Drugs, Lec 10: 02/10/2014
Wednesday is the most important lecture, don’t be late!
Will talk about prescription pharmacology.
Today: watching case study videos.
Studies of guinea pig ilium because loaded with endorphins.
Heroin addicts and OxyContine addicts have problems with constipation. WE study their GI tract to study
the effects of opioids in their body. When in withdrawal, you get diarrhea. Hypothesis, maybe the GI tract is
loaded with endorphin.
Axon terminal, synaptic cleft and dendrites form a synapse.
Drugs affect synapses in 6 different ways:
1. Direct agonists:
Heroin is a direct agonist similar enough to endorphin that it fits into its receptor (called mu receptors) and
induces the effects of endorphin.
Heroin contracts the GI tract, that’s why addicts usually have constipation. When you have diarrhea, you
take amodium. Which is a mu receptor agonist just like heroin and endorphin which contracts your
intestines so you don’t have diarrhea.
Neuropharmacology: synaptic mechanisms of drug action of direct agonists:
Heroin or morphine or oxycodone, all have almost similar molecular structure to endorphin so they can
directly activate the endorphin receptor. What they do? Direct agonists that directly mimic the
endogenous transmitter in the postsynaptic receptor.
Fit into the receptor like a key that fits but doesn’t unlock the lock, keep other things from
activating the receptor. Doesn’t do produce an effect on its own. Ex. the endogenous
NT or a synthetic direct agonist. Make the receptors unavailable. Ex. Narcan, which is a narcotic
antagonist. Doesn’t only block endorphin but all other drugs that are direct agonists (heroin, oxycodone,
Brain uses 20% of your body energy, even though it only makes up 5% of your BW. Na/K ATPase pumps,
or active transporters, use a third of that energy alone.
3. Reuptake inhibitors (SSRI): also called transport blocker or transport inhibitor. There are proteins that grab NT that leaks away from the synaptic cleft an