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Updated: Aug 24, 2026

Whole-mount Imaging of Mouse Embryo Sensory Axon Projections
Published on: December 9, 2014
TrkA and mitogen-activated protein kinase phosphorylation are enhanced in sympathetic neurons lacking functional p75
Sari S Hannila1, Gail M Lawrance, Gregory M Ross
1Department of Anatomy and Cell Biology, Queen's University, Kingston, Ontario, Canada K7L 3N6.
Abstract:
This study examined the effects of hypomorphic p75 neurotrophin receptor (p75NTR) expression and high levels of nerve growth factor (NGF) on trkA phosphorylation and downstream activation of p44/42 mitogen-activated protein kinase (MAPK). Post-ganglionic sympathetic neurons from postnatal day 1 p75NTR exon III null mutant (p75(-/-)) and 129/SvJ mice were cultured in the presence of 50 ng/mL NGF and analysed by Western blotting. Levels of phosphorylated trkA are increased in p75(-/-) neurons compared with 129/SvJ neurons, and these higher levels are maintained with continuous exposure to NGF. MAPK is also phosphorylated to a greater extent in p75(-/-) neurons than in 129/SvJ neurons, both within 10 min of exposure to NGF, and with continuous NGF treatment for 5 days. These data provide new insight into the mechanism underlying enhanced neurite outgrowth in p75(-/-) neurons, demonstrating that trkA and MAPK signalling in sympathetic neurons are increased when p75NTR function is disrupted.
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