Angel Agis-Torres

Grape Antioxidant Dietary Fiber Stimulates Lactobacillus Growth in Rat Cecum

UNLABELLED The digesta is a highly active biological system where epithelial cells, microbiota, nondigestible dietary components, and a large number of metabolic products interact. The gut microbiota can be modulated by both endogenous and exogenous substrates. Undigested dietary residues are substrates for colonic microbiota and may influence gut microbial ecology. The objective of this work was to study the capacity of grape antioxidant dietary fiber (GADF), which is rich in polyphenols, to modify the bacterial profile in the cecum of rats. Male adult Wistar rats were fed for 4 wk with diets containing either cellulose or GADF as dietary fiber. The effect of GADF on bacterial growth was evaluated in vitro and on the cecal microbiota of rats using quantitative real time polymerase chain reaction (RT-PCR). The results showed that GADF intake stimulates proliferation of Lactobacillus and slightly affects the composition of Bifidobacterium species. GADF was also found to have a stimulative effect on Lactobacillus reuteri and Lactobacillus acidophilus in vitro. These findings suggest that the consumption of a diet rich in plant foods with high dietary fiber and polyphenol content may enhance the gastrointestinal health of the host through microbiota modulation. PRACTICAL APPLICATION Grape antioxidant fiber combines nutritional and physiological properties of dietary fiber and natural antioxidants from grapes. Grape antioxidant fiber could be used as an ingredient for functional foods and as a dietary supplement to increase the intake of dietary fiber and bioactive compounds.

Cocoa polyphenols prevent inflammation in the colon of azoxymethane-treated rats and in TNF-α-stimulated Caco-2 cells.

Numerous lines of evidence support a relationship between intestinal inflammation and cancer. Therefore, much attention has recently been focused on the identification of natural compounds with anti-inflammatory activities as a strategy to suppress the early stages of colorectal cancer. Because cocoa is a rich source of bioactive compounds, the present study investigated its anti-inflammatory properties in a rat model of azoxymethane (AOM)-induced colon carcinogenesis and in TNF-α-stimulated Caco-2 cells. A total of forty male rats were fed with control or cocoa-enriched diets (12 %) during 8 weeks and injected with saline or AOM (20 mg/kg body weight) during the third and fourth week (n 10 rats/group). At the end of the experiment, colon samples were evaluated for markers of inflammation. The anti-inflammatory activity of a cocoa polyphenolic extract (10 μg/ml) was examined in TNF-α-stimulated Caco-2 cells, an in vitro model of experimentally induced intestinal inflammation. The signalling pathways involved, including NF-κB and the mitogen-activated protein kinase family such as c-Jun NH₂-terminal kinases (JNK), extracellular signal-regulated kinases and p38, were also evaluated. The results show that the cocoa-rich diet decreases the nuclear levels of NF-κB and the expression of pro-inflammatory enzymes such as cyclo-oxygenase-2 and inducible NO synthase induced by AOM in the colon. Additionally, the experiments in Caco-2 cells confirm that cocoa polyphenols effectively down-regulate the levels of inflammatory markers induced by TNF-α by inhibiting NF-κB translocation and JNK phosphorylation. We conclude that cocoa polyphenols suppress inflammation-related colon carcinogenesis and could be promising in the dietary prevention of intestinal inflammation and related cancer development.

Cocoa-rich diet prevents azoxymethane-induced colonic preneoplastic lesions in rats by restraining oxidative stress and cell proliferation and inducing apoptosis

Cocoa is a rich source of bioactive compounds with potential chemopreventive ability but up to date its effectiveness in animal models of colon carcinogenesis has not been addressed. Herein, we investigated the in vivo effect of a cocoa-rich diet in the prevention of azoxymethane (AOM)-induced colon cancer and the mechanisms involved. Our results showed that cocoa feeding significantly reduced AOM-induced colonic aberrant crypt foci formation and crypt multiplicity. Oxidative imbalance in colon tissues seems to be prevented by cocoa as indicated by reduced oxidation markers levels and increased enzymatic and non-enzymatic endogenous defences. Cocoa-rich diet also exhibited antiproliferative effects by decreasing the levels of extracellular regulated kinases, protein kinase B and cyclin D1 together with pro-apoptotic effects evidenced by reduced Bcl-x(L) levels and increased Bax levels and caspase-3 activity. Our findings provide the first in vivo evidence that a cocoa-rich diet may inhibit the early stage of colon carcinogenesis probably by preventing oxidative stress and cell proliferation and by inducing apoptosis.

Grape antioxidant dietary fibre reduced apoptosis and induced a pro-reducing shift in the glutathione redox state of the rat proximal colonic mucosa.

Grape antioxidant dietary fibre (GADF) is a grape product rich in dietary fibre and natural antioxidants. We showed previously that the GADF intake induced an epithelial hypoplasia in the rat colonic mucosa. In the present study, we propose that the antioxidant effect of GADF could modulate mucosal apoptosis via modulation of the cellular redox environment. Male Wistar rats (n 20) were fed with diets containing either cellulose (control diet group) or GADF (GADF diet group) as fibre for 4 weeks. The GSH:GSSG ratio, the redox state of the GSSG/2GSH couple (Ehc), the mitochondrial and/or cytosolic antioxidant enzyme activities (superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx)), lipid peroxidation (LPO) and apoptosis were evaluated. GADF enhanced the cytosolic GSH:GSSG ratio, shifting the redox potential (Ehc) to a more pro-reducing status. Decreased Cu,ZnSOD:CAT, Cu,ZnSOD:GPx and MnSOD:GPx ratios could indicate an enhanced capacity for reducing H2O2, contributing to decreased cytosolic LPO. Reduced apoptosis in GADF-treated mucosa was inversely related to MnSOD activity. Furthermore, apoptosis increased directly as GSSG content increased. These results suggest that the reduction in apoptosis associated with GADF intake may be due to a modulation of the glutathione redox system and endogenous antioxidant enzymes.

Chronic treatment with nicotine or potassium attenuates depolarisation-evoked noradrenaline release from the human neuroblastoma SH-SY5Y

Chronic treatment, of SH-SY5Y cells, with KCl (20 mM) for 4 days decreased 100 mM KCl-evoked noradrenaline (NA) release by 50% and nicotine (100 microM)-evoked NA release by 55%. Pretreatment with the L-type calcium channel antagonist, nifedipine, prevented this inhibitory effect of chronic exposure to 20 mM KCl on NA release. In contrast pretreatment with 10 microM nicotine for 4 days had no effect on 100 mM KCl -evoked secretion and decreased nicotinic -evoked NA release by only 25%. Inclusion of nifedipine prevented the inhibition of NA release by chronic nicotine treatment. These data are discussed in relation to effects of chronic moderate, depolarisation by either K(+) or nicotine on influx of Ca(2+) via L-type voltage sensitive calcium channels.

Growth hormone improves lipoprotein concentration and arylesterase activity in mice with an atherogenic lipid profile induced by lactalbumin

The effect of growth hormone (GH) on arylesterase (AE), one of the activities of paraoxonase, has never been studied. The aims of the present study in mice were: (a) to compare the effect of age and sex on serum lipid and lipoprotein levels after consumption of lactalbumin- v. chow-based diets and (b) to study the effect of GH administration, age and sex on serum AE activity, lipid and lipoprotein and body fat levels in mice fed a lactalbumin diet. Seventy-two mice were divided into three age- and sex-matched experimental groups: (1) control chow (CC), (2) non-GH lactalbumin (NGL) and (3) GH-treated lactalbumin (GL) mice. Lactalbumin increased total cholesterol, (LDL+VLDL)-cholesterol and TAG and diminished HDL-cholesterol in all animals (P<0.05). In comparison with their NGL counterparts, old GL males presented lower total cholesterol (15%) and (LDL+VLDL)-cholesterol (17%) levels (P<0.05), whereas values of the same parameters were higher in adult GL males (P<0.05) (22 and 23%, respectively). Adult GL females displayed higher serum HDL-cholesterol concentrations (26%) (P<0.05) than adult NGL females. AE activity was lower in old GL females (78%) and old GL males (20%) (P<0.05), but higher in adult GL males (100%) (P<0.01). GH, that was inversely related to food intake, decreased abdominal and gonadal fat in all mice (P<0.05). To conclude, lactalbumin induced an atherogenic lipoprotein profile in NGL mice that was reverted by GH, preferentially in old males, suggesting that GH therapy will be more effective in aged men. The present results suggest that AE activity was age-, sex- and body fat level-dependent and that it diminished as a consequence of improved antioxidant status.

Phosphodiesterase type 4 inhibition enhances nitric oxide- and hydrogen sulfide-mediated bladder neck inhibitory neurotransmission

Nitric oxide (NO) and hydrogen sulfide (H2S) play a pivotal role in nerve-mediated relaxation of the bladder outflow region. In the bladder neck, a marked phosphodiesterase type 4 (PDE4) expression has also been described and PDE4 inhibitors, as rolipram, produce smooth muscle relaxation. This study investigates the role of PDE4 isoenzyme in bladder neck gaseous inhibitory neurotransmission. We used Western blot and double immunohistochemical staining for the detection of NPP4 (PDE4) and PDE4A and organ baths for isometric force recording to roflumilast and tadalafil, PDE4 and PDE5, respectively, inhibitors in pig and human samples. Endogenous H2S production measurement and electrical field stimulation (EFS) were also performed. A rich PDE4 and PDE4A expression was observed mainly limited to nerve fibers of the smooth muscle layer of both species. Moreover, roflumilast produced a much more potent smooth muscle relaxation than that induced by tadalafil. In porcine samples, H2S generation was diminished by H2S and NO synthase inhibition and augmented by roflumilast. Relaxations elicited by EFS were potentiated by roflumilast. These results suggest that PDE4, mainly PDE4A, is mostly located within nerve fibers of the pig and human bladder neck, where roflumilast produces a powerful smooth muscle relaxation. In pig, the fact that roflumilast increases endogenous H2S production and EFS-induced relaxations suggests a modulation of PDE4 on NO- and H2S-mediated inhibitory neurotransmission.

Impaired Excitatory Neurotransmission in the Urinary Bladder from the Obese Zucker Rat- Role of Cannabinoid Receptors

Metabolic syndrome (MS) is a known risk factor for lower urinary tract symptoms. This study investigates whether functional and expression changes of cannabinoid CB1 and CB2 receptors are involved in the bladder dysfunction in an obese rat model with insulin resistance. Bladder samples from obese Zucker rat (OZR) and their respective controls lean Zucker rat (LZR) were processed for immunohistochemistry and western blot for studying the cannabinoid receptors expression. Detrusor smooth muscle (DSM) strips from LZR and OZR were also mounted in myographs for isometric force recordings. Neuronal and smooth muscle CB1 and CB2 receptor expression and the nerve fiber density was diminished in the OZR bladder. Electrical field stimulation (EFS) and acetylcholine (ACh) induced frequency- and concentration-dependent contractions of LZR and OZR DSM. ACh contractile responses were similar in LZR and OZR. EFS-elicited contractions, however, were reduced in OZR bladder. Cannabinoid receptor agonists and antagonists failed to modify the DSM basal tension in LZR and OZR In LZR bladder, EFS responses were inhibited by ACEA and SER-601, CB1 and CB2 receptor agonists, respectively, these effects being reversed by ACEA plus the CB1 antagonist, AM-251 or SER-601 plus the CB2 antagonist, AM-630. In OZR bladder, the inhibitory action of ACEA on nerve-evoked contractions was diminished, whereas that SER-601 did not change EFS responses. These results suggest that a diminished function and expression of neuronal cannabinoid CB1 and CB2 receptors, as well as a lower nerve fiber density is involved in the impaired excitatory neurotransmission of the urinary bladder from the OZR.