Effect of Acacia senegal on TGF-β1 and vascular mediators in a rat model of diabetic nephropathy

CONTEXT

Transforming growth factor-β1 (TGF-β1), endothelin-1 and angiotensin II are responsible for extracellular matrix accumulation within the kidney in diabetic nephropathy.

OBJECTIVE

This study evaluated the effect of adding Gum Arabic (GA) and insulin on serum glucose, renal function, TGF-β1, endothelin-1, and angiotensin II in rats with diabetic nephropathy.

METHODS

Sixty male Sprague-Dawley rats were divided into; normal, normal plus GA, diabetic rats (DM), DM plus insulin, DM plus GA, and DM plus insulin plus GA groups. Levels of glucose and creatinine in serum, TGF-β1, angiotensin II, and endothelin-1 in renal homogenate and HbA1c were measured.

RESULTS

Serum creatinine, TGF-β1, angiotensin II, and endothelin-1 were increased in diabetic rats. GA decreased serum glucose, TGF-β1, angiotensin II, endothelin-1, and HbA1c in diabetic rats. GA and insulin decreased serum glucose, creatinine, TGF-β1, angiotensin II, endothelin-1, and HbA1c in diabetic rats.

CONCLUSION

Co-administration of GA with insulin to rats with diabetic nephropathy improved the glycemic state, renal function, TGF-β1, endothelin-1, and angiotensin II.

Subacute administration of Astaxanthin inhibits vitamin K-dependent clotting factors in rats

This study investigated the effect of Astaxanthin (ASTX) on levels and activities of the clotting factors in control rats. Untreated or ASTX-treated rats (10 mg/kg, dissolved in DMSO) were used in this study. ASTX treatment was conducted for 10 days daily. ASTX significantly decreased the platelet count and prolonged values of prothrombin and activated partial thromboplastin time (PT and aPTT, respectively). Besides, it significantly reduced serum levels of vitamin K and the plasma activities and hepatic expression of vitamin K-dependent factors (FII, FVII, FIX, and FX) without altering the activities or levels of all other clotting factors nor plasma levels of fibrinogen or von Willebrand Factor. These effects were associated with a reduction in serum and fecal levels of cholesterol and triglycerides and lower serum levels of LDL-c. In conclusion, ASTX exerts an in vivo hypocoagulant effects mediated by the inhibition of vitamin K-dependent factors. PRACTICAL APPLICATIONS: The findings presented here are the first that show the ability of Astaxanthin (ASTX) to inhibit coagulation in rats by suppressing the circulatory levels of Vitamin K and decrease the synthesis and release of all Vitamin-K dependent factor (FII, FVII, FIX, and FX). Since some synthetic anti-coagulants had side effects, these findings may illustrate ASTX as a natural anti-coagulant with fewer side effects that require further investigation in more clinical trials. Besides, awareness should be established for those individuals with some bleeding disorders who are being treated with ASTX for other beneficial effects.

Antiplatelet activity of astaxanthin in control- and high cholesterol-fed rats mediated by down-regulation of P2Y12, inhibition of NF-κB, and increasing intracellular levels of cAMP

This study evaluated the antiplatelet effect of the plant carotenoid, astaxanthin (ASTX) in rats fed either control or high cholesterol plus cholic acid diet (HCCD) and possible underlying mechanisms. Adult male Wistar rats were divided into four groups (n = 8/each), namely, control (fed normal diet), control + ASTX (10 mg/kg/day), HCCD-fed rats, and HCCD + ASTX-treated rats. Diets and treatments were orally administered daily for 30 days. In both control and HCCD-fed rats, ASTX significantly increased fecal levels of triglycerides and cholesterol, reduced platelet count, prolonged bleeding time, and inhibited platelet aggregation. It also reduced platelet levels of reactive oxygen species (ROS) and Bcl-2; thromboxane B2 (TXB2) release; and the expression of P2Y₁₂, P-selectin, and CD36 receptors. Moreover, the activity NF-κB p65 and Akt was inhibited. Concomitantly, it increased the protein levels of cleaved caspase-3 and vasodilator-stimulated phosphoprotein (p-VASP) as well as intracellular levels of cAMP. However, in HCCD-fed rats, the effects of ASTX were associated with reduced serum levels of ox-LDL-c and fasting plasma glucose levels. In conclusion, antiplatelet effects of ASTX involve ROS scavenging, inhibiting NF-κB activity, down-regulating P2Y₁₂ expression, and increasing intracellular levels of cAMP that are attributed to its antioxidant, hypolipidemic, and anti-inflammatory effects.

Exendin-4 exhibits a tumour suppressor effect in SKOVR-3 and OVACR-3 ovarian cancer cells lines by the activation of SIRT1 and inhibition of NF-κB

This study investigated if EX-527 has an anti-tumour effect in SKOV-3 and OVCAR-3 ovarian cancer (OC) cell lines and if this effect involves the SIRT1/NF-κB axis. Cells were cultured in the presence or absence of EX-527, a selective SIRT-1 inhibitor. Exendin-4 significantly induced cell death in both cell lines and inhibited cell migration and invasion. Also, it decreased protein levels of Bcl-2, MMP-9, and ICAM-1 and increased those of Bax, cyclin D1 and cleaved caspase-3. Mechanistically, Exendin-4 increased the activity and nuclear accumulation of SIRT1 and decreased nuclear levels of NF-κB p65; acetylated levels of NF-κB p65, and cytoplasmic levels of p-IKKα and p-IκBα. EX-527 partially ameliorated the effect of Exendin-4 on cell death, migration, and invasion, as well as on the expression of Bcl-2, MMP-9, Bax, cleaved caspase-3 and ICAM-1. In addition, EX-527 did not affect the levels of nuclear p65 and p-p65 (Ser536); p-IκBα (Ser32) and p-IKKαβ. In conclusion, Exendin-4 can suppress OC by inhibiting NF-kB through SIRT1 dependent and independent mechanisms.

Exendin-4 Induces Cytotoxic Autophagy in Two Ovarian Cancer Cell Lines through Inhibition of Mtorc1 Mediated by Activation of AMPK and Suppression of Akt

Activation of autophagy suppresses ovarian cancer (OC). This in vitro study investigated whether the anti-tumour effect of exendin-4 against OC involves modulation of autophagy and figured out the possible mechanisms of action. SKOV-3 and OVCAR-3 cells (1 × 105/ml) were cultured in DMEM medium and treated with exendin-4 in the presence or absence of chloroquine (CQ), an autophagy inhibitor. In some cases, cells were also treated with exendin- 4 with or without pre-treatment with compound C (CC), an AMPK inhibitor, or insulin-like growth factor (IGF-1), a PI3K/Akt activator. Exendin-4 increased expression of beclin-1 and LC3I/II, suppressed expression of p62, reduced cell survival, migration, and invasion, and increased cell apoptosis and LDH release in both SKOV-3 and OVCAR-3 cells. Besides, exendin-4 reduced phosphorylation of mTORC1, 6SK, 4E-BP1, and Akt but increased phosphorylation of AMPK in both cell lines. These effects were associated with down-regulation of Bcl-2, suppression of nuclear phosphorylation of NF-κB p65, and increased expression of Bax and cleaved caspases 3/8. Chloroquine completely prevented the inhibitory effects of exendin-4 on the cell survival, Bcl-2, NF-κB, and cell invasiveness and abolished its stimulation of cell apoptosis and LDH release. Moreover, only the combined treatment with IGF-1 and CC completely abolished the observed effect of exendin-4 on the expression of beclin-1, LC3I/II, p62, as well as on cell survival, apoptosis, and LDH release. Exendin-4 exhibits a potent anti-tumour cytotoxic effect in SKOV-3 and OVCAR-3 cells by activating the markers of autophagy, mediated by activation of AMPK and inhibition of Akt.

Resveratrol protects against hepatic insulin resistance in a rat's model of non-alcoholic fatty liver disease by down-regulation of GPAT-1 and DGAT2 expression and inhibition of PKC membranous translocation

Non-alcoholic fatty liver disease (NAFLD) is associated with hepatic insulin resistance (IR). Resveratrol (RES) a potent hypolipidemic dietary polyphenol has been identified for its ability to prevent hepatic steatosis and hepatic IR in high-fat diet (HFD)-fed murine models of NAFLD. In the present study, we have carried an in vivo animal experiment to identify a novel mechanism for RES protective action. Sub-chronic (45 days) RES pretreatment in 3 days HFD-fed adult Wistar rats prevented early hepatic IR through inhibiting PKC/JNK activation; decreasing p-IRS (Ser³⁰⁷ ) and increasing p-IRS(Tyr⁶¹² ), p-Akt(Ser⁴⁷³ ) and p-GSK3(Ser⁹ ). These effects of RES were associated with reduced expression of acyl-CoA:glycerol-sn-3-phosphate acyltransferase (GPAT-1) and diacylglycerol:acyl-CoA acyltransferase (DGAT2), two critical enzymes in the glycerol-3-phosphate pathway for de novo triglycerides synthesis. These data indicate that RES protects against NAFLD, initially, by inhibiting the early development of hepatic IR.

Effects of Gum Arabic ingestion on body mass index and body fat percentage in healthy adult females: two-arm randomized, placebo controlled, double-blind trial

Background

Gum Arabic (acacia Senegal) is a complex polysaccharide indigestible to both humans and animals. It has been considered as a safe dietary fiber by the United States, Food and Drug Administration (FDA) since the 1970s. Although its effects were extensively studied in animals, there is paucity of data regarding its quantified use in humans. This study was conducted to determine effects of regular Gum Arabic (GA) ingestion on body mass index and body fat percentage among healthy adult females.

Methods

A two-arm randomized, placebo controlled, double-blind trial was conducted in the Department of Physiology at the Khartoum University. A total of 120 healthy females completed the study. They were divided to two groups: A test group of 60 volunteers receiving GA (30 gm /day) for 6 weeks and a placebo group of 60 volunteers receiving pectin (1 gm/day) for the same period of time. Weight and height were measured before and after intervention using standardized height and weight scales. Skin fold thickness was measured using Harpenden Skin fold caliper. Fat percentage was calculated using Jackson and Pollock 7 caliper method and Siri equation.

Results

Pre and post analysis among the study group showed significant reduction in BMI by 0.32 (95% CI: 0.17 to 0.47; P<0.0001) and body fat percentage by 2.18% (95% CI: 1.54 to 2.83; P<0.0001) following regular intake of 30 gm /day Gum Arabic for six weeks. Side effects caused by GA ingestion were experienced only in the first week. They included unfavorable viscous sensation in the mouth, early morning nausea, mild diarrhea and bloating abdomen.

Conclusions

GA ingestion causes significant reduction in BMI and body fat percentage among healthy adult females. The effect could be exploited in the treatment of obesity.