neurotrophins

Question 1

role of NGF

Answer 1

trophic role - nourishes and amount of NGF determines how many neurones survive in target tissue

NGF receptors present only after axons enter target - not a guidance (tropic role).

Question 2

neurotrophin receptors

Answer 2

high affinity tyrosine kinase like receptor
low affinity p75 receptor

NGF - TrkA
BDNF - TrkB
NT-3 - TrkC
NT-4/5 - TrkB

Question 3

NGF and growth of neurons in basal forebrain

Answer 3

basal forebrain nuclei are cholinergic neurons and project throughout brain to cortex & hippocampus

target regions contain NGF mRNA (NGF synthesised there)
neurones express TrkA
NGF is transported retrogradely by there neurons

Question 4

neurotrophin knockout summary

Answer 4

sympathetic neurons depend on NGF
pain/temp sensory neurones depend on NGF
vestibular neurons depend on BDNF
proprioceptive sensory neurons (and hence development muscle spindles and Golgi tendon organs) depend on NT3