Physiological profiles of cortical responses to mechanical stimulation of the tooth in the rat: An optical imaging study

Kaneko, Mari; Horinuki, Eri; Kobayashi, Masayuki

doi:10.1016/j.neuroscience.2017.06.042

Cited by 19 publications

(15 citation statements)

References 40 publications

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“…In contrast to S2/IOR activation, S1 exhibits less activation by dental pulp stimulation, which is also true for electrical stimulation of the periodontal ligament [36,37]. It is worth noting that mechanical stimulation of the periodontal ligament, by pulling the maxillary first molar, induces greater S1 activation than S2/IOR activation [38,39]. These findings suggest that S1 and S2/IOR have different roles in somatosensory information processing, namely, that non-nociceptive and nociceptive information is principally processed in S1 and S2/IOR, respectively.…”

Section: Cerebrocortical Areas That Process Oral Sensationsmentioning

confidence: 89%

Anatomical aspects of corticotrigeminal projections to the medullary dorsal horn

Kobayashi

Nakaya

2020

J Oral Sci

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Corticofugal projections to neurons in the medullary dorsal horn, i.e., the trigeminal spinal subnucleus caudalis (Sp5C), are thought to play a critical role in regulating nociceptive information processing in the trigeminal nervous system. The Sp5C consists of 5 layers, each of which exhibits its own characteristic features of cellular organization. Therefore, the layers receiving corticofugal projections must be identified when discussing the role of the cerebral cortex in nociception arising from the trigeminal nerve. It is also necessary to discriminate between layers of the Sp5C where corticofugal projections terminate, because the Sp5C involves glutamatergic neurons and GABAergic/glycinergic neurons, which correspond to excitatory and inhibitory neurons, respectively. This review summarizes descending projections from the cerebral cortex, including the primary and secondary somatosensory and insular cortices, to the Sp5C.

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Section: Cerebrocortical Areas That Process Oral Sensationsmentioning

confidence: 89%

Anatomical aspects of corticotrigeminal projections to the medullary dorsal horn

Kobayashi

Nakaya

2020

J Oral Sci

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“…The somatotopic organization of S1 and S2 may explain the mechanisms of this ectopic pain. Our previous studies have demonstrated that S2/IOR principally mediates nociception in the orofacial region (Horinuki et al, 2015, 2016; Nakamura et al, 2015, 2016; Kaneko et al, 2017). Notably, IANX expanded the excitation in S2/IOR toward the dorsal regions because the region dorsally adjacent to S2/IOR corresponds to facial S1 and S2, including the whisker pad (Remple et al, 2003).…”

Section: Discussionmentioning

confidence: 99%

“…In some cases, the initial responses were found simultaneously in both S1 and S2/IOR. Since our previous study indicated that the S2/IOR plays a critical role in the processing of nociceptive information (Kaneko et al, 2017), all ROIs were set based on the initial responses in S2/IOR. The peak amplitude was defined as the maximum amplitude of an optical response at an ROI.…”

Section: Methodsmentioning

confidence: 99%

“…Our previous optical imaging and extracellular recording studies revealed that S2/IOR exhibits somatotopic organization in response to electrical pulpal stimulation of the mandibular and maxillary incisors and molars (Nakamura et al, 2015, 2016). In addition, the systemic administration of potent analgesics, i.e., morphine, effectively suppresses excitation in S2/IOR in response to pulpal stimulation (Kaneko et al, 2017), suggesting that S2/IOR processes nociceptive information in the dental pulp.…”

Section: Introductionmentioning

confidence: 99%

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Trigeminal Nerve Transection-Induced Neuroplastic Changes in the Somatosensory and Insular Cortices in a Rat Ectopic Pain Model

Fujita

Yamamoto

Kobayashi

2019

eNeuro

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The primary sensory cortex processes competitive sensory inputs. Ablation of these competitive inputs induces neuroplastic changes in local cortical circuits. However, information concerning cortical plasticity induced by a disturbance of competitive nociceptive inputs is limited. Nociceptive information from the maxillary and mandibular molar pulps converges at the border between the ventral secondary somatosensory cortex (S2) and insular oral region (IOR); therefore, S2/IOR is a suitable target for examining the cortical changes induced by a disturbance of noxious inputs, which often causes neuropathic pain and allodynia. We focused on the plastic changes in S2/IOR excitation in a model of rats subjected to inferior alveolar nerve transection (IANX). Our optical imaging using a voltage-sensitive dye (VSD) revealed that the maxillary molar pulp stimulation-induced excitatory propagation was expanded one to two weeks after IANX at the macroscopic level. At the cellular level, based on Ca2+ imaging using two-photon microscopy, the amplitude of the Ca2+ responses and the number of responding neurons in S2/IOR increased in both excitatory and inhibitory neurons. The in vitro laser scanning photostimulation (LSPS) revealed that Layer II/III pyramidal and GABAergic fast-spiking neurons in S2/IOR received larger excitatory inputs from Layer IV in the IANX models, which supports the findings obtained by the macroscopic and microscopic optical imaging. Furthermore, the inhibitory postsynaptic inputs to the pyramidal neurons were decreased in the IANX models, suggesting suppression of inhibitory synaptic transmission onto excitatory neurons. These results suggest that IANX induces plastic changes in S2/IOR by changing the local excitatory and inhibitory circuits.

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“…Optical imaging was performed as previously described (3–6, 13, 19–21). Briefly the sham and pl-ION model rats were anesthetized with urethane (1.5 g/kg, i.p.…”

Section: Methodsmentioning

confidence: 99%

Preceding Administration of Minocycline Suppresses Plastic Changes in Cortical Excitatory Propagation in the Model Rat With Partial Infraorbital Nerve Ligation

et al. 2019

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Neuropathic pain is known to be attributable to the injured nerve, a postoperative problem induced by surgery. The infraorbital nerve (ION), a branch of the trigeminal nerve, innervates to the facial and oral regions and conveys somatosensory information to the central nervous system. The partial ligation of ION (pl-ION) is a method to mimic chronic trigeminal neuropathic pain and behavioral abnormality. To counteract induction of such abnormal pain, the effective pharmacological treatment is desired. Although recent studies have revealed the molecular mechanisms regarding chronic pain, estimation of the effectiveness of the pharmacological treatment has not been well-provided especially in the central nervous system so far. Here we examined whether pl-ION induces plastic changes in the cerebral cortex and investigated effects of minocycline on the cortical plastic changes. We performed the pl-ION to Wistar male rats (4–5 weeks old), and confirmed a mechanical nocifensive behavior in response to the mechanical stimulation with von-Frey filaments. The withdrawal threshold to mechanical stimuli of the whisker pad was decreased 1 day (1 d) after pl-ION, which continued up to 14 d after pl-ION, suggesting that pl-ION model rats presented allodynia and enhanced the response sustained at least for 14 d after pl-ION. Next, cerebrocortical activities were evaluated 3 d after pl-ION (3d-pl-ION) by the optical imaging with a voltages-sensitive dye, RH1691, to quantify the response to electrical stimulation of the whisker pad skin, mandibular molar dental pulp, and mentum skin. Electrical stimulation to the whisker pad skin induced smaller excitation in the primary sensory cortex (S1) of 3d-pl-ION in comparison to that in the sham. In contrast, cerebral cortical responses to the mandibular molar dental pulp and mentum skin stimuli increased both in S1, and the secondary somatosensory and insular oral region (S2/IOR) after pl-ION. Administration of minocycline (30 mg/kg/d) from 1 d before to 2 d after pl-ION partially recovered the pl-ION-induced changes in cortical excitation in S1 and S2/IOR in 3d-pl-ION. These results suggest that somatosensory and insular cortical excitation is changed by pl-ION, and the preceding injection of minocycline counteracts the plastic changes in the cortical activities.

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Physiological profiles of cortical responses to mechanical stimulation of the tooth in the rat: An optical imaging study

Cited by 19 publications

References 40 publications

Anatomical aspects of corticotrigeminal projections to the medullary dorsal horn

Anatomical aspects of corticotrigeminal projections to the medullary dorsal horn

Trigeminal Nerve Transection-Induced Neuroplastic Changes in the Somatosensory and Insular Cortices in a Rat Ectopic Pain Model

Preceding Administration of Minocycline Suppresses Plastic Changes in Cortical Excitatory Propagation in the Model Rat With Partial Infraorbital Nerve Ligation

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