inhalants and GHB Flashcards
how can inhalants be categorised?
- inhalants = solvent or other material producing vapour, inhaled by drug abusers
- categorised based on structural similarities
what are inhalants and what do they have in common?
- volatile liquids and gases that vaporise
- volatile solvents that are liquid at room temperature
- they give off fumes
- aerosols that contain solvents
- gases that can be sniffed/inhaled
- they are all euphoriants
what is meant by inhalants/chemicals being euphoriants?
- they produce euphoria or extreme positive mood
- this results in a high
what do behavioural effects of inhalants depend on?
- depends on duration of exposure
- depends on compound used
identify acute behavioural effects of inhalants
- positive mood
- disinhibition
- stimulation followed by lightheadedness
- drowsiness
identify behavioural effects of heavy exposure to inhalants
- slurred speech
- ataxia (loss of bodily control)
- lethargy
- hallucinations
- sometimes delusions
identify behavioural effects of very heavy exposure to inhalants
- anaesthesia
- coma
what is sudden sniffing death syndrome?
- happens when inhalants force heart to beat rapidly and erratically until user goes into cardiac arrest
what does repeated use of inhalants cause?
damage to:
- lungs
- kidneys
- liver
- subcortical brain abnormalities
- damage to myelin sheaths around axons
where have subcortical abnormalities in inhalant abusers been identified?
abnormalities in 10-40% of inhalant abusers:
- basal ganglia
- cerebellum
- pons and thalamus
identify additional adverse effects from using inhalants
- hypoxia (hypoxia)
- frostbite (due to some sprays designed to have rapid cooling effect)
- risks arise from some inhalants being flammable or explosive
what evidence is there for addiction to inhalants?
- tolerance (when user requires increased doses to produce same effect)
- withdrawal symptoms (when user stops using, get symptoms of nausea, tremor, irritability. This is relieved when start using again)
why is mechanism of inhalant action not fully understood?
- recent phenomenon
- they are chemically diverse
outline evidence for the reinforcing properties of inhalants
Funada et al. (1992)
- animal studies
- put mice in place conditioning task
- this task relies on the use of distinctive chambers
- one chamber is paired with drug administration (toluene)
- researcher found mice preferred the chamber with toluene
what is the substrate and pathway of normal reward systems?
dopamine
mesolimbic pathway
outline the findings of Riegel & French (1999) who measured the firing in ventral tegmental brain region in rats given toluene
- gave anaesthetised rats toluene
- measured firing in ventral tegmental area
- found that some neurones increased in firing rate then decreased again within minutes of toluene exposure
- also found sometimes firing rate was completely inhibited
how are the effects of inhalants mediated in the brain?
- inhalants = rapidly absorbed, fat soluble
- makes neurones very vulnerable to effects of inhalants
- due to this, inhalants distributed widely around the brain
- particularly to striatum, thalamus, deep cerebellar nuclei
identify 2 ideas that explain the effects inhalants have on CNS excitability
1/ inhalants enhance function of GABA and glycine inhibitory receptors
2/ inhalants inhibit excitatory NMDA glutamate receptors
idea is that inhalants reduce CNS excitability
identify legal issues with inhalants
- solvent misuse = not illegal
- shopkeepers not allowed to sell intoxicating substances to those likely to be inhaling them
- Scottish law = can be prosecuted for recklessly selling substances
- it is illegal to supply gas lighter refills to under 18’s
identify social issues of inhalants
- in US -> 6% of children have tried inhalants by 4th grade
- in Australia -> problem with petrol sniffing in indigenous communities
what is GHB?
- Gamma Hydroxybutyrate
- related to GABA (inhibitory neurotransmitter)
what was GHBs original use?
- made to treat cataplexy (sudden loss of muscle control)
- but reported adverse effects which resulted in a ban
compare GABA and GHB
- very similar chemical structure
- GABA has neuromodulatory effects -> this doesn’t lead to extreme effects
- GHB has more extreme effects
identify behavioural and physical effects from low doses of GHB in humans
- mild euphoria
- disinhibition
- relaxation
identify behavioural and physical effects from high doses of GHB in humans
- slurred speech
- ataxia
- lethargy
- dizziness
- nausea
- vomiting
identify behavioural and physical effects of overdosing from GHB in humans
- respiratory depression
- lack of consciousness
- seizures
what is the evidence for addiction of GHB?
- tolerance = informal reports from users that report increasing dosage
- withdrawal = symptoms reported as insomnia, anxiety and tremors when stop using
identify the effects of low doses of GHB in lab animals
- sedation
- reduced locomotor activity
- decreased anxiety
identify the effects of high doses of GHB in lab animals
- catalepsy
- paradoxical CNS excitation (absent seizures)
outline a study that looks into the tolerance to locomotor-suppressant effects of GHB in mice
- on first day of treatment, locomotion = suppressed
- later days of treatment = mice hit with same doses of GHB and locomotor activity recovered
outline study that confirms treatment with GHB stimulates the reward system
- GHB induced conditioned place preference in mice
- mice given either 125 or 250 mg GHB in least preferred chamber
- saline injection given in preferred chamber
- recorded time spent in chamber before and after conditioning
- 250mg GHB produced significant conditioned place preference
identify 2 theories that explain how the effects of GHB are mediated
1/ GHB acts on inhibitory GABA receptors
- GHB has weak affinity for GABA receptors
- GHB is metabolised into GABA (but GABA does not cross blood-brain barrier)
2/ there are specific excitatory GHB receptors
- GHB = naturally occurring
- there are selective GHB binding sites in the brain
- some evidence that GHB synthesised in the brain from GABA
idea that both GABA and GHB receptors affect dopamine release
outline legal issues with GHB?
- class C drug
can be used for legitimate use in industry
- possession and selling = offence
outline social issues with GHB?
- used in clubs
- like ketamine, ecstasy
- date rape drug
