Drugs of Abuse 1 Flashcards

1
Q

Describe reward pathway, type of neurone, originate, project to, specific area, NT

A

Collection of dopaminergic neurones that originate in the ventral tegmental area and project down to the ventral striatum (in particular the nucleus accumbens) where they release dopamine

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2
Q

Why is inhalation faster than injection as a administration route

A

because lungs are very close to the heart and the alveoli aren’t much of a barrier to diffusion, much less of a barrier than the mucous membranes, also goes straight to the brain whereas IV has to go lungs then brain

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3
Q

What is the central reward pathway known as

A

Mesolimbic dopamine system

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4
Q

Most potent cannabinoid?

A

Delta9-Tetrahydrocannabinol (Delta9-THC)

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5
Q

what protects against -ve effects of delta9-THC

A

Cannabidiol

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6
Q

Lipid solubility of cannabis? T

A

it’s very lipid soluble- will also slowly accumulate in poorly perfused fatty tissues

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7
Q

what can store cannabis?

A

Adipose tissue works as a store for the cannabis and slowly releases it back into the bloodstream- not a major issue unless you’re a chronic user

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8
Q

INHALATION = 25-35% of dose of cannabis enters bloodstream, where’s the rest?

A

50% doesn’t make it all the way down into the lungs

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9
Q

Ways THC is metabolised and successfulness of these methods? (3)

A

Liver - produces 11-hydroxy THC which is even more potent that delta9-THC

Large amount is secreted by bile but undergoes enterohepatic circulation and so can get back into the blood

Urine 25% loss

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10
Q

How long can cannabis be detected in the body post smoke

A

30 days, stored in adipose tissue remember

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11
Q

What type of receptors are the cannabinoid receptors

A

G-protein type 2

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12
Q

Where are CB2 receptors found

A

Immune cells

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13
Q

Where are CB1 receptors found (4)

A

hippocampus/cerebellum/cerebral cortex/basal ganglia

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14
Q

What effect to CB receptors have on adenylate cyclase

A

Downregulate activity

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15
Q

What is the endogenous cannabinoid

A

Anandamide

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16
Q

How do cannabinoids cause euphoria

A

GABA neurones suppress dopaminergic neurones- when the reward pathway is needed, the GABA neurones are blocked
GABA neurones have CB1 receptors
Cannabis binds to these and reduces the firing rate of GABA receptors- this allows more dopamine release (process is called disinhibition)

17
Q

What is the link between cannabis and psychosis/schizophrenia

A

Anterior Cingulate Cortex of the brain is important in error detection and monitoring behaviour to avoid losses (i.e. allows you to adjust behaviour to enhance performance)
In cannabis users there is a hypo-activity in this region

18
Q

3 regions of brain involved in feeding?

A

arcuate nucleus, ventromedial hypothalamus and the lateral hypothalamus

19
Q

What part of the brain is associated with inhibited feeding

A

Ventromedial hypothalamus

20
Q

What part of the brain is associated with increased feeding

A

Lateral hypothalamus

21
Q

What neurons in the lateral hypothalamus does cannabis effect (2)

A

MCH and orexigenic neurones

22
Q

How does cannabis cause the munchies (2)

A

Cannabis can cause presynaptic inhibition of GABA which increases MCH neuronal activity
Cannabis can also increase orexin production

23
Q

What neurons promote appetite seeking (feeding) behaviour (2)

A

MCH and orexin neurons

24
Q

How is cannabis an immunosuppressant

A

Binds to CB2 on immune cells causing their function to be downregulated

25
Q

CNS effects of cannabis? (4)

A

Psychosis, food intake, memory loss, psychomotor performance

26
Q

What part of the brain does cannabis effect to cause schizophrenia

A

Anterior cingulate cortex

27
Q

What part of the brain does cannabis effect to cause increased foot intake

A

Hypothalamus (specifically MCH and orexin neurons in the lateral hypothalamus)

28
Q

What part of the brain does cannabis effect to cause memory loss

A

Limbic regions

29
Q

What part of the brain does cannabis effect to cause poor psychomotor performance

A

Cerebral cortex

30
Q

Why is there LOW CB1 RECEPTOR EXPRESSION IN THE MEDULLA

A

Medulla has the cardiorespiratory control centre, if CB receptors were there to downregulate its activity then we could overdose

31
Q

Tissue half life of cannabis?

A

7 days

32
Q

Why were CB receptor antagonists used as anti-obesity drugs called off

A

Bc people killed themselves

33
Q

Drug use of CB receptor agonists?

A

Enhance regulatory effect of endogenous cannabinoids, (lower pain)