ABSTRACT
The purpose of this study was to investigate the changes of calcitonin gene-related peptide (CGRP) expression in the trigeminal motor nucleus (Vmo) following mandibular nerve transection. The expression of CGRP and glial fibrillary acidic protein (GFAP) were detected at 3, 7, 14, 21, 28, 35 and 42 days post-axotomy (dpa) by using immunohistochemical and double-immunofluorescence histochemical methods. And the number of CGRP-positive surviving motoneurons was examined by using image analysis system. The present results showed that there was a "biphasic" up-regulation of CGRP-immunoreactivity at 3 and 35 dpa on the ipsilateral side of the Vmo, and significant changes were also observed on the contralateral side. Quantitative analysis revealed that there was almost no loss of motoneurons in the Vmo but there was an evident increase in GFAP expression around the Vmo neurons on the ipsilateral side after axotomy. The present results suggest that the up-regulation of CGRP may exert its trophic effects in both the acute stress reaction and the recovery of the injured motoneurons, and the activated astrocytes may be well involved in this process.
ABSTRACT
Immunofluorescence histochemistry combined with retrograde tracing technique was employed to observe the effects of masseteric nerve transection on the expression of Trk ( tropomyosin-related kinase) receptor proteins, namely TrkA, TrkB and TrkC in the trigeminal mesencephalic nucleus ( Me5 ) of the rat. At 7 and 14 days following transection of masseteric nerve through which Fluorogold (FG) was applied to identify the Me5 neurons innervating masseter, brain sections were immunohistochemically processed to detect the three Trk isoforms in FG-labeled Me5 neurons. With the percentage of double-labeled neurons to the total number of FG-labeled neurons as the index,we demonstrated ( 1 ) a significant increase in the percentage of TrkA-immunoreactive (IR) Me5 neurons at both 7 and 14 days after nerve transection, (2) no significant, but gradual, increase in the percentage of TrkB-IR Me5 neruons with longer survival time post transection and ( 3 ) little change of TrkC expression. The current findings indicate that axotomy differently affected the expression of the individual Trk receptors and these expression patterns may reflect an adaptation of the Me5 neurons to the peripheral nerve injury.
ABSTRACT
Objective The changes of VGluT1-like immunoreactivity(VGluT1-LI) in the trigeminal complex of the rat in different survival time after unilateral mandibular nerve transection were examined. Methods Immunocytochemical staining method and image analysis technique were performed. Results Many VGluT1-LI were observed in the trigeminal complex of the normal rat and were mainly distributed in the terminals.A weak decrease of VGIuT1-LI in the dorsal part of principal trigeminal nucleus(Vp) could be detected at the first week after unilateral transection of mandibular nerve(P
ABSTRACT
Objective To observe the connections between the glutamic acid decarboxylase\|like immunoreactive(GAD\|LI) axonal terminals and the positive neurons showing phosphate actived glutaminase(PAG)\|LI or GABA\-A\|receptor ?3 subunit (GABA\-AR?3)\|LI and parvalbumin(PV)\|LI in the mesencephalic trigeminal nucleus(Vme) of the rat. Methods The triple\|immunofluoresence histochemical staining techniques were used in the present study,and stained sections were observed under a confocal laser\|scanning microscope. Results Many neuronal cell bodies through the whole rostrocaudal extent of Vme were showed dense GABA\-AR?3\|,PAG\| and PV\|like immunoreactivities,respectively.The majority of them were large pseudounipolar neurons(diameter 25\|50?m).About 90% of PAG\|LI neurons expressed both GABA\-AR?3\|LI and PV\|LI.Confocal laser\|scanning microscope further revealed that dense GAD\|LI axonal varicosities were found to surround the somata of Vme neurons showing both GABA\-AR?3\| and PAG\|like immunoreactivities,and formed the close contact each other.Conclusion\ The present results suggested that the GABAergic axonal terminals projecting to Vme might exert inhibitory regulation and control effect through GABA\-AR?3 subunit localizated in somata of Vme neurons on the transmission of orofacial region proprioceptive sensory information mediated by glutamate.
ABSTRACT
Objective The immunocytochemical localizations of GABA\-A\| and GABA\-B\|receptor in the mesencephalic trigeminal nucleus(Vme) of the rat were examined in order to provide morphological evidence for a possible functional analysis of GABA\|receptor in the transmission and modulation of the orofacial region trigeminal proprioceptive sensory information. Methods An immunocytochemical staining method was used in the present study,and immunostained sections were observed under light microscope. Results Many neuronal cell bodies,fibers and terminals with dense GABA\-A\| and GABA\-B\|receptor\|like immunoreactivity(\|LI) were observed to be localized in Vme,and different subunits of GABA\|receptor\|LI showed the morphological difference in their distribution:1.Immunoreactivity for GABA\-B R1 subunit was intensely distributed in the cell bodies of Vme neurons,whereas the weak immunoreactivity for GABA\-BR2 subunit was only observed in the region surrounding the somata of Vme neurons which showed negative GABA\-BR2\|LI;2.A considerable number of GABA\-A\|like immunoreactive neurons,fibers and terminals were also found in Vme.It was involved four kinds of subunits(?1,?2,?3 and ?).The heavy immunoreactivity for GABA\-AR?1 and GABA\-AR?3 subunits were only seen in the cell bodies of Vme neurons.On the other hand,the immunoreactivity for GABA\-AR?2 and GABA\-AR? subunits was only observed in the fibers and terminals in the region surrounding the somata of Vme neurons,which showed negative immunoreactivity for above subunits;3.Dense GABA\-BR2\|,GABA\-AR?2\| and GABA\-AR?\|LI fibers and terminals surround the somata of Vme neurons,especially for GABA\-AR?2\|LI.Conclusion\ The present results suggest that there are some differences in the distribution of the various subunits of GABA\-A\| and GABA\-B\|receptor in Vme.It is likely that the inhibitory regulation and control effects of GABAergic terminals on the transmission of orofacial region proprioceptive sensory information might be mainly mediated through GABA\-AR?1 and GABA\-AR?3 subunits in somata of Vme neurons.