Extent of collateral sprouting of intact nerve fibers in rats depends on the local availability of nerve growth factor.
We investigated the influence of local administration of anti-nerve growth factor (NGF) serum on collateral nerve fiber sprouting caused by chronic constriction injury (CCI) of the sciatic nerve in rats. CCI was induced in adult Sprague-Dawley rats (six per group) by constriction of the sciatic nerve of the right hind limb. Control rats received no further manipulation. In four other groups, rabbit preimmune (control) serum or low (18 ng) or high (1800 ng) doses of anti-NGF serum were injected into the operated or unoperated hind limb each day for 1 month. We used an Evans dye-labeled plasma extravasation technique to visualize the extent of collateral sprouting. Local injection of anti-NGF serum at both high and low doses, but not control serum, significantly reduced the spread of collateral sprouting from the saphenous nerve into the sciatic nerve innervation territory. High-dose anti-NGF serum did not block collateral sprouting when injected into the contralateral (unoperated) hind limb, indicating that the inhibition of sprouting was not caused by a systemic effect. In conclusion, local administration of anti-NGF serum can block sprouting of collateral fibers after nerve injury. Our findings suggest that collateral sprouting is dependent on the local availability of NGF to nearby intact cutaneous nerve fibers.
Ro
L S
LS
Department of Neurology, Chang Gung Memorial Hospital, Taipei, Taiwan.
Chen
S T
ST
Tang
L M
LM
D000818:Animals; D003250:Constriction; D006614:Hindlimb / Q000294:innervation; D007106:Immune Sera / Q000008:administration & dosage; D008297:Male; D009412:Nerve Fibers / Q000276:immunology / Q000502:physiology*; D009414:Nerve Growth Factors / Q000008:administration & dosage / Q000494:pharmacology*; D009416:Nerve Regeneration; D051381:Rats; D017207:Rats, Sprague-Dawley; D012584:Sciatic Nerve / Q000293:injuries; D012867:Skin / Q000294:innervation
D007106:Immune Sera; D009414:Nerve Growth Factors