CNS Pharmacology II: Stimulants & Depressants Flashcards
What is a Psychoactive / Psychotropic drug?
Drugs that affects mood and behaviour
Which neurotransmitters are Amphetamines structurally similar to?
Dopamine & Noradrenaline
What are THREE ways in which Amphetamines increase DA and NA transmission?
- Increase secretion of DA and NA
- Compete with DA and NA degradative enzymes
- Competing with DA and NA re-uptake systems
Which neurons are mainly stimulated by amphetamines?
Noradrenergic neurons of the ANS
What FOUR ways do amphetamines act on Dopamine (DA) synapses?
- Compete with DA uptake carrier
- Compete with DA uptake into synaptic vesicles
- Inhibit DA degradation (at higher conc. via MAO)
- Bind to DA re-uptake transporter, causing it to act in reverse and transport free DA out of the nerve terminal
What TWO ways do amphetamines act on Noradrenaline (NA) synapses?
- Increase release of NA into synaptic cleft
- Inhibit NA re-uptake transporter
What are the FOUR Dopamine pathways in the brain?
- Nigrostriatal Pathway
- Mesolimbic Pathway
- Mesocortical Pathway
- Tuberoinfundibular
Which areas of the brain, known as the Reward Pathway, do drugs of abuse modify the action of DA in?
- Ventral Tegemental Area (VTA)
- Nucleus Accumbens
Which receptor in the CNS is Nicotine an agonist for?
Nicotinic Acetylcholine Receptor (nACh)
What does ACh release in DA neurons cause?
INCREASED DA release
Which nACh receptor is believed to be linked with addiction?
a4β2
What is the mechanism of action of Cocaine on DA or NA neurons?
- Cocaine binds to DA and NA re-uptake transporters, which inhibits DA and NA removal from synaptic cleft and degradation by MAO
- DA and NA remain in synaptic cleft activating the post-synaptic receptors and enhancing neurotransmission
What are TWO examples of Methylxanthines?
- Caffeine
- Theophylline
Which neurotransmitter are Methylxanthines structurally similar to?
Adenosine
* Inhibitory NT
How do Caffeine and Theophylline act on Adenosine receptors?
Non-Selective Antagonists of the A1 and A2 receptors
Which drug is used to treat ADHD?
Methylphenidate (Ritalin)
How do CNS depressants work?
Increase GABA transmission, which inhibits post-synaptic neuron activity
What is Ethanol’s effects on CNS neurons?
- Increase inhibitory neurotransmission: GABA, Glycine, Adenosine
- Decrease excitatory neurotransmission: Glutamate (NMDA receptors)
What is the mechanism of action of Benzodiazepines?
- Benzo binds to GABAa receptor at allosteric site
- Benzo enhances affinity and response to GABA
- Benzo facilitates opening of GABA-activated Cl- channels
- Benzo increase frequency of channel opening
What are Benzodiazepines with LONG half-lives useful for?
Anxiolytics
* Rapid onset of action with long lasting action
What are Benzodiazepines with SHORT half-lives useful for?
Insomnia
* Rapid onset or sedative effects that dissipate with sleep
What drug blocks the binding and action of Benzodiazepines?
Flumazenil
* Benzo Antagonist
Which SIX neutron types are Opioid Receptors found?
- Glutamate
- NA
- ACh
- GABA
- 5-HT
- Substance P
How does Morphine induce euphoria in GABA and DA neurons?
- Inhibits GABA release
- Reduced inhibition of DA neurons (increased DA in synaptic cleft)