Neurotrophins Flashcards
trophic interactions
neuronal interactions lasting days/even a lifetime
bueker 1948
trying to increase target tissue for innervation was injecting sarcoma tissue into chick embryos
result of sarcoma 180
huge neuronal response only on side with tumour tissues
enlarged sympathetic chain and sensory ganglia
motor nerves unaffected
What indicated vascular link?
same enlarged ganglia when add tumour to egg membrane
molecule/protein secreted
Rita Levi-Montalcini
Nobel prize
discovery of NGF
how to tell if active element was protein or nucleic acid
snake venom - phosphodiesterase break down nucleic acid
mammalian equivalent of venom glands
salivary glands
NGF
3 subunits
alpha, beta and gamma
what subunit of NGF promotes outgrowth and survival?
beta
what does b subunit of NGF affect?
sympathetic chain and subpopulation of sensory neurones
2 reasons for neurons dying
normally in development and if no targets
inject NGF into embryos - effect on neurons which would have died
rescues sympathetic and sensory neurons which would have died
NGF act as target-derived neurotrophic factor
inject ab to NGF in embryo
total loss of sympathetic neurons
NGF mRNA in target tissue
present in limited supply
direct relationship of NGF and sympathetic innervation
NGF guidance role
sensory growth cones turn towards it in minutes
inject NGF into brainstem of baby rat
sympathetic axons from ganglia grow back into spinal cord and up dorsal columns
problem with NGF guidance role experiments
concentrations not physiological
NGF - possible role, not guidance but?
NGF and receptors present only after axons enter target tissue
might keep neurones in
3 chamber culture experiment
NGF in all 3 = grow
remove from b or c = end of axons whither
remove from cell body = axons and cell bodies okay
findings from 3 chamber culture experiment
terminal endings maintained locally and peripheral neurites support cell body
retrograde transport of NGF