Low-intensity pulsed ultrasound (LIPUS) stimulation has been shown to increase the expression of brain-derived neurotrophic factor (BDNF) in astrocytes of an in vitro model and rat brains of an in vivo model; however, their molecular mechanisms are still not well clarified. Here, we investigated the underlying mechanisms of BDNF enhancement by LIPUS in rat cerebral cortex astrocytes. After LIPUS stimulation in astrocytes, the protein and mRNA expressions were measured by western blot and RT-PCR, respectively. The concentration of intracellular calcium was determined spectrophotometrically. The results showed that LIPUS enhanced the phosphorylation of tropomyosin-related kinase B (TrkB) and Akt but had no effect on Erk1/2 phosphorylation. Additionally, LIPUS increased the intracellular concentration of calcium and enhanced the protein levels of calmodulin-dependent kinase (CaMK) II and CaMKIV. LIPUS also activated the phosphorylation of NF-κB-p65 but did not promote the activation of cAMP response element-binding protein (CREB). Taken together, our results suggest that LIPUS stimulation upregulates BDNF production in astrocytes through the activation of NF-κB via the TrkB/PI3K/Akt and calcium/CaMK signaling pathways. BDNF has emerged as a major molecular player in the regulation of neural circuit development and function. Therefore, LIPUS stimulation may play a crucial and beneficial role in neurodegenerative diseases.
These findings suggest that CHOP regulates not only apoptosis-related signaling but also ROS formation and inflammation in renal tubular cells during I/R. CHOP may play an important role in the pathophysiology of I/R-induced renal injury.
Severe acute pancreatitis remains a life-threatening disease with a high mortality rate among a defined proportion of those affected. Apoptosis has been hypothesized to be a beneficial form of cell death in acute pancreatitis. Honokiol, a low-molecular-weight natural product, possesses the ability of anti-inflammation and apoptosis induction. Here, we investigate whether honokiol can ameliorate severe acute pancreatitis and the associated acute lung injury in a mouse model. Mice received six injections of cerulein at 1-h intervals, then given one intraperitoneal injection of bacterial lipopolysaccharide for the induction of severe acute pancreatitis. Moreover, mice were intraperitoneally given vehicle or honokiol 10 min after the first cerulein injection. Honokiol protected against the severity of acute pancreatitis in terms of increased serum amylase and lipase levels, pancreas pathological injury, and associated acute lung injury. Honokiol significantly reduced the increases in serum tumor necrosis factor-α, interleukin 1, and nitric oxide levels 3 h and serum high-mobility group box 1 24 h after acute pancreatitis induction. Honokiol also significantly decreased myeloperoxidase activities in the pancreas and the lungs. Endoplasmic reticulum stress-related molecules eIF2α (phosphorylated) and CHOP protein expressions, apoptosis, and caspase-3 activity were increased in the pancreas of mice with severe acute pancreatitis, which was unexpectedly enhanced by honokiol treatment. These results suggest that honokiol protects against acute pancreatitis and limits the spread of inflammatory damage to the lung in a severe acute pancreatitis mouse model. The acceleration of pancreatic cell apoptosis by honokiol may play a pivotal role.
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