Glycogen synthase kinase-3 (GSK-3) is constitutively active in nonstimulated cells, where the majority of its substrates undergo inactivation/proteolysis by phosphorylation. Extracellular stimuli (e.g., insulin) catalyze inhibitory Ser9-phosphorylation of GSK-3β, turning on signaling and causing other biological consequences otherwise constitutively suppressed by GSK-3β. Regulated and dysregulated activities of GSK-3β are pivotal to health, disease, and therapeutics (e.g., insulin resistance, neurodegeneration, tumorigenesis, inflammation); however, the underlying mechanisms of multifunctional GSK-3β remain elusive. In cultured bovine adrenal chromaffin cells, 1) constitutive and negatively-regulated activities of GSK-3β up- and down-regulated insulin receptor, insulin receptor substrate-1 (IRS-1), IRS-2, and Akt levels via controlling proteasomal degradation and protein synthesis; 2) nicotinic receptor/protein kinase C-α (PKC-α) / extracellular signal-regulated kinase (ERK) pathway up-regulated IRS-1 and IRS-2 levels, enhancing insulin-induced the phosphoinositide 3-kinase (PI3K) / Akt / GSK-3β pathway; 3) inhibition of calcineurin by cyclosporin A or FK506 down-regulated IRS-2 level, attenuating insulin-like growth factor-I (IGF-I)-induced ERK and GSK-3β pathways; and 4) insulin, IGF-I or therapeutics (e.g., lithium) up-regulated the voltage-dependent Nav1.7 sodium channel.
Although reperfusion is required to salvage ischemic myocardium from necrosis, reperfusion per se induces myocardial necrosis. In this “lethal reperfusion injury”, opening of the mitochondrial permeability transition pore (mPTP) upon reperfusion is crucially involved. The mPTP primarily consists of adenine nucleotide translocator (ANT) and voltage-dependent anion channel, and its opening is triggered by binding of cyclophilin-D (CyP-D) to ANT, which increases Ca2+ sensitivity of the mPTP. Recent studies have shown that inactivation of glycogen synthase kinase-3β (GSK-3β) suppresses mPTP opening and protects cardiomyocytes. Multiple intracellular signals relevant to cardiomyocyte protection converge to GSK-3β and inactivate this kinase by phosphorylation. Although the effect of GSK-3β phosphorylation on mPTP structure and function remains unclear, suppression of ANT–CyP-D interaction by binding of phospho-GSK-3β to ANT and reduction in GSK-3β–mediated phosphorylation of p53 may contribute to elevation of the threshold for mPTP opening. Furthermore, a significant inverse correlation was observed between level of phospho-GSK-3β at the time of reperfusion and the extent of myocardium infarction in heart. Together with the infarct size–limiting effect of GSK-3β inhibitors, this finding indicates that phospho-GSK-3β is a determinant of myocardial tolerance against reperfusion-induced necrosis. Thus, GSK-3β appears to be a target of novel therapy for cardioprotection upon reperfusion.
Recent advances in stem cell biology have provided new insights that may lead to the development of regeneration therapy in the central nervous system to replenish lost neurons and to reconstitute neural circuits. The strategies for regeneration can be classified into two approaches: i) activation of endogenous neural stem cells and ii) transplantation of donor cells to replace lost cells. In the adult mammalian retina, Müller glia generate new retinal neurons in response to injury. The proliferation and differentiation of Müller glia–derived progenitors can be controlled by both intrinsic and extrinsic factors. Members of the Wnt/β-catenin signaling pathway, such as Wnt receptors and glycogen synthase kinase-3β, may be promising drug targets for neural regeneration. On the other hand, transplantation of photoreceptors or retinal pigment epithelia derived from human embryonic stem cells or induced pluripotent stem cells is also promising. Directed differentiation of pluripotent cells into retinal cells and purification to obtain retinal cells at a specific ontogenetic stage are required for donor cell preparation. Modulation of the host retinal environment to reduce the glial barrier is also critical for transplantation. To restore visual function, we need to understand the mechanisms underlying the integration of newly generated neurons or transplanted cells into the existing neural networks.
Glycogen synthase kinase-3β (GSK-3β) is a constitutively active kinase. Since its activation results in neurofibrillary tangle (NFT) deposits in aged and Alzheimer’s disease (AD) brains, GSK-3β may be inhibited under normal conditions but activated under pathological conditions. Given its link to NFT formation, we sought to determine whether GSK-3β exists in the brain as a “pathological time bomb” that promotes disease development. To address this hypothesis, we analyzed GSK-3β heterozygote (GSK+/−) mice, which express GSK-3β at 50% wild-type levels. When tested in the Morris water maze test, GSK+/− mice surprisingly exhibited retrograde amnesia. Further analysis indicated that GSK+/− mice had impaired memory reconsolidation but normal memory consolidation. Therefore, we concluded that GSK-3β activation is required for memory reconsolidation in the adult brain.
Accumulating evidence suggests that the Wnt/β-catenin signaling pathway is often involved in oncogenesis and cancer development. Accordingly, a novel anticancer drug can be developed using inhibitors of this pathway. However, at present, there is no selective inhibitor of this pathway available as a therapeutic agent. Although all the components of the Wnt/β-catenin signaling pathway can be a target for drug development, glycogen synthase kinase-3β (GSK-3β), in particular, may be a good target because GSK-3β is an essential component of the pathway, and activation of this kinase results in the inhibition of the Wnt signaling pathway. We found that the differentiation-inducing factors (DIFs), putative morphogens for Dictyostelium discoideum, inhibit the Wnt/β-catenin signaling pathway via the activation of GSK-3β, resulting in the cell-cycle arrest of human cancer cell lines. In this review, we summarize our recent findings on the antiproliferative effect of DIFs and show the possibility for development of a novel anticancer drug from DIFs and their derivatives.
The immunophilin 12-kDa FK506 binding protein (FKBP12) stabilizes intracellular Ca2+ release channel (CRC) activity in different tissues. In this work, the presence of FKBP12 in rat vas deferens (RVD) and its possible contribution to RVD function was investigated. Treatment under appropriate pH, temperature, and ionic conditions was used to strip FKBP12 from CRC binding sites; Western blotting revealed FKBP12 in control but not in treated homogenates. Disruption of the FKBP12-CRC complex in RVD decreased the Ca2+ content of sarcoplasmic reticulum (SR) by increasing Ca2+ leakage through the ryanodine receptor (RyR3 isoform) but not through 1,4,5-inositol trisphosphate receptors (IP3R1 and IP3R3 isoforms). The decrease of SR Ca2+ content was not related to inhibition of SERCA ATPase. It seems that dissociation of FKBP12-RyR leads to conformational changes in RyR that make it difficult for ryanodine to access its binding site. Rapamycin, which is commonly used as a pharmacological tool to disrupt the FKBP12-RyR complex, decreased phenylephrine-induced contractions in RVD epididymal halves. The data suggest that FKBP12 is expressed in RVD in a labile association with RyR3. Disruption of the FKBP12-RyR3 complex may lead to modifications of RVD physiology and in consequence may compromise male fertility.
Endothelin-1 (ET-1) modulates cardiac contractility by cross-talk with norepinephrine (NE) in canine ventricular myocardium. The present experiments were performed to investigate the influence of wortmannin that has inhibitory action on phosphatidylinositol 3-kinase (PI3-K) (IC50 = 3 nM) and myosin light chain kinase (MLCK) (IC50 = 200 nM) on Ca2+ signaling and the inotropic effects of ET-1 induced by cross-talk with NE. Experiments were carried out in isolated canine ventricular trabeculae and indo-1/AM–loaded single ventricular cardiomyocytes. ET-1 alone elicited a transient small negative inotropic effect (NIE). In the presence of NE at low (1 – 10 nM) and high (100 nM) concentrations, ET-1 induced a long-lasting positive inotropic effect (PIE) or a marked sustained NIE, respectively. Wortmannin up to 300 nM did not affect the contractility; and at 1 μM and higher, it decreased the basal contraction without suppressing Ca2+ transients. Wortmannin (1 μM) inhibited the long-lasting PIE of ET-1 without affecting the ET-1–induced increase in Ca2+ transients. Wortmannin at the same concentration did not affect the ET-1–induced transient and sustained NIE and the PIE mediated by β-adrenoceptor stimulation. These results imply that wortmannin exerts selective inhibitory action on the increase in myofilament Ca2+ sensitivity induced by cross-talk of ET-1 with NE probably through an inhibition of MLCK in canine ventricular myocardium.
Using ranirestat, an aldose reductase (AR) inhibitor, we investigated the relationship between sorbitol and fructose levels in the sciatic nerve and motor nerve conduction velocity (MNCV) in streptozotocin (STZ)-treated diabetic rats. Ranirestat inhibited rat and recombinant human AR with similar IC50 values and equipotently prevented sorbitol accumulation in rat erythrocytes and sciatic nerves in vitro. One week after STZ administration, sorbitol levels in rat erythrocytes and sciatic nerves significantly increased while MNCV decreased. Oral administration of ranirestat (0.03 – 1.0 mg/kg per day) for 3 weeks dose-dependently decreased the elevated sorbitol and fructose levels in the rat sciatic nerves without affecting blood glucose level. Particularly, at doses of 0.1 mg/kg per day or higher, ranirestat normalized both sorbitol and fructose levels in the sciatic nerves of STZ-treated rats. Ranirestat (0.1 – 1.0 mg/kg per day) also improved the STZ-induced decrease in MNCV in a dose-dependent manner. This improvement correlated with the decrease of sorbitol and fructose levels in the rat sciatic nerves. These findings indicate that ranirestat improves MNCV via normalization of sorbitol and fructose accumulation in the sciatic nerve.
The aim of the present study is to investigate the potential therapeutic action of RvCSd, an oriental herbal mixture, in an experimental model of rheumatoid arthritis (RA). DBA/1J mice were immunized with type II collagen. After a second collagen immunization, mice were treated with RvCSd or methotrexate (MTX) orally once a day for 35 days, and the incidence, clinical score, and joint histopathology were evaluated. The inflammatory response cytokines and cartilage protection effect were determined by measuring the levels in the joints and sera. The Th1/Th2-mediated auto-reactive response was evaluated by determining the proliferative response and cytokines of drained spleen cells stimulated with type II collagen. RvCSd treatment significantly reduced the incidence and severity of CIA, markedly abrogating joint swelling, synovial hyperplasia, and cartilage destruction. RvCSd significantly inhibited the production of interleukin (IL)-1β, tumor necrosis factor (TNF)-α and IL-6, IL-2, interferon (IFN)-γ, and matrix metalloproteinases (MMP)-1 and up-regulated anti-inflammatory cytokines IL-4, IL-10, and metalloproteinase (TIMP)-1 in mice with CIA. In conclusion, RvCSd has therapeutic effects exerted through inhibition of inflammatory and Th1 responses, regulation of MMP/TIMP, and induction of regulatory T cells in CIA; these effects make RvCSd an outstanding candidate for use as an immune suppressive and cartilage protective medicine in RA patients.
The cardioprotective effects of KR-31761, a newly synthesized K+ATP opener, were evaluated in rat models of ischemia/reperfusion (I/R) heart injury. In isolated rat hearts subjected to 30-min global ischemia/30-min reperfusion, KR-31761 perfused prior to ischemia significantly increased both the left ventricular developed pressure (% of predrug LVDP: 17.8, 45.1, 54.2, and 62.6 for the control, 1 μM, 3 μM, and 10 μM, respectively) and double product (DP: heart rate × LVDP; % of predrug DP: 17.5, 44.9, 56.2, and 64.5 for the control, 1 μM, 3 μM, and 10 μM, respectively) at 30-min reperfusion while decreasing the left ventricular end-diastolic pressure (LVEDP). KR-31761 (10 μM) significantly increased the time to contracture during the ischemic period, whereas it concentration-dependently decreased the lactate dehydrogenase release during reperfusion. All these parameters were significantly reversed by 5-hydroxydecanoate (5-HD, 100 μM) and glyburide (1 μM), selective and nonselective blockers of the mitochondrial K+ATP (mitoK+ATP) channel and K+ATP channel, respectively. In anesthetized rats subjected to 30-min occlusion of left anterior descending coronary artery/2.5-h reperfusion, KR-31761 administered 15 min before the onset of ischemia significantly decreased the infarct size (72.2%, 55.1%, and 47.1% for the control, 0.3 mg/kg, i.v., and 1.0 mg/kg, i.v., respectively); and these effects were completely and almost completely abolished by 5-HD (10 mg/kg, i.v.) and HMR-1098, a selective blocker of sarcolemmal K+ATP (sarcK+ATP) channel (6 mg/kg, i.v.) administered 5 min prior to KR-31761 (72.3% and 67.9%, respectively). KR-31761 only slightly relaxed methoxamine-precontracted rat aorta (IC50: >30.0 μM). These results suggest that KR-31761 exerts potent cardioprotective effects through the opening of both mitoK+ATP and sarcK+ATP channels in rat hearts with a minimal vasorelaxant effect.
Glutamate (Glu) is the major excitatory neurotransmitter in the central nervous system. The role of peripheral Glu and Glu receptors (GluRs) in nociceptive transmission is, however, still unclear. In the present study, we examined Glu levels released in the subcutaneous perfusate of the rat hind instep using a microdialysis catheter and the thermal withdrawal latency using the Plantar Test following injection of drugs associated with GluRs with/without capsaicin into the hindpaw. The injection of capsaicin into the rat hind instep caused an increase of Glu level in the s.c. perfusate. Capsaicin also significantly decreased withdrawal latency to irradiation. These effects of capsaicin were inhibited by pretreatment with capsazepine, a transient receptor potential vanilloid receptor 1 (TRPV1) competitive antagonist. Capsaicin-induced Glu release was also suppressed by combination with each antagonist of ionotropic GluRs (iGluRs: NMDA/AMPA receptors) and group I metabotropic GluR (mGluR), but not group II and group III mGluRs. Furthermore, these GluRs antagonists showed remarkable inhibition against capsaicin-induced thermal hyperalgesia. These results suggest that Glu is released from the peripheral endings of small-diameter afferent fibers by noxious stimulation and then activates peripheral iGluRs and group I mGluR in development and/or maintenance of nociception. Furthermore, the activation of peripheral NMDA/AMPA receptors and group I mGluR may be important in mechanisms whereby capsaicin evokes nociceptive responses.
Efavirenz, an important component of human immunodeficiency virus 1 (HIV-1) therapy, causes substantial drug interactions as an inducer of cytochromes and the transporter ABCB1. So far its effect on the expression of other transporters is unknown. We therefore investigated the effect of long-term exposure of cells to efavirenz on expression of a large number of important drug transporters and on cell proliferation as a surrogate of intracellular availability. LS180 cells were used as a surrogate for the major site of drug interactions and Jurkat cells were used as a surrogate for the main target cells of HIV therapy. Cells were treated with efavirenz over 4 weeks and mRNA expression of drug transporters was repeatedly quantified. After 4 weeks, efavirenz significantly up-regulated the mRNA of ABCB1, ABCG2, ABCC2, ABCC3, ABCC5, and SLCO3A1 in LS180 cells and ABCG2, ABCC1, ABCC4, ABCC5, and SLCO2B1 in Jurkat cells. However these changes in transporter expression did not influence cell proliferation indicating that intracellular efavirenz concentrations were likely not altered. Efavirenz induces mRNA expression of several drug transporters critically modulating the kinetics of other drugs. While these expressional changes will most likely not influence the efficiency of efavirenz itself, they might change the effect of other co-administered drugs.
The phenomenon termed postconditioning, that is, brief episodes of ischemia/reperfusion at the onset of reperfusion reduce infarct size, is thought to involve the activation of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway. Treatment with a drug activating PI3K at the onset of reperfusion may confer a similar cardioprotection. The sulfonylurea glimepiride has been shown to activate PI3K in human endothelial cells. We therefore tested in rabbit hearts whether glimepiride can produce postconditioning-mimetic actions. Langendorff-perfused rabbit hearts were subjected to 30 min of global ischemia and 120 min of reperfusion, and infarct size was determined by triphenyltetrazolium staining. Phosphorylation of Akt was analyzed by Western blotting. Glimepiride (10 μM) treatment for the first 10 min of reperfusion significantly reduced infarct size from 67.2 ± 1.3% in controls to 35.8 ± 4.5% (P<0.01). This infarct size–limiting effect of glimepiride was abolished by a selective inhibitor of PI3K (5 μM LY294002, 65.4 ± 3.4%). Phosphorylation of the PI3K substrate Akt was significantly increased in glimepiride-treated hearts when compared to controls (P<0.05). Glimepiride-induced Akt phosphorylation was inhibited by LY294002. In conclusion, our study demonstrates that glimepiride treatment upon reperfusion reduces infarct size in rabbit hearts via a PI3K/Akt-mediated pathway. The postconditioning-mimetic action of glimepiride may be beneficial for the treatment of diabetic patients with ischemic heart disease.
Many epidemiologic studies have reported that dietary flavonoids provide protection against cardiovascular disease. Quercetin, a member of the bioflavonoids family, has been proposed to have anti-inflammatory, anti-atherogenic, and anti-hypertensive properties leading to the beneficial effects against cardiovascular diseases. Recent studies demonstrated that orally administered quercetin appeared in plasma as glucuronide-conjugated forms in rats and humans. Therefore, we examined the effect of chemically synthesized quercetin glucuronide on platelet-derived growth factor (PDGF)-induced cell migration and kinase activation in cultured rat aortic smooth muscle cells (RASMCs). PDGF-induced RASMC migration was inhibited by quercetin 3-O-β-D-glucuronide (Q3GA). Q3GA also attenuated PDGF-induced cell proliferation in RASMCs. PDGF activated extracellular-signal regulated kinase (ERK) 1/2, c-Jun N-terminal kinase (JNK), p38 mitogen-activated protein (MAP) kinase, and Akt in RASMCs. PDGF-induced JNK and Akt activations were suppressed by Q3GA, whereas ERK1/2 and p38 MAP kinase activations were not affected. We also confirmed that PDGF-induced JNK and Akt activations were inhibited by antioxidants, N-acetylcysteine and diphenyleneiodonium chloride, in RASMCs. These findings suggest Q3GA would be an active metabolite of quercetin in plasma and may possess preventing effects for cardiovascular diseases relevant to vascular smooth muscle cell disorders.
In clinical practice, glucocorticoids are often used with the aim of modulating the efficacy and toxicity of chemotherapeutic agents. However, how glucocorticoids modulate the pharmacological action of chemotherapeutic agents remains to be clarified. In this study, we generated glucocorticoid receptor (GR)-deficient rat-1 cells to investigate the role of GR in the regulation of cellular sensitivity to irinotecan hydrochloride (CPT-11). Treatment of wild-type rat-1 cells with dexamethasone (DEX) significantly enhanced the cytotoxic effect of CPT-11, whereas the treatment had little effect on the cytotoxicity of CPT-11 in GR-deficient cells. Topoisomerase-I activity in wild-type cells after concomitant treatment with DEX and CPT-11 was significantly lower than that after treatment with CPT-11 alone. DEX treatment also enhanced the inhibitory action of CPT-11 on the phosphatidylinositol 3-kinase–Akt signaling pathway in wild-type cells, accompanied by facilitating caspase-3 activity. These modulatory effects of DEX on the CPT-11–induced cytotoxicity were not observed in GR-deficient cells. Our present findings reveal the underlying mechanism by which GCs enhance the chemotherapeutic effect of CPT-11 and indicate the possibility that the dosage of CPT-11 could be reduced by the combination treatment with GCs, which may attenuate the adverse effect without decreasing anti-tumor activity. [Supplementary Figures: available only at http://dx.doi.org/10.1254/jphs.08219FP]
In the present study, the effects of long-term angiotensin (Ang) II antagonism on the development of cardiac and endothelial disorders were examined in Spontaneously Diabetic Torii (SDT) rats. Blood glucose concentration started to increase markedly in the untreated SDT rats from 20 weeks of age, while the blood glucose concentrations of candesartan cilexetil–treated SDT rats were significantly lower until 30 weeks of age. Cardiac function deteriorated in SDT rats and was accompanied by severe cardiac fibrosis, cardiac hypertrophy, and microstructural pathologic change in cardiomyocytes. Cardiac function was very well preserved in the age-matched Sprague Dawley (SD) rats, but cardiac fibrosis developed with aging. Candesartan cilexetil treatment improved cardiac structural remodeling and cardiac function in SDT rats. Surprisingly, the degree of cardiac fibrosis in candesartan cilexetil–treated SDT rats was less than that of SD rats. Immunohistological staining confirmed that in addition to collagen deposition, fibroblasts and myofibroblasts were the main cellular components in the cardiac fibrotic areas. The diabetic hearts showed positive staining for ACE, Ang II, and AT1 receptors. SDT rats also showed decreased endothelial function, which was improved with candesartan cilexetil treatment. These findings indicate that Ang II is involved in the development of cardiac dysfunction by accelerating cardiac remodeling and cardiomyocyte damage in the presence of hyperglycemia. On the other hand, although the mechanisms responsible for the cardiac fibrosis that occurs under normal conditions may differ greatly from those responsible for cardiac fibrosis with hyperglycemia, Ang II seems to play an important role in both.
The actions of cysteinyl leukotrienes (CysLTs) are mediated by activating CysLT receptors, CysLT1, and CysLT2. The CysLT1 receptor mediates vascular responses to CysLTs; however, its effect on the proliferation and migration of endothelial cells is not clarified. To determine this effect, we observed proliferation and migration in EA.hy926 cells, a human endothelial cell line, and the involvement of activation of mitogen-activated protein kinases (MAPKs). We found that LTD4 did not affect the proliferation, but significantly stimulated the migration of endothelial cells. LTD4 also induced the phosphorylation of extracellular signal-regulated kinase (ERK) 1/2, but not those of p38 or JNK. The LTD4-induced migration and ERK1/2 phosphorylation were blocked by the CysLT1-receptor antagonist montelukast and the dual antagonist Bay u9773, but not by the CysLT2-receptor antagonist Bay cysLT2; the migration was also inhibited by the ERK1/2 inhibitor U0126. Our findings indicate that LTD4 stimulates the CysLT1 receptor–mediated migration of endothelial cells; this may be regulated by the ERK1/2 pathway.
Articular chondrocytes play an important role in maintaining the structure and function of the cartilage in synovial joints, which is closely influenced by mechanical or osmotic stress. In the present study, isolated rabbit articular chondrocytes were examined during hyposmotic stress using the whole-cell patch-clamp method. When exposed to hyposmotic external solutions (approximately 5% or 32% decrease in osmolarity), isolated rabbit articular chondrocytes exhibited hyposmotic cell swelling, accompanied by the activation of the swelling-activated Cl− current (ICl,swell). ICl,swell was practically time-independent at potentials negative to +50 mV but exhibited rapid inactivation at more positive potentials. ICl,swell was potently inhibited by the Cl− channel blockers 5-nitro-2-(3-phenylpropylamino)benzoic acid, glibenclamide, and tamoxifen, but was little affected by pimozide. ICl,swell was also found to be acutely inhibited by arachidonic acid in a concentration-dependent manner with an IC50 of 0.81 μM. The maximal effect (approximately 100% block) was obtained with 10 μM arachidonic acid. The arachidonic acid metabolites prostaglandin E2, leukotriene B4, and leukotriene D4 had no appreciable effect on ICl,swell, suggesting that the inhibitory effect of arachidonic acid did not require its metabolism. The present study thus reveals the presence of ICl,swell in rabbit articular chondrocytes that exhibits high sensitivity to direct inhibition by arachidonic acid.
Methylglyoxal (MGO) is a metabolite of glucose. In addition to evidence that increased plasma MGO level is associated with diabetic vascular complications, recent studies demonstrated that MGO accumulated in vascular tissues of hypertensive animals. We hypothesized that MGO could directly affect vascular reactivity. To test the hypothesis, we examined effects of MGO on contraction of isolated blood vessels. Treatment of endothelium-denuded rat aorta with MGO (420 μM, 30 min) shifted the concentration–response curve for noradrenaline (NA: 1 nM – 1 μM) to the right. The inhibitory effect was concentration-dependent (MGO: 42 – 420 μM). Indomethacin (10 μM) and cimetidine (30 μM) could not prevent the inhibitory effect of MGO. However, a non-selective K+-channel inhibitor, tetramethylammonium (10 mM), prevented it. Glibenclamide (3 μM), an ATP-sensitive K+-channel inhibitor or apamin (1 μM), a small conductance Ca2+-activated K+-channel inhibitor was ineffective, but iberiotoxin (100 nM), a large conductance Ca2+-activated K+ (BKCa)-channel inhibitor significantly prevented the effect of MGO. MGO (420 μM, 30 min) also inhibited the NA (1 nM – 1 μM)-induced contraction in mesenteric artery. The present results indicate that MGO has an inhibitory effect on contractility of isolated blood vessel, which is mediated via opening smooth muscle BKCa channel.
Activation of the unfolded protein response (UPR) has been suggested to attenuate renal ischemia-reperfusion (I/R) injury. We recently found a compound, namely BIX, that activated the UPR selectively through the activating transcription factor 6 pathway. This study examined the effect of BIX on renal I/R injury in mice. BIX selectively up-regulated renal BiP mRNA and protein. Pretreatment with BIX significantly ameliorated renal I/R injury. Co-administration of BIX and tunicamycin, a non-selective UPR inducer, provided no additional protection. Our results suggest that the UPR activation by BIX leads to a novel drug therapy against renal I/R injury.
The aim of the present study was to evaluate the inmunomodulatory effects of UR-1505, a new salicylate derivative, on the T helper (Th)2 / humoral response produced during dextran sodium sulfate (DSS)-induced rat colitis. In the in vitro studies, UR-1505 (300 μM) inhibited both the production of interleukin (IL)-10 and IL-5 in concanavalin A (Con A)-activated splenocytes and the production of immunoglobulin (Ig) G and IgA by B-lymphocytes. However, in contrast to the in vitro results, the administration of UR-1505 (10 and 30 mg/kg per day) to rats with established DSS-colitis enhanced both IL-10 and IgA production, whereas it inhibited IgG production, thus ameliorating the intestinal inflammation.
We analyzed the expression of 5-HT2 receptors and proteins related to inactivation of 5-HT in primary cultures of mouse osteoblasts. The mRNA for the 5-HT2A receptor was detectable in anaplastic osteoblasts as well as in differentiated and matured osteoblasts. The mRNA for the 5-HT2B receptor and 5-HT transporter was undetectable in anaplastic osteoblasts and became detectable in differentiated and matured osteoblasts. It was suggested that 5-HT might regulate the proliferation of anaplastic osteoblasts through the 5-HT2A receptor without control by 5-HT–inactivating mechanisms. The differentiation and maturation of osteoblasts might be regulated by the activation of the 5-HT2B receptor under the control of 5-HT inactivation.