Psychopharmacology

Psychopharmacology:

  • the study of the effects of drugs on the NS and behavior

Site of action:

  • A location at which molecules of drugs interact with molecules located on or in cells of the body, thus affecting some biochemical processes of the cell

Pharmacokinetics:

  • The process by which drugs are absorbed, distributed within the body, metabolized, and excreted

Neurotransmitter:

  • Chemical released into synapse

  • Has excitatory or inhibitory effect on another neuron

Neuromodulator:

  • Most are peptides that acts like NTs

  • Not limited to synapse- diffuse through extracellular fluid

Peptide

  • Two or more amino acids linked together

Lock and key mechanism

  • Ligand:

    • chemical that attaches to a receptor

  • Receptor is the lock, ligand is the key

  • NT are natural ligands

  • Drugs can also serve as ligands

    • Other natural chemicals

    • Man-made chemicals

NTs you’ll hear about the most…

  • Acetylcholine (ACh)

    • Movement, REM sleep, memory

  • Amino acid NT

    • GABA

      • Primary inhibitory NT

    • Glutamate

      • Primary excitatory NT

  • Monoamines

    • Dopamine (DA)

      • Movement (L-DOPA is a precursor), problem solving, reward

    • Norepinephrine (NE)

      • Fight-or-flight responses, arousal

    • Serotonin (5-HT)

      • Regulation of mood, dreaming

Postsynaptic potentials

  • EPSP - excitatory post-synaptic potential = depolarization (AP more likely)

  • IPSP - inhibitory post-synaptic potential = hyperpolarization (AP less likely)

  • The NT doesn’t directly determine type of postsynaptic potential

    • It is which type of ion channel is opened on the post-synaptic receptor

How are chemicals (NTs/ligands) removed from the synapse?

  • Degredation

    • The destruction of an NT by an enzyme

    • Ex. acetylcholinesterase

      • Breaks down acetylcholine

  • Reuptake

    • The neurotransmitter is cleared by being taken back in by the presynaptic cell

    • E.g. SSRIs block reuptake

Ways drugs affect synaptic transmission

  • Agonists

    • drugs that facilitate a response

  • Antagonists

    • drugs that block or dampen a response

Agonistic effects

  • Drug causes increase in NT synthesis (creation)

  • Drug increases release of NT

  • Drug acts as ligand and binds to receptor

Antagonist effects

  • Drug blocks release of NT

  • Drug blocks receptors

  • Drug causes NT to leak from vesicles

Dose-response curve

  • Plots the magnitude of the effect of a drug as a function of the amount of the drug that is administered

  • Maximum effect = the point at which increasing dose does not produce a stronger effect

Therapeutic index

  • Also called the margin of safety. HIGHER IS BETTER!

Tolerance

  • A decrease in the effectiveness of a drug that is administered repeatedly

    • e.g. cocaine, decreased euphoric effects

The placebo effect

Placebo

  • An inert substance given to an organism in lieu of a physiologically active drug

    • Used in researched studies and also medicine