AIM:The direct renin inhibitor aliskiren displays antihypertensive and antialbuminuric effects in humans and in animal models . Emerging evidence has shown that aliskiren localizes and persists in medullary collecting ducts even after treatment was discontinued . The purpose of the present study was to investigate whether aliskiren regulates renal aquaporin expression and improves urinary concen -trating defect induced by lithium .METHODS:The mice were either fed with normal chow or LiCl diet (40 mmol/kg dry food per day for first 4 days and 20 mmol/kg dry food per day for last 3 days ) for seven days .Some mice were intraperitoneally injected aliskiren ( 50 mg/kg BW per day in saline ) .RESULTS:Mice injected aliskiren developed decreased urine output and increased urine osmolal -ity when compared with controls .Aliskiren significantly increased protein abundance of AQP 2 and phosphorylated-S256 AQP2 in the kidney inner medulla .Immunohistochemistry and immunofluoresence showed increased apical and intracellular labeling of AQP 2 and pS256-AQP2 in collecting duct principal cells of kidneys in mice treated with aliskiren .Aliskiren treatment prevented urinary concen-trating defect in lithium-treated mice , and improved the downregulation of AQP 2 and pS256-AQP2 protein abundance in inner medulla of the kidney .In primary cultured rat inner medulla collecting duct cells , aliskiren dramatically increased AQP 2 protein abundance which was significantly inhibited either by PKA inhibitor H 89 or by adenylyl cyclase inhibitor MDL 12330, indicating an involvement of the cAMP signalling pathway in mediating aliskiren-induced increased AQP 2 expression .CONCLUSION: The direct renin inhibitor aliskiren upregulates AQP 2 protein expression in inner medullary collecting duct principal cells and prevents lithium -induced nephro-genic diabetes insipidus ( NDI) likely via PKA-cAMP pathways .

Acute ischemic stroke (AIS), as the third leading cause of death worldwide, is characterized by its high incidence, mortality rate, high incurred disability rate, and frequent reoccurrence. The neuroprotective effects of Ginkgo biloba extract (GBE) against several cerebral diseases have been reported in previous studies, but the underlying mechanisms of action are still unclear. Using a novel in vitro rat cortical capillary endothelial cell-astrocyte-neuron network model, we investigated the neuroprotective effects of GBE and one of its important constituents, Ginkgolide B (GB), against oxygen-glucose deprivation/reoxygenation and glucose (OGD/R) injury. In this model, rat cortical capillary endothelial cells, astrocytes, and neurons were cocultured so that they could be synchronously observed in the same system. Pretreatment with GBE or GB increased the neuron cell viability, ameliorated cell injury, and inhibited the cell apoptotic rate through Bax and Bcl-2 expression regulation after OGD/R injury. Furthermore, GBE or GB pretreatment enhanced the transendothelial electrical resistance of capillary endothelial monolayers, reduced the endothelial permeability coefficients for sodium fluorescein (Na-F), and increased the expression levels of tight junction proteins, namely, ZO-1 and occludin, in endothelial cells. Results demonstrated the preventive effects of GBE on neuronal cell death and enhancement of the function of brain capillary endothelial monolayers after OGD/R injury in vitro; thus, GBE could be used as an effective neuroprotective agent for AIS/reperfusion, with GB as one of its significant constituents.
Animals ; Apoptosis ; drug effects ; Brain Ischemia ; drug therapy ; Cell Survival ; Cells, Cultured ; Disease Models, Animal ; Endothelial Cells ; drug effects ; Ginkgolides ; pharmacology ; Glucose ; Lactones ; pharmacology ; Neurons ; drug effects ; Neuroprotective Agents ; pharmacology ; Oxygen ; Plant Extracts ; pharmacology ; Rats ; Stroke ; drug therapy