Effect of Aloe vera on the expression of nerve factors, p75 and TrkA receptors in the hippocampus of diabetic rats / Efecto del Aloe vera sobre la expresión de factores de crecimiento nervioso, Receptores p75 y TrkA en el hipocampo de ratas diabéticas

SUMMARY: Diabetes mellitus can lead to structural disorders in the brain. One of the most common complications of diabetes, diabetic neuropathy is associated with central nervous system disorders. Aloe vera has anti-diabetic, antioxidant, and neuroprotective effects. This study was designed to evaluate the effects of Aloe vera gel on the hippocampus changes as well as the expression of nerve growth factor and receptors TrkA and P75 in the hippocampus of streptozotocin (STZ)-induced diabetic rats. 25 male Wistar rats were randomly divided into 5 groups including: control (normal saline), diabetic (normal saline), Aloe vera gel (400 mg/kg/day; gavage), diabetic + Aloe vera gel (400 mg/kg/day; gavage) and diabetic + insulin NPH (10 IU/kg/day; subcutaneous). Experimental diabetes was induced by streptozotocin injection (60 mg/kg; intraperitoneal). All groups treated for 8 weeks. At the end of treatment course, the rat brains were removed for measuring the expression of nerve growth factor, p75 and TrkA receptors were evaluated in the hippocampus. Diabetes induction after 8 weeks caused NGF and P75 expression levels in the diabetic group than other groups significantly increased (p<0.05). The TrkA receptor expression in the diabetic group compared with the control had a significant reduction (p<0.05). On the other hand in the diabetic group receiving Aloe vera gel expression of NGF and P75 expression levels compared to the diabetic group was significantly reduced (p<0.05) and the TrkA receptor expression compared with the diabetic group had a significant increase (p<0.05). The results showed that oral administration of Aloe vera gel in diabetic rats ameliorates diabetes-induced hyperglycemia. On the other hand, Aloe vera gel cause modulation of the expression of NGF neurotrophic factor via increased expression of TrkA receptor-specific and non-specific receptor down-regulation of P75 in the hippocampus of STZ-induced diabetic rats.

RESUMEN: La diabetes mellitus puede provocar trastornos estructurales en el cerebro. Es una de las complicaciones más comunes de la diabetes y la neuropatía diabética y está relacionada con trastornos del sistema nervioso central. El Aloe vera tiene efectos antidiabéticos, antioxidantes y neuroprotectores. Este estudio fue diseñado para evaluar los efectos del gel de Aloe vera en los cambios del hipocampo, así como la expresión del factor de crecimiento nervioso y los receptores TrkA y P75 en el hipocampo de ratas diabéticas inducidas por estreptozotocina (STZ). Se dividieron al azar 25 ratas Wistar macho en 5 grupos de: control (solución salina normal), diabéticos (solución salina normal), gel de Aloe vera (400 mg / kg / día; sonda), diabéticos + gel de Aloe vera (400 mg / kg / día; sonda) y diabéticos + insulina NPH (10 UI / kg / día; subcutánea). La diabetes experimental fue inducida por inyección de estreptozotocina (60 mg / kg; intraperitoneal). Todos los grupos fueron tratados durante 8 semanas. Al final del tratamiento, se extrajeron los cerebros de las ratas para medir la expresión del factor de crecimiento nervioso y se evaluaron los receptores p75 y TrkA en el hipocampo. La inducción de diabetes después de 8 semanas provocó que los niveles de expresión de NGF y P75 en el grupo de diabéticos aumentaran significativamente en comparación con otros grupos (p <0,05). La expresión del receptor TrkA en el grupo diabético comparado con el control tuvo una reducción significativa (p <0,05). Por otro lado, el grupo de ratas diabéticas que recibieron la expresión en gel de Aloe vera de NGF y los niveles de expresión de P75 en comparación con el grupo de ratas diabéticas se redujo significativamente (p <0,05) y la expresión del receptor de TrkA en comparación con el grupo de ratas diabéticas tuvo un aumento significativo (p <0,05). Los resultados mostraron que la administración oral de gel de Aloe vera en ratas diabéticas mejora la hiperglucemia inducida por la diabetes. Por otro lado, el gel de Aloe vera causa modulación de la expresión del factor neurotrófico NGF a través del aumento de la expresión de receptor TrkA específico y no específico y regulación negativa del receptor de P75 en el hipocampo de ratas diabéticas inducidas por STZ.

Hepatocyte Growth Factor/c-Met Signaling in Regulating Urokinase Plasminogen Activator in Human Stomach Cancer: A Potential Therapeutic Target for Human Stomach Cancer

BACKGROUND: Up-regulation of the hepatocyte growth factor (HGF), its transmembrane tyrosine kinase receptor (c-Met), and urokinase type plasminogen activator (uPA), is associated with the development and metastasis of various types of cancers. However, the mechanisms by which HGF/c-Met signaling mediates cancer progression and metastasis are unclear. METHODS: We investigated the roles of HGF/c-Met in tumor progression and metastasis in NUGC-3 and MKN-28 stomach cancer cell lines. RESULTS: Treatment with HGF increased c-Met phosphorylation in a dose-dependent manner, as well as increasing cell proliferation. HGF treatment also increased the protein level and the activity of uPA in NUGC-3 and MKN-28 cells. A monoclonal antibody against human uPA receptor (uPAR), mAb 3936, inhibited HGF-mediated tumor cell invasion in a dose-dependent manner. Down-regulation of uPA using uPA-shRNA induced a decrease in in vitro cell invasion in NUGC-3 cells. CONCLUSIONS: These results suggest that NUGC-3 and MKN-28 cells express functional c-Met, which may provide a therapeutic target for interfering with metastases of cancer cells by inhibiting uPA and uPAR-mediated proteolysis.

The biologic role of ganglioside in neuronal differentiation: effects of GM1 ganglioside on human neuroblastoma SH-SY5Y cells

Human neuroblastoma SH-SY5Y cell is a cloned cell line which has many attractive features for the study of neuronal proliferation and neurite outgrowth, because it has receptors for insulin, IGF-I and PDGF. Gangliosides are sialic acid containing glycosphingolipids which form an integral part of the plasma membrane of many mammalian cells. They inhibit cell growth mediated by tyrosine kinase receptors and ligand-stimulated tyrosine kinase activity, and autophosphorylation of EGF(epidermal growth factor) and PDGF receptors. The experiment was designed to study the effects of GM1 ganglioside on growth of human neuroblastoma SH-SY5Y cells stimulated with trophic factor in vitro. The cells were plated in Eagle's minimum essential medium without serum. The number and morphologic change of SH-SY5Y cells were evaluated in the serum free medium added GM1 ganglioside with insulin or PDGF. SH-SY5Y cells were maintained for six days in serum-free medium, and then cultured for over two weeks in serum-free medium containing either insulin or PDGF. The effect of insulin on cell proliferation developed earlier and was more potent than that of PDGF. These proliferative effects were inhibited by GM1 ganglioside, and the cells showed prominent neurites outgrowth. These findings suggest that GM1 ganglioside inhibits the cell proliferation mediated by tyrosine kinase receptors and directly induces neuritogenesis as one of the neurotrophic factors.