9. Neurotransmitters an receptors Flashcards
2 cationic transmitters and what do they depend on for vesicle packaging?
monoamines and ACh
depend on ΔpH
What does glutamate depend on for vesicle packaging?
glutamate uses primarily the electrical component (ΔΨ).
3 Examples of vesicle transporter proteins
Vesicular glutamate transporter 1 (VGLUT) (2, 3)
Vesicular GABA transporter (VGAT)
Vesicular monoamine transporter 1 (VMAT1)
Vesicular acetylcholine transporter (VAChT)
4 criteria of a neurotransmitter
Present in presynaptic terminal with synthesis machinery and specialized vesicular transporter.
Released upon presynaptic stimulation.
When added to extracellular fluid should mimic effects of presynaptic stimulation.
A mechanism for removal of neurotransmitter
Examples of classical neurotransmitters
Ach Dopamine Adrenaline Serotonin Noradrenaline GABA Glutamate
Examples of neuropeptide neurotransmitters
Substance P Endorphins Enkephalins Vasopressin Oxytocin
Examples of ‘other’ neurotransmitters
NO
Adenosine
ATP
What is specialization?
neurons of certain type are only able to make specific kinds of neurotransmitters
What is developmental switch?
Neurons can change the neurotransmitters they synthesize
What do temporal characteristics of the neurotransmitter
depend on?
kinetics of receptor:
binding of ligand (transmitter)
activation of receptor
desensitization of receptor
What does operating range of transmitter concentration
depend on?
affinity of receptor - EC50
Why can we not define neurotransmitters as inhibitory or excitatory?
excitatory or inhibitory action of any signalling molecule
can be defined only in relation to some physiological /biochemical process
Action of neurotransmitter will be determined by functional properties of the corresponding receptors expressed in the particular cell/tissue
3-unit structure channel example
P2X receptors
4-unit structure channel example
glutamate receptors
Na-channels
5-unit structure channel example
nAch receptors
How does Ach cause a conformational change in the nicotinic receptor?
Binding of two molecules causes twisting of the M2 helices so bulky Leu side chains are replaced by smaller, polar residues lining the channel.
What are the 3 types of glutamate receptor?
AMPA
NMDA
metabotropic
Why are NMDA receptors not active at resting potential?
Mg++ block
Two types of GABA receptors
GABA A (ionotropic) GABA B (metabotropic)
