カエル舌下神経の求心性放電について

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Many studies have been reported about the existence of afferent fiber in the hypoglossal nerve of some species of animals. Liou, et al. reported afferent impulses in the hypoglossal nerve of the frogs. It is the main purpose of the present study to investigate the generation of the afferent impulses by a variety of stimuli given the hypoglossal nerve of frog's tongue. Both the afferent impulses in the hypoglossal and the glossopharyngeal nerve generated by stimulation to the tongue were recorded simultaneously by a cathode ray oscilloscope. The afferent impulses of the hypoglossal nerve were compared with that of the glossopharyngeal nerve with respect to the frequency of the impulses, the threshold concentration and the latent time. Changes in the afferent impulses of the hypoglossal nerve were investigated for the period of 90 days after cutting the unilateral glossopharyngeal nerve. The results are summarized as follows : 1. Mechanical stimulation, such as light touch with cotton fibers or a horse-tail hair, applied to the surface of the tongue elicited afferent impulses in the glossopharyngeal nerve, but not in the hypoglossal nerve. Stimulation by pressure and traction with a glass rod applied to the tongue elicited afferent impulses in both the glossopharyngeal and the hypoglossal nerve. In this case, the afferent impulses of the hypoglossal nerve were of lower frequency with long latent time as compared to those elicited in the glossopharyngeal nerve. 2. When the horse-tail hair stimulations were given indiscriminately to'different parts of the tongue, the glossopharyngeal nerve responded similarly, regardless of parts stimulated, while the hypoglossal nerve responded more effectively the stimulation at the root than at the apical and central parts of the tongue. 3. Stimulation by warm or cold Ringer's solution could generate afferent impulses of the glossopharyngeal nerve only in the temperature range from 25℃ to 45℃ and from 5℃ to 0℃. No response was obtained from the hypoglossal nerve with the same experiment. 4. When the tongue was stimulated either by water or Ringer's solution, the fomer generated afferent impulses of much more frequency than did the latter in the glossopharyngeal nerve, while these stimulations elicited no such response in the hypoglossal nerve. However, solutions containing NaCl, sucrose, acetic acid and quinine hydrochloride produced afferent impulses in both nerve. The hypoglossal nerve could produce the afferent impulses only with much higher threshold concentrations of substances tested and the impulses produced was of lower frequency as compared to the glossopharyngeal nerve. The hypoglossal nerve also showed relatively longer latent time in responding the stimulations by the above substances except acetic acid. 5. When the glossopharyngeal nerve in one side of the tongue was cut and stimulation given by solutions of NaCl, sucrose and acetic acid, afferent impulses were generated from the hypoglossal nerve at lower concentrations of the substanses tested in the cut side than in the control side. Such phenomenon was not observed with use of quinine hydrochloride.
九州歯科学会の論文
1973-03-31

著者

牧野敬美
九州歯科大学口腔外科学教室第1講座

カエル舌下神経の求心性放電について

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