Outgoing Vestibular Afferent Fibers In The Source And Calcitonin Gene-related Peptide In The Outgoing Expression In The Vestibular Nerve Center Of The Pathway

Objective To study the origin of afferent fibers innervating the efferent vestibular neurons in the center neural system and to explore the anatomical foundation of the physical function of efferent vestibular system. Methods In the present study, a retrograde neuron tracing technique using horseradish peroxidase (HRP) was adopted to display the innervations of group E vestibular neurons in the central neural system of rat under normal condition. HRP was injected into the surrounding of efferent vestibular neurons located around the facial genu of the rat and after allowing 48 hours for the retrograde axonal transport of this tracer, its presence in neurons of the brain stem was demonstrated histochemically. The distribution and the amount of the HRP labeled cell and fibers were recorded. Results Neurons labeled with HRP were found bilaterally in Medial vestibular nuclei (MVe) and ipsilaterally in lateral vestibular nuclei (LVe). The amount of positive HRP-labelled neurons in MVe is the most and the cells were glomerate while the labeled cells in LVe were scattered. A few HRP-labelled neuron bodies and HRP-labelled fibers were observed around the facial genu conterlaterally to the injection site. HRP-labelled cells were also found in both side PCR regions. There were no HRP-labelled neurons and fibers found in the cerebellum cortex and medulla. Conclusions The vestibular nuclei (VN) are an important origin of innervation fibers on efferent vestibular neurons. There is a direct connection between the efferent vestibular neurons and some subgroup afferent vestibular neurons. There exists a complicated efferent and afferent network in the vestibular system. Such network maybe the anatomical foundation of the fine tuning and modulation of vestibular signal and may play important role in the process of vestibular compensation .the connection between the cerebellum, the medulla and the efferent vestibular neurons was indirect. the signals from the cerebellum and the spinal cord may transmitted to the intermediary neuron firstly and by which together with the other sensational signal transmitted to efferent vestibular neurons.