PSYB65H3 Lecture Notes - Lecture 7: Nicotinic Acetylcholine Receptor, Caffeine, Diazepam
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Today will talk about pharmacology also how they react with
receptors and taken at up synapse.
- Will look at people who take medication for “fun” more than those
- In hospitals, most beds are taken up by alcoholics addiction is a
large problem in our society and also involved in many violent crimes.
Today: general overview of how drugs work, and then will talk about
- Prescription drugs
- Over the counter drugs (don’t need prescription this varies by
country (ie. Codine is over the counter in Canada but requires
prescription in America) and varies of time (over time, more and more
regulation on cigarettes))
- Social drugs (nicotine, caffeine, alcohol not prescribed, and not
purchased in drug store). Buy them wherever you go.
- Drugs not produced commercially (ie. Marijuana) or is produced
commercially but not for psychoactive effect (ie. Airplane glue
produce commercially but not usually support to put in a bag and snort
Tolerance: most drugs if taken repeatedly, result in decreasing
behavioral effect. Not all drugs do it Marijuana, indication = more
sensitive to it during first few times.
- Why does this happen? In a synapse, when you take a drug, excess
amount of NT’s will be released (more hitting the receptors) causing
stimulation of post-synaptic neurons. As you release more and more
NT’s, this bombards the receptors, and what happens is a plastic
response of the post-synaptic cell for them to either reduce the
number or the sensitivity of the post-synaptic receptors. Reduction of
number of receptors compensate for over-activation. Post-synaptic
neurons not firing as much (due to the self-regulating). So, overtime if
you keep taking the same amount, and the receptors keep dampening
themselves to down, and the effect is not as great (so tolerance to
drug increases). Not usually permanent.
- Same thing would happen with a depressant, whatever mechanism
the depressant is working by, it will reduce the post-synaptic activity
and post-synaptic receptors by their self-regulation will increase the
number of receptors on their surface. This compensates, and the same
amount of drug cannot stop being as depressed, then the drug will not
have as dramatic effect (no longer relaxing you as much).
- Certain drugs have different effects on different people. Ie. Riddylin in
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hyperactive kids will produce the same response. LSD however has no
response after a few days of use, fails to do anything.
Withdrawal: most drugs once on them for a while, it is difficult to get
off of them due to withdrawal effects. In alcoholics, you never want
them to immediately be taken off alcohol when in psychiatric ward,
first thing you do to them is put them on valium just to keep the brain
from going into withdrawal reaction (valium is a depressant and it
helps them get off from alcohol quickly and then must take them off
valium). Don’t want to do “cold turkey” because withdrawal effects can
- What causes withdrawal? Think back to stimulation (reduces
receptors) and depression (increases receptors). Ie. Stimulation over
time (ie. Ecstasy causes the brain to adjust itself to have fewer
receptors. When we take the stimulant away, the pre-synapse goes
back to “normal” activity (much less in this case than was caused by
stimulation for a while). This will result, do to fewer NT’s released, an
under-stimulation of the post-synaptic receptors and will take it a while
to build back its “normal” level of receptors. So, when person comes
off drug, instead of being hyperactive, they are depressed due to less
activation in brain.
- Withdrawal from a stimulant results in lower than normal levels of
activation (as seen by diagram (in written notes)). Withdrawal results
in exactly OPPOSITE effects of the drugs.
- In the case of depression, these calm individuals will become
hyperactive. Once again, opposite effect.
- In case of stimulation, withdrawal leads to depression (patients are
tired, lethargic) but not life-threatening.
- In case of depressant (ie. Barbituates), whenever the go off of it, the
undergo a period of hyper-stimulation (shaking, seizures) and this can
be life threatening and may lead to death. This is why you never take
someone directly off drugs in the case of a depression especially). Can
take someone off a stimulant, they’ll be depressed for a few days.
Addiction: implies the person wants to have the drug. It is a
behavioral or physical dependence on the drug. There is psychological
addiction (behavioral dependence and is very difficult to define) just
means person likes it. There is physical addiction (physical withdrawal
symptoms) ie. Bp goes up, person might shake etc.)
- General rule- The more rapid the effect of the drug, the more
addicting it is. Example- Cocaine is from the coco plant from Bolivian
Peru and people harvest it and make a tea out it they get a similar
effect to what we get from drinking coffee. So, they substitute from
coffee for cocaine. People smuggling in cocaine do it by converting the
leaves to a powder form people snort this and it has a mildly
addictive effect but usually people will use it like they would alcohol.
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