Ion gyroscale fluctuation measurement with microwave imaging reflectometer on KSTAR.

Ion gyroscale turbulent fluctuations with the poloidal wavenumber kθ ∼ 3 cm-1 have been measured in the core region of the neutral beam (NB) injected low confinement (L-mode) plasmas on Korea superconducting tokamak advanced research. The turbulence poloidal wavenumbers are deduced from the frequencies and poloidal rotation velocities in the laboratory frame, measured by the multichannel microwave imaging reflectometer. Linear and nonlinear gyrokinetic simulations also predict the unstable modes with the normalized wavenumber kθρs ∼ 0.4, consistent with the measurement. Comparison of the measured frequencies with the intrinsic mode frequencies from the linear simulations indicates that the measured ones are primarily due to the E × B flow velocity in the NB-injected fast rotating plasmas.

Design of a collective scattering system for small scale turbulence study in Korea Superconducting Tokamak Advanced Research.

The design characteristics of a multi-channel collective (or coherent) scattering system for small scale turbulence study in Korea Superconducting Tokamak Advanced Research (KSTAR), which is planned to be installed in 2017, are given in this paper. A few critical issues are discussed in depth such as the Faraday and Cotton-Mouton effects on the beam polarization, radial spatial resolution, probe beam frequency, polarization, and power. A proper and feasible optics with the 300 GHz probe beam, which was designed based on these issues, provides a simultaneous measurement of electron density fluctuations at four discrete poloidal wavenumbers up to 24 cm(-1). The upper limit corresponds to the normalized wavenumber kθρe of ∼0.15 in nominal KSTAR plasmas. To detect the scattered beam power and extract phase information, a quadrature detection system consisting of four-channel antenna/detector array and electronics will be employed.

Estimating retrospective exposure of household humidifier disinfectants.

UNLABELLED: We conducted a comprehensive humidifier disinfectant exposure characterization for 374 subjects with lung disease who presumed their disease was related to humidifier disinfectant use (patient group) and for 303 of their family members (family group) for an ongoing epidemiological study. We visited the homes of the registered patients to investigate disinfectant use characteristics. Probability of exposure to disinfectants was determined from the questionnaire and supporting evidence from photographs demonstrating the use of humidifier disinfectant, disinfectant purchase receipts, any residual disinfectant, and the consistency of their statements. Exposure duration was estimated as cumulative disinfectant use hours from the questionnaire. Airborne disinfectant exposure intensity (µg/m(3)) was estimated based on the disinfectant volume (ml) and frequency added to the humidifier per day, disinfectant bulk level (µg/ml), the volume of the room (m(3)) with humidifier disinfectant, and the degree of ventilation. Overall, the distribution patterns of the intensity, duration, and cumulative exposure to humidifier disinfectants for the patient group were higher than those of the family group, especially for pregnant women and patients ≤6 years old. Further study is underway to evaluate the association between the disinfectant exposures estimated here with clinically diagnosed lung disease. PRACTICAL IMPLICATIONS: Retrospective exposure to household humidifier disinfectant as estimated here can be used to evaluate associations with clinically diagnosed lung disease due to the use of humidifier disinfectant in Korea. The framework, with modifications to account for dispersion and use patterns, can also be potentially adapted to assessment of other household chemical exposures.

Quasi 3D ECE imaging system for study of MHD instabilities in KSTAR.

A second electron cyclotron emission imaging (ECEI) system has been installed on the KSTAR tokamak, toroidally separated by 1/16th of the torus from the first ECEI system. For the first time, the dynamical evolutions of MHD instabilities from the plasma core to the edge have been visualized in quasi-3D for a wide range of the KSTAR operation (B0 = 1.7∼3.5 T). This flexible diagnostic capability has been realized by substantial improvements in large-aperture quasi-optical microwave components including the development of broad-band polarization rotators for imaging of the fundamental ordinary ECE as well as the usual 2nd harmonic extraordinary ECE.

Serum bilirubin as a predictor of incident metabolic syndrome: a 4-year retrospective longitudinal study of 6205 initially healthy Korean men.

AIM: Serum bilirubin is an endogenous antioxidant with anti-inflammatory properties. Several cross-sectional studies have reported that bilirubin was negatively associated with oxidative stress-mediated diseases, including the metabolic syndrome (MetS). However, the clinical relevance of bilirubin as a risk factor for incident MetS remains controversial. For this reason, the longitudinal effects of baseline serum bilirubin concentrations on incident MetS were evaluated in Korean men. METHODS: This 4-year retrospective longitudinal observational study involved 6205 Korean men without MetS. Subjects underwent routine health examinations in 2007 and returned for a follow-up examination in 2011. Baseline serum bilirubin concentrations were determined using the vanadate oxidation method. RESULTS: During the 4-year period, 936 cases of incident MetS (15.1%) were identified. Its incidence decreased across baseline bilirubin quartile categories (P<0.001), with an odds ratio (OR) for developing MetS being significantly lower in the highest quartile group (≥ 1.40 mg/dL) compared with the lowest (≤ 0.90 mg/dL) after adjusting for all confounding variables [OR=0.70, 95% confidence interval (CI) 0.54-0.90; P for trend=0.019]. Among individual components of MetS, bilirubin was found to be negatively associated with only the risk of incident hypertriglyceridaemia. The OR (95% CI) for incident hypertriglyceridaemia in the highest vs lowest quartile was 0.75 (0.61-0.91; P for trend=0.002). CONCLUSION: Serum total bilirubin level was negatively associated with incidence of MetS in healthy Korean men over a 4-year period.

Air pollution interacts with past episodes of bronchiolitis in the development of asthma.

BACKGROUND: Exposure to ambient air pollution and bronchiolitis are risk factors for asthma. The aim of this study was to investigate the effect of air pollution on the development of asthma in children with past episodes of bronchiolitis. METHODS: A prospective 2-year follow-up survey consisting of parental responses to the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire, and allergy evaluations were conducted in 1743 children with a mean age of 6.8 years. Recent 5-year exposure to air pollution was estimated using a geographic information system. RESULTS: Higher exposure to ozone was associated with airway hyper-responsiveness (PC20  ≤ 16 mg/ml) at enrollment (odds ratio [OR] = 1.60, 95% CI [confidence interval] = 1.13-2.27) and with new episodes of wheezing during the 2-year period (OR = 1.92, 95% CI = 0.96-3.83). Past episodes of bronchiolitis were associated with both current wheezing and physician-diagnosed asthma. When the two factors were combined, the prevalence of bronchial hyper-reactivity (OR = 2.96, 95% CI = 1.41-6.24) and new wheezing (OR = 4.17, 95% CI = 0.89-19.66) as well as current wheezing and physician-diagnosed asthma was even greater (P for trend <0.05 for all). In children with both risk factors, lung function was significantly decreased, with atopic children being particularly vulnerable. CONCLUSION: In children, the interaction between air pollution and past episodes of bronchiolitis resulted in a greater prevalence of asthma and pointed to an association with bronchial hyper-reactivity and decreased lung function. These results suggest mechanisms underlying the development of asthma.

Assessment of the fatty liver index as an indicator of hepatic steatosis for predicting incident diabetes independently of insulin resistance in a Korean population.

AIMS: Fatty liver disease, especially non-alcoholic fatty liver disease, is considered to be the hepatic manifestation of the metabolic syndrome, both closely associated with insulin resistance. Furthermore, fatty liver disease assessed by ultrasonography is known to be a predictor of the development of Type 2 diabetes mellitus. However, it remains unclear whether fatty liver disease plays a role in the pathogenesis of Type 2 diabetes independently of insulin resistance. In this study, we investigated whether fatty liver disease assessed by the fatty liver index can predict the development of Type 2 diabetes independently of systemic insulin resistance. METHODS: We examined the clinical and laboratory data of 7860 subjects without diabetes who underwent general routine health evaluations at the Asan Medical Center in 2007 and had returned for follow-up examinations in 2011. Fatty liver index was calculated using an equation that considers serum triglyceride levels, γ-glutamyltransferase, waist circumference and BMI. RESULTS: During a 4-year period, 457 incident diabetes cases (5.8%) were identified. The odds ratios for the development of Type 2 diabetes were significantly higher in the group with a fatty liver index ≥ 60 (fatty liver index-positive) than in the group with a fatty liver index < 20 (fatty liver index-negative) after adjusting for various confounding variables including homeostasis model assessment of insulin resistance. Odds ratios were significant regardless of the insulin resistance status at baseline. CONCLUSIONS: Our results suggest that fatty liver index as a simple surrogate indicator of hepatic steatosis is valuable in identifying subjects at high risk for Type 2 diabetes. In addition, fatty liver disease itself contributes to the development of Type 2 diabetes independently of systemic insulin resistance.

Incidence trends in invasive uterine cervix cancer and carcinoma in situ in Incheon, South Korea.

INTRODUCTION: This study examined trends of invasive uterine cervix cancer and carcinoma in situ (CIS) in terms of the incidence and mortality in Incheon over a twelve year period. METHODS: Uterine cervical cancer data were retrieved from the Incheon Cancer Registry (ICR) and Korea Central Cancer Registry (KCCR) from 1997 to 2008. The time trends in age-standardized incidence rates (ASR) of invasive uterine cervix cancer patients and CIS were calculated and compared with the nation-wide cancer registry data for each year. Mortality/incidence (M/I) ratios according to age and the incidence of the pathologic subtype in Incheon each year were also examined, along with an international comparison. RESULTS: A total of 3,096 cases of invasive cervical cancer and 2,079 cases of carcinoma in situ were analyzed from 1997 to 2008. The time trend incidence of the total ASR in uterine cervical cancer decreased from 25.7 in 1997 to 13.4 in 2008, but the incidence of CIS increased from 7.6 to 15.8 in same period. In invasive cancers, the age-specific incidence rates were highest in those in their sixties while patients in their forties showed highest CIS values. The mortality rate in ICR was 3.7 from 1998 to 2002. Compared to the other countries which have high risk factors for cervix cancer, the peak incidence zone was different in Incheon. CONCLUSION: The ICR showed a decrease in the incidence of invasive cervical cancer that was similar to the nation-wide data. An early increase zone is a characteristic pattern in the age specific incidence curve. Early screening and a vaccination program should be activated for prevention of young age cervical cancer.

Peripheral contributions to the mechanical hyperalgesia following a lumbar 5 spinal nerve lesion in rats.

Using lumbar 5 (L5) dorsal root rhizotomy-bearing rats, we examined the extent to which L5 spinal nerve lesion (SNL)-induced mechanical hyperalgesia was governed by two peripheral components, that is Wallerian degeneration (WD) and peripherally-propagating injury discharge (PID). The contribution of WD to SNL-induced hyperalgesia was studied by excluding PID with lidocaine treatment that blocked nerve conduction temporarily, but completely at the time of injury, whereas PID was examined separately by using brief tetanic electrical stimulation of the spinal nerve mimicking PID. Following the disappearance of L5 rhizotomy-induced transient hyperalgesia, L5 SNL resulted in long-lasting mechanical hyperalgesia as early as one day post-SNL despite a PID block, highlighting the role of WD. In a comparative experiment, a delayed onset of hyperalgesia (7 days) was measured in L3 rhizotomy-bearing rats following L3 SNL with a PID block, in which injured fiber (L3) was separated from intact fibers (L4 and L5) anatomically until they meet at the peripheral terminals, supporting the importance of interactions between degenerating and adjacent intact fibers for WD-induced hyperalgesia. Tetanic electrical stimulation of decentralized L5 spinal nerve resulted in mechanical hyperalgesia developing within 1 day and persisting for 7 days. This hyperalgesia was prevented by lidocaine blockade of the L5 nerve, and was unaffected by lidocaine blockades of the central inputs from L3 and L4 fibers during L5 nerve stimulation, suggesting the mediation of PID-induced hyperalgesia by sensitization, not activation, of peripheral terminals of adjacent intact afferents. The similar hyperalgesia was also observed following electrical stimulation of decentralized L3 spinal nerve. Prior elimination of L4 C-fibers by local capsaicin prevented hyperalgesia induced either by L5 SNL with a PID block or by L5 nerve stimulation. These results suggest that neighboring C-afferents remaining intact after partial nerve injury play a critical role in the development of mechanical hyperalgesia through interaction with degenerating afferents, and also via peripheral sensitization by PID.

Post-growth annealing effects of Mg doped GaAs epitaxial layers on microstructural and optical properties.

The post-growth thermal annealing effects of Mg doped GaAs epitaxial layers on the microstructural and optical properties grown by molecular beam epitaxy (MBE) have been investigated. The properties of Mg doped GaAs are estimated after the process of rapid thermal annealing (RTA) in the temperature range of 600 approximately 750 degrees C. The photoluminescence (PL) peak position of as-grown sample blueshifted from 1.473 to 1.485 eV as well as the pronounced enhancement in PL intensity by annealing at 600 degrees C. In the sample grown at the temperature of T(s) = 475 degrees C, the full-width at half maximum (FWHM) of double crystal X-ray diffraction (DCXRD) decreased form 27 to 8 arcsec with increasing of annealing temperature (600 approximately 700 degrees C). The crystalline quality variation of Mg doped GaAs layers by RTA is greatly dependent upon the doping level.

Prognostic factors for neurologic outcome after endovascular revascularization of acute symptomatic occlusion of the internal carotid artery.

BACKGROUND AND PURPOSE: Management of acute symptomatic internal carotid artery (ICA) occlusion remains controversial. We evaluated outcome predictors of a good recovery in patients with acute symptomatic ICA occlusion. MATERIALS AND METHODS: We retrospectively evaluated 33 consecutive patients (men/women, 23/10; mean age, 66 years) with: 1) acute symptomatic ICA occlusion within 6 hours of symptom onset or with mismatch of symptoms and an early infarct area, 2) National Institutes of Health Stroke Scale (NIHSS) score of 6 or more, and 3) attempted endovascular revascularization of the occluded ICA. Various single and multiple variable analyses were conducted to assess the association of 14 predictors with short-term (1-month NIHSS) and long-term (1-year modified Rankin Scale [mRS]) outcomes. RESULTS: Successful recanalization (at or more than grade 2 distal residual occlusion) was obtained in 14 (42%) of 33 and good recovery (mRS

Effects of intrathecal bupivacaine in conjunction with hypothermia on neuronal protection against transient spinal cord ischemia in rats.

BACKGROUND: Excitotoxic neuronal injury from ischemia may be reduced by local anesthetics. We investigated the neuroprotective effects of intrathecally administered bupivacaine and hypothermia in a rat model of transient spinal cord ischemia. METHODS: PE-10 intrathecal catheter-implanted male Sprague-Dawley rats were randomly assigned to one of four groups: normothermia (NT) and hypothermia (HT) groups (given 15 microl of normal saline) and bupivacaine (B) and bupivacaine-hypothermia (BHT) groups (given 15 mul of 0.5% bupivacaine). Transient spinal cord ischemia was induced by inflation of a 2F Fogarty catheter placed in the aortic arch for 12 min. The rectal temperature was maintained at 37.0 +/- 0.5 degrees C for the NT and B groups, and at 34.5 +/- 0.5 degrees C for the HT and BHT groups. Motor and sensory deficit scores were assessed 2 and 24 h after reperfusion. Lumbar spinal cords were harvested for histopathology and immunoreactivity of heat shock protein 70 (HSP70). RESULTS: After reperfusion, the motor and sensory deficit scores of the NT group were significantly higher than those of the HT (P < 0.05) and BHT (P < 0.001) groups. Significant differences were evident in the motor and sensory deficit scores between the HT and BHT groups at 24 h (P < 0.05). Neuronal cell death and immunoreactivity of HSP70 were frequently observed in the NT and BT groups, but not in the HT and BHT groups. CONCLUSIONS: These results collectively suggest that intrathecal bupivacaine does not provide neuroprotection during normothermic transient spinal cord ischemia in rats, but enhances the neuroprotective effects of hypothermia.

Risk factors affecting blood PCDDs and PCDFs in residents living near an industrial incinerator in Korea.

The contamination sources of polychlorinated dibenzodioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), such as industrial incinerators, can potentially change the blood levels and isomer patterns of PCDD/DFs in residents living near the incinerators. In this study, we estimated whether the blood levels and isomer patterns of PCDD/DFs in residents living near an incinerator were affected by its presence and investigated factors that characterize the risk of high exposure to PCDD/DFs in the area. We estimated the blood levels and homologue patterns of PCDD/DFs in a group of 40 residents living within 5 km of an industrial incinerator and in a group of 20 residents living 20 km away from an incinerator. We cannot assert that the operation of incinerator facilities was only cause of increased PCDD/DFs in these residents; however, the operation of incinerator facilities in agricultural areas increased PCDD/DF exposure to individuals. The group living next to the industrial incinerator especially represented the typical isomer pattern in which the proportions of OCDDs were lower and those of PCDFs higher than those in the other groups. The high-risk population with increased blood levels of PCDD/DFs included those who had lived longer in the contaminated area as well as those who frequently ate contaminated foods.

Changes in magnesium concentration in the serum and cerebrospinal fluid of neuropathic rats.

BACKGROUND: Central sensitization of neuropathic pain is associated with an influx of extracellular calcium via the opening of N-methyl-D-aspartate (NMDA) receptor-gated ion channels, which are usually blocked by magnesium plugs. As magnesium-deficient rats develop a mechanical hyperalgesia and intrathecal or intraperitoneal magnesium suppresses neuropathic pain, the magnesium concentrations in serum and cerebrospinal fluid may be altered in neuropathic pain. We therefore compared the magnesium concentrations in serum and cerebrospinal fluid of neuropathic rats with those in injured rats without symptoms of neuropathic pain and normal rats. METHODS: Mechanical allodynia was induced in male Sprague-Dawley rats by tight ligature of the left lumbar fifth and sixth spinal nerves. The threshold of paw withdrawal was evaluated by the up-down method using withdrawal response to stimulus with a von Frey filament on the third, seventh and 14th days. Rats with a threshold of less than 4 g were selected as the symptomatic group and compared with an asymptomatic group, an unoperated control group and a sham-operated group. On the 16th day, the Mg2+ concentrations in serum and cerebrospinal fluid were measured. RESULTS: The magnesium concentrations in the serum and cerebrospinal fluid of symptomatic neuropathic rats did not differ from those in the injured rats without symptoms of neuropathic pain, sham-operated rats and normal rats. CONCLUSION: Our results suggest that physiologic homeostasis is maintained by active transport through the blood-brain barrier despite the activation of NMDA receptor-gated ion channels. However, rats with neuropathic pain may be in a magnesium-deficient condition at the effector site, such that magnesium treatment can decrease neuropathic pain.

Mechanical and heat sensitization of cutaneous nociceptors in rats with experimental peripheral neuropathy.

This study examined whether or not the properties of cutaneous nociceptive fibers are altered in the neuropathic state by comparing lumbars 5 and 6 spinal nerve ligation (SNL) rats with sham-operated controls. The rats with the unilateral SNL developed mechanical allodynia in the ipsilateral hind limb, whereas the sham group did not. Two to 5 weeks after the neuropathic or sham surgery, rats were subjected to single fiber-recording experiments to examine the properties of afferent fibers in the sural and plantar nerves. A total of 224 afferents in the C- and Adelta-ranges were characterized in the neuropathic and sham groups. Spontaneous activity was observed in 16 of 155 fibers in the neuropathic group and one of 69 fibers in the sham group. The response threshold of both the C- and Adelta-fibers to mechanical stimuli was lower in the neuropathic group than the sham group. The afferent fibers responsive to heat stimuli were all C-fibers, and none were Adelta-fibers. The response threshold of the C-fibers to the heat stimuli was lower in the neuropathic group than the sham group. The magnitude of the responses of both C- and Adelta-fibers to the suprathreshold intensity of the mechanical stimulus was greater in the neuropathic group than the sham group. However, the magnitude of the responses of C-fibers to the suprathreshold intensity of the heat stimulus in the neuropathic group was not different from that in the sham group. These results suggest that after a partial peripheral nerve injury, the nociceptors on the skin supplied by an uninjured nerve become sensitized to both mechanical and heat stimuli. This nociceptor sensitization can contribute to neuropathic pain.

Peripheral glutamate receptors contribute to mechanical hyperalgesia in a neuropathic pain model of the rat.

We hypothesized that glutamate (Glu) released from the peripheral terminals of primary afferents contributes to the generation of mechanical hyperalgesia following peripheral nerve injury. Nerve injury was performed on rats with a lumbar 5 spinal nerve lesion (L5 SNL), which was preceded by L5 dorsal rhizotomy (L5 DR) to avoid the potential central effects induced by L5 SNL through the L5 dorsal root. Mechanical hyperalgesia, as evidenced by a reduction in paw withdrawal threshold (PWT), was short-lasting (<6 days) after L5 DR, but persistent (>42 days) after L5 SNL preceded by L5 DR. When an intraplantar injection into the affected hind paw was given immediately before L5 SNL, non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist MK-801 (20 nmol), group-I metabotropic Glu (mGlu) receptor antagonist DL-amino-3-phosphonopropionic acid (DL-AP3; 70 nmol), and selective group-II mGlu receptor agonist 4-aminopyrrolidine-2,4-dicarboxylate (APDC; 20 nmol) delayed the onset of PWT reduction for 1-4 days. However, this onset was not affected by alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid/kainate receptor antagonist 2,3-dioxo-6-nitro-1,2,3,4,-tetrahydrobenzo[f]quinoxaline-7-sulfonamide (NBQX; 100 nmol). When the same injection was given after L5 SNL-induced mechanical hyperalgesia had been established, MK-801 reversed the PWT reduction for 30-75 min, whereas NBQX, DL-AP3, or APDC had no effect. These results suggest that the manipulation of the peripheral Glu receptors reduces neuropathic pain, by blocking NMDA and group-I mGlu receptors and by stimulating group-II mGlu receptor during the induction phase of neuropathic pain, but only by blocking the NMDA receptor during its maintenance phase.

Multiple effects of aspartate mutant presenilin 1 on the processing and trafficking of amyloid precursor protein.

PS1 deficiency and expression of PS1 with substitutions of two conserved transmembrane aspartate residues ("PS1 aspartate variants") leads to the reduction of Abeta peptide secretion and the accumulation of amyloid precursor protein (APP) C-terminal fragments. To define the nature of the "dominant negative" effect of the PS1 aspartate variants, we stably expressed PS1 harboring aspartate to alanine substitutions at codons 257 (D257A) or 385 (D385A), singly or in combination (D257A/D385A), in mouse neuroblastoma, N2a cells. Expression of the PS1 aspartate variants resulted in marked accumulation of intracellular and cell surface APP C-terminal fragments. While expression of the D385A PS1 variant reduced the levels of secreted Abeta peptides, we now show that neither the PS1 D257A nor D257A/D385A variants impair Abeta production. Surprisingly, the stability of both immature and mature forms of APP is dramatically elevated in cells expressing PS1 aspartate variants, commensurate with an increase in the cell surface levels of APP. These findings lead us to conclude that the stability and trafficking of APP can be profoundly modulated by coexpression of PS1 with mutations at aspartate 257 and aspartate 385.

Capsaicin-induced relaxation in rabbit coronary artery.

In the present study mechanism of inhibitory effects of capsaicin on the contractility of rabbit coronary artery were studied by measurement of isometric tension and intracellular Ca2+ concentration. Capsaicin (1 microM to 30 microM) relaxed the coronary artery pre-contracted with prostaglandin (PG) F2alpha (1 microM) in a concentration-dependent manner. The PGF2alpha-induced increase in intracellular Ca2+ concentration was also inhibited. The effects of capsaicin were readily reversed by washing capsaicin from the bath. Capsaicin-induced relaxation was not attenuated by pretreatment with capsazepine (1 microM), a blocker of vanilloid receptor or ruthenium red (1 microM), a blocker of non-selective cation channel. Previous exposure to a high concentration of capsaicin (100 microM) or repeated application of capsaicin did not eliminate the relaxation response to subsequent application of capsaicin. Increasing the external K+ concentration to 80 mM significantly attenuated the capsaicin-induced relaxation with simultaneous change in intracellular Ca2+ concentration. Pretreatment with iberiotoxin (100 nM), a blocker of Ca2+-activated K+ channel, only partially inhibited the capsaicin-induced relaxation. However, application of 4-aminopyridine (4-AP, 1 mM), a blocker of delayed rectifier K+ current significantly inhibited the capsaicin-induced relaxation with concomitant attenuation of the effect on intracellular Ca2+ concentration. These results indicate that capsaicin may have a direct relaxing effect on the smooth muscle contractility, and relaxation may be due to activation of the 4-AP-sensitive, delayed rectifier K+ channels in the rabbit coronary artery.

Effects of iontophoretically applied substance P, calcitonin gene-related peptide on excitability of dorsal horn neurones in rats.

Spontaneous pain, allodynia and hyperalgesia are well known phenomena following peripheral nerve or tissue injury, and it is speculated that secondary hyperalgesia and allodynia, are generally thought to depend on a hyperexcitability (sensitization) of neurons in the dorsal horn. It is supposed that the sensitization may be due to various actions of neurotransmitters (SP, CGRP, excitatory amino acids) released from the primary afferent fibers. In this study, we examined effects of the iontophoretically applied SP and CGRP on the response to EAA receptor agonists (NMDA and non-NMDA) in the WDR dorsal horn neurones and see if the effects of SP or CGRP mimic the characteristic response pattern known in various pain models. The main results are summarized as follows: 1) SP specifically potentiated NMDA response. 2) CGRP non-specifically potentiated both NMDA and AMPA responses. Potentiation of NMDA response, however, was significantly greater than that of AMPA response. 3) 50% of SP applied cells and 15.8% of CGRP applied cells showed reciprocal changes(potentiation of NMDA response and suppression of AMPA response). These results are generally consistent with the sensitization characteristics in diverse pain models and suggests that the modulatory effects of SP and CGRP on NMDA and non-NMDA (AMPA) response are, at least in part, contribute to the development of sensitization in various pain models.