Analysis of neural mechanisms for oral-facial motor and sensory functions in in vitro preparations

点击翻译按钮获取中文摘要

1) Synaptic mechanisms for activation of sucking rythm generatorBath application of NMDA to an in vitro brainstem-spinal cord from newborn rats induced a rythmical activity in the XII nerve, which was clearly different in cycle-time, amplitude and burst pattern from the spontaneous inspiratory activity monitored from the C5 ventral root. In the brainstem-spinal cord preparation isolated together with the jaw, oral structure and tongue, recording of the NMDA-induced tongue movements with a CCD camera has confirmed that they are closely similar to those during natural sucking movements.2) Location of sucking rythm generatorThe NMDA-induced rhythmical XII nerve activity was retained bilaterally after transection of the brainstem at the level of the rostral boundary of the facial nucleus and the bulbospinal junction as well as midline transection. To find the loation of the neurouns involved in the NMDA-induced rhythmical XII nerve activity, sulphorhodamine 101 (S-101), which is taken up t … More o neurons in association of generation of action potentials, was bath applied after the rhythmical activity was induced, and the neurons labelled with S-101 was specifically found in the gigantocellular reticular nucleus at the level of the facial nucleus in association with the rhythmical XII nerve activity.3) Coding process of introral sensory receptorsResponses to mechanical stimulation of the periodoantal ligament with von Frey hairs were recorded from single sensory fibers in an in vitro jaw-inferior alveolar nerve preparation of rats. To stimulation of the incisor periodontal ligament, both rapidly- and slowly-adapting responses were obtained, while stimulation of the molar periodontal ligament showed only rapidly-adapting responses. The majority of rapidly-adapting response to molar stimulation was on-off type, whereas it was rare in incisor stimulation. Sensory fibers from the molar ligament showed responses to stimulation of either single or more than one tooth. The threshold intensity was similar among fibers from the incisor, whereas it was various among fibers from the molar periodontal ligament.4) Postnatal development of kainate receptors in trigeminal ganglion neuronsPostanatal development of kainate receptors was studied in the trigeminal ganglion neurons isolated from rats of 2-28 postnatal days. Kainate responses during the first postnatal week changed in parallel with the expression of and increase in subtypes of glutamate receptors. Less