Effects and mechanism of stem cells from human exfoliated deciduous teeth combined with hyperbaric oxygen therapy in type 2 diabetic rats

OBJECTIVES: Mesenchymal stem cells (MSCs) are potentially ideal for type 2 diabetes treatment, owing to their multidirectional differentiation ability and immunomodulatory properties. Here we investigated whether the stem cells from human exfoliated deciduous teeth (SHED) in combination with hyperbaric oxygen (HBO) could treat type 2 diabetic rats, and explored the underlying mechanism. METHODS: SD rats were used to generate a type 2 diabetes model, which received stem cell therapy, HBO therapy, or both together. Before and after treatment, body weight, blood glucose, and serum insulin, blood lipid, pro-inflammatory cytokines (tumor necrosis factor-alpha and interleukin-6), and urinary proteins were measured and compared. After 6 weeks, rats were sacrificed and their organs were subjected to hematoxylin and eosin staining and immunofluorescence staining for insulin and glucagon; apoptosis and proliferation were analyzed in islet cells. Structural changes in islets were observed under an electron microscope. Expression levels of Pdx1, Ngn3, and Pax4 mRNAs in the pancreas were assessed by real-time quantitative polymerase chain reaction (RT-qPCR). RESULTS: In comparison with diabetic mice, those treated with the combination or SHE therapy showed decreased blood glucose, insulin resistance, serum lipids, and pro-inflammatory cytokines and increased body weight and serum insulin. The morphology and structure of pancreatic islets improved, as evident from an increase in insulin-positive cells and a decrease in glucagon-positive cells. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining of islet cells revealed the decreased apoptosis index, while Ki67 and proliferating cell nuclear antigen staining showed increased proliferation index. Pancreatic expression of Pdx1, Ngn3, and Pax4 was upregulated. CONCLUSION: SHED combined with HBO therapy was effective for treating type 2 diabetic rats. The underlying mechanism may involve SHED-mediated increase in the proliferation and trans-differentiation of islet β-cells and decrease in pro-inflammatory cytokines and apoptosis of islets.

Effects of Cinnamomum cassia extract on oxidative stress, immunreactivity of iNOS and impaired thoracic aortic reactivity induced by type II diabetes in rats

Type II diabetes is known to cause neuropathy, nephropathy and retinopathy. However, cardiovascular disorders associated with diabetes have been ignored. In traditional medicine, cinnamon (Cinnamomum cassia) bark has been used for its abilities to relieve fever, inflammation and chronic bronchitis. In the present study, the effect of Cinnamomum cassia extract (CN) on the thoracic aorta in an experimental type II diabetes model was investigated. In rats administered with nicotinamide + streptozotocin, significant endothelial dysfunction and oxidative stress were characterised by increased inducible nitric oxide synthase (iNOS) and decreased insulin/proinsulin levels. This impairment was prevented by administering 1000 mg/kg metformin or 500-1000-1500 mg/kg CN. CN administration attenuated the inflammatory response by decreasing the levels of malondialdehyde (MDA), Nitric oxide (NO) and increasing Glutathione peroxidase (GPx), glutathione (GSH). In addition, CN administration was shown to cause down-regulating effects on iNOS in thoracic aorta. These findings reveal that CN could prevent chronic complications of experimentally induced type II diabetes by attenuating inflammation, oxidant/antioxidant imbalance, and normalised contraction and relaxion responses in the thoracic aorta.

Caracterización de un modelo de diabetes tipo 2 en ratas y evaluación del papel de la angiotensina II y las especies reactivas de oxígeno en la resistencia neuronal a la insulina / Characterization of a type 2 diabetes model in rats and evaluation of the role of angiotensin II and reactive oxygen species in neuronal insulin resistance

La regulación ejercida por la insulina central en individuos diabéticos ha sido muy poco estudiada. La angiotensina II promueve el estrés oxidativo y la resistencia a la insulina. Dada la co-localización del receptor AT1 de la angiotensina II y el RI a nivel hipotalámico, en este trabajo, decidimos evaluar el efecto de la angiotensina II sobre las acciones centrales de la insulina en condiciones diabéticas, a través de un modelo animal de DM2 en ratas Sprague-Dawley, así como el posible efecto protector del tratamiento crónico con Valsartán. El modelo fue caracterizado y validado a través de la medición de diversos parámetros metabólicos, usando técnicas enzimáticas e inmunoenzimáticas. Los efectos de la angiotensina II sobre la señalización y acciones biológicas de la insulina a nivel hipotalámico fueron evaluadas in vivo e in vitro, mediante western blot, así como los cambios en los niveles de glicemia en las ratas tratadas ICV con ANG II y/o insulina. Fue evaluado además, el estado oxidativo a nivel hipotalámico, mediante la determinación de enzimas antioxidantes, así como el estado inflamatorio sistémico, mediante la determinación fluorométrica de citoquinas plasmáticas. El modelo experimental desarrollado mimetizó las características fenotípicas de la DM2. El valsartán previno parcialmente la resistencia a la insulina. En condiciones normales, se demostró que la angiotensina es capaz de inhibir la señalización de la insulina a nivel hipotalámico por un mecanismo dependiente de ERO. En condiciones diabéticas, hay una disminución basal de la activación de las proteínas de señalización de la insulina, la cual fue prevenida por el tratamiento con valsartán. El efecto hipoglicemiante inducido por la insulina central fue significativamente reducido en condiciones diabéticas. El tratamiento ICV con angiotensina II antagonizó los efectos hipoglicemiantes de la insulina central y este efecto fue potenciado en condiciones diabéticas. El valsartán bloquea la acción inducida por la ANG II ICV en todos los grupos. Los resultados demuestran que existe un estado de resistencia a la insulina en nuestro modelo de DM2, evidente tanto a nivel molecular como fisiológico, el cual es potenciado por la angiotensina y prevenido parcialmente por el tratamiento crónico con valsartán.

Effect of Bacopa monniera and Azadirachta indica on gastric ulceration and healing in experimental NIDDM rats.

Gastric ulcers were induced in normal/NIDDM rats by various physical (2 hr cold restraint stress and 4 hr pylorus ligation) and chemical agents (ethanol, 1 ml/200 g, oral, 1 hr before; aspirin, 200 mg/kg, oral, 4 hr) and duodenal ulcers were induced by cysteamine (40 mg/200 g). Ulcer healing activity was studied in gastric ulcers induced by acetic acid (50%) and HCI (0.6 M). The result indicated that in both, normal and NIDDM rats, B. monniera extract (BME, 20-100 mg/kg) did not show any significant effect on blood glucose level, while A. indica (AIE, 250-1000 mg/kg) significantly decreased it. However, both BME (50 mg/kg) and AIE (500 mg/kg) showed significant anti-ulcer and ulcer-healing activities in normal and NIDDM rats. Further, the present results also indicated that the ulcer protective effects of BME was more pronounced in non-diabetic, while that of AIE was more in NIDDM rats. The anti-ulcer and ulcer-healing activities of BME and AIE may be due to their effects on various mucosal offensive and defensive factors, and correction of blood sugar level by AIE may help to have more ulcer protective effect in NIDDM rats.

The Effect of Cilostazol on Glucose Tolerance and Insulin Resistance in a Rat Model of Non-insulin Dependent Diabetes Mellitus

BACKGROUND: It has been reported that many peripheral vasodilating drugs might improve insulin resistance. Cilostazol, a antithrombotic agent, increases peripheral blood flow in non-insulin dependent diabetic patients. The effect of cilostazol treatment on insulin resistance in streptozotocin (STZ)-induced non-insulin dependent diabetic Wistar rats was examined. METHODS: About a half of two-day old neonate siblings were injected intraperitoneally with STZ and maintained for six months, at which time they were compared with age-matched control rats for intraperitoneal glucose tolerance test (IPGTT) and for glucose infusion rate (GINF) in a euglycemic hyperinsulinemic glucose-clamp study. After that, these studies were also performed after feeding rat chow containing cilostazol (100 mg/kg/day) to rats with STZ-induced non-insulin dependent diabetes mellitus for four-weeks and compared with those of age-matched control rats. RESULTS: In the intraperitoneal glucose tolerance test studies, plasma glucose levels of STZ-induced non-insulin dependent diabetic rats were significantly higher and plasma insulin levels significantly lower than those of age-matched control rats in the age of six months. Glucose infusion rate was lower in STZ-induced non-insulin dependent diabetic rats than those of age-matched control rats. However, after a four-week cilostazol treatment, glucose infusion rate of STZ-induced non-insulin dependent diabetic rats was not significantly different from that of control rats. CONCLUSION: These findings suggested that cilostazol may improve insulin resistance in STZ-induced non-insulin dependent diabetic rats.

Esquema de restriçäo alimentar altera a resposta celular à insulina em ratos diabéticos / Scheme of food restriction change the cellular response to insulin in rats

A resistência à insulina é um elemento chave na gênese de várias alterações fisiopatológicas. O esquema de restrição alimentar meal-feeding (MF) consiste na oferta de uma única refeição diária de 2h, sem, contudo, limitar a quantidade de alimento durante esse período. Este esquema determina várias adaptações morfo-metabólicas, algumas sugerindo maior sensibilidade à insulina. No presente estudo investigou-se, em adipócitos isolados, a sensibilidade à insulina de ratos submetidos a treinamento alimentar e tornados diabéticos (MFD) comparando-os com ratos em livre curso alimentar diabéticos (FFD). A curva dose resposta da captação de 2-deoxi-D-glicose estimulada por insulina sugeriu maior sensibilidade, enquanto a captação máxima foi significativamente maior (p<0,05) nos ratos MFD. Esta maior responsividade à insulina refletiu-se nometabolismo dos adipócitos que mostraram aumento (p<0,05) na capacidade máxima de oxidar glicose a CO 2 e incorporar glicose em triacilglicerol. O aumento da resposta celular à insulina em ratos MFD refletiu-se in vivo em menor (p<0,05) insulinemia e maior (p<0,05) índice glicose/insulina (G/I). Em conjunto, os resultados indicam que o treinamento alimentar melhora a resposta à insulina em ratos diabéticos, o que pode representar uma abordagem alternativa no tratamento do diabetes mellitus.