulates autoreceptors; inhibits
synthesis/release of NT
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Most synaptic communication is done by the
two neurotransmitters:
◦ Glutamate - excitatory effects
◦ Gamma-aminobutyric acid (GABA) - inhibitory
effects
◦ Glycine - another inhibitory neurotransmitter
found in the spinal cord and lower brain stem
◦ Other neurotransmitters, have modulatsing effects
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Amino acids
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Acetylcholine
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Monoamine (catecholamines)
◦ Epinephrine
◦ Norepinephrine
◦ Dopamine
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Monoamine (Indolamine)
◦ Serotonin
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2 components
◦ Choline – A substance derived from the breakdown
of lipids
◦ Acetate – The anion found in vinegar; also called
acetic acid
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Afferent axons of the CNS
mostly excitatory
muscle movement
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Systems of Acetylcholinergic Neurons:
◦ Dorsolateral Pons – Responsible for triggering most
of the characteristics of REM sleep
◦ Basal Forebrain – Involved in activating the cerebral
cortex and facilitating learning, especially
perceptual learning
◦ Medial Septum (part of the limbic system) – Control
the electrical rhythms of the hippocampus and
modulate its functions which include the formation
of particular kinds of memories
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Excitatory and inhibitory postsynaptic
potentials
Movement, attention, learning and the
reinforcing effect of drugs
Precursors of Dopamine
◦ Tyrosine – Precursor for the two major
catecholamine neurotransmitters (DA and
norepinephrine); enzyme convert it to L-DOPA
◦ L-DOPA – Biologically active form of DOPA;
precursor of catecholamines; enzyme covert it to
Dopamine
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Systems of Dopaminergic Neuron
◦ Nigrostriatal system – located in the substantia
nigra and project their axon to the neostriatum; an
important part of the basal ganglia, involved in the
control of movement.
 Patkinson’s Disease
◦ Mesolimbic system – Located in the ventral
tegmental area and projects their axons to several
parts to the limbic system, including the nucleus
accumbens, amygdala and hypothalamus. The
nucleus accumbens play an important role in the
reinforcing effects of certain categories of stimuli,
including those of drugs people abuse.
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Systems of Dopaminergic Neuron
◦ Mesocortical system – Their axons project to the
prefrontal cortex. These neurons have an
excitatory effect on the frontal cortext and thus
affect such functions as formation of short-term
memories, planning, and strategy preparation.
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Causes an increase in vigilance –
attentiveness to events in the environment
System of Noradrenalinergic Neurons
◦ Locus Ceoruleus – Located in the pons;
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Regulation of mood
Control of eating, sleep and arousal
Regulation of pain
Controlling dreams
Suppresses certain categories of behaviors
and reduces the likelihood that an animal acts
impulsively.
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System of Serotonergic Neurons
◦ Raphe Nuclie – Found at or near the midline of the
brain stem.