Opioid Receptor Signal Transduction and Effects

Question 1

Opioid neuropeptides

Answer 1

Beta-endorphins
Enkephalins
Dynorphins

Question 2

Opioid neuropeptide mechanism of action

Answer 2

Released at several CNS site in response to noxious stimuli > inhibit synaptic transmission

Question 3

4 families of opioid receptors

Answer 3

Mu (MOR)
Delta (DOR)
Kappa (KOR)
Nociceptin (NOR)

Question 4

Type of GPCR associated with opioid receptors

Answer 4

Gi

Question 5

Opioid presynaptic effects

Answer 5

G-Beta/ gamma subunits block voltage-gated Ca++ channels = reduced neurotransmitter release = suppressed synaptic communication

Question 6

Opioid postsynaptic effects

Answer 6

G-alpha inhibitory subunits > block adenylyl and cAMP production and PKA activation = modulation of voltage-gated Na+ channels

Activate K+channels (GIRK) = hyperpolarization

Question 7

Overall effects of opioid receptor stimulation

Answer 7

Inhibit excitability and excitatory neurotransnmitters = opioid-induced analgesia