Effect of anti-diabetic drugs on bone metabolism: Evidence from preclinical and clinical studies.

Diabetes mellitus is associated with abnormal bone health and an increased risk of fracture even though patients have normal or higher BMD. The mechanisms behind diabetes mellitus- induced various skeletal disorders remain unclear. Anti-diabetic drugs may have negative or positive impact on bone metabolism. For instance, thiazolidinediones increases the bone loss and risk of fracture possibly through PPARγ activation in bone marrow cells and hamper osteoblastogenesis via decreasing Runx2 transcription factor, IGF-1 and Wnt signalling pathways. In contrast, metformin and sulfonylureas have a neutral or positive effect on bone health and reduced risk of fracture. Results from the preclinical and clinical studies convey conflicting findings over insulin safety profile on bone health. Incretin-based therapy (GLP-1 receptor agonist and DPP-4 inhibitors) and SGLT2 inhibitors are currently marketed anti- diabetic drugs. While evidence from animal studies suggest that incretin-based therapy have anabolic effect on bone, limited clinical data of DPP-4 inhibitors and GLP-1 receptor agonist indicated a neutral effect on the bone health and risk of fracture. SGLT2 inhibitors may cause bone loss or increase fracture risk due to altered calcium, phosphate and sodium concentration. Therefore, safety concerns of anti-diabetic drugs are crucial for the management of diabetes mellitus. In this review, analysis of the available evidence for effect of anti-diabetic drugs on the bone metabolism and fracture risk in diabetes mellitus is described.

Pioglitazone-induced bone loss in diabetic rats and its amelioration by berberine: A portrait of molecular crosstalk.

Diabetes mellitus and osteoporosis both are high prevalence disorders, especially in the elderly population. Pioglitazone, a PPAR-γ agonist associated with bone loss and risk of fracture in type 2 diabetes mellitus patients. In this study, ameliorative effect of berberine against pioglitazone-induced bone loss in diabetic rats and possible mechanisms has been explored. Diabetes was induced in male Wistar albino rats by streptozotocin (65 mg/kg, i.v.) after 15min of nicotinamide (230mg/kg, i.p.) administration. Diabetic rats were treated orally with pioglitazone (10mg/kg) and berberine (100mg/kg) alone and in combination of both for 12 weeks. Femur of each rat was isolated and evaluated for the bone micro-architecture, BMD, histology and mRNA expression of PPAR-γ, AMPK, and bone turnover markers (RANKL, OPG, Runx2, and osteocalcin). Urinary calcium and serum TRAP was also measured. Treatment of pioglitazone and berberine alone and in combination significantly ameliorate abnormal blood glucose, serum insulin, and HbA1c levels in streptozotocin-induced diabetic rats. Pioglitazone treatment significantly increased urinary calcium, serum TRAP, mRNA expression of RANKL, PPAR-γ as well as significantly decreased Runx2, OPG, osteocalcin and AMPK levels in diabetic rats. Pioglitazone administration also shows detrimental effect on femur epiphysis micro-architecture, BMD and histology. Whereas, berberine treatment alone and in combination with pioglitazone remarkably ameliorates the abnormal urinary calcium, mRNA expression of AMPK, bone turnover markers, femur epiphysis micro-architecture, histology and also increases BMD in diabetic rats. In conclusion, berberine shows protective effect against pioglitazone-induced bone loss in diabetic rats possibly through AMPK activation pathway.

Naringin ameliorates acetic acid induced colitis through modulation of endogenous oxido-nitrosative balance and DNA damage in rats.

The aim of this study was to evaluate the effect of naringin on experimentally induced inflammatory bowel disease in rats. Naringin (20, 40 and 80 mg/kg) was given orally for 7 days to Wistar rats before induction of colitis by intrarectal instillation of 2 mL of 4% (v/v) acetic acid solution. The degree of colonic mucosal damage was analyzed by examining mucosal damage, ulcer area, ulcer index and stool consistency. Intrarectal administration of 4% acetic acid resulted in significant modulation of serum alkaline phosphatase, lactate dehydrogenase, superoxide dismutase (SOD), glutathione (GSH), malondialdehyde (MDA) and myeloperoxidase (MPO) content along with colonic nitric oxide (NO), xanthine oxidase (XO) level and protein carbonyl content in the colonic tissue as well as in blood. Naringin (40 and 80 mg/kg) exerted a dose dependent (P < 0.05) ameliorative effect, as it significantly increased hematological parameter as well as colonic SOD and GSH. There was a significant (P < 0.05) and dose dependant inhibition of macroscopical score, ulcer area along with colonic MDA, MPO activity by the 7 days of pretreatment of naringin (40 and 80 mg/kg). Biochemical studies revealed a significant (P < 0.05) dose dependant inhibition in serum alkaline phosphatase (ALP) and lactate dehydrogenase (LDH) levels by pretreatment of naringin. Increased levels of colonic NO, XO, protein carbonyl content and DNA damage were also significantly decreased by naringin pretreatment. The findings of the present investigation propose that naringin has an anti-inflammatory, anti-oxidant and anti-apoptotic potential effect at colorectal sites as it modulates the production and expression of oxidative mediators such as MDA, MPO, NO and XO, thus reducing DNA damage.