Lecture 5 Flashcards
Neurotransmitter types
- Aminoacids (small and a lot)
- Amines (medium size and concentration)
- Peptides (large and low concentration)
Production of Amines and Aminoacids
Enzymes are synthesized in the cell body. In the synapse the enzymes are used to synthesize aminoacids and amins.
Inactivation largely through reuptake
Production of Peptides
Enzymes synthesized in the cell body. Enzymes and pre-peptide precursors go down microtubule tracks. Enzymes modify pre-peptidess to produce peptide neurotransmitters.
Inactivation through breakdown and diffusion
The prototypical neuron
- Cytoskeleton: internal scaffolding within the neuronal membrane
- Tubulin: cell body, dendrites, proximal axon
- Tau: axons
- Actin: in the growth cone, in the heads of the spines
Anterograde tracing
From soma to synapse.
Horse radish Peroxidase (HRP)
Phaseolus vulgaris-leuocoagglutinin (PHA-L)
Retrograde tracing
From synapse to soma.
Fluoro-Gold (FG)
Cholera Toxin (CT)
Fast Blue (FB)
Immunohistochemistry
Method to identify location of molecules within cells using antibodies
- Neurotransmitter candidate is injected into organism and this creates antibodies that bind to it
- Blood is withdrawn and antibodies are isolated
- Antibodies are tagged with a visible marker and are applied to sections of brain tissue.
When using different antibodies you can identify several types of neurons within the same brain region
In situ hybridization
Method to identify cells that synthesize a particular protein or peptide.
This method uses a complementary strand of mRNA (probe) that was constructed in a lab that will stick to a specific sequence of nucleic acids in a strand of mRNA.
The binding is called hybridization.
Over time the probes stick to any complementary strands of mRNA and then you can search for the neurons containing the label.
One way of labeling is by way of fluorescence, also known is FISH.
Acetylcholine general information
- Nicotinic and Muscarinic receptors
- Mediumsized transmitter
- Part of diffuse modulatory systems of the brain
- Production depends on two enzymes: Choline acetyltransferase (making Ach) and Acetylcholine esterase (recycling Ach)
- No reuptake (Ach esterase)
Novichok
- Organophosphates
- Block acetylcholine esterase
- Used in Navalny poisoning
- Neuromuscular paralysis
Vesicle packing and recycling
- Synapsin: connects pool of vesicles
- CaMKII: dissociates synapsin from vesicles
- SNAPS and SNARES: priming and docking
Vesicle fusing with membrane
- Synaptobrevin: vesicle membrane
- Syntaxin: synaps membrane
- Cleave SNARE: block transmitter release
- Ca2: brings membranes together which leads to fusion
Vesicle recovery
- Clathrin: connects to vesicular membrane and coat around it
- Dynamin: pinches vesicle from the synaptic membrane
- Actin: transport from the membrane
- Auxilin: removal of clathrin coat
Acetylcholine projections
Basal forebrain complex: Medial septal nuclei (-> hippocampus) and basal nucleus of Meynert (-> neocortex)
Pontomesencephalotegmental complex: Pons and tegmentum -> dorsal thalamus
Acetylcholine nicotinic receptor
- 5 subunits
- Fast and shortlasting action
- Gate flips open when Ach binds