L6: Neurotransmission: Drug abuse Flashcards Preview

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Flashcards in L6: Neurotransmission: Drug abuse Deck (29)
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How is addiction defined by Orford, 1985?

- loss of control over a form of behaviour pleasurable to most people
- an excessive appetite


What drug abuse did Gardner, 1964 struggle with?

- a separation of liking and wanting....


Which drug was used to keep soldiers awake for longer?

Philopon = methanphetamine
- resulted in somatosensory hallucinations - tics under the skin


Which neurotransmitter receptors do nicotine, the psychoactive component od tobacco, act on?

- acetylcholine receptors
- peripheral NS

2 broad acetylcholine receptors...
1. Nicotine specific to nicotine
2. Muscarinic - specific to an alkaloid muscarine


Which neurotransmitter receptors do alcohol act on?

- GABA-A + GABA-B receptors
- opioid receptors


Which neurotransmitter receptors do opiates act on?

- opioid receptor
-- V selective
-- help decrease sensation of pain


Which neurotransmitter receptors do MDMA (ectasy) act on?

- serotonin 2A


Which neurotransmitter receptors do cocaine act on?

- Dopamine transporter


Which neurotransmitter receptors do amphetamine act on?

- dopamine --> releases them


Which neurotransmitter receptors do Barbiturates act on?

- modulates GABA-A receptor


Which neurotransmitter receptors do cannabis act on?

- Cannabinoid CB1 receptor


What does the place preference task show about receptors and addiction?

1. Rats put into a box with two compartments they can go between
2. One side = given morphine, other a non-active control
3. transgenic mouse without opioid receptors fails to learn task
- normal = greater preference for morphine room
- middle = equal preference for the different rooms


What are some issues with the place preference task?

- anatomies of humans and mice are different
- missing receptor may be important for the development of mice = so not reflective of adult mice?
- an adaptive response?


Give a run down on cocaine

- once was in coca-cola
- obtained from coca-shrub
- local anaesthetic resembling lidocaine


How do lidocaine and cocaine act as anaestheitcs?

- block voltage-gated sodium channels
= no AP can be produced so no pain is reaching the NS


Give a run down on amphetamine

- first synthesised in 1887
- psychoactive effects discovered 1920s
- clinical use: ADHD, narcolepsy
- widely used as a decongestant
--> Benzedrine inhaler


What are cocaine and amphetamines effects on the dopamine neurotransmitter system?

- Blocks dopamine transporters (DAT)

- enhances dopamine release and reduces re-uptake
--> amphetamine is transported into the pre-synaptic terminal - displaces dopamine from vesicles leading to synaptic release

both increasing levels of dopamine at the synapse
- making it difficult to distinguish


Describe the transmission of information in the dopamine neurotransmitter system

1. depolarisation in pre-synaptic neuron = release dopamine
2. Acts post-synaptically
3. Taken back-up by the dopamine transporter (DAT)
4. Then reincorporated into vesicles by the vesiclar monoamine transporter (VMAT)


Name a few of the many psychoactive compounds in cannabis

1. ∆9-Tetrahydrocannabidol (∆9-THC) - major psychoactive component
2. Cannabidiol - quite different pharmacologcal properties
3. Canabigerol - a precursor but with it's own activity as well


Which cannabionoid receptors are found where in the brain periphery?

1. CB1 - mostly CNS
2. CB2 - mostly peripheral
3. TRPV1 - capsaicin (chilli) also acts here


What are the endogenous neurotransmitters of cannabis?

1. Anandaminde
2. 2-arachidonoglycerol (2-AG)


Who is John Huffman?

- synthesised a range of compounds
- some with high affinity + efficacy
- Rimonabant = fails appetite suppressant


What are the properties of ∆9-THC?

Partial agonist:
- high affinity
- low efficacy


What does affinity and efficacy mean?

- How well the drug binds to its receptors

- How well it does its job (effect)


What is the difference between Full, partial agonist and antagonists?

Full agonist:
- produces maximal stimulation of the target at higher doses + high efficacy

Partial agonist:
- produces smaller effect vs full, even at high higher doses
- can compete w/ full, reducing its effect
- moderate efficacy

- produces negligible effect (low efficacy), regardless of dose
- by competition at receptors, reduces effect of partial + full agonists


When a partial agonist or antagonist are administrated at the same time as a full agonist, how does it effect the full agonist?

- reduction in effect


What did Grant et al 1996 find when cocaine abusers were asked to rate craving for cocaine while observing images of either neutral or cocaine associated objects?

1. cravings greatly increased while the ppt observed cocaine-associated cues
2. Blood flow to the PFC + medial temporal cortex greatly increased
3. increased activation in ventral striatum + other basal ganglia structures
(PET - radioactive glucose metabolism)


What did Bern 2004 find suggesting the meso-limbic dopamine system may also be activated by a wide variety of natural rewards - even those with a strong cognitive element?

- imaging study
- 'funny' cartoons evoked laughter
- activation of =
-- motor areas
-- other cortical areas
-- central striatum (part of the mesolimbic dopamine system)


What are the different way for treating drug addiction?

1. substitue drug with one that has less rewarding properties
-- heroin w/ methadone
2. Block effects of a rewarding drug by treating w/ an antagonist/ partial agonist
3. Naltrexone may also be useful in reducing heavy drinking
4. Behavioural strategies?