Tolerant Rats Research Articles

The Effects of Dietary Iron and Capsaicin on Hemoglobin, Blood Glucose, Insulin Tolerance, Cholesterol, and Triglycerides, in Healthy and Diabetic Wistar Rats.

ObjectiveOur aim was to assess the effects of dietary iron, and the compound capsaicin, on hemoglobin as well as metabolic indicators including blood glucose, cholesterol, triglycerides, insulin, and glucose tolerance.Materials and MethodsOur animal model was the Wistar rat, fed a chow diet, with or without experimentally induced diabetes. Diabetic males were fed control, low, or high-iron diets, the latter, with or without capsaicin. Healthy rats were fed identical diets, but without the capsaicin supplement. We then measured the parameters listed above, using the Student t-test and ANOVA, to compare groups.ResultsHealthy rats fed a low-iron diet exhibited significantly reduced total cholesterol and triglyceride levels, compared with rats fed a control diet. Significantly reduced blood lipid was also provoked by low dietary iron in diabetic rats, compared with those fed a control diet. Insulin, and glucose tolerance was only improved in healthy rats fed the low-iron diet. Significant increases in total cholesterol were found in diabetic rats fed a high-iron diet, compared with healthy rats fed the same diet, although no statistical differences were found for triglycerides. Hemoglobin levels, which were not statistically different in diabetic versus healthy rats fed the high-iron diet, fell when capsaicin was added. Capsaicin also provoked a fall in the level of cholesterol and triglycerides in diabetic animals, versus diabetics fed with the high iron diet alone. In conclusion, low levels of dietary iron reduced levels of serum triglycerides, hemoglobin, and cholesterol, and significantly improved insulin, and glucose tolerance in healthy rats. In contrast, a high-iron diet increased cholesterol significantly, with no significant changes to triglyceride concentrations. The addition of capsaicin to the high-iron diet (for diabetic rats) further reduced levels of hemoglobin, cholesterol, and triglycerides. These results suggest that capsaicin, may be suitable for the treatment of elevated hemoglobin, in patients.

Effect of calcitonin gene-related peptide antagonist on the cardiovascular events, mortality, and prostaglandin E2 production by nitrate-induced tolerant rats with acute myocardial infarction.

BackgroundAnti-ischemic effects of NO releasing by nitroglycerin (NTG) and the release of calcitonin gene-related peptide (CGRP) are involved in the decrease of vascular remodeling in different cardiovascular diseases. Using a nitrate-free period is still generally required to prevent nitrate tolerance and should be used as the first-line option to maintain adequate symptom control and on an individual basis. Personalized anti-ischemic concerns require the urgent change of paradigm from interventional measures to predictive, preventive, and personalized treatment with organic nitrates and its combination with drugs that may improve prognosis and drugs that can be added for patients who remain symptomatic despite therapy with the other classes of agents. The purpose of this study was to evaluate the influence of human calcitonin gene-related peptide antagonist (CGRP8-37) on cardiohemodynamic events, prostaglandin E2 (PGE2) plasma concentration, the severity of ventricular arrhythmias, and mortality occurring during acute myocardial infarction (AMI) in NTG-tolerant and nontolerant rats.MethodsIn the pilot study of efficacy of calcitonin gene-related peptide antagonist (CGRP8-37), 58 male Wistar rats were included. All procedures were performed according to protocols approved by the General Animal Care and Use Committee. Adult male rats underwent surgery to induce AMI by ligating the left anterior descending coronary artery or SHAM. ECG was used to confirm myocardial ischemia. In each experiment, a rat was maintained under anesthesia for the duration of the experiment. At the end of the experiment, the rat was killed by an overdose of pentobarbital. All animals in accordance with the received pharmacological agent were randomized into three groups: I—received only NTG, 50 mg/kg daily, s.c. injections b.i.d. 3 days prior to AMI; II—received NTG by the same dose, route, and frequency of administration + CGRP antagonist (CGRP8-37), 10 μg/kg two times daily by a similar period of administration; and III—served as control (C) group without preliminary tolerance to NTG.ResultsSubcutaneous injections of NTG (50 mg/kg) 30 min prior to AMI in NTG-tolerant animals (group I) and in NTG-tolerant rats + CGRP antagonist (group II) caused minor changes in blood pressure and heart period that was accompanied before NTG s.c. administration with blunted baroreflex sensitivity in response to i.v. administration of sodium nitroprusside in these groups of rats (0.66 ± 0.05 and 0.56 ± 0.04 ms/mmHg, P < 0.05, respectively) in comparison to C (group III) animals (0.9 ± 0.1 ms/mmHg). AMI 1 h duration was associated with a high incidence of ventricular arrhythmia and significant mortality in group I (70 %) and especially in group II (90 %) animals at 72 h after reperfusion as compared with group III rats (56 %), that correlated to a decrease of PGE2 plasma content in group II (2.2 ± 0.4 ng/ml, P < 0.001) and group I (3.6 ± 0.2 ng/ml, P < 0.01) vs. control group of rats (4.8 ± 0.3 ng/ml).ConclusionsCGRP could be involved in the mechanism of nitrate tolerance via the inhibition of release of the potent vasodilator CGRP leading to exacerbation of acute myocardial ischemia. The influence of CGRP antagonist could enhance this condition.

POTENSI EFEK HIPOGLIKEMIK KOMBINASI EKSTRAK ETANOL UMBI BAWANG HUTAN (Eleutherine bulbosa) DAN KULIT BATANG KAYU MANIS (Cinnamomum burmanii) PADA TIKUS (Rattus norvegicus) DIABETES YANG DIINDUKSI STREPTOZOTOSIN DAN TOLERANSI GLUKOSA

Research on potential hypoglycemic effects of ethanol extract combination of onion forest bulbs (Eleutherine bulbosa) and burmani cortex (Cinnamomum burmanii) in streptozotocin (STZ)-induced diabetic and glucose tolerant rats (Rattus norvegicus) has been conducted. This study aimed to determine the hypoglycemic effect and the effective dose of ethanol extract combination of forest onion bulbs and cinnamon cortex. Extract was obtained by maceration using 96% ethanol. A number of 30 male rats were divided into 6 groups and each group consisted of 5 rats. The first group (negative control) was given Na.CMC; the second group (positive control 1) glibenclamide 0.45 mg/kgBW; the third group (positive control 2) acarbose 9 mg/kgBW; while the 4th, 5th, and 6th were successively given combination of ethanol extract of forest onion bulbs and cinnamon cortex at doses of 100+100, 50+50, and 25+25 mg/kgBW. Each rat group was intraperitoneally (ip) induced with STZ 40 mg/kgBW and then treated for 14 days, after the rats developed diabetic condition, glucose tolerance test was performed with the induction of sucrose 150mg/kgBW which was continued with observation in minute 60, 90, 120, 150, and 180. Treatment data were analyzed using ANOVA (analysis of variance) with 95% confidence interval. The results showed that ethanol extract combination of forest onion bulbs and cinnamon cortex had potential hypoglycemic effects in male rats of which the most effective combination dose was at a dose of 50 + 50 mg/kgBW

Differential expression of MU [μ] Opioid receptors and N-type calcium channels in the amygdala of morphine tolerant rat: An autoradiographic & immunohistochemistry study

Introduction: Recent studies have shown that amygdala plays a pivotal role in the emotional processing of pain. Opioids like morphine relieve pain by suppressing both the sensory and emotional components of pain. On chronic morphine administration, tolerance develops decreasing its analgesic effect. The underlying changes in the amygdala during morphine tolerance are not definitely known. Mu opioid receptors are binding sites for morphine while N-type voltage-gated calcium channels (VGCCs) directly control the release of neurotransmitters from presynaptic nerve endings. Aims & Objectives: The present study was designed to investigate the status of mu receptors and N-type VGCCs in the amygdala of morphine tolerant rat by autoradiography and immunohistochemistry respectively. Material & Methods: Wistar rats were made morphine tolerant by repeated administration of morphine for 5 days. Later, the rats were euthanized and cryostat sections of the brain were cut at the region of the amygdala. For autoradiographic localization, the sections were incubated with [3H] labeled DAMGO. For immunohistochemistry, the sections were exposed to primary antibody against N-type VGCCs. Results: Using image analysis software, a significant down-regulation of mu receptors and an up-regulation of N-VGCCs were observed after tolerance. This differential change in expression would indicate a less effective antinociceptive action of morphine through / though higher neurotransmitter release after tolerance. Conclusion: In conclusion, the study suggests that morphine tolerance could be associated with altered functional state of the amygdala. Keywords: Amygdala, Mu-opioid receptor, Voltage-gated calcium channel, Autoradiography, Immunohistochemistry

Effect of soluble guanylyl cyclase activator and stimulator therapy on nitroglycerin-induced nitrate tolerance in rats

article Chronic nitroglycerin (GTN) anti-ischemic therapy induces side effects such as nitrate tolerance and endothelial dysfunction. Both phenomena could be based on a desensitization/oxidation of the soluble guanylyl cyclase (sGC). Therefore, the present study aims at investigating the effects of the therapy with the sGC activator BAY 60-2770 and the sGC stimulator BAY 41-8543 on side effects induced by chronic nitroglycerin treatment. Male Wistar rats were treated with nitroglycerin (100 mg/kg/d for 3.5 days, s.c. in ethanol) and BAY 60-2770 (0.5 or 2.5 mg/kg/d) or BAY 41-8543 (1 and 5 mg/kg/d) for 6 days. Therapy with BAY 60-2770 but not with BAY 41-8543 improved nitroglycerin-triggered endothelial dysfunction and nitrate tolerance, corrected the decrease in aortic nitric oxide levels, improved the cGMP dependent activation of protein kinase I in aortic tissue and reduced vascular, cardiac and whole blood oxidative stress (fluorescence and chemiluminescence assays; 3- nitrotyrosine staining). In contrast to BAY 41-8543, the vasodilator potency of BAY 60-2770 was not impaired in isolated aortic ring segments from nitrate tolerant rats. sGC activator therapy improves partially the adverse effects of nitroglycerin therapy whereas sGC stimulation has only minor beneficial effects pointing to a

Early single Aspirin-triggered Lipoxin blocked morphine anti-nociception tolerance through inhibiting NALP1 inflammasome: Involvement of PI3k/Akt signaling pathway.

Clinical usage of opioids in pain relief is dampened by analgesic tolerance after chronic exposure, which is related to opioid-associated neuroinflammation. In the current study, which is based on a chronic morphine tolerance rat model and sustained morphine treatment on primary neuron culture, it was observed that Akt phosphorylation, cleaved-Caspase-1-dependent NALP1 inflammasome activation and IL-1β maturation in spinal cord neurons were significantly enhanced by morphine. Moreover, treatment with LY294002, a specific inhibitor of PI3k/Akt signaling, significantly reduced Caspase-1 cleavage, NALP1 inflammasome activation and attenuated morphine tolerance. Tail-flick tests demonstrated that pharmacological inhibition on Caspase-1 activation or antagonizing IL-1β dramatically blocked the development of morphine tolerance. The administration of an exogenous analogue of lipoxin, Aspirin-triggered Lipoxin (ATL), caused a decline in Caspase-1 cleavage, inflammasome activation and mature IL-1β production and thus attenuated the development of morphine tolerance by inhibiting upstream Akt phosphorylation. Additionally, treatment with DAMGO, a selective μ-opioid receptor peptide, significantly induced Akt phosphorylation, Caspase-1 cleavage and anti-nociception tolerance, all of which were attenuated by ATL treatment. Taken together, the present study revealed the involvement of spinal NALP1 inflammasome activation in the development of morphine tolerance and the role of the μ-receptor/PI3k-Akt signaling/NALP1 inflammasome cascade in this process. By inhibiting this signaling cascade, ATL blocked the development of morphine tolerance.

RNA-seq-based transcriptome profiling reveals differential gene expression in the lungs of Sprague-Dawley rats during early-phase acute hypobaric hypoxia.

Individuals subjected to hypobaric hypoxia at high altitudes may exhibit differential physiological responses in terms of susceptibility and tolerance to the development of hypoxia-related disorders. We studied early-phase gene expression in the lungs of Sprague-Dawley rats exhibiting such differential physiological responses after exposure to acute hypobaric hypoxia for 1h at a simulated altitude of 9144m. RNA-seq transcriptome profiling of lung tissues revealed differential gene expression in tolerant and susceptible groups, subsequently validated by qRT-PCR for ten selected differentially expressed genes. The gene expression pattern indicated hypometabolism and negative regulation of vasoconstriction in all groups except susceptible rats, coupled with altered MAPK, p53 and JAK-STAT signaling. Upregulation of early-phase response genes including Dusp1 (dual specificity phosphatase), Cdkn1a (cyclin-dependent kinase inhibitor 1A), Txnip (thioredoxin-interacting protein), Rgs1 (regulator of G-protein signaling 1) and Rgs2 (regulator of G-protein signaling 2) in susceptible rats indicated a progression toward growth arrest and apoptosis. Enhanced expression of cell adhesion molecules, wound healing and repair bioprocesses was observed in tolerant males. Upregulated Kcnj15 (potassium inwardly rectifying channel subfamily j membrane 15) and Vsig4 (V-set and Ig domain containing 4) variants in tolerant females suggested adaptation to hypoxia possibly by fluid reabsorption to avoid edematous conditions and suppression of T cell proliferation to avoid acute lung inflammation. Our study might help in understanding the molecular-physiological mechanisms associated with progressive damage in the lung tissues of susceptible and tissue-protective measures in tolerant rats during acute hypobaric hypoxia.

Activation of P2X7 receptors in the midbrain periaqueductal gray of rats facilitates morphine tolerance

Opiates such as morphine exhibit analgesic effect in various pain models, but repeated and chronic morphine administration may develop resistance to antinociception. The purinergic signaling system is involved in the mechanisms of pain modulation and morphine tolerance. This study aimed to determine whether the P2X7 receptor in the ventrolateral midbrain periaqueductal gray (vlPAG) is involved in morphine tolerance. Development of tolerance to the antinociceptive effect of morphine was induced in normal adult male Sprague–Dawley (SD) rats through subcutaneous injection of morphine (10mg/kg). The analgesic effect of morphine (5mg/kg, i.p.) was assessed by measuring mechanical withdrawal thresholds (MWTs) in rats with an electronic von Frey anesthesiometer. The expression levels and distribution of the P2X7 receptor in the vlPAG was evaluated through Western blot analysis and immunohistochemistry. The acute effects of intra-vlPAG injection of the selective P2X7 receptor agonist Bz-ATP, the selective P2X7 receptor antagonist A-740003, or antisense oligodeoxynucleotide (AS ODN) targeting the P2X7 receptor on morphine-treated rats were also observed. Results demonstrated that repeated morphine administration decreased the mechanical pain thresholds. By contrast, the expression of the P2X7 receptor protein was up-regulated in the vlPAG in morphine tolerant rats. The percent changes in MWT were markedly but only transiently attenuated by intra-vlPAG injection of Bz-ATP (9nmol/0.3μL) but elevated by A-740003 at doses of 10 and 100nmol/0.3μL. AS ODN (15nmol/0.3μL) against the P2X7 receptor reduced the development of chronic morphine tolerance in rats. These results suggest that the development of antinociceptive tolerance to morphine is partially mediated by activating the vlPAG P2X7 receptors. The present data also suggest that the P2X7 receptors may be a therapeutic target for improving the analgesic effect of morphine in treatments of pain when morphine tolerance occurs.

Effect of soluble guanylyl cyclase activator and stimulator therapy on nitroglycerin-induced nitrate tolerance in rats

Chronic nitroglycerin (GTN) anti-ischemic therapy induces side effects such as nitrate tolerance and endothelial dysfunction. Both phenomena could be based on a desensitization/oxidation of the soluble guanylyl cyclase (sGC). Therefore, the present study aims at investigating the effects of the therapy with the sGC activator BAY 60-2770 and the sGC stimulator BAY 41-8543 on side effects induced by chronic nitroglycerin treatment. Male Wistar rats were treated with nitroglycerin (100mg/kg/d for 3.5days, s.c. in ethanol) and BAY 60-2770 (0.5 or 2.5mg/kg/d) or BAY 41-8543 (1 and 5mg/kg/d) for 6days. Therapy with BAY 60-2770 but not with BAY 41-8543 improved nitroglycerin-triggered endothelial dysfunction and nitrate tolerance, corrected the decrease in aortic nitric oxide levels, improved the cGMP dependent activation of protein kinase I in aortic tissue and reduced vascular, cardiac and whole blood oxidative stress (fluorescence and chemiluminescence assays; 3-nitrotyrosine staining). In contrast to BAY 41-8543, the vasodilator potency of BAY 60-2770 was not impaired in isolated aortic ring segments from nitrate tolerant rats. sGC activator therapy improves partially the adverse effects of nitroglycerin therapy whereas sGC stimulation has only minor beneficial effects pointing to a nitroglycerin-dependent sGC oxidation/inactivation mechanism contributing to nitrate tolerance.

Nitroglycerin‐induced tolerance in rat conduit artery and vein

Clinical use of nitroglycerin (GTN) is limited because its long‐term therapy results in the development of nitrate tolerance. The etiology of nitrate tolerance is controversial and poorly understood. This study aimed to investigate the mechanisms of GTN‐induced tolerance and to compare them in aorta and vena cava from GTN tolerant rats. In vivo tolerance for GTN was induced by 3 days treatment with GTN (150 mg/kg/day). We evaluated the maximum relaxing effect (ME) and the potency (pD2) induced by GNT in aorta and vena cava from tolerant and control rats. The endothelial NOS3 and soluble guanylyl‐cyclase (sGC) protein expression was accessed by Western Blot. The procedures are according to the Ethics Committee. Differences were considered significant for P&lt;0.05. GTN treatment reduced the pD2 of GTN from 14.3±0.8, n=6 to 12.8±0.6, n=6, whereas ME was not different between control and tolerant rat aorta. In vena cava, ME was lower in tolerant rats (35.2 ± 2.5%, n= 6, P&lt;0.05) as compared to control rats (73.1 ± 5.7%, n=6). sGC expression was similar in aorta and vein from control and tolerant rats. However, NOS3 expression was higher in aortas from tolerant (1.08 ± 0.06 n= 6, P&lt;0.05) than in control animals (0.66 ± 0.04, n=7). Similarly, NOS3 expression was higher in veins from tolerant (1.08 ± 0.06 n= 6, P&lt;0.05) than in control animals (0.66 ± 0, 04, n= 7). Therefore, GTN‐induced tolerance in rat aorta and vein involves NOS3 but not sGC.

Blood as the carrier of ischemic tolerance in rat brain.

This study provides clear evidence that the factor inducing tolerance to ischemia is transmitted via the circulating blood. By using the remote ischemia and the cross-circulation model, the tolerance to ischemia was transmitted from donor to recipient. For this study, the following experimental groups were designed: I, sham control group; II, group of tolerant hindlimb tourniquet-treated rats; III, positive control group; IV, control for cross-circulation influence; preconditioned animals: V, tolerant animals subjected to middle cerebral artery occlusion (MCAO); VI, tolerant animals cross-circulated with SHC, followed by MCAO; VII, SHC animals cross-circulated with tolerant animals and subsequently subjected to MCAO; VIII, tolerant animals cross-circulated with ischemic rats, followed by MCAO; IX, SHC animals cross-circulated with ischemic animals and subjected to MCAO; postconditioned animals: X, ischemic animals treated with a remote limb tourniquet; XI, ischemic animals cross-circulated with SHC control rats; and XII, ischemic animals cross-circulated with tolerant rats. Results confirmed that remote ischemia induced reduction of infarct volume in the preconditioned (V, 60%) as well as in the postconditioned group (X, 52%). Significant diminution was also observed in group XII (56.6%). In the preconditioned group, decreased infarct volume was detected in groups VI and VII (about 65%) and in group IX (about 50%). The greatest infarct reduction (84%) was induced by the presence of ischemic blood in a tolerant rat before ischemia induction. In summary, the factor inducing tolerance to ischemia is generated by remote ischemia and by ischemia itself; from the site of origin to the rest of the body, it is transported by the systemic blood circulation and can be transferred from animal to animal. The effect of conditioning with two different ischemic events (brain and hindlimb ischemia) led to a cumulative, stronger tolerance response.

Development of a cyclosporin-A-induced immune tolerant rat model to test marrow allograft cell type effects on bone repair.

Bone repair is an important concept in tissue engineering, and the ability to repair bone in hypotrophic conditions such as that of irradiated bone, represents a challenge for this field. Previous studies have shown that a combination of bone marrow and (BCP) was effective to repair irradiated bone. However, the origin and role played by each cell type in bone healing still remains unclear. In order to track the grafted cells, the development of an animal model that is immunotolerant to an allograft of bone marrow would be useful. Furthermore, because the immune system interacts with bone turnover, it is of critical importance to demonstrate that immunosuppressive drugs do not interfere with bone repair. After a preliminary study of immunotolerance, cyclosporin-A was chosen to be used in immunosuppressive therapy. Ten rats were included to observe qualitative and quantitative bone repair 8 days and 6 weeks after the creation of bone defects. The defects were filled with an allograft of bone marrow alone or in association with BCP under immunosuppressive treatment (cyclosporin-A). The results showed that there was no significant interaction of cyclosporin-A with osseous regeneration. The use of this new immunotolerant rat model of bone marrow allograft in future studies will provide insight on how the cells within the bone marrow graft contribute to bone healing, especially in irradiated conditions.

Attenuation of morphine analgesic tolerance by rosuvastatin in naïve and morphine tolerance rats.

Recent studies suggested that statins have anti-inflammatory effects beyond their lipid-lowering properties. Since inflammation in the central nervous system was highly related to morphine tolerance, we sought to investigate whether statins could affect morphine tolerance by mediating glia-derived proinflammatory cytokines secretion. We have undertaken two separate studies: Firstly, we determined the effect of rosuvastatin on naïve rats during induction of morphine tolerance. Secondly, we investigated whether rosuvastation could attenuate the morphine analgesic tolerance in rats that the morphine tolerance established previously. Results demonstrated that peroral rosuvastatin not only delays, but also partially reverses the tolerance to morphine analgesia in rats. The administration of rosuvastatin during induction of morphine tolerance attenuated the activation of ERK and the release of proinflammatory cytokines in the lumbar spinal cord. Similar outcomes were observed in rats were morphine tolerance was established previously. Moreover, our study also found that repeated administration of morphine could activate the astrocytes in the spinal cord while rosuvastation succeeds in suppressing the activation of astrocytes. Our results support the idea that targeting glia-derived proinflammatory effects during morphine treatment is a novel and clinically promising method for enhancing analgesic effects of morphine. We identify a potential new application of statins in the treatment of morphine analgesic tolerance.

Influence of Dihydromyricetin on Lowering Blood Glucose Concentration and Reducing Early Kidney Damage in Imparied Glucose Tolerance Rats

Diabetic nephropathy (DN) is a common complication of diabetes and it is related to irreversible kidney damages and chronic renal failure. Impaired glucose tolerance (IGT) is an early stage in the development of diabetes and DN. Early detection of IGT and treatment of its associated early kidney damage can effectively prevent the development of DN. In this paper, the influence of dihydromyricetin (DHM) on lowering blood glucose concentration and reducing early kidney damage in IGT rats was studied. Animal model of IGT rats was built by two week intragastric injection of D-galactose and treated with eight weeks of intragastric injection of DHM at two dose levels. The concentrations of fasting blood glucose (FBG), two-hour postprandial blood glucose (2hBG), insulin levels, contents of microalbuminuia (mAlb) and blood urea nitrogen (BUN), and activities of lactate dehydrogenase (LDH) in kidney were analysed and compared with those in control groups. Experimental results indicated that DHM treatment can significantly lower the levels of two-hour postprandial blood glucose and insulin, decrease the content of mAlb and the activities of LDH in kidney, but does not influence the level of BUN. The study suggested that DHM can effectively improve the states of IGT rats and provide a protective effect against early kidney damage.

Tolerance-like innate immunity and spleen injury: a novel discovery via the weekly administrations and consecutive injections of PEGylated emulsions.

There has been an increasing interest in the study of the innate immune system in recent years. However, few studies have focused on whether innate immunity can acquire tolerance. Therefore, in this study, we investigated tolerance in the innate immune system via the consecutive weekly and daily injections of emulsions modified with polyethylene glycol (PEG), referred to as PEGylated emulsions (PE). The effects of these injections of PE on pharmacokinetics and biodistribution were studied in normal and macrophage-depleted rats. Additionally, we evaluated the antigenic specificity of immunologic tolerance. Immunologic tolerance against PE developed after 21 days of consecutive daily injections or the fourth week of PE administration. Compared with a single administration, it was observed that the tolerant rats had a lower rate of PE clearance from the blood, which was independent of the stress response. In addition, weekly PE injections caused injury to the spleen. Furthermore, the rats tolerant to PEs with the methoxy group (–OCH3) of PEG, failed to respond to the PEs with a different terminal group of PEG or to non-PEG emulsions. Innate immunity tolerance was induced by PE, regardless of the mode of administration. Further study of this mechanism suggested that monocytes play an essential role in the suppression of innate immunity. These findings provide novel insights into the understanding of the innate immune system.

Spontaneously relapsing–remitting experimental autoimmune uveitis in rats allows successful therapeutic oral tolerance induction in ongoing disease

Antigen-specific tolerance induction is a desired therapy for uveitis patients. Our relapsing–remitting rat model of experimental autoimmune uveitis (EAU) induced with IRBP peptide R14 enables us to test the effect of oral tolerance on the prevention of relapsing uveitis. We investigated several peptides overlapping the sequence of R14 for prevention and different doses of R14 for therapy to determine the tolerogenic epitope and the most effective therapeutic regimen for uveitis. Lewis rats were immunized with R14-CFA to induce EAU. Oral tolerance was induced prior to immunization (prevention) or after onset of EAU to prevent relapses (therapy). Therapeutic feeding was performed with high and/or low doses of oral antigen for clonal deletion of effector and induction of regulatory T cells. Uveitis was determined clinically and histologically; mesenteric lymph node (mLN) cells of tolerized rats were tested for surface markers, cytokines and Foxp3 expression. Preventive feeding of R14 and its major epitope R16, but none of the overlapping peptides significantly suppressed EAU and also prevented relapses, irrespective of their pathogenicity. Therapeutic feeding with R14 dramatically reduced relapses, while only the consecutive feeding of high and low-dose R14 had an ameliorating effect on the first course of disease. IL-10-producing T cells from mLN decreased after oral tolerization, and with R14-stimulation in vitro the TCRαβ+/Foxp3+ population increased in the low-dose fed group. No mLN population could be clearly assigned to successful oral tolerance induction during active autoimmune uveitis.

Tranilast, an Analogue of a Tryptophan Catabolite, Induces Allograft Tolerance By Myeloid-Derived Suppressor Cells (MDSCs).

Indoleamine 2, 3-dioxygenase (IDO) converts tryptophan in various tolerogenic metabolites. One is anthranilic acid and has been shown to induce immune tolerance in different immune-mediated diseases, including organ transplantation. Tranilast is a clinically approved and is have ready clinically used (Rizaben®) in asthma and atopic dermatitis. We examined the effect of tranilast in a rat cardiac allograft model. Lewis 1W rat hearts were grafted in MHC-mismatched Lewis 1A rats. The receiver is orally treated with 650 mg/kg of tranilast or clinically used Rizaben® (Kissei Pharmaceutical Co) daily for 30 days. Total splenocytes and purified spleen cell subtypes were sorted by FACS Aria and transferred to sublethaly irradiated rats by i.v injection the day before transplantation. Graft survival in rats treated with tranilast were significantly prolonged (64,6±42.7 days, n=15) and showed tolerance with > 100 days survival vs control group (8.3±2.3 days, n=6). When Rizaben®, was used, all treated animals (n=8) showed tolerance. Adoptive transfer of total splenocytes from tolerant tranilast-treated rats to naïve rats resulted in tolerance in all animals (n=5). We adoptively transferred tolerance only with CD161+TCR- cells from tolerant rats which resulted in tolerance (130±91.6 days, n=5, 3/5 recipients >100 days) whereas CD161-TCR- cells from the same animals did not (12.7±4.6 days, n=3). In the CD161+TCR- cells, we could distinguish 2 cells populations CD161high(NK cells) and CD161low. CD161low cells were MHCII-, CD172a+, CD11b+ and CD86+ a phenotype already described in the rat as MDSCs. When we transferred CD161high and CD161low from the same animals, we obtained prolongation of allograft survival only with the CD161low MDSCs (59±64days, n=5, 2/5 recipients >100 days) and not with the CD161high (18±14 days, n=3).Moreover, tranilast-treated and cell-transfered recipients with indefinite allograft did not have detectable levels of alloantibodies. This is the first demonstration that tranilast mediates transplantation tolerance. Tolerance was active and transferable by MDSCs. Experiments are under way to better define how MDSCs are induced by tranilast and the mechanisms by which they induce tolerance.

당뇨 쥐에 대한 한약재복합추출물로 만든 현미율무밥의 혈당강하 효과

Objectives : The purpose of this study was to evaluate boiled rice made from unpolished rice, Job`s Tears, and extract from medicinal herbs mixture (HGMCJE) for hypoglycemic effect on STZ-induced diabetic rats. Methods : In the response of glucose tolerance, control and diabetic rats groups was intubated with glucose and HGMCJE. Furthermore, boiled 100% polished rice (P rice), boiled unpolished rice mixed with white rice and Job`s tears (polished rice:unpolished rice:Job`s tears

Respiratory effects of buprenorphine/naloxone alone and in combination with diazepam in naive and tolerant rats

Respiratory depression has been attributed to buprenorphine (BUP) misuse or combination with benzodiazepines. BUP/naloxone (NLX) has been marketed as maintenance treatment, aiming at preventing opiate addicts from self-injecting crushed pills. However, to date, BUP/NLX benefits in comparison to BUP alone remain debated. We investigated the plethysmography effects of BUP/NLX in comparison to BUP/solvent administered by intravenous route in naive and BUP-tolerant Sprague-Dawley rats, and in combination with diazepam (DZP) or its solvent. In naive rats, BUP/NLX in comparison to BUP significantly increased respiratory frequency (f, P<0.05) without altering minute volume (VE). In combination to DZP, BUP/NLX significantly increased expiratory time (P<0.01) and decreased f (P<0.01), tidal volume (VT, P<0.001), and VE (P<0.001) while BUP only decreased VT (P<0.5). In BUP-tolerant rats, no significant differences in respiratory effects were observed between BUP/NLX and BUP. In contrast, in combination to DZP, BUP/NLX did not significantly alter the plethysmography parameters, while BUP increased inspiratory time (P<0.001) and decreased f (P<0.01) and VE (P<0.001). In conclusion, differences in respiratory effects between BUP/NLX and BUP are only significant in combination with DZP, with increased depression in naive rats but reduced depression in BUP-tolerant rats. However, BUP/NLX benefits in humans remain to be determined.

(341) Sphingosine 1-phosphate receptor 1 antagonism prevents morphine-induced antinociceptive tolerance and hyperalgesia

The clinical utility of morphine is hampered by the development of antinociceptive tolerance and hyperalgesia. We have reported these conditions arise in part from sphingosine-1-phosphate (S1P) signaling and ensuing nitroxidative and neuroinflammatory processes in the spinal cord of tolerant rats. We now provide support for pharmacological targeting the S1P-S1PR1 signaling pathway as a viable option for the prevention of morphine antinociceptive tolerance and hyperalgesia. Administration of clinically relevant selective S1PR1 antagonists or functional S1PR1 antagonists, in a dose-dependent manner, effectively prevents the development of tolerance and hyperalgesia with chronic morphine administration in normal rats or rats with neuropathic pain.