Effect of Silicon-Enriched Meat Consumption on Proximal Colonic Antioxidant Status of Late-Stage T2DM Rats ^†

Abstract

Colonic mucosa exhibits numerous functional alterations associated to type 2 diabetes mellitus (T2DM). Oxidative stress, a factor involved in T2DM pathogenesis and its complications, may contribute to some of the colonic alterations. Silicon (Si) is a trace element with antioxidant, anti-inflammatory and anti-diabetic effects. In this study, we examined if the intake of soluble G⁵ organic Si (2 mg/kg b.w./day), as a functional ingredient, might enhance the antioxidant status of the proximal colonic mucosal barrier in late-stage T2DM rats. A control-restructured meat matrix (RM) included in a high-saturated-fat hypercholesterolemic diet (HSFHCD-RM) and combined with low-dose streptozotocin plus nicotinamide was used to induce T2DM. Sixteen diabetic rats were divided into two groups and received different experimental diets for 8 weeks: LD group fed a HSFHCD-RM, and LD-Si group fed a Si-enriched RM (HSFHCD-Si-RM). We evaluated Si effects on the immunolocalizations and activities of antioxidant enzymes in proximal colonic mucosa. Compared to LD-group mucosa, LD-Si group showed stronger immunoreactivities in Cu, Zn-superoxide dismutase (SO1) (4.63 ± 0.02 vs. 1.5 ± 0.03; 626%, p = 0.00001), Mn-superoxide dismutase (SOD2) (3.63 ± 0.03 vs. 0.5 ± 0.05; 208.6%, p = 0.0001), catalase (CAT) (2.38 ± 0.03 vs. 0.75 ± 0.05, 131.51%, p = 0.0001), glutathione peroxidase (GPx) (3.25 ± 0.03 vs. 0.5 ± 0.05; 550.0%, p = 0.0001) and glutathione reductase (GR) (3.50 ± 0.05 vs. 2.56 ± 0.03; 36.75%, p = 0.001). Moreover, Si consumption led to higher total SOD (3.06 ± 0.42 vs. 2.53 ± 0.39; 20.94%, p = 0.001), CAT (34.10 ± 1.75 vs. 30.51 ± 1.81; 11.65%, p = 0.01) and GR (63.11 ± 13.22 vs. 51.46 ± 9.97; 22.60%, p = 0.001) activities, and lower GPx activity (191.82 ± 18.89 vs. 226.61 ± 20.07, 22.63%, p = 0.001). In summary, these results demonstrate the enhanced antioxidant status of the proximal colonic mucosa after Si intake in a late-stage T2DM model. Si effectively protected colonic mucosa against oxidative stress induced by T2DM. The incorporation of Si as a functional ingredient could be beneficial as a new nutritional tool to reverse colonic mucosa dysfunction associated to metabolic disorders, such as T2DM.