Increased expression of p38 mitogen- activated protein kinase is related to the acute renal lesions induced by gentamicin

Mitogen-activated protein kinases (MAPK) may be involved in the pathogenesis of acute renal failure. This study investigated the expression of p-p38 MAPK and nuclear factor kappa B (NF-kappaB) in the renal cortex of rats treated with gentamicin. Twenty rats were injected with gentamicin, 40 mg/kg, im, twice a day for 9 days, 20 with gentamicin + pyrrolidine dithiocarbamate (PDTC, an NF-kappaB inhibitor), 14 with 0.15 M NaCl, im, twice a day for 9 days, and 14 with 0.15 M NaCl , im, twice a day for 9 days and PDTC, 50 mg kg-1 day-1, ip, twice a day for 15 days. The animals were killed 5 and 30 days after the last of the injections and the kidneys were removed for histological, immunohistochemical and Western blot analysis and for nitrate determination. The results of the immunohistochemical study were evaluated by counting the p-p38 MAPK-positive cells per area of renal cortex measuring 0.05 mm². Creatinine was measured by the Jaffé method in blood samples collected 5 and 30 days after the end of the treatments. Gentamicin-treated rats presented a transitory increase in plasma creatinine levels. In addition, animals killed 5 days after the end of gentamicin treatment presented acute tubular necrosis and increased nitrate levels in the renal cortex. Increased expression of p-p38 MAPK and NF-kappaB was also observed in the kidneys from these animals. The animals killed 30 days after gentamicin treatment showed residual areas of interstitial fibrosis in the renal cortex, although the expression of p-p38 MAPK in their kidneys did not differ from control. Treatment with PDTC reduced the functional and structural changes induced by gentamicin as well as the expression of p-p38 MAPK and NF-kappaB. The increased expression of p-p38 MAPK and NF-kappaB observed in these rats suggests that these signaling molecules may be involved in the pathogenesis of tubulointerstitial nephritis induced by gentamicin.

Melatonin prevents inflammation and oxidative stress caused by abdominopelvic and total body irradiation of rat small intestine

We investigated the day-night differences in intestinal oxidative-injury and the inflammatory response following total body (TB) or abdominopelvic (AP) irradiation, and the influence of melatonin administration on tissue injury induced by radiation. Rats (male Wistar, weighing 220-280 g) in the irradiated groups were exposed to a dose of 8 Gy to the TB or AP region in the morning (resting period - 1 h after light onset) or evening (activity span - 13 h after light onset). Vehicle or melatonin was administered immediately before, immediately after and 24 h after irradiation (10, 2.0 and 10 mg/kg, ip, respectively) to the irradiated rats. AP (P < 0.05) and TB (P < 0.05) irradiation applied in the morning caused a significant increase in thiobarbituric acid reactive substance (TBARS) levels. Melatonin treatment in the morning (P < 0.05) or evening (P < 0.05) decreased TBARS levels after TB irradiation. After AP irradiation, melatonin treatment only in the morning caused a significant decrease in TBARS levels (P < 0.05). Although we have confirmed the development of inflammation after radiotherapy by histological findings, neither AP nor TB irradiation caused any marked changes in myeloperoxidase activity in the morning or evening. Our results indicate that oxidative damage is more prominent in rats receiving TB and AP irradiation in the morning and melatonin appears to have beneficial effects on oxidative damage irrespective of the time of administration. Increased neutrophil accumulation indicates that melatonin administration exerts a protective effect on AP irradiation-induced tissue oxidative injury, especially in the morning.

Side effects of oxysterols: cytotoxicity, oxidation, inflammation, and phospholipidosis

Oxysterols are 27-carbon atom molecules resulting from autoxidation or enzymatic oxidation of cholesterol. They are present in numerous foodstuffs and have been demonstrated to be present at increased levels in the plasma of patients with cardiovascular diseases and in atherosclerotic lesions. Thus, their role in lipid disorders is widely suspected, and they might also be involved in important degenerative diseases such as Alzheimer's disease, osteoporosis, and age-related macular degeneration. Since atherosclerosis is associated with the presence of apoptotic cells and with oxidative and inflammatory processes, the ability of some oxysterols, especially 7-ketocholesterol and 7β-hydroxycholesterol, to trigger cell death, activate inflammation, and modulate lipid homeostasis is being extensively studied, especially in vitro. Thus, since there are a number of essential considerations regarding the physiological/pathophysiological functions and activities of the different oxysterols, it is important to determine their biological activities and identify their signaling pathways, when they are used either alone or as mixtures. Oxysterols may have cytotoxic, oxidative, and/or inflammatory effects, or none whatsoever. Moreover, a substantial accumulation of polar lipids in cytoplasmic multilamellar structures has been observed with cytotoxic oxysterols, suggesting that cytotoxic oxysterols are potent inducers of phospholipidosis. This basic knowledge about oxysterols contributes to a better understanding of the associated pathologies and may lead to new treatments and new drugs. Since oxysterols have a number of biological activities, and as oxysterol-induced cell death is assumed to take part in degenerative pathologies, the present review will focus on the cytotoxic activities of these compounds, the corresponding cell death signaling pathways, and associated events (oxidation, inflammation, and phospholipidosis).

Stress-induced neuroinflammation: mechanisms and new pharmacological targets

Stress is triggered by numerous unexpected environmental, social or pathological stimuli occurring during the life of animals, including humans, which determine changes in all of their systems. Although acute stress is essential for survival, chronic, long-lasting stress can be detrimental. In this review, we present data supporting the hypothesis that stress-related events are characterized by modifications of oxidative/nitrosative pathways in the brain in response to the activation of inflammatory mediators. Recent findings indicate a key role for nitric oxide (NO) and an excess of pro-oxidants in various brain areas as responsible for both neuronal functional impairment and structural damage. Similarly, cyclooxygenase-2 (COX-2), another known source of oxidants, may account for stress-induced brain damage. Interestingly, some of the COX-2-derived mediators, such as the prostaglandin 15d-PGJ2 and its peroxisome proliferator-activated nuclear receptor PPARγ, are activated in the brain in response to stress, constituting a possible endogenous anti-inflammatory mechanism of defense against excessive inflammation. The stress-induced activation of both biochemical pathways depends on the activation of the N-methyl-D-aspartate (NMDA) glutamate receptor and on the activation of the transcription factor nuclear factor kappa B (NFκB). In the case of inducible NO synthase (iNOS), release of the cytokine TNF-α also accounts for its expression. Different pharmacological strategies directed towards different sites in iNOS or COX-2 pathways have been shown to be neuroprotective in stress-induced brain damage: NMDA receptor blockers, inhibitors of TNF-α activation and release, inhibitors of NFκB, specific inhibitors of iNOS and COX-2 activities and PPARγ agonists. This article reviews recent contributions to this area addressing possible new pharmacological targets for the treatment of stress-induced neuropsychiatric disorders.

Streptozotocin-induced mechanical hypernociception is not dependent on hyperglycemia

Since streptozotocin (STZ)-induced diabetes is a widely used model of painful diabetic neuropathy, the aim of the present study was to design a rational protocol to investigate whether the development of mechanical hypernociception induced by STZ depends exclusively on hyperglycemia. Male Wistar rats (180-200 g; N = 6-7 per group) received a single intravenous injection of STZ at three different doses (10, 20, or 40 mg/kg). Only the higher dose (40 mg/kg) induced a significant increase in blood glucose levels, glucose tolerance and deficiency in weight gain. However, all STZ-treated rats (hyperglycemic or not) developed persistent (for at least 20 days) and indistinguishable bilateral mechanical hypernociception that was not prevented by daily insulin treatment (2 IU twice a day, sc). Systemic morphine (2 mg/kg) but not local (intraplantar) morphine treatment (8 µg/paw) significantly inhibited the mechanical hypernociception induced by STZ (10 or 40 mg/kg). In addition, intraplantar injection of STZ at doses that did not cause hyperglycemia (30, 100 or 300 µg/paw) induced ipsilateral mechanical hypernociception for at least 8 h that was inhibited by local and systemic morphine treatment (8 µg/paw or 2 mg/kg, respectively), but not by dexamethasone (1 mg/kg, sc). The results of this study demonstrate that systemic administration of STZ induces mechanical hypernociception that does not depend on hyperglycemia and intraplantar STZ induces mechanical sensitization of primary sensory neurons responsive to local morphine treatment.

Participation of neuronal nitric oxide synthase in experimental neuropathic pain induced by sciatic nerve transection

Nerve injury leads to a neuropathic pain state that results from central sensitization. This phenomenom is mediated by NMDA receptors and may involve the production of nitric oxide (NO). In this study, we investigated the expression of the neuronal isoform of NO synthase (nNOS) in the spinal cord of 3-month-old male, Wistar rats after sciatic nerve transection (SNT). Our attention was focused on the dorsal part of L3-L5 segments receiving sensory inputs from the sciatic nerve. SNT resulted in the development of neuropathic pain symptoms confirmed by evaluating mechanical hyperalgesia (Randall and Selitto test) and allodynia (von Frey hair test). Control animals did not present any alteration (sham-animals). The selective inhibitor of nNOS, 7-nitroindazole (0.2 and 2 µg in 50 µL), blocked hyperalgesia and allodynia induced by SNT. Immunohistochemical analysis showed that nNOS was increased (48% by day 30) in the lumbar spinal cord after SNT. This increase was observed near the central canal (Rexed’s lamina X) and also in lamina I-IV of the dorsal horn. Real-time PCR results indicated an increase of nNOS mRNA detected from 1 to 30 days after SNT, with the highest increase observed 1 day after injury (1469%). Immunoblotting confirmed the increase of nNOS in the spinal cord between 1 and 15 days post-lesion (20%), reaching the greatest increase (60%) 30 days after surgery. The present findings demonstrate an increase of nNOS after peripheral nerve injury that may contribute to the increase of NO production observed after peripheral neuropathy.

Effect of felodipine on myocardial and renal injury induced by aldosterone-high salt hypertension in uninephrectomized rats

It has been recently shown that calcium channel blockers might have a protective effect on cardiac fibrogenesis induced by aldosterone. The objective of this study was to evaluate the protective effect of felodipine, a dihydropyridine calcium channel blocker, against heart and kidney damage caused by aldosterone-high sodium intake in uninephrectomized rats. Wistar rats were divided into three groups: CNEP (uninephrectomized + 1% NaCl in the drinking water, N = 9); ALDO (same as CNEP group plus continuous infusion of 0.75 µg/h aldosterone, N = 12); ALDOF (same as ALDO group plus 30 mg·kg-1·day-1 felodipine in the drinking water, N = 10). All results were compared with those of age-matched, untreated rats (CTL group, N = 10). After 6 weeks, tail cuff blood pressure was recorded and the rats were killed for histological analysis. Blood pressure (mmHg) was significantly elevated (P < 0.05) in ALDO (180 ± 20) and ALDOF (168 ± 13) compared to CTL (123 ± 12) and CNEP (134 ± 13). Heart damage (lesion scores - median and interquartile range) was 7.0 (5.5-8.0) in ALDO and was fully prevented in ALDOF (1.5; 1.0-2.0). Also, left ventricular collagen volume fraction (%) in ALDOF (2.9 ± 0.5) was similar to CTL (2.9 ± 0.5) and CNEP (3.4 ± 0.4) and decreased compared to ALDO (5.1 ± 1.6). Felodipine partially prevented kidney injury since the damage score for ALDOF (2.0; 2.0-3.0) was significantly decreased compared to ALDO (7.5; 4.0-10.5), although higher than CTL (null score). Felodipine has a protective effect on the myocardium and kidney as evidenced by decreased perivascular inflammation, myocardial necrosis and fibrosis.

Effect of endogenous hydrogen sulfide inhibition on structural and functional renal disturbances induced by gentamicin

Animal models of gentamicin nephrotoxicity present acute tubular necrosis associated with inflammation, which can contribute to intensify the renal damage. Hydrogen sulfide (H2S) is a signaling molecule involved in inflammation. We evaluated the effect of DL-propargylglycine (PAG), an inhibitor of endogenous H2S formation, on the renal damage induced by gentamicin. Male Wistar rats (N = 8) were injected with 40 mg/kg gentamicin (im) twice a day for 9 days, some of them also received PAG (N = 8, 10 mg·kg-1·day-1, ip). Control rats (N = 6) were treated with saline or PAG only (N = 4). Twenty-four-hour urine samples were collected one day after the end of these treatments, blood samples were collected, the animals were sacrificed, and the kidneys were removed for quantification of H2S formation and histological and immunohistochemical studies. Gentamicin-treated rats presented higher sodium and potassium fractional excretion, increased plasma creatinine [4.06 (3.00; 5.87) mg%] and urea levels, a greater number of macrophages/monocytes, and a higher score for tubular interstitial lesions [3.50 (3.00; 4.00)] in the renal cortex. These changes were associated with increased H2S formation in the kidneys from gentamicin-treated rats (230.60 ± 38.62 µg·mg protein-1·h-1) compared to control (21.12 ± 1.63) and PAG (11.44 ± 3.08). Treatment with PAG reduced this increase (171.60 ± 18.34), the disturbances in plasma creatinine levels [2.20 (1.92; 4.60) mg%], macrophage infiltration, and score for tubular interstitial lesions [2.00 (2.00; 3.00)]. However, PAG did not interfere with the increase in fractional sodium excretion provoked by gentamicin. The protective effect of PAG on gentamicin nephrotoxicity was related, at least in part, to decreased H2S formation.

Effects of propofol on damage of rat intestinal epithelial cells induced by heat stress and lipopolysaccharides

Gut-derived endotoxin and pathogenic bacteria have been proposed as important causative factors of morbidity and death during heat stroke. However, it is still unclear what kind of damage is induced by heat stress. In this study, the rat intestinal epithelial cell line (IEC-6) was treated with heat stress or a combination of heat stress and lipopolysaccharide (LPS). In addition, propofol, which plays an important role in anti-inflammation and organ protection, was applied to study its effects on cellular viability and apoptosis. Heat stress, LPS, or heat stress combined with LPS stimulation can all cause intestinal epithelial cell damage, including early apoptosis and subsequent necrosis. However, propofol can alleviate injuries caused by heat stress, LPS, or the combination of heat stress and LPS. Interestingly, propofol can only mitigate LPS-induced intestinal epithelial cell apoptosis, and has no protective role in heat-stress-induced apoptosis. This study developed a model that can mimic the intestinal heat stress environment. It demonstrates the effects on intestinal epithelial cell damage, and indicated that propofol could be used as a therapeutic drug for the treatment of heat-stress-induced intestinal injuries.

An interleukin-33/ST2 signaling deficiency reduces overt pain-like behaviors in mice

Interleukin (IL)-33, the most recent member of the IL family of cytokines, signals through the ST2 receptor. IL-33/ST2 signaling mediates antigen challenge-induced mechanical hyperalgesia in the joints and cutaneous tissues of immunized mice. The present study asked whether IL-33/ST2 signaling is relevant to overt pain-like behaviors in mice. Acetic acid and phenyl-p-benzoquinone induced significant writhing responses in wild-type (WT) mice; this overt nociceptive behavior was reduced in ST2-deficient mice. In an antigen-challenge model, ST2-deficient immunized mice had reduced induced flinch and licking overt pain-like behaviors. In the formalin test, ST2-deficient mice also presented reduced flinch and licking responses, compared with WT mice. Naive WT and ST2-deficient mice presented similar responses in the rota-rod, hot plate, and electronic von Frey tests, indicating no impairment of motor function or alteration in basal nociceptive responses. The results demonstrate that IL-33/ST2 signaling is important in the development of overt pain-like behaviors.

Ziyuglycoside II-induced apoptosis in human gastric carcinoma BGC-823 cells by regulating Bax/Bcl-2 expression and activating caspase-3 pathway

Ziyuglycoside II is an active compound of Sanguisorba officinalis L. that has anti-inflammation, antioxidation, antibiosis, and homeostasis properties. We report here on the anticancer effect of ziyuglycoside II on human gastric carcinoma BGC-823 cells. We investigated the effects of ziyuglycoside II on cell growth, cell cycle, and cell apoptosis of this cell line. Our results revealed that ziyuglycoside II could inhibit the proliferation of BGC-823 cells by inducing apoptosis but not cell cycle arrest, which was associated with regulation of Bax/Bcl-2 expression, and activation of the caspase-3 pathway. Our study is the first to report the antitumor potential of ziyuglycoside II in BGC-823 gastric cancer cells. Ziyuglycoside II may become a potential therapeutic agent against gastric cancer in the future.

Edaravone protects endotoxin-induced liver injury by inhibiting apoptosis and reducing proinflammatory cytokines

Studies have shown that edaravone may prevent liver injury. This study aimed to investigate the effects of edaravone on the liver injury induced by D-galactosamine (GalN) and lipopolysaccharide (LPS) in female BALB/c mice. Edaravone was injected into mice 30 min before and 4 h after GalN/LPS injection. The survival rate was determined within the first 24 h. Animals were killed 8 h after GalN/LPS injection, and liver injury was biochemically and histologically assessed. Hepatocyte apoptosis was measured by TUNEL staining; proinflammatory cytokines [tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6)] in the liver were assayed by ELISA; expression of caspase-8 and caspase-3 proteins was detected by Western blot assay; and caspase-3 activity was also determined. Results showed that GalN/LPS induced marked elevations in serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT). Edaravone significantly inhibited elevation of serum AST and ALT, accompanied by an improvement in histological findings. Edaravone lowered the levels of TNF-α and IL-6 and reduced the number of TUNEL-positive cells. In addition, 24 h after edaravone treatment, caspase-3 activity and mortality were reduced. Edaravone may effectively ameliorate GalN/LPS-induced liver injury in mice by reducing proinflammatory cytokines and inhibiting apoptosis.

Treatment with 1,25(OH)2D3induced HDAC2 expression and reduced NF-κB p65 expression in a rat model of OVA-induced asthma

Recent evidence indicates that a deficiency of 1,25-dihydroxyvitamin D3 (1,25[OH]2D3) may influence asthma pathogenesis; however, its roles in regulating specific molecular transcription mechanisms remain unclear. We aimed to investigate the effect of 1,25(OH)2D3 on the expression and enzyme activity of histone deacetylase 2 (HDAC2) and its synergistic effects with dexamethasone (Dx) in the inhibition of inflammatory cytokine secretion in a rat asthma model. Healthy Wistar rats were randomly divided into 6 groups: control, asthma, 1,25(OH)2D3 pretreatment, 1,25(OH)2D3 treatment, Dx treatment, and Dx and 1,25(OH)2D3 treatment. Pulmonary inflammation was induced by ovalbumin (OVA) sensitization and challenge (OVA/OVA). Inflammatory cells and cytokines in the bronchoalveolar lavage (BAL) fluid and histological changes in lung tissue were examined. Nuclear factor kappa B (NF-κB) p65 and HDAC2 expression levels were assessed with Western blot analyses and quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR). Enzyme activity measurements and immunohistochemical detection of HDAC2 were also performed. Our data demonstrated that 1,25(OH)2D3 reduced the airway inflammatory response and the level of inflammatory cytokines in BAL. Although NF-κB p65 expression was attenuated in the pretreatment and treatment groups, the expression and enzyme activity of HDAC2 were increased. In addition, 1,25(OH)2D3 and Dx had synergistic effects on the suppression of total cell infusion, cytokine release, and NF-κB p65 expression, and they also increased HDAC2 expression and activity in OVA/OVA rats. Collectively, our results indicated that 1,25(OH)2D3might be useful as a novel HDAC2 activator in the treatment of asthma.

Promoting inflammatory lymphangiogenesis by vascular endothelial growth factor-C (VEGF-C) aggravated intestinal inflammation in mice with experimental acute colitis

Angiogenesis and lymphangiogenesis are thought to play a role in the pathogenesis of inflammatory bowel diseases (IBD). However, it is not understood if inflammatory lymphangiogenesis is a pathological consequence or a productive attempt to resolve the inflammation. This study investigated the effect of lymphangiogenesis on intestinal inflammation by overexpressing a lymphangiogenesis factor, vascular endothelial growth factor-C (VEGF-C), in a mouse model of acute colitis. Forty eight-week-old female C57BL/6 mice were treated with recombinant adenovirus overexpressing VEGF-C or with recombinant VEGF-C156S protein. Acute colitis was then established by exposing the mice to 5% dextran sodium sulfate (DSS) for 7 days. Mice were evaluated for disease activity index (DAI), colonic inflammatory changes, colon edema, microvessel density, lymphatic vessel density (LVD), and VEGFR-3mRNA expression in colon tissue. When acute colitis was induced in mice overexpressing VEGF-C, there was a significant increase in colonic epithelial damage, inflammatory edema, microvessel density, and neutrophil infiltration compared to control mice. These mice also exhibited increased lymphatic vessel density (73.0±3.9 vs 38.2±1.9, P<0.001) and lymphatic vessel size (1974.6±104.3 vs 1639.0±91.5, P<0.001) compared to control mice. Additionally, the expression of VEGFR-3 mRNA was significantly upregulated in VEGF-C156S mice compared to DSS-treated mice after induction of colitis (42.0±1.4 vs 3.5±0.4, P<0.001). Stimulation of lymphangiogenesis by VEGF-C during acute colitis promoted inflammatory lymphangiogenesis in the colon and aggravated intestinal inflammation. Inflammatory lymphangiogenesis may have pleiotropic effects at different stages of IBD.