drugs of abuse Flashcards
brain regions connected by the dopaminergic ‘reward’ pathway?
1.ventral tegmental area in the brainstem to the nucleus accumbens in the basal forebrain
2.then dopaminergic projects out to control the cortical and limbic regions
3.pathways are also known as the mesocortical and mesolimbic pathways as they project from the midbrain region of the brainstem to cortical and limbic systems respectively.
what is the transmitter receptor target of Marijuana ?
cannabinoid
what is the transmitter receptor target of cocaine?
dompamine
what is the transmitter receptor target of ketamine?
glutamate
what is the transmitter receptor target of valium?
GABA
what is the transmitter receptor target of heroin?
Opioid
what is the transmitter receptor target of ecstasy?
serotonin
what is the difference between abuse and misuse?
-consider misuse as using a substance for a purpose that it was not designed/prescribed for (e.g. taking a drug for ADHD to improve study capacity)
-whereas abuse is taking a substance in order to obtain a specific sensation (e.g euphoria/high/sedation
Alcohol
-due to the speed of onset of effect and ease of administration.
-It is rapidly absorbed from the small intestines as it is highly lipid soluble and non-tissue specific.
in what 3 ways does the CNS get effected by alcohol ?
1.Enhancing GABA activity
2.Inhibition of glutamatergic NMDA receptors
3.Inhibition of voltage dependent calcium channels (VDCC)
Chronic alcohol
leads to the inverse of effects occurring: reduction in GABAergic inhibition, increased NMDA receptor number and VDCC number, which may be linked to the increased levels of anxiety and insomnia associated with dependence
What would happen if you increased GABA activity in the hippocampus (remembering that this is a region involved in learning and memory and spatial awareness)?
ncreasing inhibition in the hippocampus (a region involved in learning and memory, emotions and spatial awareness) would reduce likelihood of deposition of memories/learning and also spatial awareness; leading to memory loss, confusion and disorientation, which are common side effects of too much alcohol.
what does nicotine act as?
stimulant and relaxant and is classed as a parasympathomimetic
what part of the brain region does nicotine act on ?
centrally in the brain and peripherally in the autonomic nervous system (ANS) ganglia
what receptor does nicotine bind to?
nicotinic cholinergic receptors (nAChR)
what 3 substance does nicotine release?
1.noradrenaline
2.acetylcholine
3.adrenaline
what 3 transmitters does nicotine ?
1.endorphins
2.dopamine
3.serotonin accounting for the positive mood effects and addictive quality of the substance
what provides positive reinforcement
cognitive enhancements and increase in fine tuning of movement
Opioids
class of drugs that mimic endogenous substances that bind to opioid receptors (endorphins), which are found in the central and peripheral nervous systems
what do opioids act as?
-neuromodulators
-best painkiller currently available is the opioid morphine
what are the four types of opioid receptor found in the nervous system?
µ (mu), κ (kappa), δ (delta) and NOP
how do opioids decrease neuronal transmission?
binding to the opioid receptors and causing
what 4 things does neuronal transmission cause?
1.Decreased opening of voltage-dependent Ca2+ channels
2.Increased K+ outflow via KATP and KIR channels
3.Decreased Ca2+ release from intracellular stores
4.Decreased exocytosis of transmitter vesicles
what are the 2 things that will decrease Ca2+ release, either from intracellular stores or entry reduce?
1.plastcity changes
2. activation of second messenger cascades, reducing activity in the neurons
How does increasing K+ outflow alter the neuron’s membrane potential?
Hyperpolarised
what is decreased exocytosis?
reduce cell-cell communication, disrupting transmission of the messages that the neurons are carrying.
what happens after the neuronal activity is dampened down in decreased exocytosis?
reduction in arousal, reducing physical activity and increasing in the parasympathetic activity within the autonomic nervous system
what is linked to k-receptor activation?
sigma receptor, where a lot of the psychoactive drugs act (e.g. pentazocine and phenazocine, which act at both kappa and sigma receptors)
what is opioid dependence associated with?
decrease in µ-receptor numbers over time and increase in κ-receptor, which probably explains the changing behavioural effects of addiction
Which opioid receptor antagonist can be used to prevent relapse in both opioid and alcohol dependence?
Naltrexone