Postsynaptic mechanisms & Transduction

Question 1

What are the categories of cellular receptors for postsynaptic?

Answer 1

Ionotropic receptor
Metabotropic receptor

Question 2

Another name for ionotropic receptors:

Answer 2

Ligand-gated ion channels

Question 3

Another name for metabotropic receptors:

Answer 3

G-protein coupled receptors

Question 4

Nicotinic acetylcholinergic receptor (nAChR):

Answer 4

-Postganglionic receptor
-Neural nAChR consist of 3a, 2b subunits
-Muscle nAChR consist of 2a, 3 (b, g, d and/or e) subunits
-nAChR are non-selective cation channels (Na+, K+)
- Generate excitatory postsynaptic potentials

Question 5

AMPA receptors (GluR1-4):

Answer 5

-Activated by excitatory amino acid neurotransmitters like glutamate
-Receptors are non-selective cation channels (Na+, K+) that generate EPSPs
-Glutamate is the most common neurotransmitter of 50% of neurons in the CNS

Question 6

NMDA receptor channel:

Answer 6

-A ligand- and voltage gated receptor
-Needs glutamate and glycine to be bound for activation
-Pore allows for Ca++ entry
-At hyper-polarized membrane potential Mg++ resides within the channel pore and blocks Ca++ entry
-Depolarization will cause Mg++ to be pushed out of the pore and allow current to flow

Question 7

T/F: Activation of AMPA receptors produces very fast excitatory postsynaptic current

Answer 7

True

Question 8

T/F: Activation of NMDA receptors produces very fast excitatory postsynaptic current

Answer 8

False. Activation of NMDA receptors causes slower EPSC

Question 9

T/F: Most CNS synapses will only have either NMDA or AMPA receptors

Answer 9

False. Most CNS synapses posses both AMPA and NMDA receptors. ESPSC produced by activation of AMPA receptors provides the depolarization needed to remove Mg++blocking the NMDA receptor channel

Question 10

GABAa receptor channel:

Answer 10

-Inhibitory CNS transmitters
-GABA is used by 30% of all CNS neurons
-GABA receptors are GABA gated anion channels
-CI is the main permeant ion under physiological conditions

Question 11

Types of G-protein coupled receptors:

Answer 11

Heterotrimeric G-proteins
Monotrimeric G-proteins

Question 12

Heterotrimeric G-proteins:

Answer 12

Receptor activation causes binding of G-protein and the alpha subunit to exchange GDP for GTP> leads to the dissociation of the beta and the gamma subunits

Question 13

Monotrimeric G-proteins:

Answer 13

Receptor activation causes Ras to bind to GTP leading to stimulation of biological actions

Question 14

Glutamate metabotropic receptors:

Answer 14

• There are 3 glutamate metabotropic receptors
  -Classes based on Class I, II and III
  -Each class is broken down into more receptor subtypes

Question 15

Excitatory amino acid metabotropic receptors:

Answer 15

Receptor class: Glutamate
Receptor subtype:
Class I: mGLU R1, mGLU R5
Class II: mGLU R2-R3
Class III: mGLU R4,6,7,8