Relative contributions of afferent vagal fibers to resistance to diet-induced obesity.

BACKGROUND: We previously demonstrated vagal neural pathways, specifically subdiaphragmatic afferent fibers, regulate expression of the intestinal sodium-glucose cotransporter SGLT1, the intestinal transporter responsible for absorption of dietary glucose. We hypothesized targeting this pathway could be a novel therapy for obesity. We therefore tested the impact of disrupting vagal signaling by total vagotomy or selective vagal de-afferentation on weight gain and fat content in diet-induced obese rats. METHODS: Male Sprague-Dawley rats (n = 5-8) underwent truncal vagotomy, selective vagal de-afferentation with capsaicin, or sham procedure. Animals were maintained for 11 months on a high-caloric Western diet. Abdominal visceral fat content was assessed by magnetic resonance imaging together with weight of fat pads at harvest. Glucose homeostasis was assessed by fasting blood glucose and HbA1C. Jejunal SGLT1 gene expression was assessed by qPCR and immunoblotting and function by glucose uptake in everted jejunal sleeves. RESULTS: At 11-months, vagotomized rats weighed 19% less (P = 0.003) and de-afferented rats 7% less (P = 0.19) than shams. Vagotomized and de-afferented animals had 52% (P < 0.0001) and 18% reduction (P = 0.039) in visceral abdominal fat, respectively. There were no changes in blood glucose or glycemic indexes. SGLT1 mRNA, protein and function were unchanged across all cohorts at 11-months postoperatively. CONCLUSIONS: Truncal vagotomy led to significant reductions in both diet-induced weight gain and visceral abdominal fat deposition. Vagal de-afferentation led to a more modest, but clinically and statistically significant, reduction in visceral abdominal fat. As increased visceral abdominal fat is associated with excess morbidity and mortality, vagal de-afferentation may be a useful adjunct in bariatric surgery.

Withanolide induces apoptosis in HL-60 leukemia cells via mitochondria mediated cytochrome c release and caspase activation.

The present study is on the growth inhibitory effect of Withania somnifera methanolic leaf extract and its active component, withanolide on HL-60 promyelocytic leukemia cells. The decrease in survival rate of HL-60 cells was noted to be associated with a time dependent decrease in the Bcl-2/Bax ratio, leading to up regulation of Bax. Both the crude leaf extract and the active component activated the apoptotic cascade through the cytochrome c release from mitochondria. The activation of caspase 9, caspase 8 and caspase 3 revealed that caspase was a key mediator in the apoptotic pathway. DNA fragmentation analysis revealed typical ladders as early as 12h indicative of caspase 3 role in the apoptotic pathway. Flow cytometry data demonstrated an increase of sub-G1 peak upon treatment by 51% at 24h, suggesting the induction of apoptotic cell death in HL-60 cells.

Pure compound from Boswellia serrata extract exhibits anti-inflammatory property in human PBMCs and mouse macrophages through inhibition of TNFalpha, IL-1beta, NO and MAP kinases.

The aim of the present study is to probe the anti-inflammatory potential of the plant Boswellia serrata by studying the effect of the crude extract and the pure compound isolated from it on key inflammatory mediators like TNFalpha, IL-1beta, and NO thus enabling the understanding of the key signaling events involved. The crude methanolic extract and the pure compound were analysed for their inhibitory effect on TNFalpha, IL-1beta and IL-6. The results demonstrated that all three cytokines are down regulated when PBMCs are cultured in the presence of crude extract or the pure compound at various time points. Observations on Th1/Th2 cytokines revealed marked down regulation of Th1 cytokines IFNgamma and IL-12 while the Th2 cytokines IL-4 and IL-10 were up regulated upon treatment with crude extract and pure compound. The extract and the pure compound isolated also showed considerable inhibition of NO production in activated RAW 264.7 cells, possibly via suppression of inducible NO synthase mRNA expression. Further to elucidate the underlying mechanism of action the effect of 12-ursene 2-diketone on LPS-induced activation of MAPK has also been examined. Our results demonstrated that 12-ursene 2-diketone inhibits the expression of pro-inflammatory cytokines and mediators via inhibition of phosphorylation of the MAP kinases JNK and p38 while no inhibition was seen in ERK phosphorylation in LPS-stimulated PBMCs. The above study therefore indicates that the crude methanolic extract and the isolated pure compound are capable of carrying out a natural anti-inflammatory activity at sites where chronic inflammation is present by switching off the pro-inflammatory cytokines and mediators, which initiate the process.

In vitro glucose uptake activity of Aegles marmelos and Syzygium cumini by activation of Glut-4, PI3 kinase and PPARgamma in L6 myotubes.

The purpose of the present study is to investigate the effect of methanolic extracts of Aegles marmelos and Syzygium cumini on a battery of targets glucose transporter (Glut-4), peroxisome proliferator activator receptor gamma (PPARgamma) and phosphatidylinositol 3' kinase (PI3 kinase) involved in glucose transport. A. marmelos and S. cumini are anti-diabetic medicinal plants being used in Indian traditional medicine. Different solvent extracts extracted sequentially were analysed for glucose uptake activity at each step and methanol extracts were found to be significantly active at 100ng/ml dose comparable with insulin and rosiglitazone. Elevation of Glut-4, PPARgamma and PI3 kinase by A. marmelos and S. cumini in association with glucose transport supported the up-regulation of glucose uptake. The inhibitory effect of cycloheximide on A. marmelos- and S. cumini-mediated glucose uptake suggested that new protein synthesis is required for the elevated glucose transport. Current observation concludes that methanolic extracts of A. marmelos and S. cumini activate glucose transport in a PI3 kinase-dependent fashion.

Inhibition of MAP kinases by crude extract and pure compound isolated from Commiphora mukul leads to down regulation of TNF-alpha, IL-1beta and IL-2.

The anti-inflammatory effect of the medicinal plant, Commiphora mukul gum was studied in peripheral blood mononuclear cells (PBMC). Bioassay-guided fractionation using conventional solvent extraction procedures, subsequent column fractionation, followed by monitoring specific activity in PBMC led to the isolation of a lead compound. Both crude ethyl acetate extract and the lead compound, thus isolated, showed inhibitory effect on proliferative response of PBMC in mitogenic lymphocyte proliferation and MLR assays. Further studies on inflammatory mediators such as IFN-gamma, IL-12, TNF-alpha, IL-1beta and NO showed down regulation, whereas no inhibition was observed in the case of anti-inflammatory cytokine IL-10. Immunoblot analysis revealed the inhibitory effect of crude ethyl acetate extract on phosphorylation of all the three mitogen activated protein kinases (MAPK) such as ERK, JNK and p38 MAPK. In contrast treatment with pure compound showed no inhibitory effect on ERK. c-fos and c-jun mRNA levels were also reduced in PMA stimulated cells on treatment with crude extract and pure compound. This reduction in c-fos and c-jun levels, when taken together with inhibition of MAPK activation, provides a possible mechanism by which both crude ethyl acetate extract and purified compound isolated from C. mukul exert its action.

Novel substituted methylenedioxy lignan suppresses proliferation of cancer cells by inhibiting telomerase and activation of c-myc and caspases leading to apoptosis.

Conventional solvent fractionation and bioactivity based target assays were used to identify a new anti-cancer molecule from Phyllanthus urinaria, a herbal medicinal plant used in South India. At each step of the purification process the different fractions that were isolated were tested for specific anti-proliferative activity by assays measuring the inhibition of [(3)H]thymidine incorporation, and trypan blue drug exclusion. The ethyl acetate fraction that contained the bioactivity was further purified and resolved by HPLC on a preparative column. The purity of each of the fractions and their bioactivity were checked. Fraction 3 demonstrated a single spot on TLC and showed maximum anti-proliferative activity. This fraction was further purified and the structure was defined as 7'-hydroxy-3',4',5,9,9'-pentamethoxy-3,4-methylene dioxy lignan using NMR and mass spectrometry analysis. The pure compound and the crude ethyl acetate fraction which showed anti-proliferative activities were examined for ability to target specific markers of apoptosis like bcl2, c-myc and caspases and for effects on telomerase. Four specific cancer cell lines HEp2, EL-1 monocytes, HeLa and MCP7 were used in this study. The results indicate that 7'-hydroxy-3',4',5,9,9'-pentamethoxy-3,4-methylene dioxy lignan was capable of inhibiting telomerase activity and also could inhibit bcl2 and activate caspase 3 and caspase 8 whose significance in the induction of apoptosis is well known. We believe that this compound could serve as a valuable chemotherapeutic drug after further evaluations.

Differential proliferative response to linoleate in cultures of epithelial cells from normal human breast and fibroadenomas.

Human breast epithelial cells isolated from normal breast tissues of premenopausal women demonstrated direct evidence of a proliferative effect by linoleate (18:2 omega 6) or prostaglandin E2 (PGE2) in the presence of insulin and epidermal growth factor in serum-free cultures within a collagen gel matrix. Neither epidermal growth factor nor 18:2 omega 6 by itself was capable of stimulating growth but together they stimulated proliferation synergistically. Epithelial cells isolated from fibroadenomas on the other hand failed to exhibit any growth stimulation due to 18:2 omega 6 or PGE2. The linoleate-stimulated growth in normal breast epithelial cells was inhibited by indomethacin, a cyclooxygenase inhibitor, which however could be reversed by PGE2. The proliferative response of normal breast epithelial cells to 18:2 omega 6 was accompanied by a greater conversion of [14C]18:2 omega 6 to arachidonic acid and [14C]20:4 omega 6 to prostaglandins than that seen in epithelial cells from fibroadenomas. The turnover of [14C]18:2 omega 6 in the phospholipids of normal cells was higher than in fibroadenomas indicating a possible role of phospholipids in mediating the 18:2 omega 6 effect in normal cells. Both normal and fibroadenoma cells can proliferate in response to cholera toxin and glucocorticoids when supplemented to the insulin- and epidermal growth factor-containing medium. From the results it appears that, unlike normal cells, fibroadenoma cells may have a specific defect in the PGE2-responsive cyclic AMP-generating mechanism whereas cholera toxin-induced mechanism is operative in both types of cells.