Pre- & postsynapse
I. presynapse:
1. Neurotransmitter: chemicals that influence neighboring neurons
A. stored in synaptic vesicles
B. released from presynaptic neuron into synapse
when APs occur
II. the postsynapse:
1. neurotransmitter (NT) binds to a receptor
A. like a key fits into a lock
B. two types of receptors
a. ionotropic:
b. metabotropic:
2. receptor binding causes postsynaptic potentials
A. excitatory postsynaptic potentials (EPSPs)
graded depolarizations
B. inhibitory postsynaptic potentials (IPSPs)
graded hyperpolarizations
3. postsynaptic potential are capable of
A. temporal summation
B. spatial summation
4. examples of how postsynaptic potentials occur?
A. receptor binding causes Na+ ions to enter
(EPSPs)
B. receptor binding causes K+ ions to exit
(IPSPs)
5. What determines if a neurotransmitter (NT) produces IPSPs
or EPSPs
A. the type of neurotransmitter
B. the type of postsynaptic receptor
a. many NT can be either excitatory
or inhibitory
III. regulation of the neurotransmitter signal
1. enzymatic deactivation: enzymes breakdown the NT
2. reuptake: NT is taken back into the presynaptic neuron
3. autoreceptors: receptors found on the presynaptic neuron
a. inhibit the synthesis
& release of NT
4. axoaxonic synapse: a synapse between two axons
a. alter the amount
of NT released by the terminal button
Psychopharmacology
I. drugs can facilitate or oppose neurotransmitter functioning
1. agonist:
2. antagonist:
II. types of neurotransmitters (NT) at least 50 have been reported
1. acetylcholine: main NT of the autonomic nervous system
A. precursor is choline: from diet
B. two types of receptors
a. nicotinic receptors:
--e.g., of agonist
is nicotine
--e.g., of antagonist
is curare
b. muscarinic receptors:
--e.g., of agonist
is muscarine
--e.g., of antagonist
is atropine (belladonna)
C. acetylcholinesterase (AChE) deactivates it
D. botulinum toxin: prevents release from terminal
buttons
E. black widow spider venom: causes terminals to
release NT
2. monoamines: monoamine oxidase (MAO) deactivates these.
A. indolamines which include
a. serotonin (5-HT):
-precursor is
the amino acid tryptophan
-at lease 7
different receptors (most inhibitory)
-Prozac is a
reuptake inhibitor
-LSD stimulates
at least one type of 5-HT receptor
B. catecholamines:
a. norepinephrine (NE) or
noradrenalin:
-precursor is
the amino acid tyrosine
-four different
types of receptors
b. dopamine (DA):
-precursor
is tyrosine
-at least
5 different DA receptors (most inhibitory)
-Parkinson’s
disease (L-DOPA for treatment)
c. drugs that influence catecholamines
-cocaine
prevent reuptake
-amphetamine
increases release
-methylphenidate
3. amino acid transmitters:
A. gamma aminobutyric acid (GABA)
a. precursor is glutamate
b. two GABA receptors (both
inhibitory)
c. Valium is a GABA agonist
d. GABA receptors have binding
sites for at least 3 different chemicals
-primary
binding site is for GABA
-a second
site binds benzodiazepines (e.g., Valium)
-a third
site binds barbiturates & alcohol
B. glutamic acid (glutamate)
a. principle excitatory
NT in the brain
b. 5 types of receptors
have been identified
C. glycine
a. inhibitory NT found in
the brainstem & spinal cord
4. peptide neurotransmitters:
A. endorphins or enkephalins (endogenous opiates)
a. these resemble opiates
in structure
b. three types of receptors
have been found
c. opiates (e.g., morphine)
are endorphin agonists
5. purines
A. adenosine: NT that apparently has a calming
effect
a. caffeine blocks adenosine receptors
6. anandamide: endogenous THC substance
A. THC is an agonist (mimics anandamide)