THE INFLUENCE OF BFGF AND NGF IN END-TO-SIDE NEURORRAPHY OF THE COMMON PERONEAL NERVE TO THE TIBIAL NERVE IN RATS

Abstract

Purpose: The aim of this study was to investigate the results of end-to-side neurorraphy of the common peroneal nerve (CPN) to the tibial nerve (TN) in rats, after administration of bFGF or NGF. Materials: Five (5) groups of adult male Wistar rats, each comprising 25 animals, were studied:

1. End-to-side neurorraphy (4 groups) Group A bFGF (20ng) Group B NGF (25ng) Group C (normal saline) Group X [bFGF (20ng) + NGF (25ng)]

2. Negative control group (G) Animal keeping was conform to standard conditions set by the NIH (appropriate cages for housing; standard rat chow and water ad libitum; 12h – light/darkness exposure).

All experimental procedures were performed under the supervision of a veterinarian and were prospectively approved by the Animal Experimental Ethics Committee.

Methods: In groups A, B and X, the CPN was sharply divided at a distance of 7mm distal to its origin from the rat sciatic nerve; the proximal CPN stump was then sutured into the thigh muscles, whereas the distal CPN stump was sutured terminolaterally to the ipsilateral TN. Sub sequently, a total volume of fifty microliters (50μl) of the corresponding solution of growth factor(s) was administered in each case beneath the epineurium, proximal to the CPN/TN coaptation site, with the aid of a microsyringe. The same surgical procedure was carried out in group C (positive control group), as well, but an equal volume (i.e. 50μl) of normal saline was administered instead. Finally, in each of the animals of the remaining group G, both the proximal and the distal stump of the CPN were carefully sutured into the neighbouring muscles; hence, the latter would constitute a negative control group, thanks to the resulting atrophy of the CPN – innervated musculature. All surgical procedures took place with the animals under dissociative anaesthesia and were performed under sterile conditions, using the operating microscope and applying microsurgical techniques. In each case, the right CPN was operated upon; the contralateral (left) CPN remained intact, thus serving as control. Euthanasia was achieved by means of intracardiac administration of high – dose sodium pentobarbital.

Results: The evaluation of the outcome four (4) months postoperatively was based on clinical examination, walking-track analysis, electromyographic and histomorphometric studies. Our data indicate that the administration of the growth factors under investigation has a favorable effect on the outcome of CPN repair; the administration of bFGF, in particular, seems to improve the results of terminolateral neurorraphy in the time span studied.

Conclusions: In rats, CPN repair via end-to-side neurorraphy to the TN can be enhanced by the administration of bFGF or NGF.