Drugs of Abuse 1 Flashcards
Describe reward pathway, type of neurone, originate, project to, specific area, NT
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
Why is inhalation faster than injection as a administration route
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
What is the central reward pathway known as
Mesolimbic dopamine system
Most potent cannabinoid?
Delta9-Tetrahydrocannabinol (Delta9-THC)
what protects against -ve effects of delta9-THC
Cannabidiol
Lipid solubility of cannabis? T
it’s very lipid soluble- will also slowly accumulate in poorly perfused fatty tissues
what can store cannabis?
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
INHALATION = 25-35% of dose of cannabis enters bloodstream, where’s the rest?
50% doesn’t make it all the way down into the lungs
Ways THC is metabolised and successfulness of these methods? (3)
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
How long can cannabis be detected in the body post smoke
30 days, stored in adipose tissue remember
What type of receptors are the cannabinoid receptors
G-protein type 2
Where are CB2 receptors found
Immune cells
Where are CB1 receptors found (4)
hippocampus/cerebellum/cerebral cortex/basal ganglia
What effect to CB receptors have on adenylate cyclase
Downregulate activity
What is the endogenous cannabinoid
Anandamide
How do cannabinoids cause euphoria
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)
What is the link between cannabis and psychosis/schizophrenia
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
3 regions of brain involved in feeding?
arcuate nucleus, ventromedial hypothalamus and the lateral hypothalamus
What part of the brain is associated with inhibited feeding
Ventromedial hypothalamus
What part of the brain is associated with increased feeding
Lateral hypothalamus
What neurons in the lateral hypothalamus does cannabis effect (2)
MCH and orexigenic neurones
How does cannabis cause the munchies (2)
Cannabis can cause presynaptic inhibition of GABA which increases MCH neuronal activity
Cannabis can also increase orexin production
What neurons promote appetite seeking (feeding) behaviour (2)
MCH and orexin neurons
How is cannabis an immunosuppressant
Binds to CB2 on immune cells causing their function to be downregulated
