New Aspects of Graft-induced Central Plasticity and Neuroregeneration at T 10 in a Rat Model

Objective: Retest Brunelli’s graft induced glutamate neurotransmitter switch at the neuromuscular junction in rat for the translation of new aspects of central plasticity concepts for human reconstructive surgery in spinal cord lesions. Methods: Randomized double blind controlled study in rat, which was limited to 30 animals (Charles River, 220 to 280 g). Ethical research approval was obtained from the Animal Research Committee of the University Hospital Schleswig Holstein, UK-SH, Lubeck, D, and legitimated by the Governmental Department of Agriculture, Natural Environments and Agriculture Kiel, D, in compliance with the European Commission Recommendation to retest and review of graft-induced glutamatergic regeneration and /or cholinergic co-transmission at the neuromuscular junction for reinnervation of the skeletal obliquus abdominis internus muscle fibers. Assessments were performed to demonstrate pharmacological neuromodulation after attaching the lateral corticospinal tract at T10 to the bisected skeletal motor nerve. Medication was administered for 14 days postoperatively–a) verum Cerebrolysin® IP=12–b) shams NaCl 0.9% IP=11, and c) 7 controls (nil). 2nd Op at day 90 (16 surviving rats) for open proof of reinnervation and its type by a) CMAP, b)Vecuronium® application. Fast Blue® labeling were performed. 10 days later, on the 3rd Op N=15, euthanasia and organ fixation were performed. Extensive histology-morphology examinations were performed in Cluj. Results: Eight rats showed positive CMAPs. Reinnervation and neuromodulation were demonstrated by counting and comparison of the grafted muscle fibers diameter. Four CAMP- positive- rats received Vecuronium®: 1 CERE and 1 NaCl each demonstrated a loss of amplitude respectively two an incomplete muscle blockage due to the coexistence of glutamatergic and cholinergic neurotransmission. Confirmation of the VGluT2 in axons was observed by immunofluorescence. FB+ neurons were observed in many Rexed laminae in grafted spinal cord, but not in the brain. Conclusion: The coexistence of graft-induced cholinergic and glutamatergic neurotransmission and a great capacity of lower motor neurons and other types of spinal neurons to regenerate were observed. Because of limited animals, pharmacological neuromodulation requires further investigation.