neurotransmission and drugs

agonists and their types

turn on neurotransmitter system (EPSP, IPSP)

• presynaptic: release neurotransmitter

• postsynaptic: activate receptors 

antagonists and their types

turn off neurotransmitter system

• presynaptic: prevent release

• postsynaptic: block receptors

inverse agonists

postsynaptic, binding to receptors but induce the opposite effec

types of presynaptic agonists, not explained

L-DOPA

cocaine

amphetamine

SSRIs

L-DOPA

presynaptic agonist

• given in Parkinson’s Disease with reduced dopamine

  • precursor of dopamine where cells are able to make dopamine → necessary because of the brain blood barrier

coacaine

presynaptic agonist

• inhibits reuptake of dopamine by blocking the dopamine transporter

amphetamine

presynaptic agonist

• blocks and reverses dopamine transporter

  • increases dopamine and norepinephrine

  • stimulation, euphoria, wakefulness, cognitive control

  • treatment of ADHD/narcolepsy

  • Adderall: combination of amphetamine and dextroamphetamine

Adderall

subtype of amphetamine where it is a combo of amphetamine and dextroamphetamine

• used in ADHD treatment

SSRIs (serotonin reuptake inhibitors)

block reuptake of 5-HT

• Prozac = commonly prescribed

types of postsynaptic agonists

morphine/heroin

benzodiazepines

morphine/heroin

postsynaptic agonist

• activates opioid receptors

• euphoria, pain relief by mimic endorphines/enkephalins

• synthetic opioid drug

subtypes

• fentanyl: 100x more potent than morphine

• carfentanil: 100x more potent than fentanyl

benzodiazepines

AKA Xanax/Valium

postsynaptic agonist

• sedative, hypnotic, anxiolytic, muscle relaxant, anti epileptic

• bind to GABA receptors, widening the ion channel

  • requires GABA to operate

postsynaptic antagonists types and explanation

antipsychotic drugs: schizophrenia (primozide, halopendol)

• blocks D2 receptors, aka dopamine inactivator

atyptical antipsychotics 

• blocks serotonin receptors and some dopamine receptors

How Drugs Reach the Synapse

1. cross BBB

2. Administration

   1. oral (easy, longer, breakdown of drugs)

   2. injection (IV being the quickest, high concentration)

   3. inhalation (short route, high concentration)

types of injections

subcutaneous

intramuscular

intravenous

Long Term Effects of Drugs

1. receptor down regulation

2. neural sensitization

3. neurotoxicity

receptor down regulation

tolerance to drug, homeostatic regulation in postsynaptic cell causes receptor degradation

• withdrawal in absence, normal in neurotransmitter signal

neural sensitization

hyper-responsive to a drug

• dopamine sensitization and addiction

neurotoxicity

amphetamine → kills dopamine neurons and toxic at 10x street dose

overdose of heroin/morphine effect

inhibition of brainstem breathing circuits!

receptor down regulation

• tolerance to drug

  • receptor degradation

• withdrawal in absence

  • normal neurotransmitter gives a low signal

neural sensitization

hyper-responsive to the drug

• dopamine sensitization / addiction → wanting vs liking