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Detection of Increased Tissue Concentrations of Nerve Growth Factor
with an Improved Extraction Procedure
by Christian Zettler, Diana M. Bridges, Xin-Fu Zhou and Robert A. Rush*
(* Corresponding author: pzrar@ flinders.edu.au) Department of Physiology and Centre for
Neuroscience Flinders University of South Australia GPO Box 2100 Adelaide, 5001 Australia
Nerve growth factor (NGF) is essential for the survival and normal function of
sympathetic neurons. Precise and reliable determinations of endogenous NGF are essential
for investigations into its physiology, especially with the realization of the involvement
of this factor in various disease processes. Two-site immunoassays have been used to
estimate its endogenous concentrations in a variety of effector tissues. However, levels
appear restricted to a narrow range, display only a poor correlation with innervation
density and show obvious inter- and intra-laboratory variations, the origins of which are
unclear. This led us to examine alternative extraction procedures for NGF prior to
quantification. We have devised a new NGF isolation method that uses detergent and
acid-base treatment to efficiently solubilize NGF and dissociate it from its receptors. We
also made use of the stability of NGF under acidic conditions to facilitate isolation by
precipitating potential binding proteins, including the high affinity TrkA receptor. This
procedure increases the detectable levels of NGF in a tissue-specific manner to as much as
ten times more than that detected by traditional procedures. In this study, we show that
using this extraction procedure improves the detectable levels of NGF in extracts of
multiple tissues in the rat.
PDF article (103kb)
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