Distinct muscle targets do not vary in the developmental regulation of brain-derived neurotrophic factor. J Comp Neurol 470:317-329,2004.

Abstract

Developing neurons depend on many target-derived signals. One of these signals is the neurotrophin brain-derived neurotrophic factor (BDNF). Exogenous application of BDNF in vitro and in vivo rescues a population of lumbar motoneurons from programmed cell death. Given that BDNF does not rescue all motoneurons and that motoneurons differ in trophic factor receptor expression, subpopulations of motoneurons may have different sensitivities to the factor. These differences may be reflected in distinct target muscles specialized to produce different protein concentrations, or muscles may contain equal amounts of the factor and receptor expression determines motoneuron responsiveness. By using a sensitive electrochemiluminescent immunoassay (ECLIA), we measured normal developmental changes in BDNF protein concentration in anatomically and functionally distinct chick embryonic thigh muscles from E6 to E18. We found that there were no significant differences in BDNF protein concentration between muscles classified according to function (fast vs. slow) or anatomical position (flexor vs. extensor) and that the quantity of BDNF in the target did not appear to be activity dependent. These results suggest that, during development, the differences in the response of motoneurons to BDNF are not due to the anatomical or functional diversity of muscle targets. J. Comp. Neurol. 470:330-337, 2004.