Experimental model for local administration of nerve growth factor in microsurgical nerve reconnections

An experimental model for local administration of neuronotrophic substances at the site of peripheral nerve lesion is presented. The model consists of a subcutaneously located silicone reservoir and a connecting tube with its distal end fixed in the proximity of the severed and repaired nerve. The results of the preliminary tests of the model are presented. Sixty Sprague-Dawley rats were divided into two groups: control (saline-treated) (n = 30) and NGF-treated (n = 30). After axotomy of the sciatic nerve, an epineurial repair is performed. NGF or saline is injected daily into the subcutaneous reservoir during the first 3 weeks after axotomy and a single dose in the fourth week. The regenerated nerve observed in the NGF-treated group after four weeks of treatment presents a greater percentage of myelinated axons, thicker myeline sheaths, and more mature endoneurial layers. This experimental model provides a reliable and quantitative way to deliver neuronotrophic substances in site and at different administration rates.