Cannabis Flashcards
What is cannabis?
Cannabis is a natural substance which has been used recreationally for 4000 years
What is a drug?
Any chemical entity which is not usually required for usual bodily functions
What are the active components?
There are 60 active components (cannabinoids) most researched is delta-9-tetrahydrocannibol (THC). Highly lipid soluble and persists in body. Potency has been increasing.
Who suggested a link between schziophrenia and cannabis?
Johns (2001)
What do endocannabinoids regulate?
Endocannabinoids are an important regulatory part of glutamate homeostasis (Bassong and Niesink, 2010)
What are CB1 and CB2 receptors?
CB1 receptors are the most abundantly expressed g-coupled receptors in the mammalian brain. Binding sites in the hippocampus and amygdala (associations with learning and memory), predominately in the CNS
CB2 receptors are predominately in the periphery
How do endocannabinoids act?
Act as a retrograde neurotransmitter. Released from post synaptic neuron and diffuse retrograde lay across the synaptic cleft to stimulate CB1 on the pre-synaptic neuron.
Activation of CB1 receptors transiently decreases NT release from presynaptic terminal
GABA-Eric and glutamatergic synapses throughout the brain so have an inhibitory effect and a excitatory effect.
How does THC work?
Same as endocannabinoids but longer action and not reliant on activation of post synaptic cell because it binds directly to CB1. Exerts postsynaptic control as for all the post synaptic cell knows CB1 has been activated. Affects the regulatory role of endocannabinoids in GABA and glutamate nt. Down regulation (loss of binding sites) and desensitisation (uncoupling from g-protein) (Bassing and Neisink, 2010)
Suggestion that cannabis slows down time?
Suggest that cannabis has the feeling of slowing down time because it speeds up internal clock? (Tinkleberg et al 1976). Treating rodents with cannibinoid receptor agonist (WIN55 212.2) shortened response interval. Premature acceleration in temporal response pattern (Olesom et al 2014)
Who proposed the model of cannabis and schizophrenia?
Bassong and Niesink (2000) proposed that cannabis hampered the protective system of the endogenous cannabinoids (particularly in adolescence) causing disturbed nt release and altering and strengthening the pruning process of synapses and dendrites (glutamate) - disturbed neuro transmission in projection areas of the affected precortical areas
Who carried out a cross-sectional survey?
Tien and Anthony (1990) carried out a cross sectional survey (USA, Australia, Netherlands) twice as high risk of onset of psychosis if continuous use.
Who else associated cannabis with psychosis but with methodological flaws?
McLaren et al (2010) review of cohort study found that all but one had significant associations, dose-dependent.
- association between cannabis use and psychosis does not remain significant once factors such as psychosis risk factors are accounted for
- psychosis reported whilst intoxicated or not?
What did Zamit et al (2010) find?
Zamit 2010 was the only study reviewed by McLaren et al 2010 which had a significant association between cannabis and development of psychosis when controlling for confounding factors.
Medicinal use
Used to treat pain - increases cycloxygenase-2 (cox2) which leads to memory impairment. Cox2 inhibitors have been shown to reduce unwanted side effects (Welberg, 2014)
