Transient receptor potential (TRP) protein is a superfamily of cation channels which have 6 transmembrane domains and mainly pass calcium ion through themselves. There are seven types of subfamilies in the TRP superfamily. TRP channels can be activated by various kinds of stimuli. Some TRP channels are polymodal receptors because two or more types of stimuli can activate the same type of TRP channels. TRP proteins can play roles in a living organism as receptors for sensing outside stimuli or inside local stimuli of itself, as signal conductors, or as signal transducers. Especially, TRP channels have key roles in thermosensation, mechanosensation, taste, trigeminal olfaction and nociception. Therefore, TRP channels can be important subjects of research in ENT field.
Calcium ; Ion Channels ; Nociception ; Nociceptors ; Proteins ; Smell ; Thermoreceptors ; Transducers

OBJECTIVE: To determine the relationship between pain provocation and level and disc degeneration in lumbar discography. METHOD: Seventy-one patients with lumbar discogenic pain and total 109 discography were studied. During contrast mediun injection, the patient's pain response was reported. The patients were invited to choose among the following options: 'no pain or only pressure feeling', 'dissimilar', 'similar', and 'exact'. And pain location was chosen among the followings: 'low back', 'buttock', 'anterior thigh', 'posterior thigh', and 'lateral thigh'. Correlation between degeneration and provocation response was analyzed. And discography level and provocation area were evaluated. RESULTS: Low back and buttock area was the most common provocation pain site, but it was not specific by disc level. And provocation pain frequently appeared in irregular and fissured types, but the existence of provocation pain was significantly low in ruptured type. CONCLUSION: There was no correlation between provocation pain area and discography level. And existence rate of provocation pain in ruptured disc was very low. It might be due to low mechanical compression with little stimulation of nociceptor. We suggested that if patients have a ruptured disc with chemical irritation, provocation pain was not a good indicator of diagnosis of discogenic back pain.
Back Pain ; Buttocks ; Diagnosis ; Humans ; Intervertebral Disc Degeneration* ; Nociceptors

BACKGROUND: This study was designed to investigate the correlation between pain and non-pain sensation of the cutaneous nociceptors in healthy adults use 250 Hz and 5 Hz evoking neuroselective sinusoidal current to A delta and C-fiber separately. METHODS: Fifty healthy adult volunteers who have no history of neurological illness were examined. Twenty-five of them were male, and twenty-five were female. Their ages ranged from 20 to 46 years, with a mean equal to 29.5 years old. The thresholds for both current perception and nociceptive perception were measured bilaterally in volar aspect of wrist using a Neurometer CPT/C (Quantitative Sensory Nerve Testing Device). The manual mode for current perception threshold and the staircase method for nociceptive current perception threshold was performed individually. RESULTS: The mean values of the threshold for perception evoked by 250 Hz were 0.30 mA in left and 0.31 mA in right, 0.17 mA in left and 0.14 mA in right at 5 Hz respectively. The mean values of the nociception threshold were 0.52 mA in both site at 250 Hz and from 0.35 mA to 0.32 mA at 5 Hz (Table 1). There were no differences between left and right wrist (Fig. 1). Also a significant positive correlation between current perception and nociception thresholds was found (p<0.05) (Fig. 2, 3). There appeared to be different between genders in perception threshold evoked by 250 Hz and nociception threshold evoked by 5 Hz in left (p<0.05) (Table 2). CONCLUSIONS: There exists a meaningful correlation between both sensations of non-pain and pain perception thresholds obtained from all subjects. The measurement of the current perception threshold is considered to be a unique and valuable resource in evaluation of patient with neurologic condition, as well as in serial evaluation of patient to assess the outcome of therapeutic intervention.
Adult* ; Female ; Humans ; Male ; Nociception* ; Nociceptors ; Pain Perception ; Sensation ; Volunteers ; Wrist

Opioids profoundly inhibit evoked discharges of spinal nociceptive neurons, thereby inhibiting the transmission of pain. Intrathecal administration of opioids using implantable continuous infusion systems is an effective method of pain relief when other treatments have failed, as well as for patients with adequate analgesia on high dose therapy that produces unacceptable side effects. We report two cases of intrathecal pump implantation performed in patients suffering from intractable chronic pain. A test dose of 3 mg morphine was injected into the epidural space. No side effects were noted and patients experienced considerable pain relief. Implantation was performed one day after the test. The initial intrathecal morphine delivery dose was half of the equivalent dose of daily oral intake opioids and the infusion rate was increased gradually under close observation for opioid side effects. Two days post-implantation, both patients were discharged without any complications.
Analgesia ; Analgesics, Opioid ; Chronic Pain ; Epidural Space ; Humans ; Infusion Pumps ; Morphine ; Nociceptors ; Stress, Psychological

Using intracellular potential recording technique in vivo, a series of hyperpolarizing and depolarizing currents at different intensities with a 50-ms duration were injected to somatic nociceptive neurons (SNNs) and somatic non-nociceptive neurons (SNNNs) in the anterior cingulate gyrus (ACG) of cats. The membrane electrical responses of the neurons were recorded, and the membrane electrical parameters of the neurons were calculated for comparative study on membrane electrical properties of SNNs and SNNNs of the ACG. A total of 188 ACG neurons from 57 cats were recorded. Among the 188 neurons, 172 (91.5%) and 16 (8.5%) were SNNs and SNNNs, respectively. The I-V curves of SNNs and SNNNs in the ACG were "S" shapes. When the absolute value of injected current intensity was less than or equal to 1 nA (≤ 1 nA), the I and V of I-V curves of both SNNs and SNNNs were linearly correlated (rSNNs = 0.99, rSNNNs = 0.99). When the absolute value of injected current intensity was more than 1 nA, both SNNs and SNNNs showed a certain inward or outward rectification behavior. Compared with SNNNs, SNNs had stronger rectification and lower adaptability (P < 0.01). With the increase of injected current intensity, the changes of frequency of discharges of SNNs were higher than those of SNNNs. In addition, the membrane resistance (Rm), the membrane capacity (Cm) and the time constant (τ) of SNNs were larger than those of SNNNs (P < 0.05 or P < 0.01). The differences in the membrane electrical properties between SNNs and SNNNs in the ACG suggested the disparity in neuronal cell size and cell membrane structure between them. The results of this study provided the experimental basis for deeply elucidating the mechanisms of somatic nociceptive sensation and characteristics on the membrane electrical aspects of ACG neurons.
Animals ; Cats ; Gyrus Cinguli ; cytology ; Membrane Potentials ; Neurons ; physiology ; Nociceptors ; physiology

AIMTo research the influence of noxious stimuli on the electric activities of pain-related neurons in several subnuclei of Amygdaloid Nucleus in rats.

METHODSTrains of the electric impulses applied to the sciatic nerve were used as noxious stimuli. The discharges of neurons were channeled off by glass microelectrode.

RESULTSPain-related neurons existed in several subnuclei of Amygdaloid Nucleus. When the noxious stimuli were administered the frequency of discharges of pain-excited neurons (PEN) was increased while the frequency of pain-inhibited neurons (PIN) was decreased to the lowest level. The electric activities of PEN and PIN were matched with each other. Intraperitoneal injection of morphine (10 mg/kg) antagonized the effects of noxious stimuli on the pain-related neurons.

CONCLUSIONSeveral subnuclei of Amygdaloid Nucleus play an essential role in perceiving, integrating and transmitting the pain impulses. They are a part of the central nervous system in which pain information is controlled and managed.

Amygdala ; physiology ; Animals ; Electrophysiology ; Neurons ; physiology ; Nociceptors ; physiology ; Rats ; Rats, Wistar

AIMTo explore the cerebral cortex mechanism of visceral nociceptive sensation and its characteristics on the cell level, we investigated the membrane electrical properties of 176 stimulus-relative neurons of greater splanchnic nerve (GSN) in anterior cingulate gyrus (ACG) of 20 adult healthy cats.

METHODSWe used intracellular recording techniques of glass microelectrode and injected polarizing current into the neurons in ACG.

RESULTSAmong 176 neurons, 148 were visceral nociceptive neurons (VNNs) and 28 non-visceral nociceptive neurons (NVNNs). The membrane resistance (Rm), time constant (tau), membrane capacity (Cm), and the I-V curve of both VNNs and NVNNs in ACG were significantly different. The discharge frequency and amplitude of both VNNs and NVNNs produced by injecting depolarized current were different, too.

CONCLUSIONThe results suggest that structure of cell membrane, volume of the soma, and other aspects of morphology between VNNs and NVNNs in ACG may have significant differences. The results also might provide progressively experimental evidence for specific theory of pain sensation.

Animals ; Cats ; Gyrus Cinguli ; cytology ; physiology ; Membrane Potentials ; Nociceptors ; physiology ; Splanchnic Nerves ; physiology ; Visceral Afferents ; physiology

Cervicogenic headache (CGH) is not universally accepted as terminology used to discuss headaches associated with disorders of the cervical spine. Sjaastad was the first to describe CGH that its definition and diagnosis relied entirely on clinical features. Pain is often triggered by irritation of nociceptors from structures in the cervical spine, and so diagnostic criteria of CGH have been established with agreement that these headaches start in the neck or occipital region and are associated with tenderness of cervical paraspinal tissues. Past history and clinical features are important to detect and diagnose the disease because the significance of radiological findings and advanced diagnostic testing is unclear. Gunn's intramuscular stimulation (IMS) is a treatment modality of CGH upon radiculopathic model. We tried IMS for treatment of 3 patients with CGH. After IMS, the patients were well respond the therapy and the results were satisfactory. Therefore we recommend the IMS for the treatment of CGH.
Diagnosis ; Diagnostic Tests, Routine ; Headache ; Humans ; Neck ; Nociceptors ; Post-Traumatic Headache* ; Spine

Extracellular single unit recordings were made from the ventral posteromedial thalamic (VPM) nociceptive neurons to determine mechanoreceptive field (RF) and response properties. A total of 44 VPM thalamic nociceptive neurons were isolated from rats anesthetized with urethane-chloralose. Based on responses to various mechanical stimuli including touch, pressure and pinch applied to the RF, 32 of 44 neurons were classified as nociceptive specific (NS) neuron. The other 12 neurons, classified as wide dynamic range (WDR), showed a graded response to increasingly intense stimuli, with a maximum discharge to noxious pinch. The VPM nociceptive neurons showed various spontaneous activity ranged from 0-6 Hz. They were located throughout the VPM, and had an contralateral RF including mainly intraoral (and perioral) regions. The RF size was relatively small, and very few neurons had a receptive field involving 3 trigeminal divisions. The NS neurons activated only by pressure and pinch stimuli had high mechanical thresholds compared to WDR neurons activated also by touch stimuli. The VPM nociceptive neurons were tested with suprathershold graded mechanical stimuli. Most of 21 NS and 8 WDR neurons showed a progressive increase in number of spikes as mechanical stimulus intensity was increased. In some neurons, the responses reached a peak before the highest intensity was given. Application of 5 mM CoCl2 (10 microl) solution to the trigeminal subnucleus caudalis did not produce any significant changes in the spontaneous activity, RF size, mechanical threshold, and response to suprathresold mechanical stimuli of 9 VPM nociceptive neurons tested. 17 of 33 VPM nociceptive neurons responded to noxious heat as well as noxious mechanical stimuli applied to their RF. Application of the mustard oil, a small-fiber excitant and inflammatory irritant, to the right maxillary first molar tooth pulp induced an immediate but short-lasting neuronal discharges upto approximately 4 min in 16 of 42 VPM nociceptive neurons. These results suggest that VPM thalamic nucleus may contribute to the sensory discriminative aspect of orofacial nociception.
Animals ; Hot Temperature ; Molar ; Mustard Plant ; Neurons ; Nociception ; Nociceptors ; Plant Oils ; Rats ; Tooth

Metastatic spinal tumor may cause pain by direct tumor involvement of bone with activation of local nociceptors or compression of adjacent structures. As an adjunct to pharmacologic therapy, many patients benefit from the use of additional nerve blocks to treat cancer pain. However, they require repeated injections as nerve block under local anesthetic sometimes only give the patient temporary relief of pain. Recently, the advent of pulsed radiofrequency application has proved a successful treatment for refractory pain disorders. A 43 year-old man was presented with a constant, dull, aching pain in the posterior neck with radicular pain referred to right shoulder due to metastatic cervical spinal tumor. Right C5 and C6 medial branch nerve blocks, with local anesthetic-steroid injections were effective, but short pain relief for a couple of days. However, the pain relief lasted longer and was effective with pulsed radiofrequency application over 3 months.
Adult ; Humans ; Neck ; Neck Pain* ; Nerve Block ; Nociceptors ; Pain, Intractable ; Shoulder