The Experts below are selected from a list of 192 Experts worldwide ranked by ideXlab platform

Yoshihide Satoh - One of the best experts on this subject based on the ideXlab platform.

  • role of the vestibular nuclear complex in facilitating the Jaw Opening Reflex following stimulation of the red nucleus
    Neuroscience Research, 2016
    Co-Authors: Yoshihide Satoh, Kenichi Ishizuka, Mutsumi Takahashi, Shinichi Iwasaki
    Abstract:

    According to our previous studies, stimulation of the red nucleus (RN) facilitates the low-threshold afferent-evoked Jaw-Opening Reflex (L-JOR). It has been reported that the RN projects to the superior (SVN), lateral (LVN) and inferior vestibular (IVN) nuclei. The SVN and the LVN have reciprocal intrinsic connections with the medial vestibular nucleus (MVN). Our previous study demonstrated that stimulation of the vestibular nuclear complex (VN) modulates the L-JOR. These facts suggest that RN-induced facilitation of the L-JOR is mediated via the VN. In the present work we investigated whether electrically induced lesions of the VN, or microinjection of muscimol into the VN, affects RN-induced facilitation of the L-JOR. The L-JOR was evoked by electrical stimulation of the inferior alveolar nerve. The stimulus intensity was 1.2 times the evocation threshold. Lesions of the MVN or the LVN or the SVN, and the muscimol injection into the MVN or the LVN or the SVN, reduced the RN-induced facilitation of the L-JOR. Conversely, lesions of the IVN, and the muscimol injection into the IVN, increased the RN-induced facilitation of the L-JOR. These results suggest that the RN-induced facilitation of the L-JOR is mediated by a relay in the VN.

  • role of the red nucleus in suppressing the Jaw Opening Reflex following stimulation of the raphe magnus nucleus
    Neuroscience Research, 2014
    Co-Authors: Yoshihide Satoh, Kenichi Ishizuka, Shinichi Iwasaki
    Abstract:

    In a previous study, we found that electrical and chemical stimulation of the red nucleus (RN) suppressed the high-threshold afferent-evoked Jaw-Opening Reflex (JOR). It has been reported that the RN receives bilaterally projection fibers from the raphe magnus nucleus (RMg), and that stimulation of the RMg inhibits the tooth pulp-evoked nociceptive JOR. These facts imply that RMg-induced inhibition of the JOR could be mediated via the RN. The present study first examines whether stimulation of the RMg suppresses the high-threshold afferent-evoked JOR. The JOR was evoked by electrical stimulation of the inferior alveolar nerve (IAN), and was recorded as the electromyographic response of the anterior belly of the digastric muscle. The stimulus intensity was 4.0 (high-threshold) times the threshold. Conditioning electrical stimulation of the RMg significantly suppressed the JOR. A further study then examined whether electrically induced lesions of the RN or microinjection of muscimol into the RN affects RMg-induced suppression of the JOR. Electrically induced lesions of the bilateral RN and microinjection of muscimol into the bilateral RN both reduced the RMg-induced suppression of the JOR. These results suggest that RMg-induced suppression of the high-threshold afferent-evoked JOR is mediated by a relay in the RN.

  • role of the lateral reticular nucleus in suppressing the Jaw Opening Reflex following stimulation of the red nucleus
    Neuroscience Research, 2014
    Co-Authors: Yoshihide Satoh, Eriko Yajima, Kenichi Ishizuka, Shinichi Iwasaki
    Abstract:

    Abstract We found in a previous study that stimulation of the red nucleus (RN) facilitated the low-threshold afferent-evoked Jaw-Opening Reflex (JOR) and suppressed the high-threshold afferent-evoked JOR. It has been reported that the RN projections to the contralateral lateral reticular nucleus (LRt), and stimulation of the LRt inhibits the nociceptive JOR. These facts suggest that RN-induced modulation of the JOR is mediated via the LRt. We investigated whether electrically induced lesions of the LRt, or microinjection of muscimol into the LRt, affects RN-induced modulation of the JOR. The JOR was evoked by electrical stimulation of the inferior alveolar nerve (IAN), and was recorded as the electromyographic response of the anterior belly of the digastric muscle. The stimulus intensity was either 1.2 (low-threshold) or 4.0 (high-threshold) times the threshold. Electrically induced lesion of the LRt and microinjection of muscimol into the LRt reduced the RN-induced suppression of the high-threshold afferent-evoked JOR, but did not affect the RN-induced facilitation of the low-threshold afferent-evoked JOR. These results suggest that the RN-induced suppression of the high-threshold afferent-evoked JOR is mediated by a relay in the contralateral LRt.

  • suppression of the nociceptive Jaw Opening Reflex by stimulation of the red nucleus
    Brain Research, 2012
    Co-Authors: Eriko Yajima, Kenichi Ishizuka, Shinichi Iwasaki, Yoshihide Satoh, Kazuto Terada
    Abstract:

    We studied the effect of stimulation of the red nucleus (RN) on the Jaw-Opening Reflex (JOR) in anesthetized rats. The JOR was evoked by electrical stimulation of the tooth pulp of a lower incisor, and was recorded as the electromyographic responses of the anterior belly of the digastric muscle, bilaterally. Conditioning electrical stimulation of the RN was found to suppress the JOR bilaterally. Microinjection of monosodium glutamate into the RN also suppressed the JOR bilaterally. The suppressive effect of the magnocellular part of the RN was significantly larger than that of the parvicellular part of the RN. These results imply that the RN is involved in control of the JOR evoked by noxious stimulus.

  • Modulation of the Jaw-Opening Reflex by stimulation of the vestibular nuclear complex in rats.
    Neuroscience letters, 2009
    Co-Authors: Yoshihide Satoh, Kenichi Ishizuka, Toshiki Murakami
    Abstract:

    The effect of stimulation of the vestibular nuclear complex (VN) on the Jaw-Opening Reflex (JOR) was studied in anesthetized rats. The JOR was evoked by electrical stimulation of the inferior alveolar nerve, and was recorded as the electromyographic responses of the anterior belly of the digastric muscle, bilaterally. Conditioning electrical stimulation of the medial (MVN), lateral (LVN) and superior (SVN) vestibular nuclei facilitated the JOR bilaterally. Microinjection of monosodium glutamate into the SVN, LVN and MVN also facilitated the JOR bilaterally. In contrast, conditioning electrical stimulation of the inferior vestibular nucleus (IVN) inhibited the JOR ipsilaterally. Microinjection of monosodium glutamate into the IVN also inhibited the JOR ipsilaterally. These results suggest that the VN is involved in modulation of the JOR and plays an important role in controlling the Jaw movements.

N.-h. Park - One of the best experts on this subject based on the ideXlab platform.

  • Effect ofHerpes simplex virus infection on the trigeminal Jaw-Opening Reflex in guinea pigs
    Brain Research, 1991
    Co-Authors: J.h. Lee, Louis J. Goldberg, N.-h. Park
    Abstract:

    Herpes simplex virus (HSV) infection induces numerous electrophysiological and microscopic changes in neurons in vitro. To investigate the effect of HSV infection on in vivo neuronal activity, we induced an acute, latent and reactivated HSV infection of the trigeminal ganglia of guinea pigs through orofacial HSV inoculation and studied its effect on the trigeminal Jaw-Opening Reflex of anesthetized guinea pigs. During the acute viral infection period both the threshold for elicitation of the Reflex, and the latency to the onset of the Reflex response were increased. During the latent viral infection in the trigeminal ganglia, the Jaw-Opening Reflexes in the viral infected animals were not different from those of non-infected control animals. However, reactivation of the latent viral infection in these animals resulated in increases in both the threshold and latency of the Jaw-Opening Reflex. These changes were similar to those found in animals with the acute viral infection. These results indicate that acute or reactivated latent HSV infection of the nervous system results in functional changes in the Reflex pathways involving the trigeminal gasserian ganglia and beurons harboring infectious HSV-1.

  • Effect of Herpes simplex virus infection on the trigeminal Jaw-Opening Reflex in guinea pigs.
    Brain research, 1991
    Co-Authors: J.h. Lee, Louis J. Goldberg, N.-h. Park
    Abstract:

    Herpes simplex virus (HSV) infection induces numerous electrophysiological and microscopic changes in neurons in vitro. To investigate the effect of HSV infection on in vivo neuronal activity, we induced an acute, latent and reactivated HSV infection of the trigeminal ganglia of guinea pigs through orofacial HSV inoculation and studied its effect on the trigeminal Jaw-Opening Reflex of anesthetized guinea pigs. During the acute viral infection period both the threshold for elicitation of the Reflex, and the latency to the onset of the Reflex response were increased. During the latent viral infection in the trigeminal ganglia, the Jaw-Opening Reflexes in the viral infected animals were not different from those of non-infected control animals. However, reactivation of the latent viral infection in these animals resulted in increases in both the threshold and latency of the Jaw-Opening Reflex. These changes were similar to those found in animals with the acute viral infection. These results indicate that acute or reactivated latent HSV infection of the nervous system results in functional changes in the Reflex pathways involving the trigeminal gasserian ganglia and brainstem neurons harboring infectious HSV-1.

Kenichi Ishizuka - One of the best experts on this subject based on the ideXlab platform.

  • role of the vestibular nuclear complex in facilitating the Jaw Opening Reflex following stimulation of the red nucleus
    Neuroscience Research, 2016
    Co-Authors: Yoshihide Satoh, Kenichi Ishizuka, Mutsumi Takahashi, Shinichi Iwasaki
    Abstract:

    According to our previous studies, stimulation of the red nucleus (RN) facilitates the low-threshold afferent-evoked Jaw-Opening Reflex (L-JOR). It has been reported that the RN projects to the superior (SVN), lateral (LVN) and inferior vestibular (IVN) nuclei. The SVN and the LVN have reciprocal intrinsic connections with the medial vestibular nucleus (MVN). Our previous study demonstrated that stimulation of the vestibular nuclear complex (VN) modulates the L-JOR. These facts suggest that RN-induced facilitation of the L-JOR is mediated via the VN. In the present work we investigated whether electrically induced lesions of the VN, or microinjection of muscimol into the VN, affects RN-induced facilitation of the L-JOR. The L-JOR was evoked by electrical stimulation of the inferior alveolar nerve. The stimulus intensity was 1.2 times the evocation threshold. Lesions of the MVN or the LVN or the SVN, and the muscimol injection into the MVN or the LVN or the SVN, reduced the RN-induced facilitation of the L-JOR. Conversely, lesions of the IVN, and the muscimol injection into the IVN, increased the RN-induced facilitation of the L-JOR. These results suggest that the RN-induced facilitation of the L-JOR is mediated by a relay in the VN.

  • role of the red nucleus in suppressing the Jaw Opening Reflex following stimulation of the raphe magnus nucleus
    Neuroscience Research, 2014
    Co-Authors: Yoshihide Satoh, Kenichi Ishizuka, Shinichi Iwasaki
    Abstract:

    In a previous study, we found that electrical and chemical stimulation of the red nucleus (RN) suppressed the high-threshold afferent-evoked Jaw-Opening Reflex (JOR). It has been reported that the RN receives bilaterally projection fibers from the raphe magnus nucleus (RMg), and that stimulation of the RMg inhibits the tooth pulp-evoked nociceptive JOR. These facts imply that RMg-induced inhibition of the JOR could be mediated via the RN. The present study first examines whether stimulation of the RMg suppresses the high-threshold afferent-evoked JOR. The JOR was evoked by electrical stimulation of the inferior alveolar nerve (IAN), and was recorded as the electromyographic response of the anterior belly of the digastric muscle. The stimulus intensity was 4.0 (high-threshold) times the threshold. Conditioning electrical stimulation of the RMg significantly suppressed the JOR. A further study then examined whether electrically induced lesions of the RN or microinjection of muscimol into the RN affects RMg-induced suppression of the JOR. Electrically induced lesions of the bilateral RN and microinjection of muscimol into the bilateral RN both reduced the RMg-induced suppression of the JOR. These results suggest that RMg-induced suppression of the high-threshold afferent-evoked JOR is mediated by a relay in the RN.

  • role of the lateral reticular nucleus in suppressing the Jaw Opening Reflex following stimulation of the red nucleus
    Neuroscience Research, 2014
    Co-Authors: Yoshihide Satoh, Eriko Yajima, Kenichi Ishizuka, Shinichi Iwasaki
    Abstract:

    Abstract We found in a previous study that stimulation of the red nucleus (RN) facilitated the low-threshold afferent-evoked Jaw-Opening Reflex (JOR) and suppressed the high-threshold afferent-evoked JOR. It has been reported that the RN projections to the contralateral lateral reticular nucleus (LRt), and stimulation of the LRt inhibits the nociceptive JOR. These facts suggest that RN-induced modulation of the JOR is mediated via the LRt. We investigated whether electrically induced lesions of the LRt, or microinjection of muscimol into the LRt, affects RN-induced modulation of the JOR. The JOR was evoked by electrical stimulation of the inferior alveolar nerve (IAN), and was recorded as the electromyographic response of the anterior belly of the digastric muscle. The stimulus intensity was either 1.2 (low-threshold) or 4.0 (high-threshold) times the threshold. Electrically induced lesion of the LRt and microinjection of muscimol into the LRt reduced the RN-induced suppression of the high-threshold afferent-evoked JOR, but did not affect the RN-induced facilitation of the low-threshold afferent-evoked JOR. These results suggest that the RN-induced suppression of the high-threshold afferent-evoked JOR is mediated by a relay in the contralateral LRt.

  • suppression of the nociceptive Jaw Opening Reflex by stimulation of the red nucleus
    Brain Research, 2012
    Co-Authors: Eriko Yajima, Kenichi Ishizuka, Shinichi Iwasaki, Yoshihide Satoh, Kazuto Terada
    Abstract:

    We studied the effect of stimulation of the red nucleus (RN) on the Jaw-Opening Reflex (JOR) in anesthetized rats. The JOR was evoked by electrical stimulation of the tooth pulp of a lower incisor, and was recorded as the electromyographic responses of the anterior belly of the digastric muscle, bilaterally. Conditioning electrical stimulation of the RN was found to suppress the JOR bilaterally. Microinjection of monosodium glutamate into the RN also suppressed the JOR bilaterally. The suppressive effect of the magnocellular part of the RN was significantly larger than that of the parvicellular part of the RN. These results imply that the RN is involved in control of the JOR evoked by noxious stimulus.

  • Modulation of the Jaw-Opening Reflex by stimulation of the vestibular nuclear complex in rats.
    Neuroscience letters, 2009
    Co-Authors: Yoshihide Satoh, Kenichi Ishizuka, Toshiki Murakami
    Abstract:

    The effect of stimulation of the vestibular nuclear complex (VN) on the Jaw-Opening Reflex (JOR) was studied in anesthetized rats. The JOR was evoked by electrical stimulation of the inferior alveolar nerve, and was recorded as the electromyographic responses of the anterior belly of the digastric muscle, bilaterally. Conditioning electrical stimulation of the medial (MVN), lateral (LVN) and superior (SVN) vestibular nuclei facilitated the JOR bilaterally. Microinjection of monosodium glutamate into the SVN, LVN and MVN also facilitated the JOR bilaterally. In contrast, conditioning electrical stimulation of the inferior vestibular nucleus (IVN) inhibited the JOR ipsilaterally. Microinjection of monosodium glutamate into the IVN also inhibited the JOR ipsilaterally. These results suggest that the VN is involved in modulation of the JOR and plays an important role in controlling the Jaw movements.

Shinichi Iwasaki - One of the best experts on this subject based on the ideXlab platform.

  • role of the vestibular nuclear complex in facilitating the Jaw Opening Reflex following stimulation of the red nucleus
    Neuroscience Research, 2016
    Co-Authors: Yoshihide Satoh, Kenichi Ishizuka, Mutsumi Takahashi, Shinichi Iwasaki
    Abstract:

    According to our previous studies, stimulation of the red nucleus (RN) facilitates the low-threshold afferent-evoked Jaw-Opening Reflex (L-JOR). It has been reported that the RN projects to the superior (SVN), lateral (LVN) and inferior vestibular (IVN) nuclei. The SVN and the LVN have reciprocal intrinsic connections with the medial vestibular nucleus (MVN). Our previous study demonstrated that stimulation of the vestibular nuclear complex (VN) modulates the L-JOR. These facts suggest that RN-induced facilitation of the L-JOR is mediated via the VN. In the present work we investigated whether electrically induced lesions of the VN, or microinjection of muscimol into the VN, affects RN-induced facilitation of the L-JOR. The L-JOR was evoked by electrical stimulation of the inferior alveolar nerve. The stimulus intensity was 1.2 times the evocation threshold. Lesions of the MVN or the LVN or the SVN, and the muscimol injection into the MVN or the LVN or the SVN, reduced the RN-induced facilitation of the L-JOR. Conversely, lesions of the IVN, and the muscimol injection into the IVN, increased the RN-induced facilitation of the L-JOR. These results suggest that the RN-induced facilitation of the L-JOR is mediated by a relay in the VN.

  • role of the red nucleus in suppressing the Jaw Opening Reflex following stimulation of the raphe magnus nucleus
    Neuroscience Research, 2014
    Co-Authors: Yoshihide Satoh, Kenichi Ishizuka, Shinichi Iwasaki
    Abstract:

    In a previous study, we found that electrical and chemical stimulation of the red nucleus (RN) suppressed the high-threshold afferent-evoked Jaw-Opening Reflex (JOR). It has been reported that the RN receives bilaterally projection fibers from the raphe magnus nucleus (RMg), and that stimulation of the RMg inhibits the tooth pulp-evoked nociceptive JOR. These facts imply that RMg-induced inhibition of the JOR could be mediated via the RN. The present study first examines whether stimulation of the RMg suppresses the high-threshold afferent-evoked JOR. The JOR was evoked by electrical stimulation of the inferior alveolar nerve (IAN), and was recorded as the electromyographic response of the anterior belly of the digastric muscle. The stimulus intensity was 4.0 (high-threshold) times the threshold. Conditioning electrical stimulation of the RMg significantly suppressed the JOR. A further study then examined whether electrically induced lesions of the RN or microinjection of muscimol into the RN affects RMg-induced suppression of the JOR. Electrically induced lesions of the bilateral RN and microinjection of muscimol into the bilateral RN both reduced the RMg-induced suppression of the JOR. These results suggest that RMg-induced suppression of the high-threshold afferent-evoked JOR is mediated by a relay in the RN.

  • role of the lateral reticular nucleus in suppressing the Jaw Opening Reflex following stimulation of the red nucleus
    Neuroscience Research, 2014
    Co-Authors: Yoshihide Satoh, Eriko Yajima, Kenichi Ishizuka, Shinichi Iwasaki
    Abstract:

    Abstract We found in a previous study that stimulation of the red nucleus (RN) facilitated the low-threshold afferent-evoked Jaw-Opening Reflex (JOR) and suppressed the high-threshold afferent-evoked JOR. It has been reported that the RN projections to the contralateral lateral reticular nucleus (LRt), and stimulation of the LRt inhibits the nociceptive JOR. These facts suggest that RN-induced modulation of the JOR is mediated via the LRt. We investigated whether electrically induced lesions of the LRt, or microinjection of muscimol into the LRt, affects RN-induced modulation of the JOR. The JOR was evoked by electrical stimulation of the inferior alveolar nerve (IAN), and was recorded as the electromyographic response of the anterior belly of the digastric muscle. The stimulus intensity was either 1.2 (low-threshold) or 4.0 (high-threshold) times the threshold. Electrically induced lesion of the LRt and microinjection of muscimol into the LRt reduced the RN-induced suppression of the high-threshold afferent-evoked JOR, but did not affect the RN-induced facilitation of the low-threshold afferent-evoked JOR. These results suggest that the RN-induced suppression of the high-threshold afferent-evoked JOR is mediated by a relay in the contralateral LRt.

  • suppression of the nociceptive Jaw Opening Reflex by stimulation of the red nucleus
    Brain Research, 2012
    Co-Authors: Eriko Yajima, Kenichi Ishizuka, Shinichi Iwasaki, Yoshihide Satoh, Kazuto Terada
    Abstract:

    We studied the effect of stimulation of the red nucleus (RN) on the Jaw-Opening Reflex (JOR) in anesthetized rats. The JOR was evoked by electrical stimulation of the tooth pulp of a lower incisor, and was recorded as the electromyographic responses of the anterior belly of the digastric muscle, bilaterally. Conditioning electrical stimulation of the RN was found to suppress the JOR bilaterally. Microinjection of monosodium glutamate into the RN also suppressed the JOR bilaterally. The suppressive effect of the magnocellular part of the RN was significantly larger than that of the parvicellular part of the RN. These results imply that the RN is involved in control of the JOR evoked by noxious stimulus.

Mamoru Takeda - One of the best experts on this subject based on the ideXlab platform.

  • Resveratrol suppresses nociceptive Jaw-Opening Reflex via 5HT3 receptor-mediated GABAergic inhibition .
    Neuroscience research, 2019
    Co-Authors: Kounosuke Hirata, Yuto Nishiki, Ryosuke Goto, Mikito Inagaki, Katsuo Oshima, Yoshihito Shimazu, Mamoru Takeda
    Abstract:

    Abstract Systemic administration of the dietary constituent, resveratrol, was previously shown to inhibit the nociceptive Jaw-Opening Reflex (JOR) via the endogenous opioid system. The present study investigated whether resveratrol could similarly affect the JOR under in vivo conditions via 5HT3 receptor-mediated GABAergic inhibition. We used electrical stimulation of the tongue in pentobarbital-anesthetized rats to evoke the JOR, which was recorded as the anterior belly of the digastric muscle electromyograms (dEMG). Intravenous administration of resveratrol (2 mg/kg) reduced the dEMG amplitude in response to three times the determined threshold electrical stimulation, with maximum inhibition reached within approximately 10 min. These inhibitory effects on the JOR were reversible to control levels after approximately 20 min. Pretreatment of rats with either 5HT3 receptor antagonist, ondansetron (0.25−1 mg/kg, i.p.), or GABAA receptor antagonist, bicuculline (0.5−1 mg/kg, i.p.), significantly and dose-dependently attenuated the inhibitory effects of resveratrol on dEMG amplitude compared with untreated controls. These findings suggest that resveratrol also attenuates the nociceptive JOR via 5HT3 receptor-mediated GABAergic inhibition. The present study therefore provides new insight into a possible mechanism underlying resveratrol-induced trigeminal antinociception via the descending pain control system and highlights a potential therapeutic agent for complementary alternative medicine.

  • Local anesthetic effect of docosahexaenoic acid on the nociceptive Jaw-Opening Reflex in rats.
    Neuroscience research, 2018
    Co-Authors: Kazuki Mitome, Katsuo Oshima, Yoshihito Shimazu, Shiori Takehana, Mamoru Takeda
    Abstract:

    Abstract Although docosahexaenoic acid (DHA) administration suppresses sodium channels in primary afferent sensory neurons, the acute local effect of DHA on the trigeminal nociceptive Reflex remains to be elucidated, in vivo. Therefore, the aim of the present study was to investigate whether local administration of DHA attenuates the nociceptive Jaw-Opening Reflex (JOR) in vivo in the rat. The JOR evoked by electrical stimulation of the tongue was recorded by a digastric muscle electromyogram (dEMG) in pentobarbital-anesthetized rats. The amplitude of the dEMG response was significantly increased in proportion to the electrical stimulation intensity (1–5 x threshold). At 3 x threshold, local administration of DHA (0.1, 10 and 25 mM) dose-dependently inhibited the dEMG response, and lasted 40 min. Maximum inhibition of the dEMG signal amplitude was seen within approximately 10 min. The mean magnitude of inhibition of the dEMG signal amplitude by DHA (25 mM) was almost equal to the local anesthetic, 1% lidocaine (37 mM), a sodium channel blocker. These findings suggest that DHA attenuates the nociceptive JOR via possibly blocking sodium channels, and strongly support the idea that DHA is a potential therapeutic agent and complementary alternative medicine for the prevention of acute trigeminal nociception.

  • Volume expansion suppresses the tooth-pulp evoked Jaw-Opening Reflex related activity of trigeminal neurons in rats
    Brain research bulletin, 2002
    Co-Authors: Mamoru Takeda, Takeshi Tanimoto, Toshimi Nishikawa, Mizuho Ikeda, Shinki Yoshida, Masahiro Ito, Shigeji Matsumoto
    Abstract:

    The aim of the present study is to clarify whether physiological stimulation of vagal afferents modulates the activity of the trigeminal spinal nucleus oralis (TSNO) neurons related to the tooth-pulp (TP)-evoked Jaw-Opening Reflex (JOR) in pentobarbital-anesthetized rats. The activity of TSNO neurons and the amplitude of digastric electromyogram (dEMG) increased proportionally during 1.0-3.5 times the threshold for JOR. The amplitude of the dEMG of 14 out of 17 rats was suppressed by physiological stimulation of vagal afferents after intravenous infusion of Ficoll. Out of 23, 18 TSNO unit activities in 14 rats were also suppressed by Ficoll infusion. This suppressive effect of unit and dEMG activities returned to the control level within 25 min. After administration of naloxone (0.5 and 1.0 mg/kg, i.v.) the suppressive effect of Ficoll infusion on the activity of TSNO neurons (5/7) was significantly attenuated compared to the control (p < 0.01). The inhibition TSNO neuronal and dEMG activities by Ficoll infusion was volume-dependent in a range of 5-10% of total blood volume. Furthermore, right vagus nerve ligation greatly inhibited the suppressive effect of Ficoll-induced TSNO activity. These results therefore suggest that low-pressure cardiopulmonary baroreceptors whose afferents travel in the vagus nerve inhibit the pulpal nociceptive transmission.

  • effect of vagal afferent conditioning on trigeminal motor neuron activity associated with tooth pulp evoked Jaw Opening Reflex
    Odontology, 2001
    Co-Authors: Isao Nakanishi, Mamoru Takeda, Shigeji Matsumoto
    Abstract:

    To clarify the vagal afferent modifying effect on the neurons constituting the nociceptive Jaw-Opening Reflex (JOR), we conducted extracellular recording of trigeminal motor nucleus (TMN) neuron activity in pentobarbital-anesthestized rats. Of 12 TMN neuron responses evoked by tooth pulp (TP) stimulation, 10 were suppressed by vagal afferent conditioning (83%). The mean time of the suppressive effect on the TMN neurons paralleled that found with the digastric electromyogram (dEMG), and maximal inhibition of both TMN neuronal spikes and the dEMG amplitude were observed at a 50-ms conditioning-test interval. The ratio of inhibition was approximately 38%. Seven of 12 units were activated antidromically by digastric muscle stimulation (1–3 mA, 0.1 ms, 2 Hz) and fulfilled the criteria for antidromic activation. Vagal afferent conditioning stimulation had no effect on the antidromic TMN neuronal responses to digastric muscle stimulation. These results suggest that suppression of the TP-evoked JOR in response to vagal afferent stimulation in rats is the result of an inhibitory effect on the sensory neurons rather than on the motor neurons.