Morphological and Functional Study of Regenerated Chorda Tympani Nerves in Humans

Shibamori, Yoshiyuki; Yamamoto, Takehito; Saito, Takehisa; Manabe, Yasuhiro; Ohtsubo, Toshio; Yamagishi, Takahiro; Saitô, Hitoshi

doi:10.1177/000348940010900801

Cited by 28 publications

(5 citation statements)

References 18 publications

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“…Some previous clinical studies have reported that patients feel abnormal pain sensation after wound healing [18-20]. When considering the previous data and our findings, it is possible that an abnormal pain sensation occurs in the cutaneous tissues reinnervated by the injured nerves, but how the reinnervated nerves are involved in generation of an abnormal pain in the areas innervated by the injured IAN is not well understood.…”

Section: Discussionsupporting

confidence: 42%

Alteration of Primary Afferent Activity following Inferior Alveolar Nerve Transection in Rats

et al. 2010

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BackgroundIn order to evaluate the neural mechanisms underlying the abnormal facial pain that may develop following regeneration of the injured inferior alveolar nerve (IAN), the properties of the IAN innervated in the mental region were analyzed.ResultsFluorogold (FG) injection into the mental region 14 days after IAN transection showed massive labeling of trigeminal ganglion (TG). The escape threshold to mechanical stimulation of the mental skin was significantly lower (i.e. mechanical allodynia) at 11-14 days after IAN transection than before surgery. The background activity, mechanically evoked responses and afterdischarges of IAN Aδ-fibers were significantly higher in IAN-transected rats than naive. The small/medium diameter TG neurons showed an increase in both tetrodotoxin (TTX)-resistant (TTX-R) and -sensitive (TTX-S) sodium currents (INa) and decrease in total potassium current, transient current (IA) and sustained current (IK) in IAN-transected rats. The amplitude, overshoot amplitude and number of action potentials evoked by the depolarizing pulses after 1 μM TTX administration in TG neurons were significantly higher, whereas the threshold current to elicit spikes was smaller in IAN-transected rats than naive. Resting membrane potential was significantly smaller in IAN-transected rats than that of naive.ConclusionsThese data suggest that the increase in both TTX-S INa and TTX-R INa and the decrease in IA and Ik in small/medium TG neurons in IAN-transected rats are involved in the activation of spike generation, resulting in hyperexcitability of Aδ-IAN fibers innervating the mental region after IAN transection.

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Section: Discussionsupporting

confidence: 42%

Alteration of Primary Afferent Activity following Inferior Alveolar Nerve Transection in Rats

et al. 2010

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“…Therefore, it is possible that injury-induced plasticity of nerve terminal fields is complex, involving multiple gustatory nerve terminal fields. Such changes may underlie the apparent compensation needed to protect normal taste-elicited behaviors following nerve damage and may be induced in humans through taste nerve damage sustained as a result of disease (Arnold, 1974; Bull, 1965; May and Schlaepfer, 1975), middle ear surgery (Saito et al, 2000, 2001a,b, 2002), or oral surgery (Gent et al, 2003; Schendel and Epker, 1980). …”

Section: Discussionmentioning

confidence: 99%

Impact of chorda tympani nerve injury on cell survival, axon maintenance, and morphology of the chorda tympani nerve terminal field in the nucleus of the solitary tract

Reddaway

Davidow

Deal

et al. 2012

J of Comparative Neurology

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Chorda tympani nerve transection (CTX) has been useful to study the relationship between nerve and taste buds in fungiform papillae. This work demonstrated that the morphological integrity of taste buds depends on their innervation. Considerable research focused on the effects of CTX on peripheral gustatory structures, but much less research has focused on the central effects. Here, we explored how CTX affects ganglion cell survival, maintenance of injured peripheral axons, and the chorda tympani nerve terminal field organization in the nucleus of the solitary tract (NTS). After CTX in adult rats, the chorda tympani nerve was labeled with biotinylated dextran amine at 3, 7, 14, 30, and 60 days post-CTX to allow visualization of the terminal field associated with peripheral processes. There was a significant and persistent reduction of the labeled chorda tympani nerve terminal field volume and density in the NTS following CTX. Compared with controls, the volume of the labeled terminal field was not altered at 3 or 7 days post-CTX; however, it was significantly reduced by 44% and by 63% at 30 and 60 days post-CTX, respectively. Changes in the density of labeled terminal field in the NTS paralleled the terminal field volume results. The dramatic decrease in labeled terminal field size post-CTX cannot be explained by a loss of geniculate ganglion neurons or degeneration of central axons. Instead, the function and/or maintenance of the peripheral axonal process appear to be affected. These new results have implications for long-term functional and behavioral alterations.

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“…In surgical patients the TB recover once the CT nerve regenerates after surgery [93,104], followed by recovery of taste sensation [105,106,107]. Neurotrophins, particularly BDNF, have been reported to mediate the nerve regeneration after CT section in mice [57,58].…”

Section: Chemosensation Somatosensation Hh Signaling and Disrupmentioning

confidence: 99%

Hedgehog Signaling Regulates Taste Organs and Oral Sensation: Distinctive Roles in the Epithelium, Stroma, and Innervation

Mistretta

Kumari

2019

IJMS

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The Hedgehog (Hh) pathway has regulatory roles in maintaining and restoring lingual taste organs, the papillae and taste buds, and taste sensation. Taste buds and taste nerve responses are eliminated if Hh signaling is genetically suppressed or pharmacologically inhibited, but regeneration can occur if signaling is reactivated within the lingual epithelium. Whereas Hh pathway disruption alters taste sensation, tactile and cold responses remain intact, indicating that Hh signaling is modality-specific in regulation of tongue sensation. However, although Hh regulation is essential in taste, the basic biology of pathway controls is not fully understood. With recent demonstrations that sonic hedgehog (Shh) is within both taste buds and the innervating ganglion neurons/nerve fibers, it is compelling to consider Hh signaling throughout the tongue and taste organ cell and tissue compartments. Distinctive signaling centers and niches are reviewed in taste papilla epithelium, taste buds, basal lamina, fibroblasts and lamellipodia, lingual nerves, and sensory ganglia. Several new roles for the innervation in lingual Hh signaling are proposed. Hh signaling within the lingual epithelium and an intact innervation each is necessary, but only together are sufficient to sustain and restore taste buds. Importantly, patients who use Hh pathway inhibiting drugs confront an altered chemosensory world with loss of taste buds and taste responses, intact lingual touch and cold sensation, and taste recovery after drug discontinuation.

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Morphological and Functional Study of Regenerated Chorda Tympani Nerves in Humans

Cited by 28 publications

References 18 publications

Alteration of Primary Afferent Activity following Inferior Alveolar Nerve Transection in Rats

Alteration of Primary Afferent Activity following Inferior Alveolar Nerve Transection in Rats

Impact of chorda tympani nerve injury on cell survival, axon maintenance, and morphology of the chorda tympani nerve terminal field in the nucleus of the solitary tract

Hedgehog Signaling Regulates Taste Organs and Oral Sensation: Distinctive Roles in the Epithelium, Stroma, and Innervation

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