PSYC 415 -- Study Points for Chemistry of the Nervous System

I. a typical synapse
     A. synaptic terminal or presynaptic terminal or terminal button
          1. vesicles or synaptic vesicles containing neurotransmitter
          2. release initiated by arrival of action potentials
     B. synaptic cleft
     C. postsynaptic receptors
II. the details
     A. substances obtained in the diet are taken up from the blood (for
          example, amino acids like tyrosine)
     B. converted to neurotransmitter by a series of chemical steps (each must
          be carried out by an enzyme, a large protein molecule)
     C. neurotransmitter is packaged in vesicles (usually)
     D. arrival of the action potential stimulates release of neurotransmitter
     E. once released, a number of things can happen to it
          1. activates postsynaptic receptors - which then either directly or
               through a series of chemical steps open the ion channels on the
               postsynaptic membrane (receptors are proteins)
          2. activates presynaptic receptors - which form a feedback pathway
               that can regulate activity of the cell
          3. can be inactivated...
               a. by enzymes (proteins)
               b. by reuptake - most common (and easily influenced by drugs
                    such as SSRIs like Prozac, an antidepressant); the
                    transporters that do reuptake are proteins
III. postsynaptic potentials
     A. excitatory (EPSP) - due to opening of sodium channels (channels are
          proteins, btw)
     B. inhibitory (IPSP) - due to opening of potassium channels
     C. opening of chloride channels is also an inhibitory event
IV. overview of neurotransmitters
     A. acetylcholine
     B. amino acids - GABA, glycine, glutamate
     C. monoamines
          1. catecholamines - dopamine, norepinephrine
          2. indoleamines - serotonin, melatonin (melatonin not known to be a
               neurotransmitter but acts as a hormone in the brain)
     D. lipid-derived - endocannabinoids
     E. peptides (protein-derived) - endorphins, etc.
     F. neurotransmitters vs. neuromodulators
V. acetylcholine - from dietary choline
     A. location
          1. neuromuscular junction - excites muscle fibers creating voluntary
               movement ("without acetylcholine, you ain't goin' nowhere!")
          2. autonomic nervous system (another part of the PNS)
          3. three major systems in the brain - REM sleep, activation of
               cerebral cortex, modulation of memory formation
     B. receptors - two types
          1. nicotinic
          2. muscarinic
     C. drugs - nicotine, black widow spider venom, insecticides, curare,
          alpha-bungarotoxin, botulinum toxin
VI. GABA
     A. primary inhibitory neurtransmitter in the upper brain
     B. two kinds of receptors; the GABA-A receptor is especially complex
     C. drugs - benzodiazepines, barbiturates, alcohol, date rape drugs,
          convulsants like Metrazol
VII. glycine
     A. primary inhibitory neurotransmitter in the spinal cord and lower brain
     B. drugs - tetanus toxin, strychnine
VIII. glutamate - the primary excitatory neurotransmitter in the CNS
IX. monoamines - tend to be more modulatory than the above NTs
     A. catecholamines - from tyrosine, a dietary amino acid
          1. dopamine and norepinephrine (epinephrine or adrenalin maybe a bit)
               a. dopamine
                    - nigrostriatal system
                    - mesolimbic and mesocortical systems
                    - movement, reward, motivation, depression, schizophrenia
               b. norepinephrine
                    - locus coeruleus
                    - emotion, arousal, vigilance, mood, depression, sleep-waking
          2. drugs - amphetamine, Ritalin, antidepressants, L-dopa, MAOIs,
               alpha and beta blockers, antipsychotics
     B. indoleamines - serotonin, from tryptophan, a dietary amino acid
          1. raphe nuclei
          2. drugs - antidepressants (SSRIs), MAOIs, LSD etc.
          3. mood, nausea and vomiting, sleep-waking cycle, pain sensitivity
X. peptides or neuropeptides - snipped out of larger protein molecules
     A. endorphins
     B. drugs - morphine, heroin, codeine, etc.
XI. endocannabinoids - from fatty acids
     A. anandamide (from the Sanskrit word for bliss)
     B. drugs - marijuana
     C. neuromodulation of other neurotransmitters
     D. affective behavior, appetite, modulation of reward, pain sensitivity