Pentoxifylline contributes to the hepatic cytoprotective process in rats undergoing hepatic ischemia and reperfusion injury

Glucagon-like peptide-2 exhibits protective effect on hepatic ischemia-reperfusion injury in rats

Glucagon-like peptide-2 (GLP-2) has potent anti-inflammatory effects and protects against experimental ischemia/reperfusion (I/R) injury in pulmonary, intestinal, and myocardial tissue. However, its protective abilities against I/R injury in the liver are unknown. We investigated the potential role of GLP-2 pretreatment on hepatic I/R injury in rats. A total of 24 rats were randomly divided into three groups (n = 8). The first group was the control group; the second group was the vehicle-treated hepatic ischemia/reperfusion (HIR, vehicle saline-treated) group; and the third group was the GLP-2 pretreated I/R (GLP2-IR) group. Each rat in the third group was intraperitoneally administered 5 µg GLP-2 for 5 d before the procedure. A portal triad was created to induce ischemia with a vascular atraumatic clamp. After 40 min, the clamp was released to initiate hepatic reperfusion for 6 h. Blood samples and tissue specimens from the liver were obtained. Alanine aminotransferase, aspartate aminotransferase, and total bilirubin levels significantly increased in the salinetreated HIR group (P < 0.001), whereas GLP-2 pretreatment significantly decreased their levels (P < 0.01). Our data suggested that GLP-2 pretreatment may have a protective effect on liver I/R injury. However, dose-response studies are necessary to determine the most effective dose.

Pentoxifylline in liver ischemia and reperfusion

Pentoxifylline is a methylxanthine compound which was first filed in 1973 and registered in 1974 in the United States by Sanofi-Aventis Deustchland Gmbh for the treatment of intermittent claudication for chronic occlusive arterial disease. This methylxanthine was later discovered to be a phosphodiesterase inhibitor. Furthermore, its hemorheological properties and its function as an inhibitor of inflammatory cytokines, like TNF-α, allowed researchers to study its effects in organ ischemia and reperfusion and transplantation. Although this drug has demonstrated beneficial effects, the mechanisms by which Pentoxifylline exerts a protective effect are not fully understood. This paper focuses on reviewing the literature to define the effect of Pentoxifylline when used in liver ischemia and reperfusion injury. Our research shows different animal models in which Pentoxifylline has been used as well as different doses and time of administration, as the ideal dose and timing have not yet been ascertained in liver ischemia and reperfusion. In conclusion, Pentoxifylline has shown positive effects in liver ischemia and reperfusion injury, and the main mechanism seems to be associated with the inhibition of TNF-α.

Intraportal versus Systemic Pentoxifylline Infusion after Normothermic Liver Ischemia: Effects on Regional Blood Flow Redistribution and Hepatic Ischemia-Reperfusion Injury. HPB Surg. 2013;2013:689835. [PMID: 24072955 PMCID: PMC3773430 DOI: 10.1155/2013/689835]

Pentoxifylline (PTX) has been shown to have beneficial effects on microcirculatory blood flow. In this study we evaluate the potential hemodynamic and metabolic benefits of PTX during hepatic ischemia. We also test the hypothesis that portal PTX infusion can minimize the I/R injury when compared to systemic infusion. Methods. Twenty-four dogs (18.1 ± 0.7 kg) were subjected to portal triad occlusion (PTO) for 45 min. The animals were assigned to 3 groups: CT (control, PTO, n = 8), PTX-syst (PTO + 25 mg/Kg of PTX IV, n = 8), and PTX-pv (PTO + 25 mg/Kg of PTX in the portal vein, n = 8). Animals were followed for 120 min. Systemic hemodynamics, gastrointestinal tract perfusion, oxygen-derived variables, and liver enzymes were evaluated throughout the experiment. Results. Animals treated with PTX presented significantly higher CO in the first hour after reperfusion, when compared to the CT (~3.7 vs. 2.1 L/min, P < 0.05). Alanine aminotransferase (ALT) was similar in the PTX groups two hours after reperfusion but significantly higher in the CT (227 vs. ~64 U/L, P < 0.05). Conclusion. PTX infusion was associated with hemodynamic benefits and was able to minimize liver injury during normothermic hepatic I/R. However, local PTX infusion was not associated with any significant advantage over systemic route.

Effects of intravenous administration of pentoxifylline in pancreatic ischaemia-reperfusion injury

BACKGROUND

Therapeutic strategies to reduce the occurrence of pancreatic ischaemia-reperfusion (I-R) injury might improve outcomes in human pancreas and kidney transplantation. In addition to its haemorrheologic effects, pentoxifylline has an anti-inflammatory effect by inhibiting NF-κB activation. This group has previously demonstrated that pentoxifylline induces an anti-inflammatory response in acute pancreatitis and liver I-R models. This led to the hypothesis that pentoxifylline might reduce pancreatic and renal lesions and the systemic inflammatory response in pancreatic I-R injury. The aim of this experimental study was to evaluate the effect of pentoxifylline administration in a rat model of pancreatic I-R injury.

METHODS

Pancreatic I-R was performed in Wistar rats over 1 h by clamping the splenic vessels. The animals submitted to I-R were divided into two groups: Group 1 (n = 20, control) rats received saline solution administered i.v. at 45 min after ischaemia, and Group 2 (n = 20) rats received pentoxifylline (25 mg/kg) administered i.v. at 45 min after ischaemia. Blood samples were collected to enable the determination of amylase, creatinine, tumour necrosis factor-α (TNF-α), interleukin-6 (IL-6) and IL-10. Pancreatic malondialdehyde (MDA) content, pancreas histology and pulmonary myeloperoxidase (MPO) were also assessed.

RESULTS

Significant reductions in serum TNF-α, IL-6 and IL-10 were observed in Group 2 compared with Group 1 (P < 0.05). No differences in pancreatic MDA content or serum amylase levels were observed between the two groups. The histologic score was significantly lower in pentoxifylline-treated animals, denoting less severe pancreatic histologic damage.

CONCLUSIONS

Pentoxifylline administration reduced the systemic inflammatory response, the pancreatic histological lesion and renal dysfunction in pancreatic I-R injury and may be a useful tool in pancreas and kidney transplantation.

Pretreatment with pentoxifylline attenuates lung injury induced by intestinal ischemia/reperfusion in rats

PURPOSE

To investigate the protective effect of pentoxifylline against the lung injury observed after intestinal ischemia (I) followed by a period of reperfusion (R).

METHODS

Twenty-eight male Wistar rats were equally divided into 4 experimental groups and operated under ketamine-xylazine anesthesia. (1) Sham: falsely-operated animals; (2) SS+IR: intestinal ischemia was accomplished by clipping the superior mesenteric artery during 60 minutes, with an administration of a standard volume of saline solution (SS) 5 min before the end of the ischemia period; the clip was then releases or a 120-min period of reperfusion; (3) I+PTX+R: ischemia as above, PTX was administered (25 mg/kg) and the gut reperfused as above; (4) PTX+I+PTX+R: Five minutes before arterial occlusion PTX was administered; the superior mesenteric artery was then clipped for 60 minutes. After 55-min ischemia, an additional dosis of PTX was administered; the clip was removed for reperfusion as above. At the 60th min of reperfusion a third dosis of PTX was administered.

RESULTS

PTX markedly attenuated lung injury as manifested by significant decreases (all P<0.001 as compared with the SS+IR group) of pulmonary wet/dry tissue weight ratio, total protein content, myeloperoxidase activity and tumor necrosis factor-alpha. Moreover, it was apparent that in the group PTX+I+PTX+R the improvements have been even more significant.

CONCLUSION

PTX exerted a protective effect on the lung from the injuries caused by intestinal ischemia/reperfusion.

Pharmacological modulation of oxidative stress response in minimally invasive surgery: systematic review

This systematic review aims to synthesize the data on the effectiveness of pharmacological modulation of stress response in minimally invasive surgery. Eligible trials were clinical trials randomized or not or experimental trials that investigated the effect of pharmacological agents on modulation of surgical stress response to minimally invasive surgery. No clinical trials were identified. Eight experimental trials met the inclusion criteria and were obtained in full text. Experimental models were rats or rabbits subjected to pneumoperitoneum, or pneumoretroperitoneum, not to a whole operation. Pharmacological modulation of surgical stress response was attempted with erythromycin, melatonin, mesna, verapamil, pentoxifylline, N-acetylcysteine, and zinc. All the pharmacological agents, except pentoxifylline, seemed to reduce oxidative stress markers. However, only mesna pretreatment prevented oxidative stress, because oxidative stress markers remained in the sham levels. Contrasting data were obtained for pentoxyphilline. In conclusion, available data suggest that pharmacological modulation of surgical stress response to minimally invasive surgery might be feasible.

The effect of pentoxifylline on oxidative stress in CO2 pneumoperitoneum

BACKGROUND

Carbon dioxide (CO(2)) pneumoperitoneum induces peritoneal oxidative stress. This experimental, randomized, controlled study was designed to investigate the effect of pentoxifylline on oxidative stress induced by CO(2 )pneumoperitoneum.

METHODS

For this study, 36 Swiss albino rats were randomized into three groups. Arteria, vena femoralis, and peritoneal cavity were cannulated after anesthesia. The arterial pH, partial arterial oxygen pressure (PaO(2)), venous PO(2), arterial and venous PO(2) difference (P((a-v))O(2)), serum aspartate aminotransferase (AST), serum alanine aminotransferase (ALT), and thiobarbituric acid-reactive substances (TBARS) were studied at the end of the first and second hours in group 1 (control). In group 2, 1 cc isotonic NaCl was injected into peritoneal cavity and then CO(2) pneumoperitoneum was established. At the end of the first hour of insufflation and one hour after desufflation, the same parameters as in group 1 were studied. In group 3, the CO(2) pneumoperitoneum plus pentoxifylline group, all procedures as in group 2 were repeated, with the exception of pentoxifylline (50 mg/kg) injected in place of saline.

RESULTS

At the end of the first hour, P((a-v))O(2 )value in group 2 was significantly less than in the control group (group 1) and group 3 (p \ 0.05). There were no significant differences in PaO(2, )pH, AST, and ALT values between groups (p [ 0.05). TBARS level in group 1 was significantly lower than in the other groups, but there was no significant difference in TBARS level between groups 2 and 3. At the end of the second hour, TBARS level in group 3 was significantly lower than in group 2 (p \ 0.05).

CONCLUSIONS

Pentoxifylline may reduce the oxidative injury following laparoscopic procedures.

Pentoxifylline inhibits liver expression of tumor necrosis factor alpha mRNA following normothermic ischemia-reperfusion

BACKGROUND

Pentoxifylline (PTX) has been shown to reduce hepatic injury after normothermic ischemia and reperfusion (I-R) in rat liver.

AIM

The aim of this study was to evaluate the effects of PTX on liver expression of tumor necrosis factor alpha (TNFalpha) mRNA following normothermic liver I-R.

MATERIALS AND METHODS

A segmental normothermic ischemia of the liver was induced in male Lewis rats by occluding the blood vessels including the bile duct to the median and left lateral lobes for 90 min. At the end of ischemia the nonischemic liver lobes were resected. Rats were divided into three groups: group 1, control Ringer lactate administration; group 2, PTX treatment; group 3, sham-operated control rats. PTX (50 mg/kg) was injected intravenously 30 min before and 60 min after induction of ischemia. Survival rates were compared and the serum activities of TNFalpha, serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH) were measured. Histology of the liver was assessed 6 h after reperfusion. Liver TNFalpha mRNA was assessed by PCR amplification at 0, 60, 120, and 210 min after reperfusion.

RESULTS

PTX treatment significantly increased 7 day survival (93.3%) compared with nontreated control rats (46.6%, p<0.007). The extent of liver necrosis and the release of liver enzymes were significantly decreased after PTX treatment. Serum activities of TNFalpha were significantly decreased and liver expression of TNFalpha mRNA was inhibited after PTX treatment.

CONCLUSION

PTX protects the liver from ischemic injury and inhibits liver expression of TNFalpha mRNA.

Avaliação bioquímica dos efeitos do pré-condicionamento isquêmico após isquemia e reperfusão hepática em ratos

OBJETIVO: Comparar a lesão hepatocelular ocasionada pelo emprego do pré-condicionamento isquêmico e de duas outras modalidades de clampeamento tríade portal: clampeamento contínuo e intermitente. MÉTODO: Quarenta ratos Wistar foram divididos em quatro grupos de 10 animais cada. No Grupo Sham nenhuma espécie de clampeamento foi adotada. Nos outros três, provocamos isquemia de quarenta minutos por meio do clampeamento do pedículo hepático. No Grupo I esta isquemia foi contínua. No Grupo II, também contínua, mas precedida de cinco minutos de isquemia e 10 minutos de reperfusão (précondicionamento isquêmico). No Grupo III foi realizada isquemia intermitente em ciclos de 10 min de isquemia e cinco minutos de reperfusão. Para avaliar a lesão hepatocelular foi adotada a dosagem de transaminase glutâmico oxalacética (TGO), glutâmico pirúvica (TGP) e lactato desidrogenase (LDH), aferidas no início e no final dos procedimentos. RESULTADOS: Não houve diferença estatística nos valores basais das enzimas estudadas, demonstrando uniformidade nos grupos. Os quatro grupos apresentaram variação significativa de todas as enzimas entre os dois momentos de coleta, porém de forma diferenciada. A variação no Grupo Sham foi menor que a do grupo II. Este foi semelhante ao grupo III e em todos a elevação foi significativamente menor que no grupo I (D do Sham CONCLUSÕES: Em ratos Wistar o clampeamento contínuo do pedículo hepático, precedido de um ciclo de cinco minutos de isquemia e 10 minutos de reperfusão (pré-condicionamento isquêmico) provoca menor lesão hepática do que o clampeamento contínuo e apresenta resultados comparáveis aos obtidos através da utilização do clampeamento intermitente, em fígados normais submetidos a um período de isquemia hepática de 40 minutos e um tempo total de cirurgia de 60 minutos.

Overexpression of phosphodiesterases in experimental autoimmune myasthenia gravis: suppression of disease by a phosphodiesterase inhibitor

Myasthenia gravis (MG) and experimental autoimmune MG (EAMG) are T cell-dependent antibody-mediated autoimmune disorders, in which the nicotinic acetylcholine receptor (AChR) is the major autoantigen. DNA microarray analysis revealed increased levels of several phosphodiesterase (PDE) subtypes in lymph node cells (LNC) and muscles of EAMG rats compared with healthy controls. Quantitative real-time PCR analysis indicated that EAMG is characterized by an increase of PDE subtypes 1, 3, 4, and 7 in LNC and of PDE subtypes 2, 3, 4, and 7 in muscles. Pentoxifylline (PTX), a general PDE inhibitor, inhibited the progression of EAMG when treatment started at either the acute or chronic stages of disease. This suppression was associated with down-regulation of humoral and cellular AChR-specific responses, as well as down-regulation of PDE4, TNF-alpha, IL-18, IL-12, and IL-10 in LNC and of PDEs 1, 4, 7, and TNF-alpha in muscles. The expression of Foxp3, a transcription factor essential for CD4+CD25+ regulatory T cell function, was increased in splenocytes although the number of these cells remained unchanged. PTX also reduced the expression of the endopeptidase cathepsin-l, a marker of muscle damage, in EAMG muscles. This study demonstrates the involvement of PDE regulation in EAMG pathogenesis and suggests that PDE inhibitors may be considered for immunotherapy of MG.

Severe ischemia of the glans penis following circumcision: A successful treatment via pentoxifylline

Severe ischemia or necrosis of glans penis is rare. We report the case of an 11-year-old boy with severe glanular ischemia occurring 24 h after circumcision. This was successfully treated with pentoxifylline injection for 5 days, and while the black color of the glans penis changed to brownish at 48 h, appearances were close to normal at 5 days. The patient did not require any surgical intervention, and was discharged without sequelae. We suggest that pentoxifylline might be considered as a treatment of choice for severe ischemia of glans penis.