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In the last years, the use of natural phytochemical compounds as protective agents in the prevention and treatment of obesity and the related-metabolic syndrome has gained much attention worldwide. Different studies have shown health benefits for many vegetables such Opuntia ficus-indica and Beta vulgaris and their pigments collectively referred as betalains. Betalains exert antioxidative, anti-inflammation, lipid lowering, antidiabetic and anti-obesity effects. This review summarizes findings in the literature and highlights the therapeutic potential of betalains and their natural source as valid alternative for supplementation in obesity-related disorders treatment. Further research is needed to establish the mechanisms through which these natural pigments exert their beneficial effects and to translate the promising findings from animal models to humans. [ABSTRACT FROM AUTHOR]

Glucagon-like peptide-2 (GLP-2) reduces mouse gastric tone and small intestine transit, but its action on large intestine motility is still unknown. The purposes of the present study were 1) to examine the influence of GLP-2 on spontaneous mechanical activity and on neurally evoked responses, by recording intraluminal pressure from mouse isolated colonic segments; 2) to characterize GLP-2 mechanism of action; and 3) to determine the distribution of GLP-2 receptor (GLP-2R) in the mouse colonic muscle coat by immunohistochemistry. Exogenous GLP-2 (0.1-300 nM) induced a concentration-dependent reduction of the spontaneous mechanical activity, which was abolished by the desensitization of GLP-2 receptor or by tetrodotoxin, a voltage-dependent [Na.sup.+]-channel blocker. GLP-2 inhibitory effect was not affected by [N.sup.[omega]]-nitro-L-arginine methyl ester (a nitric oxide synthase inhibitor), apamin (a blocker of small conductance [Ca.sup.2+]-dependent [K.sup.+] channels), or [Lys1,Pro2,5,Arg3,4,Tyr6][VIP.sup.7-28] (a VIP receptor antagonist), but it was prevented by atropine or pertussis toxin (PTX), a [G.sub.i/o] protein inhibitor. Proximal colon responses to electrical field stimulation were characterized by nitrergic relaxation, which was followed by cholinergic contraction. GLP-2 reduced only the cholinergic evoked contractions. This effect was almost abolished by GLP-2 receptor desensitization or PTX. GLP-2 failed to affect the contractile responses to exogenous carbachol. GLP-2R immunoreactivity (IR) was detected only in the neuronal cells of both plexuses of the colonic muscle coat. More than 50% of myenteric GLP-2R-IR neurons shared the choline acetyltransferase IR. In conclusion, the activation of GLP-2R located on cholinergic neurons may modulate negatively the colonic spontaneous and electrically evoked contractions through inhibition of acetylcholine release. The effect is mediated by [G.sub.i] protein. enteric nervous system; gastrointestinal hormones; colonic motility; acetylcholine doi: 10.1152/ajpgi.00282.2010.

Glucagon-like peptide-2 (GLP-2) influences different aspects of the gastrointestinal function, including epithelial growth, digestion, absorption, motility, and blood flow. Intraluminal pressure from isolated mouse stomach was recorded to investigate whether GLP-2 affects gastric tone and to analyze its mechanism of action. Regional differences between diverse parts of the stomach were also examined using circular muscular strips from fundus and antrum. In the whole stomach, GLP-2 (0.3-100 nM) produced concentration-dependent relaxation with a maximum that was about 75% of relaxation to 1 [micro]M isoproterenol ([IC.sub.50] = 2.5 nM). This effect was virtually abolished by desensitization of GLP-2 receptors or by [alpha]-chymotrypsin. The relaxant response to GLP-2 was not affected by tetrodotoxin, a blocker of neuronal voltage-dependent [Na.sup.+] channels, but it was significantly reduced by [omega]-conotoxin GVIA, a blocker of neuronal N-type voltage-operated [Ca.sup.2+] channels. [N.sub.[omega]]-nitro-L-arginine methyl ester, a blocker of nitric oxide synthase, or apamin, a blocker of [Ca.sup.2+]-dependent potassium channels, failed to affect the gastric response to the peptide. However, the relaxation was significantly antagonized by [Lysl,Pro2,5,Arg3,4,Tyr6][VIP.sup.7-28], a vasoactive intestinal peptide (VIP) receptor antagonist (GLP-2 maximum effect = 45% of relaxation to 1 [micro]M isoproterenol), and virtually abolished by desensitization of the VIP receptors. GLP-2 induced concentration-dependent relaxation in carbachol-precontracted fundic strips but not in antral strips. These results provide the first experimental evidence that GLP-2 is able to induce gastric relaxation acting peripherally on the mouse stomach. The effect appears to be mediated by prejunctional neural release of VIP and confined to fundic region. enteric nervous system; gastrointestinal hormones; gastric motility; gastric fundus

Obesity-related dysmetabolic conditions are amongst the most common causes of death globally. Indicaxanthin, a bioavailable betalain pigment from Opuntia ficus-indica fruit, has been demonstrated to modulate redox-dependent signalling pathways, exerting significant anti-oxidative and anti-inflammatory effects in vitro and in vivo. In light of the strict interconnections between inflammation, oxidative stress and insulin resistance (IR), a nutritionally relevant dose of indicaxanthin has been evaluated in a high-fat diet (HFD) model of obesity-related IR. To this end, biochemical and histological analysis, oxidative stress and inflammation evaluations in liver and adipose tissue were carried out. Our results showed that indicaxanthin treatment significantly reduced body weight, daily food intake and visceral fat mass. Moreover, indicaxanthin administration induced remarkable, beneficial effects on HFD-induced glucose dysmetabolism, reducing fasting glycaemia and insulinaemia, improving glucose and insulin tolerance and restoring the HOMA index to physiological values. These effects were associated with a reduction in hepatic and adipose tissue oxidative stress and inflammation. A decrease in RONS, malondialdehyde and NO levels, in TNF-α, CCL-2 and F4-80 gene expression, in p65, p-JNK, COX-2 and i-NOS protein levels, in crown-like structures and hepatic inflammatory foci was, indeed, observed. The current findings encourage further clinical studies to confirm the effectiveness of indicaxanthin to prevent and treat obesity-related dysmetabolic conditions. [ABSTRACT FROM AUTHOR]