Chapter 6 exam Flashcards
How are neurotransmitters defined/ identified?
- Be synthesized and stored in the presynaptic neuron
- Be released by the presynaptic axon terminal upon stimulation
- Must produce a response
in the postsynaptic cell that mimics the response produced by the release of neurotransmitters from the presynaptic neuron
How might one localize neurotransmitter systems in the brain?
Immunohistochemistry is the method that uses antibodies to identify the location of molecules within cells. The molecule of interest (neurotransmitter candidate) is injected into an animal, causing an immune response and the generation of antibodies. Blood is drawn from the animal and the antibodies are isolated from the serum. The antibodies are tagged with a visible marker and applied to brain tissue sections. The antibodies label only those cells that contain the neurotransmitter candidate.
What are the precursors for the main neurotransmitters we discussed?
DA: dopa
NE &E: tyrosine
GABA: glutamate
What is the rate-limiting step for each neurotransmitter’s synthesis?
ACh: choline
DA, NE & E: Tyrosine hydroxylase (TH)
5-HT serotonin: Tryptophan
GABA: GAD
What is In Situ Hybridization?
Immunocytochemistry is a method for viewing the location of specific molecules, including proteins, in sections of brain tissue. In situ hybridization is a method for localizing specific mRNA transcripts for proteins. Together, these methods enable us to see whether a neuron contains and synthesizes a transmitter candidate and molecules associated with that transmitter.
What kinds of receptors might each neurotransmitter have (a few examples?)
ACh-Cholinergic (ion gated channels): Nicotinic receptor ( Nicotine is an agonist & Curare is an antagonist), Muscarinic receptor (Muscarine is an agonist & Atropine is an antagonist), Glutamate (ligand-gated ion channels)- AMP receptor, NMD receptor, Kainate receptor (all three help with memory)
What is micoriontophoresis?
This method enables a researcher to apply drugs or neurotransmitter candidates in very small amounts to the surface of neurons. The responses generated by the drug can be compared to those generated by synaptic stimulation (mimics synaptic transmission).
What neurotransmitter system is typically affected by Parkinson’s disease? What is an early treatment for it?
Why does this work?
The dopamine system is affected by Parkinson’s disease. Give them dopa. Making dopamine can temporarily slow the progress of Parkinson’s. Alzheimer’s disease people can also get dementia due to a decline in cells that release acetylcholine.
What are co-transmitters?
When two or more transmitters are released from one nerve terminal, they are called co-transmitters.
What is Dales’s principle?
The idea that a neuron has only one neurotransmitter is often called Dale’s principle. Many peptide-containing neurons violate Dale’s principle because these cells usually release more than one neurotransmitter: an amino acid or amine and a peptide.
How are neurotransmitters cleared from the synapse (know which ones are cleared in what way)
diffusion out of the cleft, degradation by an enzyme, or via re-uptake pumps that actively pump the neurotransmitter back into the presynaptic axon. Dopamine, NE & E: reuptake by selective transporters; degradation by MAO inside. ACh: acetylcholinesterase breaks them down. serotonin 5-HT: reuptake, GABA: reuptake.
What is the structure of a ligand-gated ion channel? Think about primary/secondary/tertiary structure!
4 transmembrane (2 alpha helices with sites)
What do various receptors do in response to ligands binding (we discussed some examples – in terms of what
must happen for the ion channels to open, and what ions they provide passage for)
For nicotinic receptors to open two alpha acetylcholine receptors need to bind. Different subunits contribute to different functions of the receptors.
What are methods used to identify whether neurotransmitters are involved at synapses?
