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Biomedical subjects

Tomio Inoue

Publications and source records attributed to Tomio Inoue.

At least 37 records · Page 2Linked to original sources
PubMed2004

Glutathione S-transferase P1 has protective effects on cell viability against camptothecin.

Glutathione S-transferase P1 (GSTP1) is one of the important xenobiotic-metabolizing enzymes. It was reported that GSTP1 was overexpressed in malignant tissues, and its expression level was associated with resistance to chemotherapeutics. We carried out transfection of GSTP1 sense and antisense vectors to examine effects of GSTP1 on cell cycle arrest and apoptosis induced by camptothecin in HeLa cells. Transfection of GSTP1 antisense vector induced apoptosis. Camptothecin-induced S- or G2/M arrest was intensified by transfection of GSTP1 antisense vector, and subsequent apoptosis was attenuated by transfection of GSTP1 sense vector. These results suggest that GSTP1 has protective effects against camptothecin-induced cytotoxicity.

Antineoplastic Agents, Phytogenic↗
PubMed2004

Clinical usefulness of ECG-gated 18F-FDG PET combined with 99mTC-MIBI gated SPECT for evaluating myocardial viability and function.

OBJECTIVES: This study sought to evaluate an imaging approach using gated 99mTc-MIBI (MIBI) SPECT and gated 18F-FDG (FDG) PET for assessment of myocardial viability and cardiac function. METHODS: Forty-eight patients (38 men, mean age 68.1 +/- 9.6 years) underwent ECG-gated FDG PET and MIBI SPECT within a week. The baseline diagnoses were coronary artery disease (31), mitral regurgitation (1), paroxysmal arrhythmia (10), and dilated cardiomyopathy (6). The gated FDG PET data were analyzed using pFAST software, and the gated MIBI SPECT data were analyzed using QGS software. Fifteen patients were diagnosed with myocardial infarction, and follow-up study was performed to assess the functional outcome four months later. An improvement in LVEF of >5% was defined as significant. The LV myocardium was divided into 17 segments, and regional defect scores were visually assessed using a 4-point scale for each segment (0 = normal, 1 = mildly reduced, 2 = moderately reduced, 3 = absent). A segment with a greater defect score on MIBI SPECT than on FDG PET was defined as a mismatch. The patients were divided into two groups: those with at least two mismatched segments (MM-group), and those with none or one (M-group). RESULTS: LVEF, EDV and ESV measured by gated FDG PET were highly correlated with those obtained by gated MIBI SPECT (r = 0.848, 0.855 and 0.911, p < 0.0001, respectively). The mean values of LVEF did not differ significantly, but EDV and ESV obtained by gated FDG PET were significantly grater than those obtained by gated MIBI SPECT (p < 0.0001). In 15 patients diagnosed with myocardial infarction, a significant association (p < 0.05) was found between the relative uptake of FDG PET and MIBI SPECT and the functional outcome 4 months later. Global LV function improved in 6 of the 8 patients showing mismatch but in only 1 of the 7 patients with matched defects, resulting in a sensitivity of 86% and specificity of 75%. The overall accuracy to predict global functional outcome was high (80%). CONCLUSION: This imaging approach allows accurate evaluation of myocardial viability. Furthermore, the high correlations of gated FDG PET and gated MIBI SPECT measurements hold promise for the assessment of left ventricular function using gated FDG PET.

Aged↗
PubMed2004

Nuclear medicine practice in Japan: a report of the 5th nationwide survey in 2002.

UNLABELLED: The Subcommittee on Survey of Nuclear Medicine Practice in Japan has performed a nationwide survey of nuclear medicine practice every five years since 1982 to provide detailed information on its current status. METHODS: Questionnaires were sent to every institution known to the Japan Radioisotope Association to provide nuclear medicine examinations. The questionnaires address the number and kind of nuclear medicine examinations performed as well as the kind and dose of the radiopharmaceuticals used during the month of June 2002. The annual number of total or specific examinations was then estimated. RESULTS: Of the institutions sent questionnaires, 1,204 were for in vivo study, 124 were for in vitro study, and 36 were for positron emission tomography (PET) study. Out of these, 95.8% answered them. A total of 1,697 gamma cameras were installed in 1,160 facilities, of which 50% were dual-head cameras. The estimated total annual number of examinations expressed by the number of administered radiopharmaceuticals was 1.60 million, similar to that of the previous survey (1997). The frequency of study with single photon emission computed tomography (SPECT) increased to 40%, from 30% in the previous survey. The scintigraphy most frequently performed was bone (35%), followed by myocardium (24%) and brain perfusion (12%). All showed a continuous increase over the past 20 years. Tumor imaging, however, fell from third to fourth place. The most commonly used radiopharmaceutical for each scintigraphy was 99mTc-HMDP for bone, 201Tl-chloride for myocardium, 67Ga-citrate for tumor, and 123I-IMP for brain. A total of 29,376 PET studies were performed yearly. Among them, 18F-FDG rapidly increased 3.7-fold. 131I therapy for thyroid cancer and hyperthyroidism was conducted yearly in 1,647 and 3,347 patients, respectively. A total of 31.35 million in vitro radioassays were carried out yearly, the number of which has been decreasing continuously since 1992. CONCLUSIONS: It was proved that the content of nuclear medicine practice in Japan has changed in the past five years. This report might be useful for understanding the current trends of nuclear medicine practice in Japan.

Health Care Surveys↗
PubMed2004

Evaluation of muscle metabolic activity in the lower limb of a transfemoral amputee using a prosthesis by using (18)F-FDG PET imaging--an application of PET imaging to rehabilitation.

This study used FDG PET to evaluate the lower limb muscles metabolic activities of transfemoral amputees during walking with prostheses. As a preliminary study, FDG PET was applied for two normal adult volunteers to evaluate muscle activity in the lower extremities after gait exercise. This same method was applied for two amputee volunteers with prostheses. We found that FDG accumulated more in both gluteus medius muscles after gait exercise compared to other muscles in normal adult volunteers. In the skilled amputee volunteer, FDG uptake increased in the adductor and gluteus medius in the amputated side, while in the unskilled the adductor, gluteus maximus, and gluteus medius showed increased FDG uptake only in the normal side. This result suggests that basic metabolic changes such as an increase in oxidative metabolism and less reliance on glycolytic activity would occur as a result of skeletal muscle training in amputees.

Adult↗
PubMed2004

Effect of mitomycin C and vinblastine on FDG uptake of human nonsmall-cell lung cancer xenografts in nude mice.

This study was designed to preliminarily evaluate the use of positron emission tomography (PET) with [18F]-2-fluoro-2-deoxy-D-glucose (FDG) for monitoring chemotherapy effects, using a nude-mouse model of human nonsmall-cell lung cancer (NSCLC), the Lu-99 cell line. Tumor-FDG uptakes and volumes were measured after administrating a single dose of mitomycin (MMC) and vinblastine (VLB) and then compared these for a nontherapy group. A significant reduction in tumor volume after either chemotherapy occurred and associated with significantly lower FDG uptake values than the control group (p < 0.001), as early as day 1. These observations suggest that FDG-PET may be useful for noninvasively monitoring the effects of cancer chemotherapy.

Animals↗
PubMed2004

Proliferative response to phenytoin and nifedipine in gingival fibroblasts cultured from humans with gingival fibromatosis.

The response of gingival fibroblasts cultured from humans with gingival fibromatosis to phenytoin (PHT) and nifedipine (NIF) was investigated. PHT and NIF induced proliferation, and increased the expression of immunoreactive endothelin-1 (ET-1). ET-1 (0.1 nm-1 microm) itself also induced proliferation in a concentration-dependent manner. The proliferation was inhibited by BQ-123 (ETA receptor antagonist; 1 microm) and TAK044 (ETA/ETB receptor antagonist; 1 microm), but not by BQ-788 (ETB receptor antagonist; 1 microm). The proliferation induced by PHT (0.25 microm) and NIF (0.25 microm) was inhibited by BQ-123 (1 microm). In addition, the results of Western blot analysis indicated the presence of ETA and ETB receptors in/on the fibroblasts. These findings suggest that PHT- and NIF-induced gingival proliferation may be mediated by endogenously generated ET-1, possibly via ETA receptors.

Anticonvulsants↗
PubMed2004

Diagnostic use of T2-weighted inversion-recovery magnetic resonance imaging in acute coronary syndromes compared with 99mTc-Pyrophosphate, 123I-BMIPP and 201TlCl single photon emission computed tomography.

BACKGROUND: The incidence of missed diagnoses of acute cardiac ischemia in the emergency department could be reduced by a new imaging modality. In the present study, the clinical significance of (99m)Tc-pyrophosphate (PYP), (123)I-beta-methyl-p-iodephenyl-pentadecanoic acid (BMIPP), (201)TlCl scintigraphy (imaging) and T2-weighted inversion-recovery magnetic resonance imaging (MRI) for the detection of culprit lesion in patients with acute coronary syndromes (ACS) was compared. METHODS AND RESULTS: The study group comprised 18 patients with ACS: 12 patients with acute myocardial infarction (AMI) (11 males; mean age, 63+/-11 years) and 6 patients with unstable angina (UA) (3 males, mean age, 67+/-5 years). Of the 12 patients with AMI, 10 underwent (201)TlCl and PYP single photon emission computed tomography (SPECT) studies as a dual-energy acquisition ((201)TlCl/PYP) and 8 underwent (201)TlCl SPECT within 1 week of the BMIPP study. All 18 patients underwent BMIPP SPECT and MRI. The MRI pulse sequence was black blood turbo short-inversion-time inversion recovery (STIR) (breath-hold T2-weighted studies). The T2-weighted inversion-recovery MRI showed higher sensitivity and negative predictive value than PYP and (201)TlCl, and higher specificity and positive predictive value than BMIPP and (201)TlCl. The area under the receiver-operating characteristic curve for PYP, BMIPP, (201)TlCl and MRI was 0.787, 0.725, 0.731 and 0.878, respectively. The difference between the areas of MRI and BMIPP was significant (p<0.05). CONCLUSION: Accurate detection of culprit lesion is improved by using MRI rather than BMIPP, particularly for patients with ACS.

Acute Disease↗
PubMed2004

Superiority of 3-dimensional stereotactic surface projection analysis over visual inspection in discrimination of patients with very early Alzheimer's disease from controls using brain perfusion SPECT.

UNLABELLED: In Alzheimer's disease (AD), regional cerebral blood flow (rCBF) in the posterior cingulate gyri and precunei has been reported to decrease even at a very early stage. It may be helpful to use statistical image analysis to distinguish slight decreases in rCBF in this area. We compared a 3-dimensional stereotactic surface projection (3D-SSP) technique with visual inspection in the discrimination of patients with very early AD from age-matched controls using brain perfusion SPECT. METHODS: SPECT was obtained in 38 patients with probable AD at a very early stage and after a mean interval of 15 mo and in 76 age-matched healthy volunteers. We randomly divided these subjects into 2 groups. The first group was used to identify the areas with significant decreases of rCBF in patients compared with healthy control subjects based on the voxel-based analysis using 3D-SSP. The second group was used to compare the discrimination ability between patients and control subjects by 3D-SSP with that by visual inspection. In the second group, a Z-score map for a SPECT image of a subject was obtained by comparison with mean and SD SPECT images of control subjects for each voxel after anatomic standardization and voxel normalization to reference regions. Receiver operating characteristic (ROC) curves for a Z-score discriminating patients with AD from control subjects were analyzed in areas with significant decreases of rCBF identified in the first group. For visual inspection, 6 physicians graded the rCBF decrease on SPECT images for ROC curves. They inspected the images twice at an interval of >2 wk, and intra- and interobserver reliabilities were determined. RESULTS: Visual inspection showed fair-to-excellent intra- and interobserver reliabilities. The 3D-SSP demonstrated an accuracy of 86.2% for discriminating patients with AD from control subjects when analyzing the posterior cingulate gyri and precunei with global mean normalization. In contrast, visual inspection did not show an accuracy of >74.0% for this discrimination. CONCLUSION: The ability of 3D-SSP to discriminate patients with very early AD from control subjects is superior to that of visual inspection. It is clinically useful and reliable to adopt the use of 3D-SSP as an adjunct to visual interpretation.

Aged↗
PubMed2004

[A questionnaire about radiation safety management of the draining-water system at nuclear medicine facilities].

We conducted a questionnaire survey about radiation-safety management condition in Japanese nuclear medicine facilities to make materials of proposition for more reasonable management of medical radioactive waste. We distributed a questionnaire to institutions equipped with Nuclear Medicine facilities. Of 1,125 institutions, 642 institutes (52.8%) returned effective answers. The questionnaire covered the following areas: 1) scale of an institution, 2) presence of enforcement of radiotherapy, 3) system of a tank, 4) size and number of each tank, 5) a form of draining-water system, 6) a displacement in a radioactive rays management area, 7) a measurement method of the concentration of medical radioactive waste in draining water system, 8) planned and used quantity of radioisotopes for medical examination and treatment, 9) an average displacement of hospital for one month. In most institutions, a ratio of dose limitation of radioisotope in draining-water system was less than 1.0, defined as an upper limitation in ordinance. In 499 hospitals without facilities of hospitalization for unsealed radioisotope therapy, 473 hospitals reported that sum of ratios of dose limits in a draining-water system was less than 1.0. It was calculated by used dose of radioisotope and monthly displacement from hospital, on the premise that all used radioisotope entered in the general draining-water system. When a drainage including radioactivity from a controlled area join with that from other area before it flows out of a institution, it may be diluted and its radioactive concentration should be less than its upper limitation defined in the rule. Especially, in all institutions with a monthly displacement of more than 25,000 m3, the sum of ratio of the concentration of each radionuclide to the concentration limit dose calculated by used dose of radioisotope, indicated less than 1.0.

Humans↗
PubMed2004

Cerebral metabolic reduction in severe malaria: fluorodeoxyglucose-positron emission tomography imaging in a primate model of severe human malaria with cerebral involvement.

Cerebral metabolic changes in Japanese macaques (Macaca fuscata) infected with Plasmodium coatneyi, a primate model of severe human malaria with cerebral involvement, were directly evaluated by fluorodeoxyglucose-positron emission tomography (FDG-PET). We observed diffuse and heterogeneous reduction of metabolism in the cerebral cortex in the acute phase of malaria infection. Neuropathologic examination showed preferential sequestration of parasitized red blood cells in the cerebral microvasculature. However, hemorrhagic change or necrosis was not observed in hematoxylin and eosin-stained and Nissl-stained brain tissues. This suggests that reduction of cerebral metabolism occurs before parenchymal changes appear in the brain. This may be one reason why more than half of the patients with cerebral malaria have no neurologic sequelae after recovery.

Animals↗
PubMed2003

Coeruleotrigeminal inhibition of nociceptive processing in the rat trigeminal subnucleus caudalis.

It has been accepted that the descending system from the nucleus locus coeruleus (LC)/nucleus subcoeruleus (SC) plays a significant role in spinal nociceptive processing. The present study was designed to examine modulation of nociceptive processing in the caudal part of the trigeminal sensory nuclear complex, the trigeminal subnucleus caudalis which is generally considered to be involved in the relay of oral-facial nociceptive information. Experiments were performed on anesthetized Sprague-Dawley rats. The site of LC/SC stimulation was confirmed by histology using potassium ferrocyanide to produce a Prussian blue reaction product marking the iron deposited from the stimulating electrode tip. Only data from rats which had electrode placements in the LC/SC were used. Electrical stimulation was delivered at a stimulus intensity below 100 microA in the present study. Stimulation at sites inside the LC/SC produced a reduction of both spontaneous activity and responses of subnucleus caudalis neurons to somatic input, especially nociceptive input. Increasing stimulation frequency in the LC/SC resulted in an increase in inhibitory effects on nociceptive responses of subnucleus caudalis neurons. At three of nine sites outside the LC/SC, electrical stimulation was effective on descending inhibition. A significant difference in the inhibitory effects was observed when the inhibitory effects were compared between sites of stimulation inside the LC/SC and three effective sites of stimulation outside the LC/SC. These findings suggest that nociceptive processing in the subnucleus caudalis is under the control of the descending modulation system from the LC/SC. To understand the effects of repetitive stimulation with high frequency on fine unmyelinated LC/SC fibers, the existence of recurrent collateral excitation in the LC/SC may be considered.

Action Potentials↗
PubMed2003

FDG-PET scanning after radiation can predict tumor regrowth three months later.

PURPOSE: Positron emission tomography (PET) with 2-[(18)F]fluoro-2-deoxy-D-glucose (FDG) is well known for providing excellent clinical information regarding malignant tumors. We investigated whether dual-time FDG-PET performed immediately post radiation could predict early regrowth of malignant tumors. MATERIALS AND METHODS: Twenty patients with malignant tumors were included in this study. All patients received radiation, and each underwent FDG-PET before the initiation of therapy and within 10 days of completing their course of irradiation. PET images after irradiation were obtained at 60 min and 180 min post FDG injection. For 26 lesions in 20 patients, standardized uptake value (SUV) before and after treatment was calculated and then correlated with postradiation tumor response and outcome at 3 months status post irradiation. RESULTS: Retention index [RI = (SUV on delayed image - SUV on early image)/SUV on early image] after irradiation showed a significant difference between patients with residual tumor and those without residual tumor at 3 months status post irradiation (p < 0.0025). All 9 lesions in 6 patients with residual tumors showed more than 0.1 of RI, whereas none of the lesions with less than 0.1 of RI revealed residual tumors. CONCLUSIONS: Dual-time FDG-PET imaging just after irradiation is potentially useful for predicting early regrowth of malignant tumors.

Adult↗
PubMed2003

Asymptomatic radiation-induced telangiectasia in children after cranial irradiation: frequency, latency, and dose relation.

PURPOSE: To determine the frequency, dose relation, and latency of radiation-induced telangiectasias in children after cranial irradiation. MATERIALS AND METHODS: The authors identified 90 children who had undergone cranial irradiation between 1981 and 2001 and undergone magnetic resonance (MR) imaging with follow-up for at least 6 months. Patients were assigned to low-dose (LD) and high-dose (HD) groups. All 24 children in the LD group received a radiation dose of 18.0 or 19.8 Gy. The 66 patients in the HD group received a dose of 32.0 Gy or greater. Telangiectasias were defined as small low-signal-intensity foci on intermediate- or T2-weighted MR images. For the patients who underwent serial MR imaging, the first depicted appearance of each telangiectatic lesion was recorded. Statistical analyses were performed. RESULTS: Telangiectasias in at least one area were observed in 18 (20%) patients. The frequency of telangiectasia was 13% (three of 24 patients) in the LD group as compared with 23% (15 of 66 patients) in the HD group; this difference was not significant (P =.22, Fisher exact test). In 12 patients (one from LD and 11 from HD group) who underwent serial MR imaging follow-up for up to 10 years (mean, 8.1 years), a total of 31 lesions were detected. Twelve (39%) of these lesions were detected by the 3rd year, and 21 (68%) were evident by the 5th year. Six (50%) of the 12 patients who underwent serial MR imaging had telangiectatic foci after 5 years. CONCLUSION: Radiation-induced telangiectasia appears to occur in at least 20% of children who undergo cranial irradiation. In this small series, higher radiation dose was not significantly associated with higher frequency of telangiectasia, although there was a trend in this direction.

Adolescent↗
PubMed2003

Coeruleotrigeminal suppression of nociceptive sensorimotor function during inflammation in the craniofacial region of the rat.

Descending action from the locus coeruleus (LC) on the trigeminal sensorimotor function was evaluated in a rat model of oral-facial inflammation. For the induction of oral-facial inflammation, mustard oil (20% solution in 20microl mineral oil) was injected into the region of the temporomandibular joint (TMJ). One week before testing, rats received bilateral lesions of the LC using a cathodal current. The electromyogram (EMG) threshold, which is the threshold intensity for the onset of EMG activity of the masseter muscle evoked by pressure on the TMJ region, was used in the present study as an indicator of the trigeminal sensorimotor function. Following mustard oil injection, in the LC-lesioned rats, EMG thresholds significantly decreased at 30min, which lasted up to 240min. In contrast, EMG thresholds in the LC-intact rats returned to the level before injection after 180min. Systemic naloxone (1.3mg/kg, i.v.) produced a further decrease of EMG thresholds in both the LC-intact and LC-lesioned rats. Under the existence of naloxone, EMG thresholds in the LC-lesioned rats were significantly lower than those of the LC-intact rats. These results suggest that oral-facial inflammation activates the coeruleotrigeminal modulating system and that an action of this system is independent of the opioid depressive mechanism.

Animals↗
PubMed2003

Performance evaluation of a hand-held, semiconductor (CdZnTe)-based gamma camera.

We have designed and developed a small field of view gamma camera, the eZ SCOPE, based on use of a CdZnTe semiconductor. This device utilises proprietary signal processing technology and an interface to a computer-based imaging system. The purpose of this study was to evaluate the performance of the eZ scope in comparison with currently employed gamma camera technology. The detector is a single wafer of 5-mm-thick CdZnTe that is divided into a 16x16 array (256 pixels). The sensitive area of the detector is a square of dimension 3.2 cm. Two parallel-hole collimators are provided with the system and have a matching (256 hole) pattern to the CdZnTe detector array: a low-energy, high-resolution parallel-hole (LEHR) collimator fabricated of lead and a low-energy, high-sensitivity parallel-hole (LEHS) collimator fabricated of tungsten. Performance measurements and the data analysis were done according to the procedures of the NEMA standard. We also studied the long-term stability of the system with continuous use and variations in ambient temperature. Results were as follows. INTRINSIC ENERGY RESOLUTION: 8.6% FWHM at 141 keV.LINEARITY: There was excellent linearity between the observed photopeaks and the known gamma ray energies for the given isotopes. INTRINSIC SYSTEM UNIFORMITY: For the central field of view, the integral uniformity and the differential uniformity were, respectively, 1.6% and 1.3% with the LEHR collimator and 1.9% and 1.2% with the LEHS collimator. SYSTEM SPATIAL RESOLUTION: The FWHM measurements made at the surface of the collimator were 2.2 mm (LEHR) and 2.9 mm (LEHS).CONTRAST TEST: The average S/N ratios (i.e. counts in the irradiated pixel divided by counts in the surrounding pixels) for the inner ring pixels (8)/outer ring pixels (16) using the LEHS collimator and LEHR collimator were 3.2%/0.2% and 3.7%/0.3%, respectively. COUNT RATE CHARACTERISTICS: We could not determine the maximum count rate and the 20% loss count rate from these data because the plateau was not reached while using the solutions measured. SYSTEM SENSITIVITY: The average acquisitions were 11,052 cpm/MBq (LEHR) and 28,590 cpm/MBq (LEHS). TEMPERATURE DEPENDENCE: The system displayed minimum corresponding shift in cps with temperature changes in the measured temperature range. We designed and developed a semiconductor-based gamma camera using CdZnTe. The basic performance of this camera compares favourably with the existing gamma camera technology that is deployed in the medical field today. The most significant differences include the spatial resolution, sensitivity, high count rate characteristics and energy resolution. We believe that this device will be of value for a number of clinical applications including sentinel node detection and radiopharmaceutical-guided surgery.

Cadmium↗
PubMed2003

Scoring analysis of salivary gland scintigraphy in patients with Sjögren's syndrome.

The purpose of the present study was to evaluate the validity of a scoring system based on excretion rate of salivary gland scintigraphy in patients with Sjögren's syndrome (SjS). Total scintigraphic scores were compared with the results of the Saxon test. One hundred and twenty-four subjects who were clinically diagnosed with SjS and 11 normal ones underwent salivary gland scintigraphy and the Saxon test. In salivary gland scintigraphy, the difference between maximum and minimum counts after stimulation using vitamin C divided by maximum counts was defined as the excretion rate. We then defined a scoring system with 4 grades: severe dysfunction = 3 (excretion rate < 25%), moderate dysfunction = 2 (25% < or = excretion rate < 40%), mild dysfunction = 1 (40% < or = excretion rate < 50%) and normal function = 0 (50% < or = excretion rate). The summation of the total scintigraphic score (0-12) of all 4 salivary glands was used as a semi-quantitative index indicating total salivary gland function, and total scintigraphic scores were compared with the results of the Saxon test. A significant inverse linear correlation (R2 = 0.95) was observed between total scintigraphic scores and mean values of the Saxon test within a range of abnormal scintigraphic scores (> or = 4). The scoring system developed in the present study is a clinically available, objective, and reproducible method for evaluation of salivary gland function in patients with SjS.

Adult↗
PubMed2003

Coeruleospinal inhibition of nociceptive processing in the dorsal horn during unilateral hindpaw inflammation in the rat.

Behavioral and neurochemical studies have shown that the coeruleospinal modulation system is activated by peripheral inflammation, and that this modulation system is active in only the dorsal horn ipsilateral, but not in the dorsal horn contralateral, to the site of inflammation; the present study was designed to confirm electrophysiologically this previous finding. Extracellular recordings from dorsal horn neurons were continued for at least 4 h after the induction of inflammation. Unilateral hindpaw inflammation was produced by a subcutaneous injection of carrageenan (2 mg in 0.15 ml saline). Background activity and responses to noxious heating were compared between rats receiving bilateral lesions in the locus coeruleus/subcoeruleus (LC/SC) and non-operated control rats. In neurons located in the dorsal horn ipsilateral to the inflamed paw, prior to inflammation, there was no significant difference in either the background activity or the heat-evoked response in neurons in LC/SC-lesioned compared to LC/SC-intact rats. Four hours after the induction of inflammation, there was a significant increase in both the background activity and heat-evoked response in neurons in LC/SC-lesioned compared to LC/SC-intact rats. In neurons located in the dorsal horn contralateral to the inflamed paw, 4 h after inflammation, no significant increase in either the background activity or the heat-evoked response in neurons in LC/SC-lesioned rats was observed, as well as in the case before inflammation. These results suggest that the coeruleospinal modulation system is active in only the dorsal horn ipsilateral, but not in the dorsal horn contralateral, to the site of inflammation during the development of unilateral hindpaw inflammation.

Action Potentials↗