LOCAL APPLICATION OF ANTI-NGF BLOCKS THE COLLATERAL SPROUTING IN RATSFOLLOWING CHRONIC CONSTRICTION INJURY OF THE SCIATIC-NERVE

Systemic administration of anti-nerve growth factor (NGF) antibodies c an block nociceptive fiber sprouting into denervated adult rat skin. H owever, the effect of local application of anti-NGF on collateral spro uting in rats caused by chronic constriction injury (CCI) has not been well studied. We investigated the influence of local anti-NGF on coll ateral sprouting caused by CCI of the rat's sciatic nerve. Using a dye -labeled plasma extravasation technique, we can easily evaluate the ex tent of collateral sprouting by the clearly defined blue coloration ar eas. Our results showed that local application of anti-NGF either in a high or low dose significantly prevented the spread of collateral spr outing from the saphenous nerve into the sciatic innervation territory . In contrast, distilled water did not show a significant block of the saphenous nerve collateral sprouting. Our study suggests that collate ral sprouting is dependent on the local availability of NGF by the nea rby intact cutaneous nerve fibers.