Lecture 6 Flashcards
What are three classes of neurotransmitters?
Amino acids, amines, peptides
What are the different types of neurotransmitters?
- Only one neurotransmitter (Dale’s principle)
- Co-transmitters: two or more transmitters released from one nerve terminal
- Nomenclature (-ergic): cholinergic, noradrenergic, GABAergic, etc.
How are different particular transmitter systems defined?
By molecule, synthetic machinery, packaging, reuptake/degradation, and action
What are the 3 study criteria for establishing a neurotransmitter?
1) Synthesis and storage in presynaptic neuron
2) Released by presynaptic axon terminal
3) When applied, mimics postsynaptic cell response produced by release of neurotransmitter from the presynaptic neuron
What are 3 ways we study neurotransmitter systems?
1) Localizing transmitters and transmitter-synthesizing enzymes
2) In situ hybridization: localize synthesis of protein or peptide to a cell to detect mRNA
3) Immunocytochemistry: localize molecules to cells
What is the qualifying condition for studying synaptic mimicry?
Molecules evokes same response as neurotransmitters
What is microiontophoresis?
technique in which drugs can be ejected in very small amounts to assess postsynaptic actions
What are microelectrodes?
measures effects on membrane potential
What receptors are used in molecular analysis?
1) Transmitter-gated ion channels (ionotropic receptors)
- GABA (a) receptors
- 4-5 subunits, each made with various combos of subunit polypeptides
2) G-protein-coupled receptors (metabotropic receptors)
- GABA (b) receptors
- 7-transmembrane signaling molecules
What was the first identified neurotransmitter? Where is it typically found?
ACh (Acetylcholine) - vertebrate neuromuscular junctions
What happens in Cholinergic Neurons?
ACh synthesis and degradation
What enzyme is needed for ACh synthesis?
ChAT enzyme (Choline acetyltransferase)
What enzyme mediates ACh degradation?
acetylcholinesterase (AChE)
What are catecholaminergic neurons involved in?
movement, mood, attention, and visceral function
What is the precursor for dopamine, norepinephrine, epinephrine?
Tyrosine! They all contain catechol group
What enzymes are involved in making catecholamines?
Tyrosine hydroxylase, Dopa decarboxylase, Dopamine Beta-hydroxylase, phentolamine N-methyltransferase
What are serotonergic neurons derived from?
Tryptophan
What do serotonergic neurons regulate?
mood, emotional behavior, sleep
What can people take to help with serotonergic neurons?
SSRIs - Selective serotonin reuptake inhibitors
How is serotonin made?
2 steps from tryptophan with tryptophan hydroxylase and 5-HTP decarboxylase
What are examples of amine acidergic neurons?
Glutamate - major excitatory CNS neurotransmitter
CABA - major inhibitory CNS neurotransmitter
Glycine
What is glutamic acid decarboxylase (GAD)?
Key enzyme in GABA synthesis & good marker for GABAergic neurons
Why are GABAergic neurons important?
major source of synaptic inhibition in the CNS
What transporters are needed to load GABA and Glutamate into synaptic vesicles?
Vesicular GABA transporter (vGAT) and Vesicular glutamate transporter (vGlut)