M. Tal et R. Liberman, LOCAL INJECTION OF NERVE GROWTH-FACTOR (NGF) TRIGGERS DEGRANULATION OF MAST-CELLS IN RAT PAW, Neuroscience letters, 221(2-3), 1997, pp. 129-132
We examined the relationship between hyperalgesia and degranulation of
mast cells in rats following treatment with nerve growth factor (NGF)
and inflammatory mediators. Intracutaneous injection to the rat's paw
of NGF (50-5000 ng, 50 mu l) evoked dose-dependent thermal hyperalges
ia as measured by paw withdrawal latency to noxious heat. Even more in
tense hyperalgesia was induced by an 'inflammatory mediators soup' con
taining BK, 5HT, PGE2 and histamine (10 mu M). Counts of mast cells in
the dermis were performed on coded slides under x 1000 magnification
after fixation in Carnoy's solution and staining with toluidine blue.
After injection of three different concentrations of NGF (50, 500, 500
0 ng in 50 mu l), the proportion of mast cells that were degranulated
was significantly higher (P < 0.001) than after saline injection. No s
ignificant differences were found among the three concentrations of NG
F. The effect of inflammatory soup on the proportion of degranulated m
ast cells was similar to that of NGF. These results indicate that NGF
activates cutaneous mast cells and stimulates the release of inflammat
ory tissue mediators in the acute phase of NGF-induced hyperalgesia in
the rat's paw. However, the finding that degranulation was not dose-d
ependent indicates that other mechanisms, independent of mast cells, a
re probably operating in response to NGF. (C) 1997 Elsevier Science Ir
eland Ltd.