Phychotomeimetic drugs

Question 1

What is LSD?

Answer 1

synthetic derivative of naturally occuring ergots.
-synthesised in 1943 by Albert Hoffman.
- has somatic, peceptual and psycological effects.

Question 2

what does cross tolerance of LSD and mescaline tell us?

Answer 2

suggests they are both psycotomimetics that act on the same class of receptor.

Question 3

what receptor does LSD act upon in the periphery and brain?

Answer 3

acts as a 5HT2 receptor antagonist in the periphery.

shown to act as a 5HT receptor agonist/partial agonist in the brain.

Question 4

how do we know raphe neurones are not the brain neurones needed for the effect of LSD change in perception?

Answer 4

LSD and mescaline show cross tolerance but dont act the same way as 5ht autoreceptor antagonists. shows that this isn’t what causes change in perception

Question 5

what effect does LSD have on brain activity?

Answer 5

shown to have an entropic effect. causes massive activation of different areas of the brain. area that reacts to visual stimulus activity is greatly increased.

Question 6

What is PCP?

Answer 6

pnecyclidine. a dissasociative anaesthetic. same class as ketamine. can cause a canonic like state without muscle relaxation.

Question 7

What receptors was PCP shown to interact with based on radioligand binding studies?

Answer 7

Sigma opiate receptors that modulate Nadr release.

non competitive antagonist for NMDA glutamate receptors

Question 8

how does cocaine effect neurotransmission?

Answer 8

acts on catecholamine (such as dopamine) neurotransmission. it blocks uptake of dopamine and thus increases their levels and transmission.

Question 9

what are some of the actions of cocaine?

Answer 9

-local anaesthetic
-causes euphoria
-appetite suppressant
-increasing the dose can elecit tremors, convulsions, CNS depression
-in susceptible individuals can precipitate toxic psychosis.

Question 10

what are actions of amphetamines?

Answer 10

appetite suppressant
causes euphoria
raises blood pressure

Question 11

what uses do amphetamines have and their risks?

Answer 11

for weight control
narcolepsy
attention deficit disorders

can also cause psychosis

Question 12

how do amphetamines work in neurotransmission?

Answer 12

is an indirect sympathomimetic. it stimulates the release of catecholamines and elevates number of transmitters and can cause reverse transport. AMPH binds to the transporter in exchange for dopamine.

Question 13

What does MDMA act on?

Answer 13

acts on 5HT and caceholamine transmission. has net effect of increasing 5HT and blocking MAO.

Question 14

What is the definition of addiciton?

Answer 14

persistent disorder of brain function in which compulsive drug use occurs despite serious negative consequences for the afflicted individual.

Question 15

what are features of addicition?

Answer 15

-compulsion to take drug
-withdrawal syndrome
-tolerance

Question 16

what is reward?

Answer 16

selection of behaviours appropriate for survival achieved by reward and punisment systems. fundamental to motivation and avoidance.

Question 17

what is the Operant chamber?

Answer 17

a chamber used by Olds and Milner in 1954 which allowed a rat to self deliver a stimulus or drug by pressing a lever. showed rat would self administer if electrode placed on medial forebrain bundle. known as reinforcement.

Question 18

what is the medial forebrain bundle made of and what type of pathway is it?

Answer 18

dopamine pathway made of the prefrontal cortex, nucleus accumbens and ventral tegmental area. (VTA)

Question 19

how do addictive drugs interact with the reward pathway?

Answer 19

-Increase release of dopamine in the nucleus accumbens as seen in all addictive drugs.
-NOT THE CASE IN AVERSIVE DRUGS

Question 20

How does methamphetamine increase extracellular dopamine?

Answer 20

interacts at vesicular monoamine transporter 2 (VMAT2) to inhibit DA uptake and promote DA release from synpatic vesicles. increases cytosolic DA for reverse transport by dopamine transporter (DAT)

Question 21

What does ethanol do to Dopamine release?

Answer 21

Increases dopamine release in the nucleus accumbens.

Question 22

what what used to show evidence of dopamine signalling alterations in addiction?

Answer 22

flouromethylspiroperidol to label dopamine receptors in PET imaging studies on humans.

Question 23

What do opiates, nicotine, cocaine and ampthetamines all do to dopaminergic transmission?

Answer 23

increase transmission in the limbic system.

Question 24

what has imaging studies shown about the dopamine receptor density in cocaine abusers.

Answer 24

shows decreased density. may compramise the reward syste, and produce drug cravings.

Question 25

What have animal gene studies shown that can occur long term in addiction?

Answer 25

increased dopamine causes increased cAMP > CREB > immediate early gene expression

alters level of receptor expression. shows genetic basis for addiction