Sulindac, 3,3'-diindolylmethane and curcumin reduce carcinogenesis in the Pirc rat, an Apc-driven model of colon carcinogenesis.

BACKGROUND: Recently, we showed that Sulindac (SU; 320 ppm) reduces precancerous lesions in the colon of Pirc rats, mutated in the Apc gene. Surprisingly, previous data in Apc-mutated mice showed that SU, with reported efficacy in Familial Adenomatous Polyposis (FAP), increases colon carcinogenesis. Therefore, we assessed the effect of SU 320 ppm in a long-term carcinogenesis experiment in Pirc rats. Moreover, since side effects of SU hamper its chronic use and a combination of drugs could be more effective and less toxic than single agents, we also studied whether two natural compounds, 3,3'-diindolylmethane (DIM; 250 ppm) and curcumin (CUR; 2000 ppm), with or without lower doses of SU could affect carcinogenesis METHODS: Pirc rats were fed an AIN76 diet containing SU, DIM and CUR and sacrificed at 8 months of age to measure intestinal tumours. Apoptosis and proliferation in the normal colon mucosa, as well as gene expression profile were studied RESULTS: Colon tumours were significantly reduced by SU 320 ppm (62 % reduction over Controls), by DIM and CUR without or with SU 80 and 160 ppm (50, 53 and 58 % reduction, respectively) but not by SU 80 ppm alone. Total tumours (colon and small intestine) were reduced by SU (80 and 320 ppm) and by DIM and CUR. Apoptosis in the normal mucosa was significantly increased by SU 320 ppm, and slightly increased by DIM and CUR with or without SU. A slight reduction in Survivin-Birc5 expression was observed with all the treatments compared to Controls. Proliferative activity was not varied CONCLUSIONS: The results on SU reinforce the validity of Pirc rats to identify chemopreventive products. Moreover, the efficacy of the DIM and CUR combination to lower colon tumours, suggests an alternative strategy to be exploited in patients at risk.

3-Iodothyronamine: a modulator of the hypothalamus-pancreas-thyroid axes in mice.

BACKGROUND AND PURPOSE Preclinical pharmacology of 3-iodothyronamine (T1AM), an endogenous derivative of thyroid hormones, indicates that it is a rapid modulator of rodent metabolism and behaviour. Since T1AM undergoes rapid enzymatic degradation, particularly by MAO, we hypothesized that the effects of T1AM might be altered by inhibition of MAO. EXPERIMENTAL APPROACH We investigated the effects of injecting T1AM (i.c.v.) on (i) feeding behaviour, hyperglycaemia and plasma levels of thyroid hormones and (ii) T1AM systemic bioavailability, in overnight fasted mice, under control conditions and after pretreatment with the MAO inhibitor clorgyline. T1AM (1.3, 6.6, 13, 20 and 26 µg·kg(-1) ) or vehicle were injected i.c.v. in fasted male mice not pretreated or pretreated i.p. with clorgyline (2.5 mg·kg(-1) ). Glycaemia was measured by a glucorefractometer, plasma triiodothyronine (fT3) by a chemiluminescent immunometric assay, c-fos activation immunohistochemically and plasma T1AM by HPLC coupled to tandem-MS. KEY RESULTS T1AM, 1.3 µg·kg(-1) , produced a hypophagic effect (-24% vs. control) and reduced c-fos activation. This dose showed systemic bioavailability (0.12% of injected dose), raised plasma glucose levels and reduced peripheral insulin sensitivity (-33% vs. control) and plasma fT3 levels. These effects were not linearly related to the dose injected. Clorgyline pretreatment strongly increased the systemic bioavailability of T1AM and prevented the hyperglycaemia and reduction in fT3 induced by T1AM. CONCLUSIONS AND IMPLICATIONS T1AM induces central and peripheral effects including hyperglycaemia and a reduction in plasma fT3 levels in fasted mice. These effects critically depend on the concentration of T1AM or its metabolites in target organs.

Effects of dietary extra-virgin olive oil on behaviour and brain biochemical parameters in ageing rats.

The aim of the present study was to verify whether extra-virgin olive oil, a dietary component naturally containing phenolic antioxidants, has the potential to protect the brain from the deleterious effects of ageing. To accomplish this goal, we used male rats fed a high-energy diet containing either maize oil, or extra-virgin olive oil with high or low phenol content (720 or 10 mg total phenols/kg oil, corresponding to a daily dose of 4 or 0.05 mg total phenols/kg body weight, respectively) from age 12 months to senescence. The measured endpoints were biochemical parameters related to oxidative stress and functional tests to evaluate motor, cognitive and emotional behaviour. Olive oil phenols did not exert major protective actions on motor and cognitive function, as we observed only a tendency to improved motor coordination on the rotarod in the old animals treated with the oil rich in phenols (40 % average increase in the time to first fall; P = 0.18). However, an interesting finding of the present study was a reduced step-through latency in the light-dark box test, found in the older animals upon treatment with the oil rich in antioxidant phenols, possibly indicating an anxiety-lowering effect. This effect was associated with decreased glutathione reductase activity and expression in the brain, a phenomenon previously associated with decreased anxiety in rodents. These results indicate a previously undetected effect of a diet containing an olive oil rich in phenols. Further studies are warranted to verify whether specific food antioxidants might also have an effect on emotional behaviour.

Active and passive smoking and lifestyle determinants of 8-oxo-7,8-dihydro-2'-deoxyguanosine levels in human leukocyte DNA.

We investigated the effects of smoking and exposure to environmental tobacco smoke (ETS) on oxidative DNA damage by measuring 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) levels in DNA of leukocytes of healthy donors (30 smokers, 29 nonsmokers, and 28 ETS-exposed subjects). Nonsmokers had lower 8-oxodGuo levels compared with smokers (5.94 +/- 0.87 x 10(-6) and 19.85 +/- 4.75 x 10(-6) 2-deoxyguanosine, respectively, means +/- SE, P = 0.00007). Subjects exposed to ETS had higher mean value of 8-oxodGuo compared with nonsmokers (9.18 +/- 1.53 x 10(-6) 2-deoxyguanosine, mean +/- SE), nonsignificant by univariate analysis (P = 0.074). Multiregression analysis indicated that the increase of 8-oxodGuo levels induced by ETS was significant (P = 0.045) and that coffee and tea consumption reduced DNA oxidation (P = 0.0053). Oxidative leukocyte DNA damage was positively correlated with plasma cotinine levels in ETS-exposed subjects (r = 0.47, P < 0.01, n = 28) and was increased by age in nonsmokers and ETS-exposed subjects (P = 0.049). The results seem to confirm that ETS exposure is capable of inducing some oxidative DNA damage in circulating leukocytes and that coffee and tea consumption might partially protect against smoking-induced oxidation damage.

n-3 polyunsaturated fatty acids supplementation decreases asymmetric dimethyl arginine and arachidonate accumulation in aging spontaneously hypertensive rats.

BACKGROUND: Plasma accumulation of asymmetric dimethyl arginine (ADMA) is considered as a risk factor for endothelial dysfunction and a strong predictor for coronary heart diseases. Eicosapentaenoic (EPA) and docosahexaenoic (DHA) increasing plasma levels have been positively associated with reduced cardiovascular mortality with a mechanism( s) yet unclear. We hypothesised that ADMA reduction might be a part of EPA and DHA beneficial effects on the cardiovascular system. AIM: To verify this hypothesis we measured ADMA plasma levels in aged spontaneously hypertensive rats (SHR) supplemented for 8 weeks with EPA and DHA. METHODS: 16-month-old SHR were supplemented with EPA and DHA (EPA-DHA) or with olive oil (1 g/kg/day; OLIVE). At the end of the treatments, the plasma of each animal was analysed for 1) the total fatty acid composition, by gas-cromatography, 2) ADMA levels, by high pressure liquid chromatography, 3) nitrite and homocysteine concentration by chemiluminescence and by polarisation immunoassay respectively. Moreover, the activity of dimethyl arginine dimethyl amino hydrolase, the main enzyme involved in ADMA metabolism, was measured spectrophotometrically in the kidney from each rat. RESULTS: Animals supplemented with EPA and DHA showed: 1) lower ADMA and arachidonate plasma levels (587.4 +/- 113.7 nM and 0.49 +/- 0.11 mM respectively) than the values found in OLIVE rats (1365 +/- 399 nM and 1.07 +/- 0.07 mM respectively) 2) higher nitrite content (0.73 +/- 0.05 microM) than OLIVE (0.23 +/- 0.08 microM). CONCLUSIONS: EPA and DHA supplementation reduced ADMA accumulation in SHR in parallel with a decrease of arachidonate availability. This finding suggests that the control of the inflammatory ground of endothelium might play an important role in EPA and DHA effect on this novel and highly predictive cardiovascular risk factor.