The Distribution Of Substance P (SP) And Calcitonin-gene Related Peptide (CGRP) Positive Neurons In Superior Olive In Mice

AIMTo study the distribution of neurons which are positive to substance P (SP) and calcitonin-gene related peptide (CGRP) in the superior olivary complex in mice, and the meaning of such distribution. .MethodsLocate epicele following the stereotaxic atlas of rat's brain; drill a hole on the skull,inject colchicine (80～100μg/rat) gently into the epicele with a microinjector,observe the rats for 10mins.We perfuse the brain 48h after injection.After decapitation,we divest the skull,and then get the brainstem.We put the brainstem into 40g/L paraform for another 12 hours, and then put it into 300g/L sucrose phosphate buffer(pH 7.4,4℃) till it sinks to the bottom.Superior olivary complex was used for frozen section (40μm) following the stereotaxic atlas of rat's brain.The frozen sections were divided into 3 groups:SP- immunohistochemical group,SPc-immunohistochemical group and CGRP- immunohistochemical group.Superior olivary complex was used for frozen section (10μm) following the stereotaxic atlas of rat's brain.The frozen sections were divided into 4 groups: SP-immunofluorescence group,CGRP-immunofluorescence group,both SP and CGRP-immunofluorescence group,and control group.The first antibody of control group was replaced with antibody dilution, other reagents and procedures were the same as experiment groups.ResultsImmunohistochemical stain:The body of SP positive neurons mainly located in Tz,and it was fusiform shape with small volume, its diameter was from 10-12μm,and there was no obvious evection. A lot of SP positive fibers, with shape of bead-like and spot, were seen in LSO,especially in the median line part.The body of SPc positive neurons mainly located in Tz,MSO,LSO,and it was round and ellipse shape with large volume,its diameter was from 25-30μm,and there were several evections and obvious nervous fibers.CGRP positive neurons mainly located in LSO,with orbicular-ovate monopolar or bipolar cell. These neurons were out of transaction and vertical to the long axis of LSO,their diameters were from 12-16μm,and the neurons in median line part were more than in other parts.Immunofluorescence stain:SP positive neurons mainly located in Tz,and they were fusiform shape and orbicular-ovate with small volume,their diameters were from 11-13μm.CGRP positive neurons mainly located in Tz and LSO.The neurons in Tz were polygon with small volume,their diameters were from 11-13 μm; the neurons in LSO were orbicular-ovate with small volume,their diameters were from 10-12μm.There were many nervous bodies marked with both CGRP and SP in nucleus of trapezoid body,and their bodies were surrounded with CGRP positive endings.There was no color in control group.ConclusionSP and CGRP are cooperative in hearing conduct,and SP positive neurons in Tz may probably contribute to regulating the CGRP positive neurons in LSO,and then regulate the nervous activity of olivocochlear bundle (ocb).