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Biomedical subjects

A Iriki

Publications and source records attributed to A Iriki.

53 records · Page 3Linked to original sources
PubMed1981

Inhibitory actions produced by local electrical stimulation in the caudal spinal trigeminal nucleus in rat.

Inhibitory actions induced by local electrical stimulation (LES) on the tooth pulpal afferent activities were investigated in the caudal part of the rat spinal trigeminal nucleus. For the LES, ipsilateral Yin-Hsiang (intrasegmental point) or Ho-Ku (extrasegmental point) was used as a cathodal point which was stimulated electrically by a single pulse of 0.1 msec in duration or by 0.1 msec-pulse train at 45 Hz for 15 min. We found at least three types of inhibitions in the caudal trigeminal nucleus: Type I--this inhibition is the most forceful, caused by naloxone-reversible endogenous opiate system with a slow onset and prolonged aftereffect. This inhibition is presumably postsynaptic action. Type II--this is evoked by postsynaptical acting inhibition and begins within milliseconds after the stimulus is applied. Type III--this inhibition is elicited by presynaptic action and also begins within milliseconds after the onset of the stimulation. Type I and II inhibitions are evoked by stimulating either intra- or extrasegmental LES points, however, Type III is produced by stimulation of intrasegmental and rarely provoked by extrasegmental point stimulation. Naloxone failed to reverse Type II and III inhibitions. During LES, Type I to III inhibitions co-work for producing the suppressive effect and after the cessation of its stimulation, only Type I inhibition produces the so-called aftereffect of the LES.

Afferent Pathways↗
PubMed1980

Morphine and electroacupuncture: comparison of the effects on the cortical evoked responses after tooth pulp stimulation in rats.

The effects of morphine and electroacupuncture on the cortical evoked responses after tooth pulp stimulation were investigated in rats. Morphine suppressed these responses more strongly in secondary somatosensory areas than those in primary somatosensory areas, while electroacupuncture suppressed the responses to the same degree in both areas. These results might suggest that there are some differences in noxious-suppressive action between morphine and the endogenous opiates released by electroacupuncture stimulation.

Acupuncture Therapy↗
PubMed1980

Quantitative relations between noxious stimulus intensity and magnitude of central afferent evoked responses in rat.

Relations between intensities of electrical noxious stimulus applied to the tooth pulp and magnitudes of evoked responses at various relay stations of tooth pulp afferents were investigated with lightly anesthetized rats. The stimulus-response function in each relay station and the cerebral cortex follows the power function only in the range of lower, but noxious, stimulus intensities; however, it deviates from it in the range of higher ones, the exponent of the function becoming smaller. The higher the relay station locates, the smaller the exponent value is.

Afferent Pathways↗
PubMed1980

Electroacupuncture suppresses the cortical evoked responses in somatosensory I and II areas after tooth pulp stimulation in rat.

Rat cortical evoked responses (CERs) of the somatosensory area I and II following tooth pulp stimulation were decreased in amplitude by electroacupuncture stimulation. Suppression was more marked with the contralateral CERs than with the ipsilateral ones. Onset latencies of somatosensory II CER of both sides were lengthened after electroacupuncture stimulation.

Acupuncture Therapy↗
PubMed1980

Diazepam-induced suppression of jaw opening reflex in rats.

Effec of an i.p. injection of diazepam on the jaw opening reflex evoked by electrical stimuli applied to the tooth pulp innervated by mainly high threshold afferents and the lower lip innervated by low threshold afferents was investigated using Wistar albino rats. Small doses of diazepam, less than 2.5 mg/kg, suppressed to the same degree the jaw opening reflexes evoked by stimulation of tooth pulp or lower lip. However, when larger doses thab 5.0 mg/kg were administered, the suppression of tooth pulp-evoked jaw opening reflex was greater than that of lower lip-evoked one. In this case, the period of suppression of tooth pulp-evoked jaw opening reflex was longer than that of lower lip-evoked one. It is concluded that (1) the pain relieving effect of diazepam appears only when larger doses tha 5.0 mg/kg are administered and that (2) the pain-relieving effect lasts longer than muscle-relaxative effect of diazepam.

Analgesics↗
PubMed1980

Effective conditions of electroacupuncture stimulation for suppressing tooth pulp-evoked jaw-opening reflex in the rat.

The effects of electroacupuncture (EA) on the rat jaw-opening reflex elicited by tooth pulp stimulation were studied to decide the effective stimulus conditions for electroacupuncture stimulation (EAS). The present study revealed that one of the most important factors for producing a strong EA effect was the stimulus pulse-frequency and that the stimulus pulse-duration was not an essential factor for this effect. In the rat, the following stimulus conditions were very useful for the quantitative study of the EA effect. (1) Stimulation time is 15 min. (2) Stimulus pulse-frequency is 30 to 150 Hz. (3) Stimulus pulse-duration is 0.1 to 5 ms. When the EAS was applied to the Ho-Ku point under these conditions, the degree of the suppression of the jaw-opening reflex was about 50% of the control.

Action Potentials↗
PubMed1979

Effects of diazepam (cercine) on the somatosensory evoked responses following tooth pulp stimulation in rat.

Effect of diazepam on the somatosensory evoked responses (SER) following tooth pulp stimulation was investigated in Wistar albino rats. The SERs were recorded from the contralateral surface of the skull with a silver ball electrode and 200 responses were averaged with a medical computer. Generally, SERs were found to be composed of a sequence of four components named P1 (first positive wave), N1 (first negative wave), P2 (second positive wave), and N2 (second negative wave) in a 100 msec analysis time. Diazepam enhanced only the amplitude of the P1 component to about 500% of the control, while it suppressed other N1, P2, and N2 components to about 30, 40, and 20% of the control, respectively. The maximum suppressed effect appeared about 30 min after the diazepam injection and the effect was maintained for about 150 min. One possible explanation for the present result is that the activities of the synapses mostly in cortical layter IV evoked by tooth pulp stimulation may be enhanced but the activities of the cortical cells may be suppressed by diazepam injection.

Animals↗
PubMedDate not supplied

Electroacupuncture suppression of the rat jaw opening response after stimulating the caudal spinal trigeminal nucleus.

Suppressive effects of electroacupuncture on the jaw opening responses evoked by stimulation of two areas (anterior and posterior) within the caudal spinal trigeminal nucleus were investigated using lightly anesthetized rats. Electroacupuncture stimulation markedly suppressed the jaw opening responses evoked by stimulating the posterior area, but suppressed only slightly those evoked by stimulating the anterior area.

Acupuncture Therapy↗