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Linoleic acid (LA), an n-6 polyunsaturated fatty acid (PUFA), is essential for fetal growth and development. A maternal high LA (HLA) diet alters cardiovascular development in adolescent rats and hepatic function in adult rats in a sex-specific manner. We investigated the effects of an HLA diet on adolescent offspring hepatic lipids and hepatic lipid metabolism gene expression, and the ability of the postnatal diet to alter these effects. Female Wistar Kyoto rats were fed low LA (LLA; 1.44% energy from LA) or high LA (HLA; 6.21% energy from LA) diets during pregnancy and gestation/lactation. Offspring, weaned at postnatal day (PN) 25, were fed LLA or HLA and euthanised at PN40 (n = 6–8). Maternal HLA increased circulating uric acid, decreased hepatic cholesterol and increased hepatic Pparg in males, whereas only hepatic Srebf1 and Hmgcr increased in females. Postnatal (post-weaning) HLA decreased liver weight (% body weight) and increased hepatic Hmgcr in males, and decreased hepatic triglycerides in females. Maternal and postnatal HLA had an interaction effect on Lpl, Cpt1a and Pparg in females. These findings suggest that an HLA diet both during and after pregnancy should be avoided to improve offspring disease risk. [ABSTRACT FROM AUTHOR]

In numerous subtypes of central and peripheral neurons, small and intermediate conductance Ca2+-activated K+ (SK and IK, respectively) channels are important regulators of neuronal excitability. Transcripts encoding SK channel subunits, as well as the closely related IK subunit, are coexpressed in the soma of colonic afferent neurons with receptors for the algogenic mediators ATP and bradykinin, P2X3 and B2, highlighting the potential utility of these channels as drug targets for the treatment of abdominal pain in gastrointestinal diseases such as irritable bowel syndrome. Despite this, pretreatment with the dual SK/IK channel opener SKA-31 had no effect on the colonic afferent response to ATP, bradykinin, or noxious ramp distention of the colon. Inhibition of SK or IK channels with apamin or TRAM-34, respectively, yielded no change in spontaneous baseline afferent activity, indicating these channels are not tonically active. In contrast to its lack of effect in electrophysiological experiments, comparable concentrations of SKA-31 abolished ongoing peristaltic activity in the colon ex vivo. Treatment with the KV7 channel opener retigabine blunted the colonic afferent response to all applied stimuli. Our data therefore highlight the potential utility of KV7, but not SK/IK, channel openers as analgesic agents for the treatment of abdominal pain. NEW & NOTEWORTHY Despite marked coexpression of small (Kcnn1, Kcnn2) and intermediate (Kcnn4) conductance calcium-activated potassium channel transcripts with P2X3 (P2rx3) or bradykinin B2 (Bdkrb2) receptors in colonic sensory neurons, pharmacological activation of these channels had no effect on the colonic afferent response to ATP, bradykinin or luminal distension of the colon. This is in contrast to the robust inhibitory effect of the KV7 channel opener, retigabine. [ABSTRACT FROM AUTHOR]

Purpose: To compare prefrontal cortex oxygenation in recreationally-active women using oral contraceptives (WomenOC; n = 8) to women with a natural menstrual cycle (WomenNC; n = 8) during incremental exercise to exhaustion.Methods: Participants performed incremental cycling to exhaustion to determine lactate threshold 1 (LT1) and 2 (LT2) and peak oxygen uptake (VO2peak). Prefrontal cortex oxygenation was monitored via near-infrared spectroscopy through concentration changes in oxy-haemoglobin (Δ[HbO2]), deoxy-haemoglobin (Δ[HHb]), total-haemoglobin (Δ[tHb]) and tissue saturation index (TSI).Results: 17β-oestradiol and progesterone were lower in WomenOC (35 ± 26; 318 ± 127 pmol·L-1, respectively) than WomenNC (261 ± 156; 858 ± 541 pmol·L-1, respectively). There were no differences in full blood examination results or serum nitric oxide (p > 0.05). However, WomenOC presented lower concentrations in ferric-reducing ability of plasma (- 8%; effect size; ES - 0.52 ± 0.61), bilirubin (- 32%; ES - 0.56 ± 0.62) and uric acid (- 17%; ES - 0.53 ± 0.61). Cardiopulmonary parameters were similar between groups during cycling, including VO2peak (p = 0.99). While there was a significant effect of time on all parameters measured by near-infrared spectroscopy during incremental cycling, there was no effect of OC at LT1, LT2 or exhaustion calculated as a change from baseline (TSI; p = 0.096, Δ[HbO2]; p = 0.143, Δ[HHb]; p = 0.085 and Δ[tHb]; p = 0.226). The change in TSI from LT1 to LT2 was significantly different between groups (WomenNC; mean difference + 2.06%, WomenOC; mean difference - 1.73%; p = 0.003).Conclusion: Prefrontal tissue oxygenation declined at a lower relative exercise intensity in WomenOC as compared to WomenNC, however, this did not influence VO2peak. The results provide the first evidence for variance in the cerebral oxygenation response to exercise, which may be associated with female sex hormones. [ABSTRACT FROM AUTHOR]

Cystic fibrosis (CF), the result of mutations in the CF transmembrane conductance regulator (CFTR), causes essential fatty acid deficiency. The aim of this study was to characterize fatty acid handling in two rodent models of CF; one strain which harbors the loss of phenylalanine at position 508 (Phe508del) in CFTR and the other lacks functional CFTR (510X). Fatty acid concentrations were determined using gas chromatography in serum from Phe508del and 510X rats. The relative expression of genes responsible for fatty acid transport and metabolism were quantified using real-time PCR. Ileal tissue morphology was assessed histologically. There was an age-dependent decrease in eicosapentaenoic acid and the linoleic acid:α-linolenic acid ratio, a genotype-dependent decrease in docosapentaenoic acid (n-3) and an increase in the arachidonic acid:docosahexaenoic acid ratio in Phe508del rat serum, which was not observed in 510X rats. In the ileum, Cftr mRNA was increased in Phe508del rats but decreased in 510X rats. Further, Elvol2, Slc27a1, Slc27a2 and Got2 mRNA were increased in Phe508del rats only. As assessed by Sirius Red staining, collagen was increased in Phe508del and 510X ileum. Thus, CF rat models exhibit alterations in the concentration of circulating fatty acids, which may be due to altered transport and metabolism, in addition to fibrosis and microscopic structural changes in the ileum. [ABSTRACT FROM AUTHOR]

The effective management of visceral pain is a significant unmet clinical need for those affected by gastrointestinal diseases, such as inflammatory bowel disease (IBD). The rational design of novel analgesics requires a greater understanding of the mediators and mechanisms underpinning visceral pain. Interleukin-13 (IL-13) production by immune cells residing in the gut is elevated in IBD, and IL-13 appears to be important in the development of experimental colitis. Furthermore, receptors for IL-13 are expressed by neurons innervating the colon, though it is not known whether IL-13 plays any role in visceral nociception per se. To resolve this, we used Ca2+ imaging of cultured sensory neurons and ex vivo electrophysiological recording from the lumbar splanchnic nerve innervating the distal colon. Ca2+ imaging revealed the stimulation of small-diameter, capsaicin-sensitive sensory neurons by IL-13, indicating that IL-13 likely stimulates nociceptors. IL-13-evoked Ca2+ signals were attenuated by inhibition of Janus (JAK) and p38 kinases. In the lumbar splanchnic nerve, IL-13 did not elevate baseline firing, nor sensitize the response to capsaicin application, but did enhance the response to distention of the colon. In line with Ca2+ imaging experiments, IL-13-mediated sensitization of the afferent response to colon distention was blocked by inhibition of either JAK or p38 kinase signaling. Together, these data highlight a potential role for IL-13 in visceral nociception and implicate JAK and p38 kinases in pronociceptive signaling downstream of IL-13. [ABSTRACT FROM AUTHOR]

Transient receptor ion channel 1 (TRPV1) is a nociceptor involved in visceral hypersensitivity. Aminoglycosides like neomycin are not only potent antibiotics but in vitro data suggest that neomycin also acts as a TRPV1-antagonist and alleviates somatic pain responses. To what extent neomycin reduces visceral hypersensitivity remains unknown. Therefore, we aimed to investigate whether neomycin can inhibit in vivo TRPV1-dependent hypersensitivity responses in two rat models of visceral pain. In the first model rats were pretreated with intraperitoneal (i.p.) capsazepine, the selective TRPV1 antagonist SB-705498, neomycin or vehicle alone and 30 min later instilled with intracolonic TRPV1-activating capsaicin. Likewise, rats were pretreated with 10 days oral neomycin and then subjected to intracolonic capsaicin. The visceromotor response (VMR) to distension was measured before and after capsaicin application. In addition, the VMR to distension was measured in adult maternal separated rats before and after acute stress. Before the 2nd distension protocol these rats were treated with i.p. neomycin, amoxycillin or vehicle alone. Our results showed that capsaicin administration induced an enhanced VMR to distension that was prevented by i.p. capsazepine, SB-705498 and neomycin. Oral neomycin treatment changed bacterial faecal content but could not inhibit capsaicin induced visceral hypersensitivity. In maternal separated rats acute stress induced an enhanced response to distension that was reversed by i.p. neomycin, but not amoxycillin. These data indicate that (i.p.) neomycin can inhibit visceral hypersensitivity to distension in a nonbactericidal manner and suggest that TRPV1-modulation may be involved. [ABSTRACT FROM AUTHOR]

Zadow, EK, Edwards, KH, Kitic, CM, Fell, JW, Adams, MJ, Singh, I, Kundur, A, Johnstone, ANB, Crilly, J, Bulmer, AC, Halson, SL, and, and Wu, SSX. Compression socks reduce running-induced intestinal damage. J Strength Cond Res 36(9): 2461–2464, 2022—Exercise is associated with a reduction in splanchnic blood flow that leads to the disruption of intestinal epithelium integrity, contributing to exercise-induced gastrointestinal syndrome. Strategies that promote intestinal blood flow during exercise may reduce intestinal damage, which may be advantageous for subsequent recovery and performance. This study aimed to explore if exercise-associated intestinal damage was influenced by wearing compression garments, which may improve central blood flow. Subjects were randomly allocated to wear compression socks (n = 23) or no compression socks (control, n = 23) during a marathon race. Blood samples were collected 24 hours before and immediately after marathon and analyzed for intestinal fatty acid–binding protein (I-FABP) concentration as a marker of intestinal damage. The magnitude of increase in postmarathon plasma I-FABP concentration was significantly greater in control group (107%; 95% confidence interval [CI], 72–428%) when compared with runners wearing compression socks (38%; 95% CI, 20–120%; p = 0.046; d = 0.59). Wearing compression socks during a marathon run reduced exercise-associated intestinal damage. Compression socks may prove an effective strategy to minimize the intestinal damage component of exercise-induced gastrointestinal syndrome. [ABSTRACT FROM AUTHOR]

Trenbolone (TREN) is used for anabolic growth-promotion in over 20 million cattle annually and continues to be misused for aesthetic purposes in humans. The current study investigated TREN’s effects on body composition and cardiometabolic risk factors; and its tissue-selective effects on the cardiovascular system, liver and prostate. Male rats ( n = 12) were implanted with osmotic infusion pumps delivering either cyclodextrin vehicle (CTRL) or 2 mg/kg/day TREN for 6 weeks. Dual-energy X-ray Absorptiometry assessment of body composition; organ wet weights and serum lipid profiles; and insulin sensitivity were assessed. Cardiac ultrasound examinations were performed before in vivo studies assessed myocardial susceptibility to ischemia–reperfusion (I/R) injury. Circulating sex hormones and liver enzyme activities; and prostate and liver histology were examined. In 6 weeks, fat mass increased by 34 ± 7% in CTRLs ( p < 0.01). Fat mass decreased by 37 ± 6% and lean mass increased by 11 ± 4% with TREN ( p < 0.05). Serum triglycerides, HDL and LDL were reduced by 62%, 57% and 78% ( p < 0.05) respectively in TREN rats. Histological examination of the prostates from TREN-treated rats indicated benign hyperplasia associated with an increased prostate mass (149% compared to CTRLs, p < 0.01). No evidence of adverse cardiac or hepatic effects was observed. In conclusion, improvements in body composition, lipid profile and insulin sensitivity (key risk factors for cardiometabolic disease) were achieved with six-week TREN treatment without evidence of adverse cardiovascular or hepatic effects that are commonly associated with traditional anabolic steroid misuse. Sex hormone suppression and benign prostate hyperplasia were confirmed as adverse effects of the treatment. [ABSTRACT FROM AUTHOR]

Visceral pain is a leading cause of morbidity in gastrointestinal diseases, which is exacerbated by the gut‐related side‐effects of many analgesics. New treatments are needed and further understanding of the mediators and mechanisms underpinning visceral nociception in disease states is required to facilitate this. The pro‐inflammatory cytokine TNFα is linked to pain in both patients with inflammatory bowel disease and irritable bowel syndrome, and has been shown to sensitize colonic sensory neurons. Somatic, TNFα‐triggered thermal and mechanical hypersensitivity is mediated by TRPV1 signalling and p38 MAPK activity respectively, downstream of TNFR1 receptor activation. We therefore hypothesized that TNFR1‐evoked p38 MAPK activity may also be responsible for TNFα sensitization of colonic afferent responses to the TRPV1 agonist capsaicin, and noxious distension of the bowel. Using Ca2+ imaging of dorsal root ganglion sensory neurons, we observed TNFα‐mediated increases in intracellular [Ca2+] and sensitization of capsaicin responses. The sensitizing effects of TNFα were dependent on TNFR1 expression and attenuated by p38 MAPK inhibition. Consistent with these findings, ex vivo colonic afferent fibre recordings demonstrated an enhanced response to noxious ramp distention of the bowel and bath application of capsaicin following TNFα pre‐treatment. Responses were reversed by p38 MAPK inhibition and absent in tissue from TNFR1 knockout mice. Our findings demonstrate a contribution of TNFR1, p38 MAPK and TRPV1 to TNFα‐induced sensitization of colonic afferents, highlighting the potential utility of these drug targets for the treatment of visceral pain in gastrointestinal disease. Key points: The pro‐inflammatory cytokine TNFα is elevated in gastrointestinal disease and sensitizes colonic afferents via modulation of TRPA1 and NaV1.8 activity. We further develop this understanding by demonstrating a role for p38 MAPK and TRPV1 in TNFα‐mediated colonic afferent sensitization. Specifically, we show that:TNFα sensitizes sensory neurons and colonic afferents to the TRPV1 agonist capsaicin.TNFα‐mediated sensitization of sensory neurons and colonic nociceptors is dependent on TNFR1 expression.TNFα sensitization of sensory neurons and colonic afferents to capsaicin and noxious ramp distension is abolished by inhibition of p38 MAPK.Collectively these data support the utility of targeting TNFα, TNFR1 and their downstream signalling via p38 MAPK for the treatment of visceral pain in gastrointestinal disease. [ABSTRACT FROM AUTHOR]

Circulating bilirubin is associated with reduced serum cholesterol concentrations in humans and in hyperbilirubinaemic Gunn rats. However, mechanisms contributing to hypocholesterolaemia remain unknown. Therefore, this study aimed to investigate cholesterol synthesis, transport and excretion in mutant Gunn rats. Adult Gunn and control rats were assessed for daily faecal sterol excretion using metabolic cages, and water was supplemented with [1‐13C]‐acetate to determine cholesterol synthesis. Bile was collected to measure biliary lipid secretion. Serum and liver were collected for biochemical analysis and for gene/protein expression using RT‐qPCR and western blot, respectively. Additionally, serum was collected and analysed from juvenile rats. A significant interaction of sex, age and phenotype on circulating lipids was found with adult female Gunn rats reporting significantly lower cholesterol and phospholipids. Female Gunn rats also demonstrated elevated cholesterol synthesis, greater biliary lipid secretion and increased total faecal cholesterol and bile acid excretion. Furthermore, they possessed increased hepatic low‐density lipoprotein (LDL) receptor and SREBP2 expression. In contrast, there were no changes to sterol metabolism in adult male Gunn rats. This is the first study to demonstrate elevated faecal sterol excretion in female hyperbilirubinaemic Gunn rats. Increased sterol excretion creates a negative intestinal sterol balance that is compensated for by increased cholesterol synthesis and LDL receptor expression. Therefore, reduced circulating cholesterol is potentially caused by increased hepatic uptake via the LDL receptor. Future studies are required to further evaluate the sexual dimorphism of this response and whether similar findings occur in females with benign unconjugated hyperbilirubinaemia (Gilbert's syndrome). Key points: Female adult hyperbilirubinaemic (Gunn) rats demonstrated lower circulating cholesterol, corroborating human studies that report a negative association between bilirubin and cholesterol concentrations.Furthermore, female Gunn rats had elevated sterol excretion creating a negative intestinal sterol balance that was compensated for by elevated cholesterol synthesis and increased hepatic low‐density lipoprotein (LDL) receptor expression.Therefore, elevated LDL receptor expression potentially leads to reduced circulating cholesterol levels in female Gunn rats providing an explanation for the hypocholesterolaemia observed in humans with elevated bilirubin levels.This study also reports a novel interaction of sex with the hyperbilirubinaemic phenotype on sterol metabolism because changes were only reported in females and not in male Gunn rats.Future studies are required to further evaluate the sexual dimorphism of this response and whether similar findings occur in females with benign unconjugated hyperbilirubinaemia (Gilbert's syndrome). [ABSTRACT FROM AUTHOR]

New findings What is the central question of this study? Does obesity with insulin resistance decrease left ventricular pump function and/or myocardial tolerance to ischaemia in a rodent model of metabolic syndrome, and what mechanisms are involved in these changes?, What is the main finding and its importance? These data suggest that although left ventricular pump function may be maintained with obesity and insulin resistance, the hearts from these animals are more prone to ischaemia-reperfusion injury, which is in part due to changes in the functionality of the myocardial reperfusion injury salvage kinase (RISK) pathway. Interventions/therapies aimed at normalizing RISK pathway function have the potential to normalize myocardial tolerance to ischaemia-reperfusion in patients with the metabolic syndrome., Obesity and its comorbidities (dyslipidaemia, insulin resistance and hypertension) that together constitute the metabolic syndrome are all risk factors for ischaemic heart disease. Although obesity has been reported to be an independent risk factor for congestive heart failure, whether obesity-induced heart failure develops in the absence of increased afterload (induced by hypertension) is not clear. We have previously shown that obesity with insulin resistance decreases myocardial tolerance to ischaemia-reperfusion, but the mechanism for this decreased tolerance remains unclear. We hypothesize that obesity with insulin resistance induces adverse cardiac remodelling and pump dysfunction, as well as adverse changes in myocardial prosurvival reperfusion injury salvage kinase (RISK) pathway signalling to reduce myocardial tolerance to ischaemia-reperfusion. Wistar rats were fed an obesogenic (obese group) or a standard rat chow diet (control group) for 32 weeks. Echocardiography was performed over the 32 weeks before isolated Langendorff-perfused hearts were subjected to 40 min coronary artery ligation followed by reperfusion, and functional recovery (rate-pressure product), infarct size and RISK pathway function were assessed (Western blot analysis). Obesity with insulin resistance increased myocardial lipid accumulation but had no effect on in vivo or ex vivo left ventricular structure/function. Hearts from obese rats had lower reperfusion rate-pressure products (13115 ± 562 beats min−1 mmHg for obese rats versus 17781 ± 1109 beats min−1 mmHg for control rats, P < 0.05) and larger infarcts (36.3 ± 5.6% of area at risk in obese rats versus 14.1 ± 2.8% of area at risk in control rats, P < 0.01) compared with control hearts. These changes were associated with reductions in RISK pathway function, with 30-50 and 40-60% reductions in Akt and glycogen synthase kinase 3 beta (GSK-3β) expression and phosphorylation, respectively, in obese rat hearts compared with control hearts. Total endothelial nitric oxide synthase expression was reduced by 25% in obese rats. We conclude that obesity with insulin resistance had no effect on basal cardiac structure or function but decreased myocardial tolerance to ischaemia-reperfusion. This reduction in ischaemic tolerance was likely to be due to compromised RISK pathway function in obese, insulin-resistant animals. [ABSTRACT FROM AUTHOR]

Abstract: Numerous dietary compounds, ubiquitous in fruits, vegetables and spices have been isolated and evaluated during recent years for their therapeutic potential. These compounds include flavonoid and non-flavonoid polyphenols, which describe beneficial effects against a variety of ailments. The notion that these plant products have health promoting effects emerged because their intake was related to a reduced incidence of cancer, cardiovascular, neurological, respiratory, and age-related diseases. Exposure of the body to a stressful environment challenges cell survival and increases the risk of chronic disease developing. The polyphenols afford protection against various stress-induced toxicities through modulating intercellular cascades which inhibit inflammatory molecule synthesis, the formation of free radicals, nuclear damage and induce antioxidant enzyme expression. These responses have the potential to increase life expectancy. The present review article focuses on curcumin, resveratrol, and flavonoids and seeks to summarize their anti-inflammatory, cytoprotective and DNA-protective properties. [ABSTRACT FROM AUTHOR]

Abstract: Pain is a principal contributor to the global burden of arthritis with peripheral sensitization being a major cause of arthritis-related pain. Within the knee joint, distal endings of dorsal root ganglion neurons (knee neurons) interact with fibroblast-like synoviocytes (FLS) and the inflammatory mediators they secrete, which are thought to promote peripheral sensitization. Correspondingly, RNA sequencing has demonstrated detectable levels of proinflammatory genes in FLS derived from arthritis patients. This study confirms that stimulation with tumor necrosis factor (TNF-α) results in expression of proinflammatory genes in mouse and human FLS (derived from osteoarthritis and rheumatoid arthritis patients), as well as increased secretion of cytokines from mouse TNF-α-stimulated FLS (TNF-FLS). Electrophysiological recordings from retrograde labelled knee neurons cocultured with TNF-FLS, or supernatant derived from TNF-FLS, revealed a depolarized resting membrane potential, increased spontaneous action potential firing, and enhanced TRPV1 function, all consistent with a role for FLS in mediating the sensitization of pain-sensing nerves in arthritis. Therefore, data from this study demonstrate the ability of FLS activated by TNF-α to promote neuronal sensitization, results that highlight the importance of both nonneuronal and neuronal cells to the development of pain in arthritis. [ABSTRACT FROM AUTHOR]

Background: Severe traumatic haemorrhage is the leading cause of death in young adults. Trauma Induced Coagulopathy is a complex and multifactorial phenomenon associated with severe traumatic haemorrhage. Fibrinogen is one of the first coagulation factors to become depleted in TIC and evidence suggests that severely injured trauma patients with hypofibrinogenaemia have poor outcomes. It is postulated that early fibrinogen replacement can improve clinical outcomes. This study investigated cryoprecipitate transfusion in hyopfibrinogeneamic trauma patients.Methods: This retrospective, single center, observational study investigated the use of cryoprecipitate in severely injured trauma patients admitted to an Australian Level I Trauma Centre. The primary outcome was time to administration of cryoprecipitate after identification of hypofibrinogenaemia using ROTEM (FIBTEM A5). Data collected included demographics, ISS, laboratory values of coagulation and blood product usage.Results: 71 patients received cryoprecipitate with a median time of 61 minutes [IQR 37-93] from FIBTEM A5 result to initial cryoprecipitate administration. At 24 hours following admission to ED, Clauss Fibrinogen levels increased by 1.30g/L [IQR 0.45-1.85] and FIBTEM A5 assay increased by 8mm [IQR 3.0-11.3]. Changes in both variables were highly significant (p<0.001) and Clauss Fibrinogen versus FIBTEM A5 values showed moderate to strong correlation (R=0.75-0.80).Conclusion: This study demonstrated that early administration of cryoprecipitate was both feasible and efficacious in fibrinogen replacement in severe traumatic haemorrhage. High-level evidence supporting cryoprecipitate or fibrinogen concentrate replacement with regards to efficacy and feasibility is required to guide future clinical practice. This study provided baseline data to inform the design of further clinical trials investigating fibrinogen replacement in traumatic haemorrhage. [ABSTRACT FROM AUTHOR]

The ability to sense visceral pain during appendicitis is diminished with age leading to delay in seeking health care and poorer clinical outcomes. To understand the mechanistic basis of this phenomenon, we examined visceral nociception in aged mouse and human tissue. Inflamed and noninflamed appendixes were collected from consenting patients undergoing surgery for the treatment of appendicitis or bowel cancer. Supernatants were generated by incubating samples in buffer and used to stimulate multiunit activity in intestinal preparations, or single-unit activity from teased fibres in colonic preparations, of young and old mice. Changes in afferent innervation with age were determined by measuring the density of calcitonin gene-related peptide-positive afferent fibres and by counting dorsal root ganglia back-labelled by injection of tracer dye into the wall of the colon. Finally, the effect of age on nociceptor function was studied in mouse and human colon. Afferent responses to appendicitis supernatants were greatly impaired in old mice. Further investigation revealed this was due to a marked reduction in the afferent innervation of the bowel and a substantial impairment in the ability of the remaining afferent fibres to transduce noxious stimuli. Translational studies in human tissue demonstrated a significant reduction in the multiunit but not the single-unit colonic mesenteric nerve response to capsaicin with age, indicative of a loss of nociceptor innervation. Our data demonstrate that anatomical and functional deficits in nociception occur with age, underpinning the atypical or silent presentation of appendicitis in the elderly. [ABSTRACT FROM AUTHOR]

Biliverdin reductase (BVR)-A is a pleotropic enzyme converting biliverdin to bilirubin and a signaling molecule that has cytoprotective and immunomodulatory effects. We recently showed that biliverdin inhibits the expression of complement activation fragment 5a receptor one (C5aR1) in RAW 264.7 macrophages. In this study, we investigated the role of BVR-A in determining macrophage inflammatory phenotype and function via regulation of C5aR1. We assessed expression of C5aR1, M1-like macrophage markers, including chemokines (RANTES, IP-10), as well as chemotaxis in response to LPS and C5a in bone marrow-derived macrophages from BVR fl/fl and LysM-Cre:BVR fl / fl mice (conditional deletion of BVR-A in myeloid cells). In response to LPS, macrophages isolated from LysM-Cre:BVR fl/fl showed significantly elevated levels of C5aR1 as well as chemokines (RANTES, IP10) but not proinflammatory markers, such as iNOS and TNF. An increase in C5aR1 expression was also observed in peritoneal macrophages and several tissues from LysM-Cre:BVR fl/fl mice in a model of endotoxemia. In addition, knockdown of BVR-A resulted in enhanced macrophage chemotaxis toward C5a. Part of the effects of BVR-A deletion on chemotaxis and RANTES expression were blocked in the presence of a C5aR1 neutralizing Ab, confirming the role of C5a-C5aR1 signaling in mediating the effects of BVR. In summary, BVR-A plays an important role in regulating macrophage chemotaxis in response to C5a via modulation of C5aR1 expression. In addition, macrophages lacking BVR-A are characterized by the expression of M1 polarization-associated chemokines, the levels of which depend in part on C5aR1 signaling. [ABSTRACT FROM AUTHOR]

Purpose: Compression socks are frequently used in the treatment and prevention of lower-limb pathologies; however, when combined with endurance-based exercise, the impact of compression socks on haemostatic activation remains unclear.Objectives: To investigate the effect of wearing compression socks on coagulation and fibrinolysis following a marathon.Methods: Sixty-seven participants [43 males (mean ± SD: age: 46.7 ± 10.3 year) and 24 females (age: 40.0 ± 11.0 year)] were allocated into a compression (SOCK, n = 34) or control (CONTROL, n = 33) group. Venous blood samples were obtained 24 h prior to and immediately POST-marathon, and were analyzed for thrombin-anti-thrombin complex (TAT), tissue factor (TF), tissue factor pathway inhibitor (TFPI), and D-Dimer.Results: Compression significantly attenuated the post-exercise increase in D-Dimer compared to the control group [median (range) SOCK: + 9.02 (- 0.34 to 60.7) ng/mL, CONTROL: + 25.48 (0.95-73.24) ng/mL]. TF increased following the marathon run [median (range), SOCK: + 1.19 (- 7.47 to 9.11) pg/mL, CONTROL: + 3.47 (- 5.01 to 38.56) pg/mL] in all runners. No significant post-exercise changes were observed for TAT and TFPI.Conclusions: While activation of coagulation and fibrinolysis was apparent in all runners POST-marathon, wearing compression socks was shown to reduce fibrinolytic activity, as demonstrated by lower D-Dimer concentrations. Compression may reduce exercise-associated haemostatic activation when completing prolonged exercise. [ABSTRACT FROM AUTHOR]

Purpose: Modulating gut bacteria via regular prebiotics/probiotics consumption may improve the metabolism of acute alcohol ingestion. This study investigated the impact of 8-weeks prebiotics/probiotics supplementation on microbiome changes and responses to acute alcohol consumption.Methods: 38 participants (21 females, 23.6 ± 3.4 kg m−2, mean ± SD) attended the laboratory on two occasions separated by an 8-week intervention period. On each of these visits, a dose of alcohol (0.40 ± 0.04 g kg−1, Vodka + Soda-Water) was consumed over 10 min. Breath alcohol concentration was sampled over 5 h and alcohol pharmacokinetics was analysed using WinNonlin non-compartmental modelling (Cmax, tmax, AUClast). For the intervention, participants were randomised to receive Placebo + Placebo (PLA), Placebo + Prebiotics (PRE), Probiotics + Placebo (PRO), or Probiotics + Prebiotics (SYN) in a double-blinded manner. Probiotics were a commercially available source of Lactobacillus acidophilus (NCFM®) and Bifidobacterium lactis (Bi-07). Prebiotics were a commercially available source of Larch Gum (from Larix occidentalis). Placebo was microcrystalline cellulose. Each visit, participants provided a stool sample, which was analysed to determine the presence of L. acidophilus and B. lactis. Differences between trials were analysed using paired samples t tests.Results: Increased counts for at least one bacterial strain (L. acidophilus or B. lactis) were observed for all participants on SYN (n = 10) and PRO (n = 10) trials. No difference in Cmax or tmax was observed between trials when analysed by treatment condition or microbiome outcome. A significant decrease in AUClast was observed between trials for PLA (p = 0.039) and PRE (p = 0.030) treatments, and when increases in at least one bacterial strain (p = 0.003) and no microbiome changes (p = 0.016) were observed.Conclusion: Consumption of probiotics appears to alter faecal counts of supplemental bacterial strains in otherwise healthy individuals. However, translation to any possible beneficial impact on alcohol metabolism remains to be elucidated. [ABSTRACT FROM AUTHOR]

Background Unconjugated bilirubin (UCB), an endogenous antioxidant, may protect the heart against ischemia–reperfusion (I–R) injury. However, the ‘cardioprotective’ potential of bilirubin therapy remains unclear. We tested whether pre- or post-ischemic treatment of ex vivo perfused hearts with bilirubin ditaurate (BRT) improves post-ischemic functional outcomes and myocardial oxidative damage. Methods Isolated Langendorff perfused hearts (male, Wistar rats) were treated with 50 μM BRT for 30 min before (Pre) or after (Post) 30 min of zero-flow ischemia. Functional outcomes were monitored, with myocardial damage estimated from creatine kinase efflux, infarct size, and left ventricular lipid/protein oxidation assessed by measuring malondialdehyde and protein carbonyls. Ischemia induced contractile dysfunction and cellular injury, with both BRT treatments improving I–R outcomes. Results Final post-ischemic recoveries for left ventricular diastolic/developed pressures were significantly enhanced in treated groups: end-diastolic pressure (Control, 78 ± 14, Pre, 51 ± 15*, Post, 51 ± 13 mm Hg*); left ventricular developed pressure, (LVDP; Control 44 ± 15, Pre, 71 ± 19*, Post, 84 ± 13 mm Hg*). Myocardial injury/infarction (MI) was also significantly reduced with BRT treatment: post-ischemic creatine kinase efflux (Control, 1.24 ± 0.41, Pre, 0.86 ± 0.31*, Post, 0.51 ± 0.29 U/g/mL*; infarct size, Control, 67 ± 17, Pre, 39 ± 15*, Post, 22 ± 11%*). These changes were accompanied by significantly reduced malondialdehyde and protein carbonyl content in Pre and Post treated hearts (*P < 0.05 vs. Control). Conclusions These data collectively reveal significant cardioprotection upon BRT treatment, with post-treatment being particularly effective. Significant reductions in infarct size and lipid and protein oxidation indicate a mechanism related to protection from oxidative damage and indicate the potential utility of this molecule as a post-MI treatment. [ABSTRACT FROM AUTHOR]

Chronic visceral pain affects millions of individuals worldwide and remains poorly understood, with current therapeutic options constrained by gastrointestinal adverse effects. Visceral pain is strongly associated with inflammation and distension of the gut. Here we report that the voltage-gated sodium channel subtype NaV1.9 is expressed in half of gut-projecting rodent dorsal root ganglia sensory neurons. We show that NaV1.9 is required for normal mechanosensation, for direct excitation and for sensitization of mouse colonic afferents by mediators from inflammatory bowel disease tissues, and by noxious inflammatory mediators individually. Excitatory responses to ATP or PGE2 were substantially reduced in NaV1.9(-/-) mice. Deletion of NaV1.9 substantially attenuates excitation and subsequent mechanical hypersensitivity after application of inflammatory soup (IS) (bradykinin, ATP, histamine, PGE2, and 5HT) to visceral nociceptors located in the serosa and mesentery. Responses to mechanical stimulation of mesenteric afferents were also reduced by loss of NaV1.9, and there was a rightward shift in stimulus-response function to ramp colonic distension. By contrast, responses to rapid, high-intensity phasic distension of the colon are initially unaffected; however, run-down of responses to repeat phasic distension were exacerbated in NaV1.9(-/-) afferents. Finally colonic afferent activation by supernatants derived from inflamed human tissue was greatly reduced in NaV1.9(-/-) mice. These results demonstrate that NaV1.9 is required for persistence of responses to intense mechanical stimulation, contributes to inflammatory mechanical hypersensitivity, and is essential for activation by noxious inflammatory mediators, including those from diseased human bowel. These observations indicate that NaV1.9 represents a high-value target for development of visceral analgesics. [ABSTRACT FROM AUTHOR]

Abstract: Epidemiological studies report a negative association between circulating bilirubin concentrations and the risk for cancer and cardiovascular disease. Structurally related tetrapyrroles also possess in vitro anti-genotoxic activity and may prevent mutation prior to malignancy. Furthermore, few data suggest that tetrapyrroles exert anti-carcinogenic effects via induction of cell cycle arrest and apoptosis. To further investigate whether tetrapyrroles provoke DNA-damage in human cancer cells, they were tested in the single cell gel electrophoresis assay (SCGE). Eight tetrapyrroles (unconjugated bilirubin, bilirubin ditaurate, biliverdin, biliverdin-/bilirubin dimethyl ester, urobilin, stercobilin and protoporphyrin) were added to cultured Caco2 and HepG2 cells and their effects on comet formation (% tail DNA) were assessed. Flow cytometric assessment (apoptosis/necrosis, cell cycle, intracellular radical species generation) assisted in revealing underlying mechanisms of intracellular action. Cells were incubated with tetrapyrroles at concentrations of 0.5, 5 and 17μM for 24h. Addition of 300μM tertiary-butyl hydroperoxide to cells served as a positive control. Tetrapyrrole incubation mostly resulted in increased DNA-damage (comet formation) in Caco2 and HepG2 cells. Tetrapyrroles that are concentrated within the intestine, including protoporphyrin, urobilin and stercobilin, led to significant comet formation in both cell lines, implicating the compounds in inducing DNA-damage and apoptosis in cancer cells found within organs of the digestive system. [Copyright &y& Elsevier]

Circulating unconjugated bilirubin (UCB) has been reported to protect against lung and colorectal cancer. The present study aimed to explore, for the first time, whether mildly elevated circulating UCB, as found in Gilbert`s syndrome (GS), is associated with changes of DNA damage. A random 76 individuals, matched for age and gender, were recruited from the general population and allocated into the GS group (UCB ≥17.1 µM; n = 38) or control group (UCB <17.1 µM; n = 38). Chromosomal and cytological changes were determined in lymphocytes and buccal cells using the cytokinesis-block micronucleus cytome assay (CBMN) and buccal micronucleus cytome assay (BMcyt). No significant differences were found between GS subjects and the control group in the CBMN and BMcyt determined endpoints. Subsequently, when age dependency of effects were analysed, lower formation of buccal micronucleated cells (by 73.3%) and buccal nuclear buds (by 70.9%) in the GS subgroup ≥30 years were found, compared to the GS subgroup <30 years. These findings suggest DNA protection in epithelial tissue of older individuals with GS. [ABSTRACT FROM PUBLISHER]

Abstract: A protective association between bilirubin and atherosclerosis/ischemic heart disease clearly exists in vivo. However, the relationship between bilirubin and in vivo oxidative stress parameters in a clinical population remains poorly described. The aim of this study was to assess whether persons expressing Gilbert syndrome (GS; i.e., unconjugated hyperbilirubinemia) are protected from thiol oxidation and to determine if this, in addition to their improved lipoprotein profile, could explain reduced oxidized low-density lipoprotein (oxLDL) status in them. Forty-four matched GS and control subjects were recruited and blood was prepared for the analysis of lipid profile and multiple plasma antioxidants and measures of oxidative stress. GS subjects possessed elevated plasma reduced thiol (8.03±1.09 versus 6.75±1.39nmol/mg protein; P<0.01) and glutathione concentrations (12.7±2.39 versus 9.44±2.45μM; P<0.001). Oxidative stress status (reduced:oxidized glutathione; GSH:GSSG) was significantly improved in GS (0.49±0.16 versus 0.32±0.12; P<0.001). Protein carbonyl concentrations were negatively associated with bilirubin concentrations and were significantly lower in persons with >40μM bilirubin versus controls (<17.1μmol/L; P<0.05). Furthermore, absolute oxLDL concentrations were significantly lower in GS subjects (P<0.05). Forward stepwise regression analysis revealed that bilirubin was associated with increased GSH:GSSG ratio and reduced thiol concentrations, which, in addition to reduced circulating LDL, probably decreased oxLDL concentrations within the cohort. In addition, a marked reduction in total cholesterol concentrations in hyperbilirubinemic Gunn rats is presented (Gunn 0.57±0.09 versus control 1.69±0.40mmol/L; P<0.001), arguing for a novel role for bilirubin in modulating lipid status in vivo. These findings implicate the physiological importance of bilirubin in protecting from atherosclerosis by reducing thiol and subsequent lipoprotein oxidation, in addition to reducing circulating LDL concentrations. [Copyright &y& Elsevier]

Background and Purpose: Bilirubin and biliverdin possess antioxidant and anti-inflammatory properties and their exogenous administration protects against the effects of inflammation and trauma in experimental models. Despite the therapeutic potential of bile pigments, little is known about their in vivo parenteral or enteral absorption after exogenous administration. This study investigated the absorption and pharmacokinetics of bile pigments after i.v., i.p. and intraduodenal (i.d.) administration in addition to their metabolism and routes of excretion.Experimental Approach: Anaesthetized Wistar rats had their bile duct, jugular and portal veins cannulated. Bile pigments were infused and their circulating concentrations/biliary excretion were measured over 180 min. KEY RESULTS After i.v. administration of unconjugated bilirubin, biliverdin and bilirubin ditaurate, their plasma concentrations decreased exponentially over time. Subsequently, native and metabolized compounds appeared in the bile. When administered i.p., their absolute bioavailabilities equalled 14.0, 16.1 and 33.1%, respectively, and correspondingly 38, 28 and 34% of the same bile pigment doses were excreted in the bile. Administration of unconjugated bilirubin and bilirubin ditaurate i.d. increased their portal and systemic concentrations and their systemic bioavailability equalled 1.0 and 2.0%, respectively. Correspondingly, 2.7 and 4.6%, of the doses were excreted in the bile. Biliverdin was rapidly metabolized and these products were absorbed and excreted via the urine and bile.Conclusions and Implications: Bile pigment absorption from the peritoneal and duodenal cavities demonstrate new routes of administration for the treatment of inflammatory and traumatic pathology. Oral biliverdin administration may lead to the production of active metabolite that protect from inflammation/complement activation. [ABSTRACT FROM AUTHOR]

Biliverdin (BV) administration induces antioxidant and anti-inflammatory effects, with previous reports also identifying anti-anaphylactic potential. Interestingly however, intra-duodenal administration of BV in rats leads to the formation of bilirubin-10-sulfonate (BRS), which might be responsible for BV's purported effects. This study aimed to assess the intravenous, intraperitoneal and intraduodenal pharmacokinetics of BRS and BV in order to assess their therapeutic potential in future studies. Bile and venous blood were intermittently collected before and after administration, which was subsequently analysed using liquid chromatography-mass spectrometry for quantification of bile pigment concentrations. Interestingly, i.p. BRS administration led to a greater circulating concentration and had a reduced excretion rate, which resulted in a substantially elevated AUC 180 when compared to BV administration. Furthermore, BRS was excreted intact in the bile, in contrast to BV which was excreted after chemical reduction and conjugation. Intraperitoneal and intraduodenal administration substantially increased blood BRS concentrations (p<0.05), however, the bioavailability of BV was higher than BRS following i.p. administration (i.p. BV 28.4%, BRS 15.5%) but lower following i.d. administration (i.d. BV 0.04%, BRS 0.07%), over 180 minutes. When BRS was administered i.v., BRS had a significantly (p<0.05) longer distribution (191.9 vs 54.1 minutes) half-life compared to BV, and significantly reduced (p<0.05) volume of distribution (0.026 vs 0.145 L kg−1). As a consequence, intraperitoneal and intraduodenal administration resulted in significantly greater blood concentrations of BRS (p<0.05) over 180 minutes. Therefore, BRS may be more likely to induce antioxidant or molecular effects, when compared to BV, due to greater concentrations and a longer half-life. Cumulatively, these data demonstrate that BRS has a superior pharmacokinetic profile when compared to BV, which is a result of its resistance to hepatic metabolism and excretion. These data therefore provide a basis to explore the capacity of BRS to protect from inflammatory pathology. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Biliverdin, a by-product of haem catabolism, possesses potent endogenous antioxidant and anti-inflammatory properties. Bilirubin-C10-sulfonate (BRS), an active metabolite formed after enteral administration of BV in the rat, also possess antioxidant properties. Therefore, we investigated the anti-inflammatory and antioxidant activity of BV and BRS in an in vivo model of monosodium urate induced sterile inflammation. Subcutaneous air pouches were created on the dorsal flanks of Wistar rats (10–12 weeks of age). Prior to stimulation of the 6-day old pouch with monosodium urate (25 mg), groups were pre-treated with intraperitoneal BRS (27 mg/kg) and BV (27 mg/kg). Total and differential leukocyte counts were determined in pouch fluid aspirate at 1, 6, 12, 24 and 48 h after monosodium urate stimulation. Biliverdin (BV), BRS and unconjugated bilirubin (UCB) concentrations in the serum and pouch fluid were quantified using liquid chromatography-mass spectrometry. Pouch fluid cytokine concentrations (IL-1β, IL-1α, TNF-α, IL-17A, IL-12, GM-CSF, IL-33, IFN-γ, IL-18, IL-10, MCP-1, CXCL-1 and IL-6) were assessed after 6 h. In addition, 24 h protein carbonyl and chloramine concentrations were assessed in pouch fluid using ELISA and spectrophotometry, respectively. BRS and BV significantly (p < 0.05) inhibited leukocyte (total, neutrophil and macrophage) infiltration into the pouch fluid from 6 to 48 h. For example, after 6 h neutrophil counts decreased following BRS (0.32 ± 0.11 × 106 cells mL−1) and BV (0.17 ± 0.03 × 106 cells mL−1) compared to MSU only (3.51 ± 1.07 × 106 cells mL−1). Both BV and BRS significantly (p < 0.05) reduced pouch GM-CSF (BV: 5.8 ± 1.2 pg mL−1, BRS: 6.9 ± 1.5 pg mL−1 vs MSU only: 13.0 ± 1.9 pg mL−1) and MCP-1 concentrations at 6 h (BV: 1804 ± 269 pg mL−1, BRS: 7927 ± 2668 pg mL−1 vs MSU only: 17,290 ± 4503 pg ml−1), whilst BV additionally inhibited IL-6 (4354 ± 977 pg mL−1 vs MSU only: 25,070 ± 5178 pg mL−1) and IL-18 (17.6 ± 2.0 pg mL−1 vs MSU only: 81.5 ± 19.9 pg mL−1) concentrations at 6 h (p < 0.05). Despite these differences, no change in pouch chloramine or protein carbonyl concentrations occurred at 24 h (p > 0.05). Serum BV concentrations rapidly diminished over 6 h, however, BRS was readily detected in the serum over 48 h, and in pouch fluid over 12 h. This study is the first to elucidate anti-inflammatory activity of BRS and the efficacy of BV administration in a model of gouty inflammation. Reduced leukocyte infiltration and cytokine production in response to sterile inflammation further support the importance of these molecules in physiology and their therapeutic potential in sterile inflammation. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Hypochlorous acid (HOCl), an oxidant produced by myeloperoxidase (MPO), induces protein and lipid oxidation, which is implicated in the pathogenesis of atherosclerosis. Individuals with mildly elevated bilirubin concentrations (i.e., Gilbert syndrome; GS) are protected from atherosclerosis, cardiovascular disease, and related mortality. We aimed to investigate whether exogenous/endogenous unconjugated bilirubin (UCB), at physiological concentrations, can protect proteins/lipids from oxidation induced by reagent and enzymatically generated HOCl. Serum/plasma samples supplemented with exogenous UCB (≤250µM) were assessed for their susceptibility to HOCl and MPO/H2O2/Cl(-) oxidation, by measuring chloramine, protein carbonyl, and malondialdehyde (MDA) formation. Serum/plasma samples from hyperbilirubinemic Gunn rats and humans with GS were also exposed to MPO/H2O2/Cl(-) to: (1) validate in vitro data and (2) determine the relevance of endogenously elevated UCB in preventing protein and lipid oxidation. Exogenous UCB dose-dependently (P<0.05) inhibited HOCl and MPO/H2O2/Cl(-)-induced chloramine formation. Albumin-bound UCB efficiently and specifically (3.9-125µM; P<0.05) scavenged taurine, glycine, and N-α-acetyllysine chloramines. These results were translated into Gunn rat and GS serum/plasma, which showed significantly (P<0.01) reduced chloramine formation after MPO-induced oxidation. Protein carbonyl and MDA formation was also reduced after MPO oxidation in plasma supplemented with UCB (P<0.05; 25 and 50µM, respectively). Significant inhibition of protein and lipid oxidation was demonstrated within the physiological range of UCB, providing a hypothetical link to protection from atherosclerosis in hyperbilirubinemic individuals. These data demonstrate a novel and physiologically relevant mechanism whereby UCB could inhibit protein and lipid modification by quenching chloramines induced by MPO-induced HOCl., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Dietary sources of polyphenols, which are derivatives and/or isomers of flavones, isoflavones, flavonols, catechins and phenolic acids, possess antioxidant properties and therefore might be important in preventing oxidative-stress-induced platelet activation and attenuating adverse haemostatic function. Free radicals, including reactive oxygen and nitrogen species, promote oxidative stress, leading to platelet hyperactivation and the risk of thrombosis. The consumption of antioxidant/polyphenol rich foods might therefore impart anti-thrombotic and cardiovascular protective effects via their inhibition of platelet hyperactivation or aggregation. Most commonly-used anti-platelet drugs such as aspirin block the cyclooxygenase (COX)-1 pathway of platelet activation, similar to the action of antioxidants with respect to neutralising hydrogen peroxide (H2 O2 ), with a similar effect on thromboxane production via the COX-1 pathway. Polyphenols also target various additional platelet activation pathways (e.g. by blocking platelet-ADP, collagen receptors); thus alleviating fibrinogen binding to platelet surface (GPIIb-IIIa) receptors, reducing further platelet recruitment for aggregation and inhibiting platelet degranulation. As a result of the ability of polyphenols to target additional pathways of platelet activation, they may have the potential to substitute or complement currently used anti-platelet drugs in sedentary, obese, pre-diabetic or diabetic populations who can be resistant or sensitive to pharmacological anti-platelet therapy., (© 2013 The British Dietetic Association Ltd.)

Gilbert's syndrome (GS) is characterized by a benign, mildly elevated bilirubin concentration in the blood. Recent reports show clear protection from cardiovascular disease in this population. Protection of lipids, proteins and other macromolecules from oxidation by bilirubin represents the most commonly accepted mechanism contributing to protection in this group. However, a recent meta-analysis estimated that bilirubin only accounts for ~34% of the cardioprotective effects within analysed studies. To reveal the additional contributing variables we have explored circulating cholesterol and triacylglycerol concentrations, which appear to be decreased in hyperbilirubinemic individuals/animals, and are accompanied by lower body mass index in highly powered studies. These results suggest that bilirubin could be responsible for the development of a lean and hypolipidemic state in GS. Here we also discuss the possible contributing mechanisms that might reduce circulating cholesterol and triacylglycerol concentrations in individuals with syndromes affecting bilirubin metabolism/excretion, which we hope will stimulate future research in the area. In summary, this article is the first review of lipid status in animal and human studies of hyperbilirubinemia and explores possible mechanisms that could contribute to lowering circulating lipid parameters and further explain cardiovascular protection in Gilbert's syndrome., (Copyright © 2012. Published by Elsevier Ltd.)

In vitro anti-genotoxic properties of bile pigments have been explored and confirmed recently. Despite these reports mechanisms to explain DNA protection by endogenous bile pigments remain unclear. Surprisingly, the quantification of cellular pigment absorption which could represent a fundamental prerequisite for intracellular (e.g., anti-mutagenic) effects, has not been explored. Therefore, we aimed to measure the amounts of un-/conjugated bilirubin as well as biliverdin absorbed into colonies of Salmonella typhimurium, utilising HPLC analyses, and to observe whether intracellular compound concentrations could predict anti-genotoxic effects. HPLC analyses confirmed that bacterial bile pigment absorption was concentration-dependent. Plate bile pigment concentrations were inversely associated with genotoxicity of all tested mutagens, irrespective of strain and test conditions. However, protection against frame-shift mutation in strain TA98 most strongly depended on the bacterial absorption of bilirubin and biliverdin, which indicates that bile pigments can protect by intercepting mutations extracellularly and specifically inhibit frame-shift mutations intracellularly., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Bile pigments, including bilirubin and biliverdin, are endogenous compounds belonging to the porphyrin family of molecules. In the past, bile pigments and bilirubin in particular were thought of as useless by-products of heme catabolism that can be toxic if they accumulate. However, in the past 20 years, research probing the physiological relevance of bile pigments has been mounting, with evidence to suggest bile pigments possess significant antioxidant and anti-mutagenic properties. More specifically, bile pigments are potent peroxyl radical scavengers and inhibit the mutagenic effects of a number of classes of mutagens (polycyclic aromatic hydrocarbons, heterocyclic amines, oxidants). Coincidentally, persons with elevated circulating bilirubin concentrations have a reduced prevalence of cancer and cardio-vascular disease. Despite the encouraging in vitro anti-mutagenic effects of bile pigments, relatively little research has been conducted on their inhibitory capacity in bacterial and cultured cell assays of mutation, which might link the existing in vitro and in vivo observations. This is the first review to summarise the published data and it is our hope it will stimulate further research on these potentially preventative compounds.

The aim of this study was to explore the potential pro- and anti-mutagenic effects of endogenous bile pigments unconjugated bilirubin (BR), biliverdin (BV) and a synthetic, water soluble conjugate, bilirubin ditaurate (BRT) in the Ames Salmonella test. The bile pigments were tested over a wide concentration range (0.01-2 micromol/plate) in the presence of three bacterial strains (TA98, TA100, TA102). A variety of mutagens including benzo[alpha]pyrene (B[alpha]P), 2,4,7 trinitrofluorenone (TNFone), 2-aminofluorene (2-AF), sodium azide (NaN(3)) and tertiary-butyl hydroperoxide (t-BuOOH), were used to promote the formation of mutant revertants. Tests were conducted with (B[alpha]P, 2-AF, t-BuOOH) and without (TNFone, NaN(3), t-BuOOH) metabolic activation incorporating the addition of the microsomal liver preparation, S9. The bile pigments alone did not induce mutagenicity in any of the strains tested (p>0.05). Anti-mutagenic effects of the bile pigments were observed in the presence of all mutagens except for NaN(3) and the anti-mutagenic effects appeared independent of the strain tested. For TNFone induced genotoxicity, the order of effectiveness was BR> or =BRT>BV. However, the order was BV> or =BRT> or =BR for 2-AF. Antioxidant testing in the TA102 strain revealed bile pigments could effectively inhibit the genotoxic effect of t-BuOOH induced oxidative stress. The apparent antioxidant and anti-mutagenic behaviour of bile pigments further suggests their presence in biological systems is of possible physiological importance.