DPP-4 inhibition with alogliptin on top of angiotensin II type 1 receptor blockade ameliorates albuminuria via up-regulation of SDF-1α in type 2 diabetic patients with incipient nephropathy.

Dipeptidyl peptidase-4 (DPP-4) inhibitor is a new class of anti-diabetic drug which exerts its glucose-lowering action by suppressing the degradation of a gut incretin hormone glucagon-like peptide-1 (GLP-1). To elucidate whether treatment with stronger DPP-4 inhibitor on top of angiotensin II type 1 receptor blocker (ARB) provides greater renal protective effects, we performed a crossover study with two DPP-4 inhibitors, sitagliptin and alogliptin, in twelve type 2 diabetic patients with incipient nephropathy taking ARBs. This study consisted of three treatment periods: sitagliptin 50 mg/day for 4 weeks (first period), alogliptin 25 mg/day for 4 weeks (second period), and sitagliptin 50 mg/day for 4 weeks (third period). Significant changes in body mass index, blood pressure, serum lipids, serum creatinine, estimated glomerular filtration rate, and HbA1c were not observed among the three treatment periods. Reduced urinary levels of albumin and an oxidative stress marker 8-hydroxy-2'-deoxyguanosine (8-OHdG), increased urinary cAMP levels, and elevated plasma levels of stromal cell-derived factor-1α (SDF-1α) which is a physiological substrate of DPP-4 were observed after the switch from sitagliptin to a stronger DPP-4 inhibitor alogliptin. Given a large body of evidence indicating anti-oxidative action of cAMP and up-regulation of cellular cAMP production by SDF-1α, the present results suggest that more powerful DPP-4 inhibition on top of angiotensin II type 1 receptor blockade would offer additional protection against early-stage diabetic nephropathy beyond that attributed to glycemic control, via reduction of renal oxidative stress by SDF-1α-cAMP pathway activation.

Modulation of renal superoxide dismutase by telmisartan therapy in C57BL/6-Ins2(Akita) diabetic mice.

Renal superoxide excess, which is induced by an imbalance of the superoxide-producing enzyme NAD(P)H oxidase and the superoxide-scavenging enzyme superoxide dismutase (SOD) under hyperglycemia, increases oxidative stress and contributes to the development of diabetic nephropathy. In this study, we treated non-obese and hypoinsulinemic C57BL/6-Ins2(Akita) (C57BL/6-Akita) diabetic mice with telmisartan (5 mg kg(-1) per day), an angiotensin II type 1 receptor blocker, or amlodipine (5 mg kg(-1) per day), a calcium channel blocker, for 4 weeks and compared the effects of these two anti-hypertensive drugs on renal NAD(P)H oxidase, SOD and transcription factor Nrf2 (NF-E2-related factor 2), which is known to upregulate several antioxidant enzymes including SOD. Vehicle-treated C57BL/6-Akita mice exhibited higher renal NAD(P)H oxidase and lower renal SOD activity with increased levels of renal superoxide than the C57BL/6-wild-type non-diabetic mice. Interestingly, telmisartan treatment not only reduced NAD(P)H oxidase activity but also enhanced SOD activity in C57BL/6-Akita mouse kidneys, leading to a reduction of renal superoxide levels. Furthermore, telmisartan-treated C57BL/6-Akita mice increased the renal protein expression of SOD and Nrf2. In parallel with the reduction of renal superoxide levels, a reduction of urinary albumin levels and a normalization of elevated glomerular filtration rate were observed in telmisartan-treated C57BL/6-Akita mice. In contrast, treatment with amlodipine failed to modulate renal NAD(P)H oxidase, SOD and Nrf2. Finally, treatment of C57BL/6-Akita mice with apocynin, an NAD(P)H oxidase inhibitor, also increased the renal protein expression of SOD and Nrf2. Collectively, our data suggest that NAD(P)H oxidase negatively regulates renal SOD, possibly by downregulation of Nrf2, and that telmisartan could upregulate renal SOD by the suppression of NAD(P)H oxidase and subsequent upregulation of Nrf2, leading to the amelioration of renal oxidative stress and diabetic renal changes.

Reduction of circulating superoxide dismutase activity in type 2 diabetic patients with microalbuminuria and its modulation by telmisartan therapy.

Growing evidence indicates that oxidative stress induced by excessive superoxide has a central role in the pathogenesis of diabetic nephropathy (DN). Telmisartan, one of the currently available angiotensin II type 1 receptor blockers (ARBs), has been shown to exert a more powerful proteinuria (albuminuria) reduction in patients with DN, but whether the prominent renoprotective effect of telmisartan is mediated through enhancing antioxidant defense capacity and reducing oxidative stress has not been fully elucidated. The present study first revealed that the serum activity of superoxide dismutase (SOD) responsible for superoxide removal is reduced in the DN stage of microalbuminuria, but not in normoalbuminuria in type 2 diabetic patients. We next examined the alteration of SOD and oxidative stress following an 8-week treatment with telmisartan (40 mg per day) in 12 type 2 diabetic patients with microalbuminuria. Interestingly, the telmisartan treatment not only reduced the circulating levels of two oxidative stress markers, 8-hydroxy-2'-deoxyguanosine (8-OHdG) and nitrotyrosine (NT), but also enhanced serum SOD activity. Notably, a significant correlation was observed between the increase in serum SOD activity and the reduction in albuminuria. We further compared the anti-oxidative effect of telmisartan with that of losartan, another member of the ARB class, by implementing an 8-week interval crossover treatment with these ARBs in another 12 microalbuminuric type 2 diabetic patients. The patients showed higher serum SOD activity, and lower circulating levels of 8-OHdG and NT, during treatment with telmisartan than with losartan. These results suggest that telmisartan has a more potent antioxidative effect through its ability to enhance SOD activity in type 2 diabetic patients with microalbuminuria.

Small intestinal follicular lymphoma with multiple tumor formations diagnosed by double-balloon enteroscopy.

Follicular lymphoma of the small intestine remains relatively rare, especially in its early stage. Recently, double-balloon endoscopy has enabled observation of the entire small intestine. We describe a case of follicular lymphoma with multiple lesions in the small intestine detected by double-balloon endoscopy. The patient showed multiple whitish granules in descending portion of the duodenum on screening esophagogastroduodenoscopy, which were subsequently diagnosed as follicular lymphoma by immunohistochemistry. Endoscopic examination of the entire small intestine revealed multiple follicular lymphoma tumors in inferior portion of the duodenum and in the proximal jejunum. Double-balloon endoscopy is useful for evaluating tumor distribution of follicular lymphoma.

MEK activation suppresses CPT11-induced apoptosis in rat intestinal epithelial cells through a COX-2-dependent mechanism.

Resistance to chemotherapeutic agents is one of the distinct features of cancer cells. We evaluate the role of activated MEK-ERK signaling in Camptotecin/irinotecan (CPT-11)-induced cell death using constitutively activated MEK1-transfected normal rat intestinal epithelial cells (IEC-caMEK cells). A CPT-11-induced inhibitory concentration of 50% was determined by WST assay. Apoptosis was evaluated by DNA staining and fragmented DNA analysis. Protein expressions were analyzed by western blotting. We also examined the role of cyclooxygenase-2 in the cell systems. IEC-caMEK cells possessed survival advantages compared to control cells. Apoptosis was remarkably suppressed in IEC-caMEK cells. Western blot analysis revealed increased expression of Bcl-2, Bcl-xL, Mcl-1, and COX-2 and decreased expression of Bak in IEC-caMEK cells. The COX-2 selective inhibitor ameliorated the antiapoptotic nature of IEC-caMEK cells. MEK activation suppressed CPT-11-induced apoptosis in IEC-caMEK cells via a COX-2- dependent mechanism. Therefore, MEK-ERK signaling may contribute to the drug-resistant nature of cancer cells.

Protective effect of a novel rice extract against ethanol-induced gastric mucosal injury in rat.

The aim of this study was to investigate the protective action of rice extract on ethanol-induced mucosal damage in vivo and wound healing of epithelial cells in vitro. Also, the effect of rice extract on gastric mucosal prostaglandin E(2) level, HSP72 expression, gastric acid secretion, and contribution of vanilloid receptor-mediated action was studied. In addition, using cultured gastric mucosal cells (RGM-1), the effect of rice extract on cytoprotection and wound healing of epithelial cells was evaluated. Rice extract significantly reduced gastric mucosal damage produced by ethanol in vivo, and heat treatment (80 degrees C, 3 min) of this agent did not alter its protective effect. Rice extract also protected RGM-1 from ethanol-induced damage in a dose-dependent manner. Rice extract accelerated wound healing of gastric epithelial cells. Our results demonstrate that rice extract could be an alternative ulcer treatment that provides cytoprotection and enhancement of wound healing not dependent on acid secretion, prostaglandin E(2) level, HSP72 expression, or vanilloid receptors.

Gene expression profiling following constitutive activation of MEK1 and transformation of rat intestinal epithelial cells.

BACKGROUND: Constitutive activation of MEK1 (caMEK) can induce the oncogenic transformation of normal intestinal epithelial cells. To define the genetic changes that occur during this process, we used oligonucleotide microarrays to determine which genes are regulated following the constitutive activation of MEK in normal intestinal epithelial cells. RESULTS: Microarray analysis was performed using Affymetrix GeneChip and total RNA from doxycycline inducible RIEtiCAMEK cells in the presence or absence of doxycycline. MEK-activation induced at least a three-fold difference in 115 gene transcripts (75 transcripts were up-regulated, and 40 transcripts were down-regulated). To verify whether these mRNAs are indeed regulated by the constitutive activation of MEK, RT-PCR analysis was performed using the samples from caMEK expressing RIE cells (RIEcCAMEK cells) as well as RIEtiCAMEK cells. The altered expression level of 69 gene transcripts was confirmed. Sixty-one of the differentially expressed genes have previously been implicated in cellular transformation or tumorogenesis. For the remaining 8 genes (or their human homolog), RT-PCR analysis was performed on RNA from human colon cancer cell lines and matched normal and tumor colon cancer tissues from human patients, revealing three novel targets (rat brain serine protease2, AMP deaminase 3, and cartilage link protein 1). CONCLUSION: Following MEK-activation, many tumor-associated genes were found to have significantly altered expression levels. However, we identified three genes that were differentially expressed in caMEK cells and human colorectal cancers, which have not been previously linked to cellular transformation or tumorogenesis.

Expression of HSP72 in the gastric mucosa is regulated by gastric acid in rats-correlation of HSP72 expression with mucosal protection.

BACKGROUND AND AIM: The real mechanism of adaptive cytoprotection in the gastric mucosa is not well established. In the present study, we investigated the effect of acid suppressing agents on a 72-kDa heat shock protein (HSP72) expression, which is known as endogenous cytoprotective factor, in the gastric mucosa. Also, the association of gastric mucosal protective function against HCl-challenge was compared between HSP72-induced and -reduced group. MATERIALS AND METHODS: Expression of HSP72 was measured by Western blotting in the gastric mucosa before and after administration of famotidine or omeprazole. The gastric mucosal protective function against 0.6 N HCl was compared between control group and HSP72-reduced group. Also, the effect of increased expression of gastric HSP72 by additional administration of zinc sulfate or zinc L-carnosine, which is known as HSP72-inducer, on mucosal protective function was studied. RESULTS: HSP72 expression in the gastric mucosa was reduced by acid suppressing agents. The lowest expression level of HSP72 was observed 12 h (famotidine, H2-receptor antagonist) or 48 h (omeprazole, proton pump inhibitor) after administration. The gastric mucosal protective ability against 0.6 N HCl was also reduced when HSP72 expression was decreased by famotidine or omeprazole. This phenomenon was reversed by HSP72 induction by additional administration of zinc derivatives. CONCLUSION: Our results might indicate that the expression of HSP72 in the gastric mucosa is physiologically regulated by gastric acid, and that HSP72 induction could be important in view of mucosal protection especially when HSP72 expression is reduced by administration of acid suppressing agents such as proton pump inhibitor or H2 receptor antagonist.

Systemic stress increases serum leptin level.

BACKGROUND AND AIM: Leptin, the product of the obese (ob) gene, is a circulating peptide mainly synthesized by adipocytes. Leptin inhibits food intake and decreases body weight. A recent report has suggested that the gastric mucosa is also the source of leptin, and that the stomach leptin also contributes to the regulation of the serum leptin level. The aim of the present study was to investigate the effect of water-immersion stress on serum, stomach and adipose tissue leptin levels to understand the relationship between stress and eating behavior. METHODS: Male Sprague-Dawley rats were used in this experiment. The leptin level in the serum, gastric mucosa and adipose tissue was measured using ELISA system before and after the initiation of water-immersion stress. RESULTS: The serum leptin level was significantly increased by water-immersion stress. The peak was observed 9 h after the initiation of the stress (P < 0.01). However, the gastric leptin level significantly decreased 6 and 9 h after the stress. The adipose tissue leptin level significantly increased 3 h after the stress. CONCLUSIONS: The results suggest that changes in serum leptin levels could be associated with stimulation of leptin secretion from the gastric mucosa and leptin production in the adipose tissue by systemic stress and that leptin might be regulated by stress-related events.

Over-expression of 70-kDa heat shock protein confers protection against monochloramine-induced gastric mucosal cell injury.

The major heat shock protein, HSP70, is known to be involved in cytoprotection against environmental stresses mediated by their function as a "molecular chaperone". Monochloramine (NH(2)Cl) is a potent cytotoxic oxidant generated by neutrophil-derived hypochlorous acid and Helicobacter pylori urease-induced ammonia. In this study, to evaluate the cytoprotective effect of HSP70 against NH(2)Cl-induced gastric mucosal cell injury, rat gastric mucosal cells (RGM-1) were stably transfected with pBK-CMV containing the human HSP70 gene (7018-RGM-1) or pBK-CMV alone (pBK-CMV-12) as control cells. These cells were treated with various concentrations of NH(2)Cl. Cell Viability was determined by MTT assay and the direct plasma membrane damage was analyzed by lactate dehydrogenase (LDH) release assay. Apoptosis was determined by DNA fragmentation analysis. NH(2)Cl caused injury to pBK-CMV-12 cells in a concentration-dependent manner. NH(2)Cl-induced gastric cell injury was significantly diminished in HSP70 over-expressing cell line (7018-RGM-1) both necrosis and apoptosis compared to the control cell line (pBK-CMV-12) transfected with CMV vector alone. These result suggest that overexpression of HSP70 plays an important role in protecting gastric cells against NH(2)Cl-induced injury.

Attenuation of gastric mucosal inflammation induced by aspirin through activation of A2A adenosine receptor in rats.

AIM: To determine whether a specific adenosine A(2A) receptor agonist (ATL-146e) can ameliorate aspirin-induced gastric mucosal lesions in rats, and reduce neutrophil accumulation and production of pro-inflammatory cytokines. METHODS: Gastric lesions were produced by oral gavage of aspirin (200 mg/kg) and HCl (0.15 mol/L, 8.0 mL/kg). 4-{3-[6-Amino-9-(5-ethylcarbamoyl-3,4-dihydroxy-tetrahydro-furan-2-yl)-9H-purin-2-yl]-prop-2-ynyl}-cyclohexanecarboxylic acid methyl ester (ATL-146e, 2.5-5 mug/kg, IP) was injected 30 min before the administration of aspirin. Tissue myeloperoxidase (MPO) concentration in gastric mucosa was measured as an index of neutrophil infiltration. Gastric mucosal concentrations of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) were determined by ELISA. Also, we examined the effect of ATL-146e on tissue prostaglandin E2 (PGE2) production and gastric secretion. RESULTS: Intragastric administration of aspirin induced multiple hemorrhagic erosions in rat gastric mucosa. The total length of gastric erosions (ulcer index) in control rats was 29.8+/-7.75 mm and was reduced to 3.8+/-1.42 mm after pretreatment with 5.0 g/kg ATL-146e (P<0.01). The gastric contents of MPO and pro-inflammatory cytokines were all increased after the administration of aspirin and reduced to nearly normal levels by ATL-146e. Gastric mucosal PGE2 concentration was not affected by intraperitoneal injection of ATL-146e. CONCLUSION: The specific adenosine A(2A) receptor agonist, ATL-146e, has potent anti-ulcer effects presumably mediated by its anti-inflammatory properties.

Effect of cilostazol, a selective type-III phosphodiesterase inhibitor, on water-immersion stress-induced gastric mucosal injury in rats.

BACKGROUND: Cilostazol, a specific type-III phosphodiesterase inhibitor, is widely used for the treatment of ischemic symptoms of peripheral vascular disease. Recent studies have reported that the mechanism of cilostazol is related to the suppression of pro-inflammatory cytokine production and improvement of local microcirculation disturbances. The pathogenesis of stress-induced gastric mucosal lesions is characterized by the activation of inflammatory cells and the production of inflammatory cytokines. The effects of cilostazol on the development of gastric mucosal lesions have not been reported. In the present study, we examined the effect of a cilostazol on water-immersion stress-induced gastric mucosal lesions. METHODS: Rats were subjected to water-immersion stress with or without pretreatment with a single intraperitoneal injection of the selective type-III phosphodiesterase inhibitor, cilostazol. We measured the gastric mucosal lesion and the concentrations of myeloperoxidase (MPO), interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), and cytokine-induced neutrophil chemoattractant-1 (GRO/CINC-1), as an index of neutrophil accumulation and pro-inflammatory cytokine production. RESULTS: Cilostazol ameliorated the gastric mucosal injury induced by water-immersion stress (P<0.001). The gastric contents of MPO, TNF-alpha, IL-1beta, and CRO/CINC-1 were all increased after water-immersion stress and were reduced to almost normal levels by cilostazol. CONCLUSIONS: In this study, we demonstrated that a selective type-III phosphodiesterase inhibitor, cilostazol, inhibited stress-induced gastric inflammation and damage via suppressing the production of pro-inflammatory cytokines. Cilostazol may be useful for preventing gastric mucosal lesions.

Oncogenic potential of MEK1 in rat intestinal epithelial cells is mediated via cyclooxygenase-2.

BACKGROUND & AIMS: The mitogen-activated protein kinase/extracellular signal-regulated protein kinase kinase (MEK) pathway plays an important role in the regulation of cell growth and differentiation. Constitutively active components of the MEK signaling cascade can induce oncogenic transformation in many cell systems. Downstream MEK signaling also plays an important role in the regulation of cyclooxygenase-2 (COX-2), which is known to be involved in colorectal cancer. Therefore, we determined the role of COX-2 on the oncogenic potential of MEK1 in nontransformed rat intestinal epithelial cells. METHODS: Constitutively active MEK1 (CA-MEK) mutant transfected rat intestinal epithelial cells were established and tested for their ability to grow in soft agar and form tumors in vivo. The effect of CA-MEK on sodium butyrate (NaB)-induced apoptosis was evaluated by the Annexin V assay. The transcriptional activity and posttranscriptional stability of the COX-2 gene was determined by transient transfection with COX-2 reporter variants and by Northern analysis. To address the role of COX-2 in tumor growth in vivo, xenografted mice were treated with celecoxib (100 mg/kg) or vehicle. RESULTS: CA-MEK transfected RIE-1 and IEC-6 cells formed colonies in soft agar and tumors in nude mice. These cells showed resistance to NaB-induced apoptosis and cell cycle arrest. MEK activation led to increased expression of COX-2, Bcl-X(L), Mcl-1, and phosphorylated Bad and decreased expression of Bak. Along with elevated COX-2 levels, PGI(2) and PGE(2) levels were also increased. Pharmacologic inhibition of COX-2 inhibited MEK-induced tumor growth in vivo through enhanced apoptosis. CONCLUSIONS: COX-2 and its bioactive lipid products may play an important role in MEK-induced transformation.

Rolipram, a specific type IV phosphodiesterase inhibitor, ameliorates aspirin-induced gastric mucosal injury in rats.

Inhibition of type IV phosphodiesterase (PDE IV) activity reduces the production of various proinflammatory cytokine and suppresses neutrophil activation. Nonsteroidal anti-inflammatory drugs such as aspirin induce gastric mucosal lesions. In the pathogenesis of aspirin-induced gastric mucosal lesion, the contributions, of activated inflammatory cells and proinflammatory cytokine production are critical. The specific PDE IV inhibitor rolipram is known to be a potent inhibitor of inflammation by increasing intracellular cyclic AMP in leukocytes. The aim of the present study was to determine whether rolipram can ameliorate aspirin-induced gastric mucosal lesions in rats and whether the agent can inhibit the inrease in neutrophil accumulation and the production of proinflammatory cytokines. Gastric lesions were produced by administration of aspirin (200 mg/kg) and HCI (0.15 N; 8.0 ml/kg). Rolipram was injected 30 min before aspirin administration. The tissue myeloperoxidase concentration in gastric mucosa was measured as an indicat or of neutrophil infiltration. The gastric mucosal concentrations of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) were determined by ELISA. The intragastric administration of aspirin induced multiple hemorrhagic erosions in rat gastric mucosa. Gastric mucosal lesions induced by aspirin were significantly inhibited by treatment with rolipram. The mucosal myeloperoxidase concentration was also suppressed by rolipram. Increases in the gastric content of TNF-alpha and IL-1beta after aspirin administration were inhibited by pretreatment with rolipram. We demonstrated that the specific type IV PDE inhibitor, rolipram, could have a potent antiulcer effect, presumably mediated by its anti-inflammatory properties.

Selective A2A adenosine agonist ATL-146e attenuates acute lethal liver injury in mice.

BACKGROUND: D-Galactosamine (GalN)/lipopolysaccharide (LPS)-induced liver injury is an experimental model of fulminant hepatic failure in which tumor necrosis factor-alpha (TNF-alpha) plays a pivotal role. We examined the effects of a highly selective adenosine A2A receptor agonist (ATL-146e) on GalN/LPS-induced fulminant hepatic failure. METHODS: Mice were given an intraperitoneal dose of GalN (800 mg/g body weight)/LPS (100 ng/g body weight) with and without ATL-146e (0.01 microg/kg) treatment. Liver injury was assessed biochemically and histologically. Also, TNF-alpha levels in the serum were determined. RESULTS: The serum liver enzyme (ALT) level in vehicle-treated mice was 20 960 +/- 2800 IU/ml and was reduced by 63% to 7800 +/- 1670 IU/ml by treatment with 0.01 microg/kg per minute ATL146e, P < 0.05. Treatment with ATL-146e significantly reduced serum TNF-alpha and greatly reduced inflammation assessed by histopathologic examination compared with control mice treated with GalN/LPS. ATL-146e also reduced lethality at 12 h from 65% to 13%. CONCLUSION: The present findings suggest that the highly selective adenosine A2A receptor agonist (ATL-146e) prevents endotoxin-induced lethal liver injury by suppression of TNF-alpha secretion.

Selective adenosine A receptor agonist, ATL-146e, attenuates stress-induced gastric lesions in rats.

BACKGROUND: Activation of adenosine A(2A) receptors reduces the production of various pro-inflammatory cytokines and suppresses neutrophil activation. Water-immersion restraint is well known to cause gastric mucosal lesions due to stress. The pathogenesis of stress-induced gastric mucosal lesions is characterized by activation of inflammatory cells and production of inflammatory cytokines. Agonists of adenosine A(2A) receptors are known to be anti-inflammatory, but the effects of these compounds on the development of gastric mucosal lesions has not been reported. In the present study, the effect of a potent and selective adenosine A(2A) receptor agonist, ATL-146e, on water-immersion stress-induced gastric mucosal lesions was studied. METHODS: Rats were subjected to water-immersion stress with or without pretreatment with a single intraperitoneal injection of a potent and selective agonist of the adenosine A(2A) receptor. The gastric concentrations of myeloperoxidase (MPO), as an index of neutrophil accumulation, and the pro-inflammatory cytokines, tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta), were measured. RESULTS: The total length of gastric erosions (ulcer index) in control rats was 21.6 +/- 3.23 mm and was reduced by 86% to 3.1 +/- 0.83 mm by pretreatment with 5.0 microg/kg ATL146e (P < 0.001). The gastric content of MPO, TNF-alpha and IL-1beta were all increased after water-immersion stress and reduced to near normal levels by ATL-146e. CONCLUSION: A specific adenosine A(2A) agonist inhibits stress-induced gastric inflammation and damage. A(2A) agonist compounds may be useful for preventing ulcers and appear to act by blocking gastric inflammation.

Specific type IV phosphodiesterase inhibitor ameliorates thioacetamide-induced liver injury in rats.

BACKGROUND AND AIMS: Rolipram is a specific type IV phosphodiesterase inhibitor that suppresses the activity of immune cells and the production of pro-inflammatory cytokines. In this study, we assessed the effect of rolipram on acute liver injury using thioacetamide (TAA)-induced liver injury in rats as a model. METHODS: Rats were treated with rolipram (0.5-5 mg/kg, intraperitoneally) or vehicle and injected 30 min later with TAA (100 mg/kg, subcutaneously). Serum transaminase concentrations and tumor necrosis factor-alpha (TNF-alpha), interleukin 1beta (IL-1beta) and growth related oncogene/cytokine-induced neutrophil chemoattractant-1 (GRO/CINC-1) levels were measured and livers were examined for microscopic changes. Dose-dependent protection against TAA liver injury was based on transaminase levels and inflammatory cytokine production, and was measured 9 h after TAA when the peak release of cytokines occurred. RESULT: Rolipram suppressed liver injury based on serum aspartate transaminase (AST), alanine transaminase (ALT) and histology and reduced TNF-alpha, IL-1beta and GRO/CINC-1 levels. Rolipram, at doses of 0.5-5 mg/kg, suppressed serum transaminase and TNF-alpha production in a dose-dependent manner, and these effects were significant at doses of 2.5 and 5 mg/kg. CONCLUSION: In our rodent model of acute liver injury, rolipram clearly reduced liver damage and inhibited pro-inflammatory cytokine production. These results suggest that specific type IV phosphodiesterase inhibitors, such as rolipram, have potent hepatoprotective effects that are associated with suppressing inflammatory cytokine production.