Glutamate is not only a neurotransmitter but also an important neurotoxin in central nervous system (CNS). Chronic elevation of glutamate induces both neuronal and glial cell apoptosis. However, its effect on astrocytes is complex and still remains unclear. In this study, we investigated whether morphine, a common opioid ligand, could affect glutamate-induced apoptosis in astrocytes. Primary cultured astrocytes were incubated with glutamate in the presence/absence of morphine. It was found that morphine could reduce glutamate-induced apoptosis of astrocytes. Furthermore, glutamate activated Ca²⁺ release, thereby inducing endoplasmic reticulum (ER) stress in astrocytes, while morphine attenuated this deleterious effect. Using siRNA to reduce the expression of κ-opioid receptor, morphine could not effectively inhibit glutamate-stimulated Ca²⁺ release in astrocytes, the protective effect of morphine on glutamate-injured astrocytes was also suppressed. These results suggested that morphine could protect astrocytes from glutamate-induced apoptosis via reducing Ca²⁺ overload and ER stress pathways. In conclusion, this study indicated that excitotoxicity participated in the glutamate mediated apoptosis in astrocytes, while morphine attenuated this deleterious effect via regulating Ca²⁺ release and ER stress. Full article

Pancreatic cancer is a highly lethal malignancy and one of the leading causes of cancer-related death. During the development and progression of cancer, tumor angiogenesis plays a crucial role. A great deal of evidence has revealed that human mast cells (MCs) contributed to tumor angiogenesis through releasing several pro-angiogenetic factors, among which tryptase is one of the most active. However, the role of mast cell tryptase (MCT) in human pancreatic cancer angiogenesis is still not well documented. In this study, we examined the MCT levels in serum from pancreatic cancer patients and evaluated the correlationship of the MCT level and tumor angiogenesis. In addition, the effect of MCT on endothelial cell proliferation and tube formation was investigated both in vitro and in nude mice bearing pancreatic tumor. It was found that MCT contributes to endothelial cell growth and tube formation via up-regulation of angiopoietin-1 expression. Moreover, using the MCT inhibitor nafamostat, tryptase-induced angiogenesis was obviously suppressed both in vitro and in vivo. Our findings suggest that MCT plays an important role in pancreatic cancer angiogenesis and tumor growth via activating the angiopoietin-1 pathway, and tryptase inhibitors may be evaluated as an effective anti-angiogenetic approach in pancreatic cancer therapy. Full article