Neuronal Survival Flashcards
(22 cards)
What is an important concept about neuronal survival?
Generally, more neurons are initially produced that ultimately used. After proliferation and differentiation, some neurons die due to signals from target tissue.
What were key studies done that helped learn about development of neural system?
Viktor Hamburger and Rita Levi-Montalcini performed studies in chick embryos
How many times has Viktor Hamburgers paper been cited?
12,056!
What chick embryos might lead to 50% neuron survival
normal embryonic chick
What chick embryos might result in 10% neuron survival
Chick embryos with a limb bud removed
What chick embryos might result in 75% neuron survival?
Chick embryos with an extra limb bud or paralyzed chick embryos
What was the first neurotrophic factor to be discovered? What does it do?
Nerve Growth Factor (NGF) stimulates neurite outgrowth and neuronal survival of sympathetic and sensory neurons
What did E. Beuker and V. Hamburger do?
They implanted mouse sarcomas into chick embryos to induce neurite outgrowth
What did R. Levi-Montalcini and S. Cohen do?
They found that sarcoma factor causes survival of neurons. They purified NGF from mice submaxillary gland
If you add NGF to sensory ganglia what happens? If you don’t add?
If you add NGF, sensory ganglia have neurite outgrowth
If you don’t add, no neurite outgrowth
What is the Campenot chamber system?
It is a petri dish that is separated into three compartments by a teflon insert. Cell bodies are placed in center
What happens if you remove NGF from a side compartment and main compartment?
Cell bodies still survive because NGF is endocytosed and translocated to cell body from neurites.
What are the major neurotrophins?
NGF, BDNF, NT-3, NT-4/5
What are the high affinity receptors?
Trk A, B, or C
What are the low affinity receptor
p75^ntr
What are the 4 steps of neurotrophin signaling?
- NT binds as a dimer
- Causes receptor dimeriz a tion
- Autophosphorylation and partner receptor tyrosine phosphorylation
- Triggering of different signaling cascades
T/F: one neuronal cell type responds to one neurotrophin
False, they can respond to different neurotrophins
Before target innervation DRG sensory neurons depend on ____ for __________________________
NT-3 for proliferation and differentiation
After target innervation, these neurons depend on _______ for ______________
NGF for survival
What do neurotrophins do during development?
- neuronal proliferation
- neuronal diffferentiation
- neuronal survival
- axon outgrowth
What do neurons do during adulthood?
- synaptic transmission
- ion channel expression
How do neurotrophins influence apoptosis.
They activate cell death inhibitors, avoiding activation of caspases, and thus promoting survival.
