Reward and Drug Addiction Flashcards
Psychoactive Drugs
- Drugs: Chemical substances which interact with the biochemistry of the body
- Psychoactive drugs: Any chemicals that influence the way we feel or act
Agonists vs Antagonists
- Agonist: mimics the action of the neurotransmitter
- Antagonist: blocks the action of the neurotransmitter
- Synapse Level: effect on the post-synaptic neuron
- Receptor Level: effect on the receptor
Pre-synaptic Receptors
Post-synaptic Receptors
Autoreceptors
- inhibiting the exocytosis of their own neurotransmitters, noradrenaline or adrenaline, as part of a negative feedback loop
Reuptake
- after a signal has been transmitted
- reabsorbed by the nerve cells
- allows neurotransmitters to be reused and helps regulate neurotransmitter levels present in the synapse
Pharmacokinetics
The study of how the body interacts with administered substances for the entire duration of exposure
Intake
Routes include:
- Digestive tract: desired but slow
- Respiratory tract: faster
- Through skin: ex. ibuprofen gel, nicotine patch; fairly quick
- Through mucous membranes: ex. snorting cocaine
- Intravenous injection (directly into blood)
- Intramuscular injection (into the muscles)
- Subcutaneous injection (under the skin)
Distribution
- distribution can be different depending on whether its water-soluble or lipid-soluble
- blood stream (capillaries) to tissues (capillaries reach all organs and all parts of it)
- only difference in the blood-barrier of capillaries in the brain
Elimination
- all drugs are eventually eliminated from the body (by chemical breakdown (enzymes) or excretion (urine)
- drugs can be stored in the body for varying lengths of time (depending on their biological half-life)
Physical Dependence
- A side effect of the tolerance that your body has built up to the drug; Body maintaining homeostasis
- Will develop even with therapeutic doses
Psychological Dependence
- That association of “this is good i enjoy it” to the drug
- When drug directly interacts with the brain’s reward system
- Addicts will crave the drug, even while disliking the effects
Tolerance (Metabolic and Functional)
Metabolic Tolerance:
- Your body gets better at clearing the drug
- Better elimination of the drug
Functional Tolerance:
- Exposure to the drug makes changes to structures over time
- Change in receptor numbers; Change in receptor sensitivity; Change in intra-cellular cascades
Withdrawal
Person will start to feel the body’s counteraction/response to the drug that they have stopped taking (the counteraction that have built up the body’s tolerance towards the drug)
Mesotelencephalic Dopamine System
Opiate Addictiveness
- In Ventral Tegmental Area (VTA), opiates inhibit GABA-nergic interneurons
- This releases inhibition from neurons which project to Nucleus Accumbens
- More dopamine release WHICH is what makes you want it again and again
- In Nucleus Accumbens, effects are independent from but similar to Dopamine from VTA