Chapters 1-3 Flashcards
PHARMACOKINETICS
THE BODY’S ACTION ON THE DRUG
Absorption
Distribution
Excretion
Metabolism
Cytochrome (CYP)-450 - CYP enzymes are estimated to account for the biotransformation of about 60% of the most commonly prescribed drugs in America. These enzymes are primarily in the liver and are classified according to family (1, 2, or 3) and isoform. There are six important enzymes (pathways) in psychopharmacology expressed in this nomenclature:
CYP1A2
CYP2B6
CYP2C9
CYP2C19
CYP2D6
CYP3A4
PHARMACODYNAMICS
THE DRUG’S ACTION ON THE BODY
Four mechanisms for this action:
1. Enzyme activity
2. Nonspecific chemical or physical interactions
3. Acting as antimetabolites-
4. Binding to cell receptors- Receptors are proteins that bind to compounds generating cellular signals
Neurotransmission: anatomical/chemical/electrical
anatomical infrastructure but chemical operation
consists of neurons & synapses. Synapses can form on many parts of neuron & are asymmetric (communication in one direction) so presynaptic elements differ from postsynaptic elements
Neurons are cells of chemical communication in brain
structure of neuron
general structure but they are really unique depending upon where in the brain they are/function
soma= cell body, command center, contains nucleus
axon= sends information which forms presynaptic terminals as the axon passes by/ends
dendrites= receive information from other neurons through them (some through dendrite spines)
6 key neurotransmitters in brain (even though > 12)
serotonin, norepinephrine, dopamine, acetylcholine, glutamate, GABA (y-aminobutyric acid)
classic neurotransmission process step 1-3
- start w/ electrical process > neurons send electrical impulses from one part of cell to another part of same cell via axons. Needs chemical messenger (neurotransmitter) at receptors of second neuron usually at synaptic connections but not always
- electrical impulse in first neuron is converted to chemical signal at synapse between it and second neuron (excitation-secretion coupling) typically in one direction from presynaptic axon terminal to second postsynaptic neuron
- in second neuron, chemical info from first neuron gets converted back to electrical impulse or by the chemical info from first neuron more chemical messages are triggered within second neuron to change molecular & genetic functioning
is communication between neurons at synapses chemical or electrical?
chemical
retrograde neurotransmission & examples
postsynaptic neurons can “talk back” to presynaptic neurons
ex: endocannibinoids, neurotrophic factors like nerve growth factor, & nitric oxide
volume neurotransmission & example
aka nonsynaptic diffusion neurotransmission; part of chemically addressed nervous system
neurotransmission that does not need synapses
chemical messages spill over from neuron to neuron by diffusion (much like cell phone tower)
ex: dopamine in prefrontal cortex; not many dopamine receptors, so it is free to spill over & diffuse to neighboring dopamine receptors & stimulate them even though there is no synapse at these sites
ex: somatodendric autoreceptors
where’s somatodendric site of neuron
top of neurons
where’s anoxal end of neuron
bottom
in excitation-secretion coupling, electrical impulses open what ion channels
voltage-sensitive sodium channels (VSSC) and voltage-sensitive calcium channels (VSCC) by changing ionic charge across neuronal membranes
in short, what does excitation-secretion coupling do
The way the neuron transduces an electrical stimulus into a chemical event
signal transduction cascades
cascade of events after stimulation of postynaptic receptor. They can activate third messenger enzymes (kinases) which add phosphate groups to proteins to = phosphoproteins. Others activate phosphatases which remove phosphate from phosphoproteins. This balances determines degree of downstream chemical activity that gets translated into diverse bio responses like gene expression & synaptogenesis
figure 1-9 pg. 10
two major targets of signal transduction
phosphoproteins and genes
what are the two signal transduction cascades in brain triggered by neurotransmitters
G-protein-linked & ion-channel-linked
first messenger
extracellular
second messenger (G-protein cascade vs ion-channel)
intracellular
G-protein= the second messenger is a chemical
Ion-channel= the second messenger can be an ion like calcium
epigenome
genomes= words while epigenome= the story that arranges the words (p.23)
turn genes on/off by modifying chromatin in the cell nucleus
epigenetics= parallel to genetics; determines what genes are made into RNA & protein for expression & which are silenced
general action of methylation of genes
silences them
3 target sites of psychotropics
- one of the transporters for a neurotransmitter
- receptors coupled to G proteins
- enzymes
2 types of neurotransmitter transport
presynaptic reuptake & vesicular storage
2 major subclasses of plasma membrane transporters for neurotransmitters
- solute carrier SLC6 gene family (sodium/chloride coupled transporters). Includes transporters for monoamines serotonin, norepinephrine, dopamine & also GABA & the amino acid gylcine
- solute carrier SLC1 gene family (high-affinity glutamate transporters)
3 subclasses of intracellular synaptic vesicle transporters for neurotransmitters
- SLC18 gene family (vesicular monoamine transporters/VMATs for serotonin, norepinephrine, dopamine, & histamine) & VAChT
- SLC32 gene family (vesicular inhibitory amino acid transporters/VIAATs)
- SLC17 gene family (vesicular glutamate transporters)
how do monoamines get the energy for neurotransmitter transport
They require energy to concentrate monoamines into presynaptic neuron
Energy provided by transporters in SLC6 gene family= downhill transport of sodium & uphill transport of monoamine
sodium-dependent cotransporters (usually involves cotransport of chloride & sometimes countertransport of\ potassium)
how often to neurotransmitter transporters go in and out of the membrane
12