Chapter 9: Caffeine and Methylxanthines

Question 1

Even though caffeine and methylxanthines are bases, why are they so readily absorbed orally?

Answer 1

because the bases have extremely low PKAs, allowing them to still be lipid soluble in an acidic environment.

Question 2

at physiological pH, the methylxanthines are _____ and are thus _____ soluble

Answer 2

at physiological pH, the methyl-xanthines are NOT IONIZED and are thus LIPID soluble

Question 3

which type of methylxanthines have longer half lives than caffeine?

Answer 3

theophyllines and theobromines

Question 4

describe the genetic influences on caffeine metabolism

Answer 4

genetics can influence how fast methylxanthines are metabolized. CYP1A2 genes are responible in creating the enzymes necessary for caffeine metabolism. the -1A type are rapid caffeine metabolizers, and the -1F type are slow metabolizers.

Question 5

How do antibiotics affect caffeine metabolism?

Answer 5

antibiotics can inhibit the CYP1A2 enzyme.

Question 6

Caffeine half life in women is longer _____ ovulation and shorter ___ ovulation

Answer 6

Caffeine half life in women is longer AFTER ovulation (luteal) and shorter BEFORE ovulation (follicular)

Question 7

affect of contraceptives on the half life of caffeine?

Answer 7

oral contraceptives doubles the half life of caffeine

Question 8

affect of pregnancy on half life of caffeine

Answer 8

pregnancy increases the half life of caffeine (excretion of caffeine slows down during pregnancy)

Question 9

Which neurotransmitter is affected by caffeine?

Answer 9

adenosine

Question 10

methylxanthines are ______ ANTAGONISTS

Answer 10

methyl-xanthines are ADENOSINE RECEPTOR ANTAGONISTS. they BLOCK A1 and A2 receptors.

Question 11

usually, adenosine is an _____ neuromodulator. How do methylxanthines influence adenosine and DOPAMINE?

Answer 11

an INHIBITORY NEUROMODULATOR, it inhibits neurotransmission in synapses. Methyl-xanthines block A1 and A2A receptors, which typically inhibit and modulate the amount of dopamine in the brain. By blocking these A1 and A2a receptors, methyl-xanthines block dopamine modulators, thus INCREASING dopamine levels.

Question 12

adenosine receptors often form _____, where 2 or more receptors become attached to each other and consequently influence one another’s operation

Answer 12

adenosine receptors often form RECEPTOR MOSAICS, where 2 or more receptors become attached to each other and consequently influence one another’s operation

Question 13

T/F adenosince and thus caffeine, act on NE, DA, ACh, Glu, and GABA due to receptor mosaics

Answer 13

true

Question 14

Where are most A2A receptors found?

Answer 14

in the striatum, which plays a role with increased transmission at dopamine receptors (nigrostriatal dopamine system)

Question 15

What kind of receptors are blocked with high doses of caffeine, which is reponsible for heightened anxiety and aversion?

Answer 15

A2a receptors are blocked at high doses.

Question 16

What does chocolate contain that allows it to work on the cannabinoid receptor?

Answer 16

chocolate contains anadamide, which works at the cannabinoid receptor

Question 17

which nervous system is stimulated due to methylxanthines causing the release of epinephrine from adrenal glands?

Answer 17

the sympathetic nervous system is stimulated (fight or flight) due to increased amounts of epinephrine.

Question 18

caffeine’s most direct effect is seen in the _____

Answer 18

muscles:

smooth muscles: results in bronchi dilation (used to treat asthma), affects blood vessels.
striatal muscles: reduces fatigue and increases athletic performance

Question 19

What part of the body is affected which may lead to caffeine causing convulsions?

Answer 19

high doses of methyl-xanthines stimulates the spinal cord, which increases the excitability of spinal reflexes, may then cause convulsions.

Question 20

Which regulatory center is responsible for increasing the breathing rate caused by caffeine administration?

Answer 20

the medulla regulatory center is stimulatted in high doses of caffeine, producing increases in breathing rates.

Question 21

T/F: coffee has been seen to create improvements in reaction times on visual, cognitive and verbal reasoning tasks in regular coffee users as well as non coffee drinkers

Answer 21

TRUE. this indicates that caffeine does not only produce performance enhancing effects in people suffering from withdrawal symptoms.

Question 22

T/F: caffeine affects sprinting performance

Answer 22

false. caffeine shows improvement of long-distnace/sub maximal activities.

Question 23

Caffeine produces the tendency for people to wake up in the middle of the night in response to very quiet noises because:

Answer 23

caffeine lowers ACOUSTIC AROUSAL THRESHOLD.

Question 24

Do sleeping effects of caffeine respond to tolerance?

Answer 24

yes, after 7 days, total sleep time and awakenings had returned to baseline levels.

Question 25

What part of the brain interacts with adenosine in order to make you fall asleep? How does caffeine produce insomnia affects?

Answer 25

the VENTROLATERAL PREOPTIC NUCLEUS is the sleep inducing center of the brain which gets turned on when there is a lot of adenosine. It generates synchronous brain activity. in the presence of caffeine, the adenosine receptors in the ventrolateral preopoptic nucleus are blocked, which makes the brain keep producing dysynchronous brain activities. The VPNO still remains turned off, and thus you stay wake longer

Question 26

low doses of caffeine produce an ___ in spontaneous motor activity, whereas high doses do not.

Answer 26

low doses of caffeine produce an INCREASE in spontaneous motor activity, whereas high doses do not; in fact, high doses results in the depression of spontaneous motor activity and will eventrually lead to convulsions and death.

Question 27

when is automutilation in non humans seen in response to methylxanthines?

Answer 27

when animals are given high doses of caffeine for over 14 days.

Question 28

T/F: caffeine disrupts conditioned discriminations and will results in an increased amounts of responding that had originally been suppressed by punishment with electric shock. Why or why not?

Answer 28

True, caffeine will increase the amounts of responding to behaviors that were once punished by electric shock. this is most likely due to chatecholamine and dopamine release

Question 29

At low doses, what does caffeine generalize to?

Answer 29

at low doses, caffeine generalizes to amphetamines and cocaine.

Question 30

How can you block discrimination of caffeine?

Answer 30

dopamine receptor blockers or A1 receptor blockers

Question 31

Would you be able to block discrimination with an A2A receptor blocker?

Answer 31

no, A2A receptor blockers counteract the ability of the A1 receptor blocker to interfere with stimulus effects of caffeine.

Question 32

What is a turkey drug?

Answer 32

drugs that are legal but sold as a controlled substance. Ex/ drugs that look like amphetamine ( a controlled substance) but is just a mixture of caffeine and ephedrine, legal drugs.

Question 33

T/F Caffeine seems to increase feelings of self confidence

Answer 33

true

Question 34

name the positive and negative effects of caffeine

Answer 34

increase in self confidence, increase in well beign and energy and motivation.

negative: increased anxiety and nervousness because caffeine blocks A2a receptors at high doses.

Question 35

In terms of adenosine receptors, what causes tolerance?

Answer 35

an upregulation of adenosine receptors: more receptors are being made. Thus, when caffeine is not present, there is a large inhibitory response (you crash). You need more caffeine than last time to wake you up.

cardiovascular effects (increased HR and BP) fade within 2-5 days of using caffeine,
and caffeine-induced insomnia may fade within 7 days.

Question 36

What is a symptom of caffeine that may never show complete tolerance?

Answer 36

caffeine-induced urination may never show complete tolerance.

Question 37

What are some withdrawal effects of caffeine and why does this happen?

Answer 37

drowsiness, flu like symptoms, headaches, fatigue. Caused by increasing amounts of adenosine receptor density and thus the body is more sensitive to adenosine (the body is more inhibited and sleepy)

Question 38

Severity of caffeine is related to _____ (duration/dose/metabolism)

Answer 38

dose.

Question 39

T/F Caffeine is a reinforcer

Answer 39

false. caffeine is not a robust reinforcer.

Question 40

Caffeine can act as a PRIMER for ____, an affect which can be blocked by _____

Answer 40

Caffeine can act as a PRIMER for COCAINE, an affect which can be blocked by administration of DA receptor blockers.

Question 41

Usually, caffeine preference is enhanced when followed by a vigilance task, such as an attention task, and diminished when participants know that administration is followed by a relaxation task. Which theory is this consistant with?

Answer 41

consistent with psychological tool theory

Question 42

People who report ____ subjective effects with caffeine shoe increased preference rather than people who report ____ subjective effects.

Answer 42

People who report POSITIVE subjective effects with caffeine shoe increased preference rather than people who report ADVERSE subjective effects.

Question 43

T/F DSM recognizes caffeine dependence as a legitamate issue

Answer 43

True

Question 44

individuals who carry a specific genotype related to ____ receptors exhibit higher anxiety levels when taking higher doses of caffeine

Answer 44

individuals who carry a specific genotype related to A2A receptors exhibit higher anxiety levels when taking higher doses of caffeine

Question 45

How might caffeine help with parkinsons disease?

Answer 45

parkingsons disease is characterized by difficulty in initiating and terminating motor movements due to depletion of dopamine release from the substantia nigra pars compacta, which projects into the striatum(where most A2a receptors are). Caffeine increases activity in the striatum via blocking of A2a receptors without requiring dopamine from the substantia nigra pars compacta, increasing dopamine release.