In:
European Journal of Neuroscience, Wiley, Vol. 11, No. 5 ( 1999-05), p. 1668-1676
Kurzfassung:
Neurotrophins exert their biological functions on neuronal cells through two types of receptors, the trk tyrosine kinases and the low‐affinity neurotrophin receptor (p75 NTR ), which can bind all neurotrophins with similar affinity. The p75 NTR is highly expressed in developing motoneurons and in adult motoneurons after axotomy, suggestive of a physiological role in mediating neurotrophin responses under such conditions. In order to characterize this specific function of p75 NTR , we have tested the effects of nerve growth factor (NGF) on embryonic motoneurons from control and p75 NTR ‐deficient mice. NGF antagonizes brain‐derived neurotrophic factor (BDNF)‐ and neurotrophin‐3 (NT‐3)‐mediated survival in control but not p75 NTR ‐deficient motoneurons. Survival of cultured motoneurons in the presence of 0.5 ng/mL of either ciliary neurotrophic factor (CNTF) or glial‐derived neurotrophic factor (GDNF) was not reduced by 20 ng/mL NGF. Dose–response investigations revealed that five times higher concentrations of BDNF are required for half‐maximal survival of p75 NTR ‐deficient motoneurons in comparison to motoneurons from wild‐type controls. After facial nerve lesion in newborn wild‐type mice, local administration of NGF reduced survival of corresponding motoneurons to less than 2% compared to the unlesioned control side. In p75 NTR ‐deficient mice, the same treatment did not enhance facial motoneuron death on the lesioned side. In the facial nucleus of 1‐week‐old p75 NTR –/– mice, a significant reduction of motoneurons was observed at the unlesioned side in comparison to p75 NTR +/+ mice. The observation that motoneuron cell numbers are reduced in the facial nucleus of newborn p75 NTR ‐deficient mice suggests that p75 NTR might not function as a physiological cell death receptor in developing motoneurons.
Materialart:
Online-Ressource
ISSN:
0953-816X
,
1460-9568
DOI:
10.1046/j.1460-9568.1999.00585.x
Sprache:
Englisch
Verlag:
Wiley
Publikationsdatum:
1999
ZDB Id:
2005178-5
SSG:
12
Bookmarklink