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Building the nervous system > Neurotrophins > Flashcards

Flashcards in Neurotrophins Deck (8)
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What are neurotrophins

Extracellular molecules that enhance the survival of neurons


What was the result of grafting a limb bud from one chick onto another

Chick with missing limb had fewer neurons/synapses
Chick with extra limb had more DRG/synapses
amount of target is proportional to the amount of synapses formed


How was nerve growth factor discovered

Sarcomas implanted from mouse to chick embryo
This stimulated the growth of axons inside the chick
Even happened when they weren't in direct contact suggesting the factor was a diffusible one


What is the structure of nerve growth factor

alpha2 beta gamma2


How was the action of NGF investigated

Campenot chamber - If NGF was present in any chamber the neurons survived
If it was only present in the centre the axons retracted from the edges


What are the two types of NGF receptor

1.Tyrosine receptor kinase - high affinity - ligand induced dimerization followed by downstream phosphorylation
2.p75-NTR - Low affinity - can relay a survival or cell death signal depending on the cellular context and the ligand that has bound


How dependency change as neurons grow

New born neurons may have no dependency
NT-3 can support many neuron types early in development
Arrival at target often coincides with a change in dependency and new expression of NT by the target cells
Trigeminal neurons - start - BDNF NT-3
Finish NGF and MSP


Why was the cytokine LIF, IL-6 and CNTF given optimism in becoming a neurodegenerative disease treatment

Because cutting the motor neurons during development of a limb causes neurons to die - if treated first with the cytokine the number of dead neurons were reduced.