• Korean Journal of Acupuncture
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• 제32권3호
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• pp.136-143
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• 2015

This study was performed to comparative investigate the distribution of primary sensory and motor neurons associated with Cheonji(PC1) acupoint by using neural tracing technique. A total 4 SD rats were used in the present study. After anesthesia, the rats received microinjection of $6{\mu}l$ of cholera toxin B subunit(CTB) into the corresponding sites of the acupoints Cheonji(PC1) in the human body for observing the distribution of the related primary sensory neurons in dorsal root ganglia(DRGs) and motor neurons in the spinal cord(C3~T4) and sympathetic ganglia. Three days after the microinjection, the rats were anesthetized and transcardially perfused saline and 4% paraformaldehyde, followed by routine section of the DRGs, sympathetic chain ganglia(SCGs) and spinal cord. Labeled neurons and nerve fibers were detected by immunohistochemical method and observed by light microscope equipped with a digital camera. The labeled neurons were recorded and counted. From this research, the distribution of primary sensory and motor neurons associated with Cheonji(PC1) acupoints were concluded as follows. Muscle meridian related Cheonji(PC1) are controlled by spinal segments of C5~T1, C6~T4, respectively.

• 동의생리병리학회지
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• 제29권5호
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• pp.416-421
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• 2015

This study was performed to comparative investigate the distribution of primary sensory and motor neurons associated with Daereung(PC7) acupoints by using neural tracing technique. A total 16 SD rats were used in the present study. After anesthesia, the rats received microinjection of 6 ㎕ of cholera toxin B subunit(CTB) into the corresponding sites of the acupoints Daereung(PC7), in the human body for observing the distribution of the related primary sensory neurons in dorsal root ganglia(DRGs) and motor neurons in the spinal cord(C3∼T4) and sympathetic ganglia. Three days after the microinjection, the rats were anesthetized and transcardially perfused saline and 4% paraformaldehyde, followed by routine section of the DRGs, sympathetic chain ganglia(SCGs) and spinal cord. Labeled neurons and nerve fibers were detected by immunohistochemical method and observed by light microscope equipped with a digital camera. The labeled neurons were recorded and counted. From this research, the distribution of primary sensory and motor neurons associated with Daereung(PC7) acupoints were concluded as follows. Muscle meridian related Daereung(PC7) controlled by spinal segments of C5∼T1, C6∼T4, respectively.

• BMB Reports
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• 제49권9호
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• pp.474-487
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• 2016

Itch is one of the most distressing sensations that substantially impair quality of life. It is a cardinal symptom of many skin diseases and is also caused by a variety of systemic disorders. Unfortunately, currently available itch medications are ineffective in many chronic itch conditions, and they often cause undesirable side effects. To develop novel therapeutic strategies, it is essential to identify primary afferent neurons that selectively respond to itch mediators as well as the central nervous system components that process the sensation of itch and initiate behavioral responses. This review summarizes recent progress in the study of itch, focusing on itch-selective receptors, signaling molecules, neuronal pathways from the primary sensory neurons to the brain, and potential decoding mechanisms based on which itch is distinguished from pain.

• The Korean Journal of Physiology and Pharmacology
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• 제8권3호
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• pp.129-132
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• 2004

Single unit responses of the ventral posterior medial (VPM) thalamic neurons to stimulation were monitored in anesthetized rats during activation of contralateral primary somatosensory (SI) cortex by GABA antagonist. The temporal changes of afferent sensory transmission were quantitatively analyzed by poststimulus time histogram (PSTH). Mainly, afferent sensory transmission to VPM thalamus was facilitated (15 neurons of total 23) by GABA antagonist (bicuculline) applied to contralateral cortex, while 7 neurons were suppressed. However, when ipsilateral cortex was inactivated by GABA agonist, musimol, there was significant suppression of afferent sensory transmission of VPM thalamus. This suppressed responsiveness by ipsilateral musimol was not affected by bicuculline applied to contralateral cortex. These results suggest that afferent transmission to VPM thalamus may be subjected to the interhemispheric modulation via ipsilateral cortex during inactivation of GABAergic neurons in contralateral SI cortex.

• International Journal of Oral Biology
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• 제30권2호
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• pp.71-76
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• 2005

The mesencephalic trigeminal nucleus (Mes V) contains cell bodies of primary afferent sensory neurons that relay proprioceptive information from the periodontium and masticatory muscles and function as typical sensory neurons or potentially as integrative interneurons. In the present study, we studied these two potential functions using combined experimental approaches of retrograde labeling and whole cell patch clamp recording. Mes V neurons that presumably originate from periodontal nerve fibers in subsets of Mes V nucleus were identified by retrograde labeling with a fluorescent dye, DiI, which was applied onto inferior alveolar nerve. These cells were elliptical perikarya shaped cells about $40{\mu}m$ in diameter. In these neurons, we measured high voltage-activated calcium channel (HVACC) currents. $GABA_B$ agonist, baclofen, inhibited calcium currents, and the HVACC currents inhibition by baclofen was voltage-dependent, exhibited prepulse facilitation, indicating that it was mediated by $G_i/_G_o$ protein. Taken together, our results demonstrate that Mes V neurons not only have cell bodies originating from periodontium, but also receive synaptic inputs including GABAergic neurons suggesting that Mes V neurons function as both primary sensory neurons and integrative interneurons.

• International Journal of Oral Biology
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• 제46권3호
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• pp.119-126
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• 2021

Activation of transient receptor potential vanilloid 1 (TRPV1), a calcium permeable channel expressed in primary sensory neurons, induces the release of glutamate from their central and peripheral afferents during normal acute and pathological pain. However, little information is available regarding the glutamate release mechanism associated with TRPV1 activation in primary sensory neurons. To address this issue, we investigated the expression of vesicular glutamate transporter (VGLUT) in TRPV1-immunopositive (+) neurons in the rat trigeminal ganglion (TG) under normal and complete Freund's adjuvant (CFA)-induced inflammatory pain conditions using behavioral testing as well as double immunofluorescence staining with antisera against TRPV1 and VGLUT1 or VGLUT2. TRPV1 was primarily expressed in small and medium-sized TG neurons. TRPV1+ neurons constituted approximately 27% of all TG neurons. Among all TRPV1+ neurons, the proportion of TRPV1+ neurons coexpressing VGLUT1 (VGLUT1+/TRPV1+ neurons) and VGLUT2 (VGLUT2+/TRPV1+ neurons) was 0.4% ± 0.2% and 22.4% ± 2.8%, respectively. The proportion of TRPV1+ and VGLUT2+ neurons was higher in the CFA group than in the control group (TRPV1+ neurons: 31.5% ± 2.5% vs. 26.5% ± 1.2%, VGLUT2+ neurons: 31.8% ± 1.1% vs. 24.6% ± 1.5%, p < 0.05), whereas the proportion of VGLUT1+, VGLUT1+/TRPV1+, and VGLUT2+/TRPV1+ neurons did not differ significantly between the CFA and control groups. These findings together suggest that VGLUT2, a major isoform of VGLUTs, is involved in TRPV1 activation-associated glutamate release during normal acute and inflammatory pain.

• 동의생리병리학회지
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• 제32권1호
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• pp.30-34
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• 2018

This research was practiced to comparative investigate the distribution of sensory and motor neuron linkaged with Yangji(TE4) by using neural-tracer technology. A total 16 S-D rats were used in the present research. After anesthesia, the rats received micro-injection of $6{\mu}{\ell}$ of cholera toxin B subunit(CTB) into the relation positions of the Yangji(TE4), in the human body for observing the distribution of the linkaged sensory neurons in dorsal root ganglia(DRGs) and motor neurons in the spinal cord(C3~T4) and sympathetic ganglia. 3 days after the micro injection, the rats were anesthetized and transcardially perfused saline and 4% paraformaldehyde, followed by routine section of the DRGs, sympathetic chain ganglia(SCGs) and spinal cord. Marked neurons and nerve fibers were detected by immunohistochemical method and observed by light microscope. The marked neurons were recorded and counted. From this study the distribution of primary sensory and motor neurons linkaged with Yangji(TE4) were concluded as follows. Yangji(TE4) dominated by spinal segments of C5~T1, C6~T4, individually.

• The Korean Journal of Pain
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• 제35권2호
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• pp.160-172
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• 2022

Background: The authors established an in vitro model of diabetic neuropathy based on the culture system of primary neurons and Schwann cells (SCs) to mimic similar symptoms observed in in vivo models of this complication, such as impaired neurite extension and impaired myelination. The model was then utilized to investigate the effects of insulin on enhancing neurite extension and myelination of diabetic neurons. Methods: SCs and primary neurons were cultured under conditions mimicking hyperglycemia prepared by adding glucose to the basal culture medium. In a single culture, the proliferation and maturation of SCs and the neurite extension of neurons were evaluated. In a co-culture, the percentage of myelination of diabetic neurons was investigated. Insulin at different concentrations was supplemented to culture media to examine its effects on neurite extension and myelination. Results: The cells showed similar symptoms observed in in vivo models of this complication. In a single culture, hyperglycemia attenuated the proliferation and maturation of SCs, induced apoptosis, and impaired neurite extension of both sensory and motor neurons. In a co-culture of SCs and neurons, the percentage of myelinated neurites in the hyperglycemia-treated group was significantly lower than that in the control group. This impaired neurite extension and myelination was reversed by the introduction of insulin to the hyperglycemic culture media. Conclusions: Insulin may be a potential candidate for improving diabetic neuropathy. Insulin can function as a neurotrophic factor to support both neurons and SCs. Further research is needed to discover the potential of insulin in improving diabetic neuropathy.

• Journal of Ginseng Research
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• 제39권3호
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• pp.257-264
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• 2015

Background: Korean Red Ginseng-a steamed root of Panax ginseng Meyer-has long been used as a traditional medicine in Asian countries. Its antipruritic effect was recently found, but no molecular mechanisms were revealed. Thus, the current study focused on determining the underlying molecular mechanism of Korean Red Ginseng extract (RGE) against histamine-induced itch at the peripheral sensory neuronal level. Methods: To examine the antipruritic effect of RGE, we performed in vivo scratching behavior test in mice, as well as in vitro calcium imaging and whole-cell patch clamp experiments to elucidate underlying molecular mechanisms. Results: The results of our in vivo study confirmed that RGE indeed has an antipruritic effect on histamine-induced scratching in mice. In addition, RGE showed a significant inhibitory effect on histamine-induced responses in primary cultures of mouse dorsal root ganglia, suggesting that RGE has a direct inhibitory effect on sensory neuronal level. Results of further experiments showed that RGE inhibits histamine-induced responses on cells expressing both histamine receptor subtype 1 and TRPV1 ion channel, indicating that RGE blocks the histamine receptor type 1/TRPV1 pathway in sensory neurons, which is responsible for histamine-dependent itch sensation. Conclusion: The current study found for the first time that RGE effectively blocks histamine-induced itch in peripheral sensory neurons. We believe that the current results will provide an insight on itch transmission and will be helpful in understanding how RGE exerts its antipruritic effects.

• The Journal of Korean Physical Therapy
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• 제22권4호
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• pp.97-101
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• 2010

Purpose: Sensory input is very important for proper performance of human. Two-point discrimination is the most widely used tactile sensory test. The purpose of this study was to find the changes in cortical activation patterns between tactile stimulation and two-point discrimination. Methods: Two healthy subjects participated in our study. fMRI scanning was done during 4 repeated blocks of tactile stimulation and two point discrimination of the right index finger tip. In one block, stimuli were repeated 10 times every three seconds. To determine the changes of cortical neurons during sensory input, intensity index was analyzed. Results: When tactile stimulation of the right index finger tip was completed, only contralateral primary somatosensory area was activated. In contrast, during two-point discrimination, both the primary somatosensory area and ipsilateral supplementary sensory area were activated. Conclusion: During two point discrimination, both primary somatosensory area and ipsilateral supplementary sensory area were activated. Therefore, two-point discrimination is required more complex and conscious activity than tactile stimulation.