Suppressive effects of γ-conglutin on differentiation of 3T3-L1 preadipocytes

Combined Gamma Conglutin and Lupanine Treatment Exhibits In Vivo an Enhanced Antidiabetic Effect by Modulating the Liver Gene Expression Profile

Previous studies have individually shown the antidiabetic potential of gamma conglutin (Cγ) and lupanine from lupins. Until now, the influence of combining both compounds and the effective dose of the combination have not been assessed. Moreover, the resulting gene expression profile from this novel combination remains to be explored. Therefore, we aimed to evaluate different dose combinations of Cγ and lupanine by the oral glucose tolerance test (OGTT) to identify the higher antidiabetic effect on a T2D rat model. Later, we administered the selected dose combination during a week. Lastly, we evaluated biochemical parameters and liver gene expression profile using DNA microarrays and bioinformatic analysis. We found that the combination of 28 mg/kg BW Cγ + 20 mg/kg BW lupanine significantly reduced glycemia and lipid levels. Moreover, this treatment positively influenced the expression of Pdk4, G6pc, Foxo1, Foxo3, Ppargc1a, Serpine1, Myc, Slc37a4, Irs2, and Igfbp1 genes. The biological processes associated with these genes are oxidative stress, apoptosis regulation, and glucose and fatty-acid homeostasis. For the first time, we report the beneficial in vivo effect of the combination of two functional lupin compounds. Nevertheless, further studies are needed to investigate the pharmacokinetics and pharmacodynamics of the Cγ + lupanine combined treatment.

Lupinus albus γ-Conglutin: New Findings about Its Action at the Intestinal Barrier and a Critical Analysis of the State of the Art on Its Postprandial Glycaemic Regulating Activity

γ-Conglutin (γ-C) is the glycoprotein from the edible seed L. albus, studied for long time for its postprandial glycaemic regulating action. It still lacks clear information on what could happen at the meeting point between the protein and the organism: the intestinal barrier. We compared an in vitro system involving Caco-2 and IPEC-J2 cells with an ex vivo system using pig ileum and jejunum segments to study γ-C transport from the apical to the basolateral compartment, and its effects on the D-glucose uptake and glucose transporters protein expression. Finally, we studied its potential in modulating glucose metabolism by assessing the possible inhibition of α-amylase and α-glucosidase. RP-HPLC analyses showed that γ-C may be transported to the basolateral side in the in vitro system but not in the pig intestines. γ-C was also able to promote a decrease in glucose uptake in both cells and jejunum independently from the expression of the SGLT1 and GLUT2 transporters.

Lupin γ-conglutin protects against cell death induced by oxidative stress and lipotoxicity, but transiently inhibits in vitro insulin secretion by increasing KATP channel currents

Lupin γ-conglutin beneficially modulates glycemia, but whether it protects against oxidative and lipotoxic damage remains unknown. Here, we studied the effects of γ-conglutin on cell death provoked by hydrogen peroxide and palmitate in HepG2 hepatocytes and insulin-producing MIN6 cells, and if a modulation of mitochondrial potential and reactive oxygen species (ROS) levels was involved. We also investigated how γ-conglutin influences insulin secretion and electrical activity of β-cells. The increased apoptosis of HepG2 cells exposed to hydrogen peroxide was prevented by γ-conglutin, and the viability and ROS content in γ-conglutin-treated cells was similar to that of non-exposed cells. Additionally, γ-conglutin partially protected MIN6 cells against hydrogen peroxide-induced death. This was associated with a marked reduction in ROS. No significant changes were found in the mitochondrial potential of γ-conglutin-treated cells. Besides, we observed a partial protection against lipotoxicity only in hepatocytes. Unexpectedly, we found a transient inhibition of insulin secretion, plasma membrane hyperpolarization, and higher K_ATP channel currents in β-cells treated with γ-conglutin. Our data show that γ-conglutin protects against cell death induced by oxidative stress or lipotoxicity by decreasing ROS and might also indicate that γ-conglutin promotes a β-cell rest, which could be useful for preventing β-cell exhaustion in chronic hyperglycemia.

Neuropeptide B promotes proliferation and differentiation of rat brown primary preadipocytes

Neuropeptide B (NPB) is reported to regulate energy homeostasis and metabolism via the NPBWR1 and NPBWR2 receptors in various tissues. However, the molecular mechanisms triggered from their interaction are not well investigated in brown adipose tissue. In this study, we specifically analyzed the role of NPB in controlling brown adipogenesis in rat brown preadipocytes. We first detected the expression of NPBWR1 and NPB on mRNA and protein level in brown preadipocytes and observed that NPB increased viability and proliferation of preadipocytes. Moreover, NPB stimulated expression of adipogenic genes (Prdm16, Ucp1) and suppressed the expression of antiadipogenic preadipocyte factor 1 (Pref1) during the differentiation process. Altogether, this led to an increase in intracellular lipid accumulation during preadipocyte differentiation, coupled with an increase in adrenaline‐induced oxygen consumption mediated by NPB. Furthermore, Ucp1 expression stimulated by NPB was attenuated by blockade of p38 kinase. In summary, we conclude that NPB promotes proliferation and differentiation of rat brown preadipocytes via p38‐dependent mechanism and plays an important role in controlling brown adipose tissue formation.