Neuronal regeneration in denervated muscle following sensory and muscular neurotization.
OBJECTIVE
Neurotization of denervated muscles has been shown to improve muscle bulk, but the neuronal regeneration response has not been compared previously in different surgical techniques of neurotization. Thus, using a rat model of experimental skeletal muscle denervation, we studied neuronal regeneration following sensory neurotization by two methods: sensory nerve to motor branch of muscle and direct sensory nerve implantation to muscle.


METHODS
The lateral head of the gastrocnemius muscle was denervated in 36 rats, of which the first 12 served as denervated controls. In the second group of 12, the sural nerve was anastomosed to the motor branch of the gastrocnemius muscle (sensory-to-motor nerve neurotization) and in the remaining 12 rats the sural nerve was split into 4 fascicles and embedded into 4 quadrants of the muscle (direct sensory nerve-to-muscle neurotization). Immunohistochemistry was used to examine nerve fibers in muscle containing the sensory neuropeptides substance P (SP) and calcitonin gene-related peptide (CGRP), and general neuronal marker protein gene product 9.5 (PGP 9.5).


RESULTS
Semiquantitative analysis showed that, compared to the control side, the number of nerve fibers on the experimental side was highest (p < 0.01) for group III (direct sensory nerve-to-muscle neurotization) for all 3 markers. The difference was 71%, 298%, and 254% for PGP 9.5, CGRP, and SP, respectively.


CONCLUSIONS
This method may be a good option for inducing neuronal regeneration in denervated muscles, and has therapeutic implications for prevention of atrophy of denervated muscles and as an adjunct for reconstruction of soft tissue defects.
Noordin
Shahryar
S
Section of Orthopaedics, Department of Surgery, Aga Khan University, Karachi, Pakistan.
Ahmed
Mahmood
M
Rehman
Rasham
R
Ahmad
Tashfeen
T
Hashmi
Pervaiz
P
D000818:Animals; D007150:Immunohistochemistry; D008297:Male; D009121:Muscle Denervation / Q000379:methods; D018482:Muscle, Skeletal / Q000294:innervation* / Q000378:metabolism; D009416:Nerve Regeneration / Q000502:physiology*; D016067:Nerve Transfer / Q000379:methods*; D009474:Neurons / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley