Supplementation with l-glutathione improves oxidative status and reduces protein nitration in myenteric neurons in the jejunum in diabetic Rattus norvegicus.

Diabetes mellitus is a syndrome with multiple etiologies, characterized by chronic hyperglycemia that increases the production of reactive oxygen species and decreases antioxidant defenses. The present study evaluated oxidative stress parameters and protein nitration in myenteric neurons in the jejunum in diabetic rats supplemented with l-glutathione. Rats (90 days of age) were distributed into four groups (n = 6/group): normoglycemic (N), normoglycemic supplemented with l-glutathione (NGT), diabetic (D), and diabetic supplemented with l-glutathione (DGT). At 210 days of age, the animals were sacrificed, and the jejunum was collected, washed, and subjected to various procedures: tert-butyl hydroperoxide chemiluminescence (CL), determination of total antioxidant capacity (TAC), determination of catalase activity, quantification of nitric oxide (NO), and double-labeling of HuC/D-immunoreactive myenteric neurons and nitrotyrosine (3-NT). Diabetes increased oxidative stress in the jejunum in the D group, reflected by increases in lipid peroxidation, TAC, catalase activity, and NO. The D group exhibited an increase in the percentage of myenteric neurons that were double-labeled with 3-NT. Supplementation with l-glutathione did not cause differences in the average CL curves between the D and DGT groups, but reductions of TAC and catalase activity were observed. Supplementation with l-glutathione promoted a reduction of neurons that contained 3-NT in the DGT group. Diabetes mellitus promoted oxidative stress in the jejunum, and supplementation with l-glutathione improved oxidative status by preventing protein nitration in myenteric neurons in diabetic animals that received supplementation.

Supplementation with L-glutamine prevents tumor growth and cancer-induced cachexia as well as restores cell proliferation of intestinal mucosa of Walker-256 tumor-bearing rats.

This study aimed to evaluate the intestinal mucosa of the duodenum and jejunum of Walker-256 tumor-bearing rats supplemented with L-glutamine. Thirty-two male 50-day-old Wistar rats (Rattus norvegicus) were randomly divided into four groups: control (C), control supplemented with 2 % L-glutamine (GC), Walker-256 tumor (WT), and Walker-256 tumor supplemented with 2 % L-glutamine (TWG). Walker-256 tumor was induced by inoculation viable tumor cells in the right rear flank. After 10 days, celiotomy was performed and duodenal and jejunal tissues were removed and processed. We evaluated the cachexia index, proliferation index, villus height, crypt depth, total height of the intestinal wall, and number of goblet cells by the technique of periodic acid-Schiff (PAS). Induction of Walker-256 tumor promoted a reduction of metaphase index in the TW group animals, which was accompanied by a reduction in the villous height and crypt depths, resulting in atrophy of the intestinal wall as well as increased PAS-positive goblet cells. Supplementation with L-glutamine reduced the tumor growth and inhibited the development of the cachectic syndrome in animals of the TWG group. Furthermore, amino acid supplementation promoted beneficial effects on the intestinal mucosa in the TWG animals through restoration of the number of PAS-positive goblet cells. Therefore, supplementation with 2 % L-glutamine exhibited a promising role in the prevention of tumor growth and cancer-associated cachexia as well as restoring the intestinal mucosa in the duodenum and jejunum of Walker-256 tumor-bearing rats.

Is L-glutathione more effective than L-glutamine in preventing enteric diabetic neuropathy?

BACKGROUND: Diabetes and its complications appear to be multifactorial. Substances with antioxidant potential have been used to protect enteric neurons in experimental diabetes. AIM: This study evaluated the effects of supplementation with L-glutamine and L-glutathione on enteric neurons in the jejunum in diabetic rats. METHODS: Rats at 90 days of age were distributed into six groups: normoglycemic, normoglycemic supplemented with 2 % L-glutamine, normoglycemic supplemented with 1 % L-glutathione, diabetic (D), diabetic supplemented with 2 % L-glutamine (DG), and diabetic supplemented with 1 % L-glutathione (DGT). After 120 days, the jejunums were immunohistochemically stained for HuC/D+ neuronal nitric oxide synthase (nNOS) and vasoactive intestinal polypeptide (VIP). Western blot was performed to evaluate nNOS and VIP. Submucosal and myenteric neurons were quantitatively and morphometrically analyzed. RESULTS: Diabetic neuropathy was observed in myenteric HuC/D, nNOS, and VIP neurons (p < 0.05). In the submucosal plexus, diabetes did not change nitrergic innervation but increased VIPergic neuronal density and body size (p < 0.05). Supplementation with L-glutathione prevented changes in HuC/D neurons in the enteric plexus (p < 0.05), showing that supplementation with L-glutathione was more effective than with L-glutamine. Myenteric nNOS neurons in the DGT group exhibited a reduced density (34.5 %) and reduced area (p < 0.05). Submucosal neurons did not exhibit changes. The increase in VIP-expressing neurons was prevented in the submucosal plexus in the DG and DGT groups (p < 0.05). CONCLUSION: Supplementation with L-glutathione exerted a better neuroprotective effect than L-glutamine and may prevent the development of enteric diabetic neuropathy.

Combined use of systemic quercetin, glutamine and alpha-tocopherol attenuates myocardial fibrosis in diabetic rats.

This study aimed to analyze the effects of the quercetin (100 mg/kg), 1% glutamine and 1% α-tocopherol antioxidants in the myocardium of rats with streptozotocin-induced diabetes mellitus. Twenty male rats were subdivided into four groups (n = 5): N (normoglycemic); D (diabetic); NT (normoglycemic treated with antioxidants); and DT (diabetic treated with antioxidants) treated for 60 days. Clinical parameters, oxidative stress markers, inflammatory cytokines, myocardial collagen fibers and immunoexpression of superoxide dismutase 1 (SOD-1), glutathione peroxidase-1 (GPx-1), interleukin-1ß (IL-1-ß), transforming growth factor-beta (TGF-ß), and fibroblast growth factor-2 (FGF-2) were evaluated. Results showed reduced body weight, hyperphagia, polydipsia and hyperglycemic state in groups D and DT. The levels of glutathione (GSH) were higher in NT and DT compared to N (p < 0.01) and D (p < 0.001) groups, respectively. Greater GSH levels were found in DT when compared to N animals (p < 0.001). In DT, there was an increase in IL-10 in relation to N, D and NT (p < 0.05), while GPx-1 expression was similar to N and lower compared to D (p < 0.001). TGF-ß expression in DT was greater than N (p < 0.001) group, whereas FGF-2 in DT was higher than in the other groups (p < 0.001). A significant reduction in collagen fibers (type I) was found in DT compared to D (p < 0.05). The associated administration of quercetin, glutamine and α-tocopherol increased the levels of circulating interleukin-10 (IL-10) and GSH, and reduced the number of type I collagen fibers. Combined use of systemic quercetin, glutamine and alpha-tocopherol attenuates myocardial fibrosis in diabetic rats.

In vitro antioxidant potential and in vivo effects of Schinus terebinthifolia Raddi leaf extract in diabetic rats and determination of chemical composition by HPLC-ESI-MS/MS.

The present study investigated the in vitro and in vivo antioxidant potential and phytochemical composition of Schinus terebinthifolia, which is widely used in folk medicine for various therapeutic purposes. The in vitro analyses indicated that the hydroethanolic extract (HE) had 312.50 ± 0.50 mg GAE/g of total phenols. It also presented anti-DPPH• and anti-ABTS•+ activity, reduced phosphomolybden and metal ions and blocked the bleaching of ß-carotene. The HE at concentrations of 3.0 and 2.0 µg/mL had TRAP values of 2.223 ± 0.018 and 1.894 ± 0.026 µM Trolox, respectively. The HE increased the availability of antioxidants in plasma in treated animals in vivo. HPLC-ESI-MS/MS indicated the presence of 11 phenols: cumaric acid, (+)-catechin, myricetin-3-O-glicuronide, kaempferol-3-O-glucoside, myricetin, myricitrin, quercetin, gallic acid, methyl galate, pentagalloyl glucose and ethyl galate. Thus, S. terebinthifolia has potential for the prevention or treatment of diseases that are related to oxidative stress, such as diabetes mellitus.

Desired and side effects of the supplementation with l-glutamine and l-glutathione in enteric glia of diabetic rats.

BACKGROUND/AIMS: Enteric neuropathy associated with Diabetes Mellitus causes dysfunction in the digestive system, such as: nausea, diarrhea, constipation, vomiting, among others. The aim of this study was to compare the effects of supplementation with 2% l-glutamine and 1% l-glutathione on neurons and enteric glial cells of ileum of diabetic rats. METHODS: Thirty male Wistar rats have been used according to these group distributions: Normoglycemic (N), Normoglycemic supplemented with l-glutamine (NG), Normoglycemic supplemented with l-glutathione (NGO), Diabetic (D), Diabetic supplemented with l-glutamine (DG) and Diabetic supplemented with l-glutathione (DGO). After 120days, the ileum was processed for immunohistochemistry of HuC/D and S100ß. Quantitative and morphometric analysis have been performed. RESULTS: Diabetic rats presented a decrease in the number of neurons when compared to normoglycemic animals. However, diabetes was not associated with a change in glial density. l-Glutathione prevented the neuronal death in diabetic rats. l-Glutathione increased a glial proliferation in diabetic rats. The neuronal area in diabetic rats increased in relation to the normoglycemics. The diabetic rats supplemented with l-glutamine and l-glutathione showed a smaller neuronal area in comparison to diabetic group. The glial cell area was a decreased in the diabetics. The diabetic rats supplemented with l-glutamine and l-glutathione did not have significant difference in the glial cell body area when compared to diabetic rats. CONCLUSION: It is concluded that the usage of l-glutamine and l-glutathione as supplements presents both desired and side effects that are different for the same substance in considering normoglycemic or diabetic animals.