Effects of a liquid diet on the response properties of temporomandibular joint nociceptive neurons in the trigeminal subnucleus caudalis of growing rats

Studies at spinal levels indicate that peripheral tissue or nerve injury induces a state of hyperexcitability of spinal dorsal horn neurons that participates in the development of persistent pain and hyperalgesia. It has not been demonstrated that persistent injury in the orofacial region leads to a similar state of central hyperexcitability in the trigeminal system. The purpose of the present study was to conduct a parametric analysis of the response properties of nociceptive and nonnociceptive neurons in trigeminal nucleus caudalis (medullary dorsal horn, MDH) in a rat model of persistent orofacial inflammation. Neurons were recorded extracellularly and classified as low-threshold mechanoreceptive (LTM, n = 49), wide dynamic range (WDR, n = 82), and nociceptive-specific (NS, n = 11) neurons according to their response properties to mechanical stimuli applied to their cutaneous receptive fields (RFs). The inflammation was induced 24 h before the recordings by injecting complete Freund’s adjuvant (CFA) into the temporomandibular joint (TMJ) capsule or the perioral (PO) skin. The mean areas of the high-threshold RFs of WDR neurons in TMJ (8.66 ± 0.61 cm2, n = 25) and PO (5.61 ± 2.07 cm2, n = 25) inflamed rats were significantly larger than those in naive rats (1.10 ± 0.16 cm2, n = 32). The mean RF size in TMJ-inflamed rats also was significantly larger than that in PO-inflamed rats ( P < 0.01). Furthermore the mean area of the RFs of NS neurons (3.74 ± 1.44 cm2, n = 5) was significantly larger in TMJ inflamed rats as compared with naive rats (0.4 ± 0.09 cm2, n = 3) ( P < 0.05). The background activity in the TMJ- and PO-inflamed rats was generally greater in WDR and NS neurons, but less in LTM neurons, when compared with naive rats. The responses of WDR neurons to noxious mechanical stimuli were increased significantly in TMJ-inflamed rats ( P < 0.05) as compared with naive rats. WDR neuronal responses to mechanical stimulation also were increased in PO-inflamed rats but to a lesser extent than in TMJ-inflamed rats. The injection of CFA into the TMJ or PO skin resulted in reduced responses of LTM neurons to mechanical stimuli. The responses of MDH nociceptive neurons to 48–55°C heating were greater in inflamed rats as compared with naive rats. A subpopulation of WDR neurons recorded from TMJ ( n = 4 of 10)- or PO ( n = 3 of 13)-injected rats responded to cooling in addition to heating of the RFs but did not grade their responses with changes in stimulus intensity. These results indicate that persistent orofacial inflammation produced hyperexcitability of MDH nociceptive neurons. TMJ inflammation resulted in more robust changes in MDH nociceptive neurons as compared with PO inflammation, consistent with previous studies of increased inflammation, increased MDH Fos-protein expression, and increased MDH preprodynorphin mRNA expression in this deep tissue orofacial model of pain and hyperalgesia. The inflammation-induced MDH hyperexcitability may contribute to mechanisms of persistent pain associated with orofacial deep tissue painful conditions.

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Response properties of nociceptive and non-nociceptive neurons in the ratʼs trigeminal subnucleus caudalis (medullary dorsal horn) related to cutaneous and deep craniofacial afferent stimulation and modulation by diffuse noxious inhibitory controls

Pain ◽

10.1016/0304-3959(90)90010-b ◽

1990 ◽

Vol 41 (3) ◽

pp. 331-345 ◽

Cited By ~ 150

Author(s):

James W. Hu

Keyword(s):

Dorsal Horn ◽

Diffuse Noxious Inhibitory Controls ◽

Afferent Stimulation ◽

Nociceptive Neurons ◽

Response Properties ◽

Medullary Dorsal Horn ◽

Trigeminal Subnucleus Caudalis

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Response properties of nociceptive neurons in the spinal dorsal horn of aged rat

Neuroscience Research ◽

10.1016/s0168-0102(98)82707-7 ◽

1998 ◽

Vol 31 ◽

pp. S197

Author(s):

Kenro Kanda ◽

Koichi Iwata ◽

Yoshiyuki Tsuboi ◽

Nobuyuki Shimizu ◽

Akimasa Tashiro ◽

...

Keyword(s):

Dorsal Horn ◽

Spinal Dorsal Horn ◽

Aged Rat ◽

Nociceptive Neurons ◽

Response Properties ◽

Spinal Dorsal

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Effect of functional lateral shift of the mandible on hyaluronic acid metabolism related to lubrication of temporomandibular joint in growing rats

European Journal of Orthodontics ◽

10.1093/ejo/cjaa012 ◽

2020 ◽

Vol 42 (6) ◽

pp. 658-663

Author(s):

Xiyuan Guo ◽

Ippei Watari ◽

Yuhei Ikeda ◽

Wu Yang ◽

Takashi Ono

Keyword(s):

Hyaluronic Acid ◽

Articular Cartilage ◽

Temporomandibular Joint ◽

Experimental Period ◽

Lateral Shift ◽

Control Group ◽

Condylar Cartilage ◽

Growing Rats ◽

Shift Group ◽

Recovery Group

Summary Background Hyaluronic acid (HA) is a major molecular component of the articular cartilage of the temporomandibular joint (TMJ) influencing joint lubrication. Functional lateral shift of the mandible (FLSM) can lead to malocclusion. This study investigated the effects of FLSM on HA metabolism and lubrication of the TMJ in growing rats. Methods Thirty 5-week-old male Wistar rats were divided into shift, recovery, and control groups. Rats in the shift and recovery groups were fitted with guiding plates to produce a 2-mm FLSM which were removed from the rats in the recovery group 14 days later. Animals were sacrificed at 14 and 28 days after the appliances were attached. Immunohistochemistry of HA-binding protein (HABP), hyaluronan synthase (HAS), and hyaluronoglucosaminidases (HYALs) was examined. Results The thickness of HABP-positively stained areas in the lateral regions in the bilateral condyle was reduced during the experimental period in the shift group compared with that in the control group. The proportion of HAS2-stained areas was bilaterally decreased in different regions of condylar cartilage during the experimental period in the shift group. The reduction of the HYAL2-stained area proportion in the condylar cartilage was more significant than that of HYAL1 at 14 days after appliance attachment in the shift group. HAS2 staining was not recovered in the recovery group. Limitations This research was based on animal experiments with a limited experimental period. Conclusion FLSM altered lubrication related HA metabolism in the articular cartilage of the TMJ in growing rats.

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Modulation of paratrigeminal nociceptive neurons following temporomandibular joint inflammation in rats

Experimental Neurology ◽

10.1016/j.expneurol.2008.08.005 ◽

2008 ◽

Vol 214 (2) ◽

pp. 209-218 ◽

Cited By ~ 30

Author(s):

Yoko Yamazaki ◽

Ke Ren ◽

Masahiko Shimada ◽

Koichi Iwata

Keyword(s):

Temporomandibular Joint ◽

Joint Inflammation ◽

Nociceptive Neurons ◽

Temporomandibular Joint Inflammation

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Parabrachial area and nucleus raphe magnus-induced modulation of nociceptive and nonnociceptive trigeminal subnucleus caudalis neurons activated by cutaneous or deep inputs

Journal of Neurophysiology ◽

10.1152/jn.1994.71.6.2430 ◽

1994 ◽

Vol 71 (6) ◽

pp. 2430-2445 ◽

Cited By ~ 73

Author(s):

C. Y. Chiang ◽

J. W. Hu ◽

B. J. Sessle

Keyword(s):

Spontaneous Activity ◽

Inhibitory Effects ◽

Conditioning Stimulation ◽

Nucleus Raphe Magnus ◽

Nociceptive Neurons ◽

Nociceptive Responses ◽

Significant Difference ◽

Raphe Magnus ◽

Trigeminal Subnucleus Caudalis ◽

Stimulation Of

1. The aim of this study was to test whether parabrachial area (PBA) stimulation exerts inhibitory influences on the spontaneous activity and responses evoked by skin and deep afferent inputs in trigeminal subnucleus caudalis (Vc) neurons, and to compare these effects with those of nucleus raphe magnus (NRM) stimulation. A total of 92 nonnociceptive and nociceptive Vc neurons was recorded in urethan/alpha-chloralose-anesthetized rats. Each neuron was functionally classified as low-threshold mechanoceptive (LTM), wide dynamic range (WDR), nociceptive-specific (NS), nociceptive convergent with both skin and deep inputs (S+D), or deep nociceptive (D); the LTM neurons could be subdivided as rapidly adapting (RA) or slowly adapting (SA). Conditioning stimulation was applied to histologically verified sites in PBA and NRM. 2. The spontaneous or evoked activity of all classes of neurons could be inhibited by PBA as well as by NRM stimulation, but generally the incidence and magnitude of inhibition were lower for the LTM neurons. Occasionally, facilitation of neuronal activity was also produced by PBA and NRM stimulation. 3. The spontaneous activity of 11 LTM neurons (6 RA, 5 SA), 13 nociceptive neurons (6 WDR, 7 NS), and 5 D neurons was tested with stimulation of PBA or NRM or both. LTM spontaneous activity was more significantly inhibited by NRM stimulation than by PBA stimulation, whereas both NRM and PBA stimulation had similar and significant inhibitory effects on NS, WDR, and D neurons. 4. The evoked nonnociceptive responses of 28 LTM neurons (16 RA, 12 SA) and of 6 WDR neurons were also tested with stimulation of PBA or NRM or both. The magnitudes of inhibition of the responses produced by PBA conditioning stimulation were statistically significantly less than those induced by NRM conditioning stimulation. 5. The cutaneous and deep nociceptive responses of cutaneous nociceptive neurons (9 NS, 19 WDR) and seven D neurons, respectively, were also tested with PBA and NRM stimulation. There was a significant difference in potency between PBA- and NRM-induced inhibition, but no difference in the magnitude of inhibitory effects among NS, WDR, and D neurons. For both PBA and NRM conditioning stimulation, graded increases in intensities of stimulation produced linear increases in inhibitory effects on nociceptive responses; an increase in stimulation frequency from 5 to 400 Hz also produced increases in inhibition of the nociceptive responses. 6. In five S+D nociceptive convergent neurons, the responses elicited by deep inputs were more powerfully inhibited by PBA stimulation than those elicited by cutaneous inputs.(ABSTRACT TRUNCATED AT 400 WORDS)

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Central Sensitization of Nociceptive Neurons in Trigeminal Subnucleus Oralis Depends on Integrity of Subnucleus Caudalis

Journal of Neurophysiology ◽

10.1152/jn.00944.2001 ◽

2002 ◽

Vol 88 (1) ◽

pp. 256-264 ◽

Cited By ~ 40

Author(s):

Chen Yu Chiang ◽

Bo Hu ◽

James W. Hu ◽

Jonathan O. Dostrovsky ◽

Barry J. Sessle

Keyword(s):

Brain Stem ◽

Central Sensitization ◽

Mustard Oil ◽

Tooth Pulp ◽

Nociceptive Neurons ◽

Response Properties ◽

Functional Integrity ◽

Anesthetized Rats ◽

Noxious Stimuli

Our recent studies have shown that application to the tooth pulp of the inflammatory irritant mustard oil (MO) produces a prolonged (>40 min) “central sensitization” reflected in neuroplastic changes in the mechanoreceptive field (RF) and response properties of nociceptive brain stem neurons in subnuclei oralis (Vo) and caudalis (Vc) of the trigeminal spinal tract nucleus. In view of the previously demonstrated ascending modulatory influence of Vc on Vo, our aim was to determine whether the Vo neuroplastic changes induced by MO application to the tooth pulp depend on an ascending influence from Vc. In chloralose/urethan-anesthetized rats, MO application to the pulp produced significant increases in Vo nociceptive neuronal orofacial RF size and responses to mechanical noxious stimuli that lasted as long as 40–60 min. These changes were not affected by vehicle (saline) microinjected into Vc at 20 min after MO application, but 0.3 μl of a 5 mM CoCl2 solution microinjected into the ipsilateral Vc produced a reversible blockade of the MO-induced Vo neuroplastic changes. A similar volume and concentration of CoCl2 solution injected into subnucleus interpolaris of the trigeminal spinal tract nucleus did not affect the MO-induced neuroplastic changes in Vo. These findings indicate that inflammatory pulp-induced central sensitization in Vo is dependent on the functional integrity of Vc.

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