Lecture 6: Neurobiology of Drug Addiction Flashcards
What are psychoactive drugs?
Act on the CNS to alter mood, thought, behaviour, manage illness. Are often abused.
List routes of drug administration
- Oral - easiest but most complex
- Inhalation - fastest way to brain
- Absorption - through skin
- Intravenous - few barriers to overcome
- Intracranial - directly into brain at lower dose
What is the blood brain barrier
Tight seal of capillary cells that protects brain from most substances but can become compromised via injury. Foods can be actively transported across, O2 and CO2 can diffuse across, but 98% of therapeutic drugs can’t
List four structures outside the BBB
Pineal gland: interacted with blood born hormones
Pituitary gland: secretes hormones into blood
Area Postrema: vomiting reflex
Arcuate Nucleus: feeding and energy homeostasis
How does metabolization and excretion occur?
Metabolization in kidneys liver and intestine via cytochrome p450 - liver enzymes that eat up many different drugs. Excretion via bodily fluids. What can’t be broken down becomes toxic
Lost places where drug action occurs at synapse
Synthesis Storage Release Receptor Inactivation Uptake Breakdown
What are two functions of drugs?
Agonist: increase transmission
Antagonist: decrease transmission
Define and describe tolerance
A decreased response to drug with passage of time and repeat exposure. Can be metabolic, cellular, psychological
Define and describe sensitization
Response increases over time and exposure. Happens for intermittent use vs chronic in cocaine. Occurs because of: increasing receptors, change in metabolism, change in reuptake, or change in number or size of synapse
List classes of psychoactive drugs
Anti anxiety and sedatives Antipsychotics Antidepressants and mood stabilizers Opioid analgesics Psychotropics
Define and describe anti anxiety and sedative drug effects
Anti anxiety or benzodiazepines are safer at higher levels. Sedatives include alcohol and barbiturates such as anesthetic. Can develop cross tolerance because of common GABA receptor. Agonist drug that increases GABA reception at various modes
Define and describe antipsychotics
End hallucinations and false beliefs, incidence in schizophrenia. FGA produce Parkinson’s symptoms because only worked on dopamine. SGA include blocking serotonin which is better. Antagonist drug that decreases dopamine and serotonin
Define and describe antidepressants
Agonist drugs which allows more serotonin to be released. MAOI only did serotonin but TCAs include norepinephrine and dopamine. SSRIs are like TCA but only work on selective serotonin
Define and describe mood stabilizers
Mute intensity of mania, with lithium, anti epileptics or antipsychotic Blocks the excitability of neurons therefore antagonist.
Define and describe opioids
Sleep inducing and pain relieving, effects at brainstem, opioid receptors occur in our body especially in brain and spinal cord. Tolerance occurs quickly. There are detoxing drugs which compete with opioids to block receptors. Eg, narcan.
