Alpha motoneurons are present in normal numbers but with reduced soma size in neurotrophin-3 knockout mice.
Neurotrophin-3 (NT-3) is essential for survival of proprioceptive and mechanoreceptor neurons, but its role in motoneuron development in vivo has seemed slight. Recent evidence however has suggested that NT-3 may be involved in motoneuron maturation. Here, we quantitatively assess the number and state of development of motoneurons within the lumbar lateral motor column (LLMC) of newborn NT-3 (-/-), (+/-) and (+/+) mutant mice. We find that the number of alpha motoneurons in the LLMC is the same in all genotypes, but soma size is significantly reduced in (-/-) mutants. This suggests that NT-3 is not required for normal production and survival of alpha motoneurons, but is essential for their full maturation and/or maintenance. We also confirm a previous report that gamma motoneurons are absent in NT-3 (-/-) mice.
Woolley
A
A
Department of Anatomy and Structural Biology, School of Medical Sciences, University of Otago, Dunedin, New Zealand.
Sheard
P
P
Dodds
K
K
Duxson
M
M
D000818:Animals; D002452:Cell Count; D048429:Cell Size; D018507:Gene Expression Regulation, Developmental; D005838:Genotype; D051379:Mice; D018345:Mice, Knockout; D009046:Motor Neurons / Q000166:cytology*; D020933:Neurotrophin 3 / Q000235:genetics / Q000378:metabolism*; D013116:Spinal Cord / Q000166:cytology*
D020933:Neurotrophin 3