PSYCH 261 - Drugs & Toxins: Ketamine, Caffeine, Alcohol, Morphine

Felt like putting these ones in their own deck.

Ketamine

generalized anesthetic

• NMDA receptor antagonist (blocks NMDA receptors)

Ketamine blocks ___ receptors on ___ interneurons

NMDA glutamate receptors; GABAergic interneurons

• reducing inhibition of glutamergic neurons

Glutamatergic neuron

neuron that mainly releases glutamate

Ketamine metabolizes into ___

hydronorketamine (HNK)

Ketamine blocks ___ receptors on post synaptic cell; Ketamine and HNK activate ___ receptors on post synaptic cell

block NMDA glutamate receptors; activate AMPA glutamate receptors

Caffeine

nervous system stimulant

Adenosine A₁ Receptor

presynaptic receptor for adenosine in cortex

Adenosine A_2A Receptor

postsynaptic receptor for adenosine in striatum

Adenosine drives ___

sleep pressure

Normally, adenosine binds to ___ receptors in the presynaptic cell, reducing the release of ___

binds to A₁ receptors; reduces release of excitatory neurotransmitters

Caffeine blocks A₁ receptors, reducing its impendence of ___

neurotransmitter release

Normally, adenosine binds to ___ in the postsynaptic cell, reducing the activity of

A_2A receptors; dopamine receptors

Caffeine blocks A_2A receptors, reducing the dampening of ___

dopamine receptors

• blocking A_2A → more excitation

Caffeine also interferes with ___

GABA receptors (normally inhibitory)

Caffeine causes the release of ___ from internal stores, thus increasing neurotransmitter release

calcium

Alcohol

inhibitory effect; central nervous system depressant

Ethanol inhibits ___ channels, and possibly ___ channels

voltage-gated calcium channels; possibly voltage-gated potassium channels

Ethanol binds to __

• adenosine transporters in the presynaptic cell → increases amount of extracellular adenosine

• ionotropic receptors for acetylcholine, serotonin, GABA and glutamate, in the postsynaptic cell → influences passage of ions

Increased extracellular adenosine leads to ___

activation of adenosine receptors in the postsynaptic cell → reduced release of neurotransmitters

• inhibition of postsynaptic cell → reduce excitation

Ethanol interferes with ___

• metabotropic receptors (ex. glutamate receptors) → less postsynaptic activation

• cellular processes (ex. gene expression)

• cell membrane, changes charges → can put cell at risk

• can also cross BBB

Morphine

• opiate

• pain relieving; sedation; euphoria

Opioid receptors are __

metabotropic

Morphine binds to and activates ___

μ-opioid receptors, which release g-proteins

G-protein released from μ-opioid receptors inhibits ___ channels and opens ___ channels

inhibits Ca²⁺ channels; opens K⁺ channels

Desensitization (with morphine)

receptor is phosphorylated preventing G-protein signaling

• so, need higher doses to get previous effect