Effects of antioxidants on drug absorption in in vivo intestinal ischemia/reperfusion

Bryostatin-1 attenuates intestinal ischemia/reperfusion-induced intestinal barrier dysfunction, inflammation, and oxidative stress via activation of Nrf2/HO-1 signaling

Bryostatin-1 (Bryo-1) exerts antioxidative stress effects in multiple diseases, and we confirmed that it improves intestinal barrier dysfunction in experimental colitis. Nevertheless, there are few reports on its action on intestinal ischemia/reperfusion (I/R). In this study, we mainly explored the effect of Bryo-1 on intestinal I/R injury and determined the mechanism. C57BL/6J mice underwent temporary superior mesenteric artery (SMA) obturation to induce I/R, on the contrary, Caco-2 cells suffered to oxygen and glucose deprivation/reperfusion (OGD/R) to establish the in vitro model. RAW264.7 cells were stimulated with LPS to induce macrophage inflammation. The drug gradient experiment was used to demonstrate in vivo and in vitro models. Bryo-1 ameliorated the intestinal I/R-induced injury of multiple organs and epithelial cells. It also alleviated intestinal I/R-induced barrier disruption of intestines according to the histology, intestinal permeability, intestinal bacterial translocation rates, and tight junction protein expression results. Bryo-1 significantly inhibited oxidative stress damages and inflammation, which may contribute to the restoration of intestinal barrier function. Further, Bryo-1 significantly activated Nrf2/HO-1 signaling in vivo. However, the deletion of Nrf2 in Caco-2 and RAW264.7 cells attenuated the protective functions of Bryo-1 and significantly abolished the anti-inflammatory effect of Bryo-1 on LPS-induced macrophage inflammation. Bryo-1 protects intestines against I/R-induced injury. It is associated with intestinal barrier protection, as well as inhibition of inflammation and oxidative stress partly through Nrf2/HO-1 signaling.

Cognitive Effects of Astaxanthin Pretreatment on Recovery From Traumatic Brain Injury

Traumatic brain injury (TBI), caused by mechanical impact to the brain, is a leading cause of death and disability among young adults, with slow and often incomplete recovery. Preemptive treatment strategies may increase the injury resilience of high-risk populations such as soldiers and athletes. In this work, the xanthophyll carotenoid Astaxanthin was examined as a potential nutritional preconditioning method in mice (sabra strain) to increase their resilience prior to TBI in a closed head injury (CHI) model. The effect of Astaxanthin pretreatment on heat shock protein (HSP) dynamics and functional outcome after CHI was explored by gavage or free eating (in pellet form) for 2 weeks before CHI. Assessment of neuromotor function by the neurological severity score (NSS) revealed significant improvement in the Astaxanthin gavage-treated group (100 mg/kg, ATX) during recovery compared to the gavage-treated olive oil group (OIL), beginning at 24 h post-CHI and lasting throughout 28 days (p < 0.007). Astaxanthin pretreatment in pellet form produced a smaller improvement in NSS vs. posttreatment at 7 days post-CHI (p < 0.05). Cognitive and behavioral evaluation using the novel object recognition test (ORT) and the Y Maze test revealed an advantage for Astaxanthin administration via free eating vs. standard chow during recovery post-CHI (ORT at 3 days, p < 0.035; improvement in Y Maze score from 2 to 29 days, p < 0.02). HSP profile and anxiety (open field test) were not significantly affected by Astaxanthin. In conclusion, astaxanthin pretreatment may contribute to improved recovery post-TBI in mice and is influenced by the form of administration.

Astaxanthin pretreatment attenuates acetaminophen-induced liver injury in mice

BACKGROUND

Acetaminophen (APAP) is a conventional drug widely used in the clinic because of its antipyretic-analgesic effects. However, accidental or intentional APAP overdoses induce liver injury and even acute liver failure (ALF). Astaxanthin (ASX) is the strongest antioxidant in nature that shows preventive and therapeutic properties, such as ocular protection, anti-tumor, anti-diabetes, anti-inflammatory, and immunomodulatory effects. The aim of present study was to determine whether ASX pretreatment provides protection against APAP-induced liver failure.

METHODS

Male C57BL/6 mice were randomly divided into 7 groups, including control, oil, ASX (30mg/kg or 60mg/kg), APAP and APAP+ASX (30mg/kg or 60mg/kg) groups. Saline, olive oil and ASX were administered for 14days. The APAP and APAP+ASX groups were given a peritoneal injection of 700mg/kg or 300mg/kg APAP to determine the 5-day survival rate and for further observation, respectively. Blood and liver samples were collected to detect alanine transaminase (ALT), aspartate transaminase (AST), inflammation, oxidative stress and antioxidant systems, and to observe histopathologic changes and key proteins in the mitogen-activated protein kinase (MAPK) family.

RESULTS

ASX pretreatment before APAP increased the 5-day survival rate in a dose-dependent manner and reduced the ALT, AST, hepatic necrosis, reactive oxygen species (ROS) generation, lipid peroxidation (LPO), oxidative stress and pro-inflammatory factors. ASX protected against APAP toxicity by inhibiting the depletion of glutathione (GSH) and superoxide dismutase (SOD). Administration of ASX did not change the expression of c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK) and P38. However, phosphorylation of JNK, ERK and P38 was reduced, consistent with the level of tumor necrosis factor alpha (TNF-α) and TNF receptor-associated factor 2 (TRAF2).

CONCLUSION

ASX provided protection for the liver against APAP hepatotoxicity by alleviating hepatocyte necrosis, blocking ROS generation, inhibiting oxidative stress, and reducing apoptosis by inhibiting the TNF-α-mediated JNK signal pathway and by phosphorylation of ERK and P38, which made sense in preventing and treating liver damage.

Efficacy of Astaxanthin for the Treatment of Atopic Dermatitis in a Murine Model

Atopic dermatitis (AD) is a common chronic inflammatory skin disease associated with various factors, including immunological abnormalities and exposure to allergens. Astaxanthin (AST) is a xanthophyll carotenoid that has recently been demonstrated to have anti-inflammatory effects and to regulate the expression of inflammatory cytokines. Thus, we investigated whether AST could improve the dermatitis and pruritus in a murine model of AD using NC/Nga mice. In addition to a behavioral evaluation, the effects of AST on the AD were determined by the clinical skin severity score, serum IgE level, histological analyses of skin, and by reverse transcription-PCR and Western blotting analyses for the expression of inflammation-related factors. AST (100 mg/kg) or vehicle (olive oil) was orally administered once day and three times a week for 26 days. When compared with vehicle-treated group, the administration of AST significantly reduced the clinical skin severity score. In addition, the spontaneous scratching in AD model mice was reduced by AST administration. Moreover, the serum IgE level was markedly decreased by the oral administration of AST compared to that in vehicle-treated mice. The number of eosinophils, total and degranulated mast cells all significantly decreased in the skin of AST-treated mice compared with vehicle-treated mice. The mRNA and protein levels of eotaxin, MIF, IL-4, IL-5 and L-histidine decarboxylase were significantly decreased in the skin of AST-treated mice compared with vehicle-treated mice. These results suggest that AST improves the dermatitis and pruritus in AD via the regulation of the inflammatory effects and the expression of inflammatory cytokines.

Reperfusion in non-occlusive mesenteric ischaemia (NOMI): effectiveness of CT in an emergency setting

OBJECTIVE

To investigate the CT features of reperfusion (presence/absence) in non-occlusive mesenteric ischaemia (NOMI) and their prognostic value in an emergency setting.

METHODS

A revision was undertaken of imaging from 20 patients (16 males/4 females) with a dismissal summary of NOMI. All patients had previously undergone a minimum of one multidetector CT examination, and consequently underwent surgery (n = 8), autopsy (n = 2), angiography (n = 1) or endoscopy (n = 9). An evaluation of the CT scans was conducted to determine vessels, mesentery, bowel and peritoneal cavity features. The superior mesenteric artery (SMA) average diameter of NOMI cases were compared with 30 controlled cases. Kappa, Kolmogorov-Smirnov (K-S) and Fisher's exact tests were used for statistical analysis.

RESULTS

A mean SMA diameter significantly smaller than that of the controlled cases was found for patients with NOMI (K-S test: D = 0.75, p = 3.7 × 10-08). Fisher's exact tests showed a strong connection between the presence of reperfusion and mesenteric fat stranding (p = 0.026), bowel wall thickening (p = 3.2 × 10-05) and a high attenuation of the bowel wall on unenhanced CT images (p = 2.8 × 10-04). A reduction in mortality was significantly linked to the combination of normal mesenteric vessels and wall thickening (p = 0.034).

CONCLUSION

Analysis of not only vessels findings but also mesentery and bowel CT features will support the identification of NOMI with or without a reperfusion event in an emergency setting. A strong correlation between some CT features and lower mortality exists.

ADVANCES IN KNOWLEDGE

CT features of NOMI with or without reperfusion are demonstrated. Correctly assessing the presence of reperfusion in NOMI, may allow better management of these conditions in the emergency setting.

Resveratrol Reduces Morphologic Changes in the Myenteric Plexus and Oxidative Stress in the Ileum in Rats with Ischemia/Reperfusion Injury

BACKGROUND

Intestinal ischemia/reperfusion injury can be caused by surgical procedures and inflammatory bowel disease. It is normally associated with the increased production of free radicals and changes in the enteric nervous system.

AIMS

Given the antioxidant and neuroprotective properties of resveratrol, the present study assessed its influence on oxidative stress in the intestinal wall and the morphology of myenteric neurons in the ileum of rats subjected to ischemia/reperfusion.

METHODS

Resveratrol was orally administered daily at a dose of 10 mg/kg for 5 days. Changes in the ileum response to ischemia after 45 min were investigated followed by 3 h reperfusion. Lipoperoxide and carbonylated protein levels, and the activity of the antioxidant enzymes glutathione reductase, glutathione peroxidase, and glucose-6-phosphate dehydrogenase were measured following ischemia/reperfusion injury.

RESULTS

The density and morphometry of the general neuronal population, nitrergic neurons and glial cells, and morphometry of VIP varicosities in the ileum were also studied. Lipoperoxide and carbonylated protein levels were 171 and 40% higher during the ischemia/reperfusion, respectively, compared to control cohorts, and resveratrol attenuated these values. The glutathione ratio was 64% lower during ischemia/reperfusion, compared to control cohorts. Resveratrol increased the reduced/oxidized glutathione ratio, attenuated the changes in the activity of the antioxidant enzymes and the detrimental morphologic changes caused by ischemia/reperfusion in the general neuronal population and nitrergic neurons.

CONCLUSIONS

Oral treatment with resveratrol reduced the oxidative stress in the ileum and attenuated the morphologic changes that occurred in the myenteric plexus of the ileum in rats subjected to ischemia/reperfusion.

Acute arterial mesenteric ischemia and reperfusion: Macroscopic and MRI findings, preliminary report

AIM: To explore the physiopathology and magnetic resonance imaging (MRI) findings in an animal model of acute arterial mesenteric ischemia (AAMI) with and without reperfusion.

METHODS: In this study, 8 adult Sprague-Dawley rats underwent superior mesenteric artery (SMA) ligation and were then randomly divided in two groups of 4. In group I, the ischemia was maintained for 8 h. In group II, 1-h after SMA occlusion, the ligation was removed by cutting the thread fixed on the back of the animal, and reperfusion was monitored for 8 h. MRI was performed using a 7-T system.

RESULTS: We found that, in the case of AAMI without reperfusion, spastic reflex ileus, hypotonic reflex ileus, free abdominal fluid and bowel wall thinning are present from the second hour, and bowel wall hyperintensity in T2-W sequences are present from the fourth hour. The reperfusion model shows the presence of early bowel wall hyperintensity in T2-W sequences after 1 h and bowel wall thickening from the second hour.

CONCLUSION: Our study has shown that MRI can assess pathological changes that occur in the small bowel and distinguish between the presence and absence of reperfusion after induced acute arterial ischemia.

Mesenteric ischemia: the importance of differential diagnosis for the surgeon

Background

Intestinal ischemia is an abdominal emergency that accounts for approximately 2% of gastrointestinal illnesses. It represents a complex of diseases caused by impaired blood perfusion to the small and/or large bowel including acute arterial mesenteric ischemia (AAMI), acute venous mesenteric ischemia (AVMI), non occlusive mesenteric ischemia (NOMI), ischemia/reperfusion injury (I/R), ischemic colitis (IC). In this study different study methods (US, CT) will be correlated in the detection of mesenteric ischemia imaging findings due to various etiologies.

Methods

Basing on our institutions experience, 163 cases of mesenteric ischemia/infarction from various cases, investigated with CT and undergone surgical treatment were retrospectively evaluated, in particular trought the following findings: presence/absence of arterial/venous obstruction, bowel wall thickness and enhancement, presence/absence of spastic reflex ileus, hypotonic reflex ileus or paralitic ileus, mural and/or portal/mesenteric pneumatosis, abdominal free fluid, parenchymal ischemia/infarction (liver, kidney, spleen).

Results

To make an early diagnosis useful to ensure a correct therapeutic approach, it is very important to differentiate between occlusive (arterial, venous) and non occlusive causes (NOMI). The typical findings of each forms of mesenteric ischemia are explained in the text.

Conclusion

The radiological findings of mesenteric ischemia have different course in case of different etiology. In venous etiology the progression of damage results faster than arterial even if the symptomatology is less acute; bowel wall thickening is an early finding and easy to detect, simplifying the diagnosis. In arterial etiology the damage progression is slower than in venous ischemia, bowel wall thinning is typical but difficult to recognize so diagnosis may be hard. In the NOMI before/without reperfusion the ischemic damage is similar to AAMI with additional involvement of large bowel parenchymatous organs. In reperfusion after NOMI and after AAMI the CT and surgical findings are similar to those of AVMI, and the injured bowel results quite easy to identify. The prompt recognition of each condition is essential to ensure a successful treatment.

Intestinal Ischemia: US-CT findings correlations

Background

Intestinal ischemia is an abdominal emergency that accounts for approximately 2% of gastrointestinal illnesses. It represents a complex of diseases caused by impaired blood perfusion to the small and/or large bowel including acute arterial mesenteric ischemia (AAMI), acute venous mesenteric ischemia (AVMI), non occlusive mesenteric ischemia (NOMI), ischemia/reperfusion injury (I/R), ischemic colitis (IC). In this study different study methods (US, CT) will be correlated in the detection of mesenteric ischemia imaging findings due to various etiologies.

Methods

Basing on experience of our institutions, over 200 cases of mesenteric ischemia/infarction investigated with both US and CT were evaluated considering, in particular, the following findings: presence/absence of arterial/venous obstruction, bowel wall thickness and enhancement, presence/absence of spastic reflex ileus, hypotonic reflex ileus or paralitic ileus, mural and/or portal/mesenteric pneumatosis, abdominal free fluid, parenchymal ischemia/infarction (liver, kidney, spleen).

Results

To make an early diagnosis useful to ensure a correct therapeutic approach, it is very important to differentiate between occlusive (arterial,venous) and nonocclusive causes (NOMI). The typical findings of each forms of mesenteric ischemia are explained in the text.

Conclusion

At present, the reference diagnostic modality for intestinal ischaemia is contrast-enhanced CT. However, there are some disadvantages associated with these techniques, such as radiation exposure, potential nephrotoxicity and the risk of an allergic reaction to the contrast agents. Thus, not all patients with suspected bowel ischaemia can be subjected to these examinations. Despite its limitations, US could constitutes a good imaging method as first examination in acute settings of suspected mesenteric ischemia.

Effect of aminoguanidine on ischemia/reperfusion injury in rat small intestine

Ischemia/reperfusion (I/R) injury is induced by reactive oxygen species (ROS). During intestinal I/R, the amount of nitric oxide (NO), which is a ROS, is increased. In this study, we examined the protection against I/R injury by inhibition of NO generation. Wistar/ST rats were exposed to 1 h of ischemia, followed by reperfusion for 4 h. The rats were intravenously injected with 100 mg/kg aminoguanidine (AG), which is a selective inducible NO synthase (iNOS) inhibitor, for 5 min before ischemia. The increase in NO(2)(-) by intestinal I/R was significantly inhibited by AG 1 h after reperfusion. Moreover, the increase in area under curve of 0 to 1 h after reperfusion (AUC(0-1)) of paracellular marker was inhibited. However, 3 h after reperfusion, the survival ratio of rats was significantly decreased in the intestinal I/R condition with AG. The amount of NO(2)(-) and AUC of 3 to 4 h after reperfusion (AUC(3-4)) of paracellular marker in intestinal I/R groups were increased by AG compared with those in the I/R condition without AG 3 h after reperfusion. These data indicated that AG, which was given by single pre-administration, can clearly inhibit intestinal I/R injury 1 h after reperfusion. However, the injury occurs again 3 h after reperfusion and grows worse.

The effects of green tea polyphenols on drug metabolism

INTRODUCTION

Tea, made from the dried leaves of the plant Camellia sinensis Theaceae, is a very popular beverage consumed worldwide. Recently, green tea extract-based dietary supplements have also been widely consumed for the acclaimed beneficial health effects, such as weight reduction. Although tea consumption is considered to be innocuous, the potential interactions between tea polyphenols and drugs have been demonstrated in studies in vitro and in vivo.

AREAS COVERED

This article reviews the current literature on the chemistry and biotransformation of tea constituents, mainly catechins from green tea. The article also provides a review of their effects on the absorption, efflux, metabolism and elimination of different drugs.

EXPERT OPINION

Tea catechins may bind to certain drugs to affect their absorption and bioactivities. Tea catechins may inhibit the activities of drug-metabolizing enzymes and drug transporters or affect the expression of these proteins, either upregulation or downregulation. Although these effects have been demonstrated in studies in vitro and in animal models, such effects have only been observed in limited cases in humans at common doses of human tea consumption. The ingestion of tea catechins from dietary supplements, which could be in large bullet doses, may produce more profound effects on drug metabolism, and such effects with drugs need to be further investigated.