Identification of centrum neural circuitry involved in innervation of the C7 nerve root: a viral transsynapfic tracing study

Abstract

Objective The distribution of positively labeled neurons in the brain and spinal cord was studied after injecting the attenuated strain of pseudorabies virus(PRV)into the C7nerve root so as to provide a baseline for further studying of brain functional reorganization after contrallateral C7 transfer. Methods Twenty adult Sprague Dawley rats were randomly divided into 4 groups according to the time of being sacrificed:6 hours,12 hours,24 houm and 36 hours groups.2ul of the virus was slowly injected into the risht C7 nerve root.After survival times of 6 to 36 hours,the spinal cord(C1-C7)and brain were processed immunocytochemically using a polyelonal antibody against the PRV.The positively labeled neurons were observed. Results PRV positively labeled neurons were found in some spinal cord and brain regions from 6 hours to 36 hours post injection,such as the gray matter in the C1-C7 spinal cord,the lateral paragigantoceUular nuclei,and the A5 cells,red nucleus,primary and secondary motor cortex,primary and secondary somatosensory cortex etc.The longer the survival time the more numher of positively labeled cells from the spinal cord to brain regions. Conclusion The spinal cord and brain structures labelled from the C7 nerve root by the transsynaptic tracing technique are synaptically connected with C7 and presumably are involved in the neural regulation of C7. Key words: Brachial plexus; Brain; Spinal cord; Transsynaptie tracing; C7 nerve root