Hesperidin protects against stress induced gastric ulcer through regulation of peroxisome proliferator activator receptor gamma in diabetic rats.

Stress induced gastric ulcer is a serious health problem in diabetic patients. Some studies reported that hesperidin (HDN), a citrus bioflavonoid, can bind to and stimulate peroxisome proliferator-activator receptor-gamma (PPAR-γ) which may mediate its antidiabetic, anti-inflammatory and anti-oxidant effects. This work aims to study the possible protective effect of HDN against stress induced gastric ulcer in diabetic rats as well as the possible involvement of PPARγ in this effect. Type 2 diabetes was induced using streptozotocin and nicotinamide. Diabetic rats received either HDN (100 mg/kg/day, orally) & omeprazole (20 mg/kg/day, orally) or HDN (100 mg/kg/day, orally) + GW9662, PPARγ antagonist, (1 mg/kg/day, i.p.) for 8 weeks then acute gastric injury was induced by cold restraint stress technique. Glycemic controls and gastroprotective effects were evaluated by measuring serum levels of glucose and insulin, gastric free and total acidity and gastric ulcer indices. Histopathological examination of gastric mucosa was also performed. To determine the underlying mechanism of action, gastric mucosal expression of nuclear factor (erythroid-derived 2)-like 2 (Nrf2), hemeoxygenase-1 (HO-1), cluster of differentiation 45 (CD45), cyclooxygenase-2 (COX-2), nuclear factor kappa B (NFκB) and inducible nitric oxide synthase (iNOS), gastric contents of reduced glutathione (GSH), malondialdehyde (MDA), tumor necrosis factor alpha (TNF-α) and nitric oxide (NO); as well as superoxide dismutase (SOD) and catalase activities were measured. HDN significantly improved glycemic level; it also reduced gastric acidity and gastric ulcer index and histopathological changes comparable to that produced by omeprazole. Moreover, HDN reduced lipid peroxidation and inflammatory markers levels and enhanced antioxidant capacity. The use of GW9662 significantly abrogated the gastric protective effect of HDN as well as reduced the antioxidant and anti-inflammatory effects. Our work showed, for the first time that, HDN has promising protective effect against stress induced gastric ulcer in diabetic rats through activation of PPARγ.

Renoprotective effect of Hypericum perforatum against diabetic nephropathy in rats: Insights in the underlying mechanisms.

Oxidative stress and inflammation play a key role in the initiation and progression of diabetic nephropathy (DN). The present study aimed to investigate the possible protective effect of hypericum perforatum (HP) against DN. Rats were allocated into six groups: control, received normal saline; diabetic untreated (DM), received single dose of streptozotocin (STZ) after injection of nicotinamide (NA); gliclazide, received STZ,NA + gliclazide (10 mg/kg); DM + HP50, DM + HP100, DM + HP200, received STZ,NA and HP 50, 100, 200 mg/kg, respectively. Gliclazide and HP were administered daily via gavage for 8 weeks. Serum glucose, insulin, kidney function and histopathological picture were assessed. Furthermore, oxidative/nitrosative stress, inflammatory cytokines, apoptotic and fibrotic markers were measured. Diabetic untreated group showed increase in serum glucose, urea, creatinine with albuminurea. Renal expression of protein for nuclear factor kappa-B (NF-кB), renal expression of inducible nitric oxide synthase (iNOS), cyclooxygenase II (COXII), collagen IV, fibronectin were elevated. Malondialdehyde (MDA), nitric oxide (NO), tumour necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß), intracellular adhesion molecule (ICAM-1), monocellular chemoattractant protein-1 (MCP-1), tumour growth factor- ß (TGF-ß), caspase-3 and cytochrome c contents were also increased consequently with decline of serum insulin, expression of peroxisome proliferator-activated receptor (PPARγ), renal reduced glutathione (GSH) content and superoxide dismutase (SOD) activity. Treatment with either gliclazide or HP mitigated the deleterious effects of STZ on the tested parameters. These findings indicate for the first time that HP may have a renoprotective effect against DN through reduction of oxidative/nitrosative stress, enhancement of antioxidant defense mechanisms, decline of inflammatory cytokines, antifibrotic, antiapoptotic and blood glucose lowering properties.