Unit 4

• Types of Neurotransmitters


  • Amino acid neurotransmitters
  • Peptide neurotransmitters (neuropeptides)
  • Amine neurotransmitters
  • Gas neurotransmitters

  
• Amino acid neurotransmitters


  • GABA- most widespread inhibitory transmitter
  • Glutamate- most widespread excitatory transmitter
• Peptide neurotransmitters (neuropeptides)


  • Opioid peptides (endorphins)
  • Oxytocin, vasopressin
• Amine neurotransmitters


  Acetylcholine, dopamine, serotonin
• Gas neurotransmitters


  • Serve as retrograde transmitter
  • Nitric oxide, carbon monoxide
• Keys


  Ligands (endogenous neurotransmitters and hormones or exogenous drugs or toxins)
• Ionotropic


  Direct receptor system that hits it directly to open
• Metabotropic


  Indirect receptor doesn't open but it attaches to the G protein
• 75% of all drugs made act via metabotropic receptors
• Enzymes


  • Proteins
  • Complex chains of molecules that shift changes in protein
• Agonists


  Mimics or enhances a neurotransmitter
• Antagonists


  May reduce release of neurotransmitter or block receptors
• Neuromodulators


  Indirectly affect transmitter release or receptor response
• Full agonist


  Initiates normal effects of the receptor

  
• Partial agonist


  Has less of an effect than the endogenous ligand would

  
• Competitive antagonist


  Compete against others
• Non-competitive antagonist


  Either hit baseline response rate or not
• Acetylcholine (ACh)


  The neurotransmitter released at the neuromuscular junction
• Types of ACh receptors


  • Nicotinic
  • Muscarinic
• Nicotinic receptors


  • Ionotropic
  • Excitatory
  • Peripheral
• Muscarinic receptors


  • Metabotropic
  • Excitatory or inhibitory
  • CNS

  
• Ways drugs can affect synaptic transmission


  • Presynaptic
  • Postsynaptic

  
• Classes of drugs


  • Stimulants
  • Opiates
  • Cannabinoids
  • Depressants
  • Psychedelics
• Nicotine


  • Primary psychoactive and addictive drug in tobacco
  • Activates nicotinic ACh receptors in the ventral tegmental area (DA)
  • In the periphery, it activates muscles and causes twitching
  • Centrally, it increases alertness and decreases reaction time
• Smoking is the primary cause of preventable death in the world
• Smoking kills 493,000 people a year in the US and 4 million worldwide
• Heroin kills 400 people a year in the US
• Only 5% of each attempt to stop smoking are successful; about the same statistic for heroin
• Adenosine


  A neuromodulator that is normally released with catecholamines
• Caffeine blocks the effect of adenosine


  Stimulates catecholamine release, causing arousal
• 400 million cups of coffee are consumed every day in America
• A study of 40,000 individuals found a greater than 50% increased mortality risk in young men and women who drank more than 4 cups of coffee a day
• Neuromodulator


  Chemicals that indirectly impact neurotransmitter release or receptor response

  
• Adenosine acts to inhibit the release of catecholamines


  Caffeine binds to adenosine receptors and prevents the inhibition of catecholamines
• Cocaine


  • Leaves from coca shrub alleviate hunger, enhance endurance and sense of well-being, but are not addictive
  • Cocaine, the purified extract, is highly addictive, especially crack cocaine which enters the brain more rapidly
• CART (Cocaine-amphetamine-regulated transcript)


  Peptide involved in pleasure sensations from these drugs and in appetite suppression
• Cocaine


  Blocks monoamine transporters, especially dopamine, blocking reuptake of catecholamines and enhancing their effects
• Chronic cocaine use downregulates brain metabolism, like Alzheimer disease
• Amphetamine and methamphetamine


  • Synthetic stimulants that block reuptake and increase release of catecholamines
  • Short-term effects include alertness, euphoria and stamina
  • Long-term abuse causes sleeplessness, weight loss, schizophrenic symptoms
• Adderall, Ritalin, Strattera


  • Stimulant medications used to treat ADHD
  • Increase activity in prefrontal cortex, some subcortical regions, and cerebellum - all centers for executive function
  • Stimulate inhibitory attentional and impulse control systems to function better