prof review 335

• Opium


  • Morphine
  • Codeine
  • Thebaine
  • Heroin
  • hydrocodone & oxycodone
• Semisynthetics


  Partially derived from opiates, partially synthetic
• Opiates


  Natural opioid compounds derived from the opium poppy
• Opioids


  Synthetic or semi-synthetic compounds that bind to opioid receptors
• Opiate Receptors


  • Mu
  • Kappa
  • Delta
• Mu receptors


  • Located in limbic system and thalamus, responsible for most opioid effects including analgesia
• Kappa receptors


  • Located in limbic system, have opposing effects to mu receptors
• Delta receptors


  • Located in nucleus accumbens and VTA, involved in addictive properties and some analgesia
• Resting potential


  Negative charge maintained by active transport mechanism pumping 3 Na+ out and 2 K+ in
• Ion channels


  Allow passage of ions across impermeable membrane, can be gated or non-gated
• All-or-None Law


  Principle that action potential will always be the same
• Action Potential


  1. Depolarization towards zero and positive numbers

  2. Hyperpolarization further away from zero, more negative

  3. Threshold reached, voltage-gated Na+ channels open, Na+ rushes in until charge turns positive

  4. K+ leaves
• Monoamines


  • Catecholamines (Tyrosine -> L-Dopa -> Dopamine -> Norepinephrine -> Epinephrine)
  • Indolamines (Tryptophan -> Serotonin)
• Monoamine Oxidase (MAO)


  Enzyme that destroys monoamines
• Catechol-O-Methyltransferase (COMT)


  Enzyme that destroys catecholamines
• Monoamine reuptake


  Unlike acetylcholine, monoamines are reuptaken
• Stimulants


  Accelerate monoamine release, cocaine blocks reuptake, antidepressants like SSRIs and MAOIs affect monoamines
• Monoamine Receptors


  • Dopamine (6 subtypes)
  • Serotonin (4 subtypes including 5HT1A and 5HT2)
• Limbic System


  • Involved in control of motivations and emotions, lots of drug action
• Hypothalamus and Ventral Tegmental Area (VTA)


  • Home of pleasure centers, part of mesolimbic dopamine system that terminates in nucleus accumbens
• Hippocampus


  • Involved in spatial memory, subtle drug effects
• Amygdala and Septum


  • Involved in serotonin transmission
• Retrograde transmission


  Transmission of signals from post-synaptic to pre-synaptic neuron
• Heroin is a semisynthetic opioid that can cause constipation and is offered as a maintenance medication in some areas to people who use opioids
• Hyperpolarization


  Makes the cell more negative than resting potential, decreasing likelihood of action potential
• Mu receptors


  Associated with most opioid effects
• Benzodiazepines are associated with the most dangerous withdrawal symptoms
• Receptors affected by CBD

  • Adenosine
  • Delta opiate receptors
  • 5HT1A receptors
  • TRPV1
• Early studies showing MDMA has neurotoxic properties were later shown to have involved administration of the wrong drug
• Nucleus Accumbens


  • Associated with the reinforcing drug "rush" sensation
• The ultimate effect of cannabinoids on activity in brain regions is not inhibitory only
• DMT


  Metabolized by monoamine oxidase (MAO)
• Endocannabinoid


  1. arachidonylglycerol (2-AG)
• Nicotinic receptors


  • Have 3 different states: basal, active, desensitized
• MAO is not a neurotransmitter, it is an enzyme that metabolizes monoamines
• Cocaine


  Works by reducing monoamine reuptake from the synapse and increasing the amount of monoamine released into the synapse
• DMT is found in Ayahuasca
• Cocaine is the most reinforcing drug
• Nicotine


  Causes downregulation of nicotinic receptors with repeated use
• Serotonin is an example of an indolamine monoamine that is affected by some psychedelics