GABA(B) receptors are heterodimeric G protein-coupled receptors composed of R1 and R2 subunits that mediate slow synaptic inhibition in the brain by activating inwardly rectifying K(+) channels (GIRKs) and inhibiting Ca(2+) channels. We demonstrate here that GABA(B) receptors are intimately associated with 5'AMP-dependent protein kinase (AMPK). AMPK acts as a metabolic sensor that is potently activated by increases in 5'AMP concentration that are caused by enhanced metabolic activity, anoxia, or ischemia. AMPK binds the R1 subunit and directly phosphorylates S783 in the R2 subunit to enhance GABA(B) receptor activation of GIRKs. Phosphorylation of S783 is evident in many brain regions, and is increased dramatically after ischemic injury. Finally, we also reveal that S783 plays a critical role in enhancing neuronal survival after ischemia. Together our results provide evidence of a neuroprotective mechanism, which, under conditions of metabolic stress or after ischemia, increases GABA(B) receptor function to reduce excitotoxicity and thereby promotes neuronal survival.

BACKGROUND:The epidemiology of adverse drug events (ADEs) and medication errors has received little evaluation outside the U.S. and Europe, and extrapolating from these data might not be valid, especially regarding selecting and prioritizing solutions. OBJECTIVE: To assess the incidence and preventability of ADEs and medication errors in Japan. DESIGN: The Japan Adverse Drug Events (JADE) study was a prospective cohort study. PATIENTS: A cohort of 3,459 adults admitted to a stratified random sample of seven medical and eight surgical wards and three intensive care units in three tertiary care hospitals over 6 months. MAIN MEASURES: We measured ADE and medication error rates from daily reviews of charts, laboratories, incident reports, and prescription queries by on-site reviewers; presence of a signal was considered an incident. Two independent physicians reviewed incidents to determine whether they were ADEs or medication errors and to assess severity and preventability. KEY RESULTS: We identified 1,010 ADEs and 514 medication errors (incidence: 17.0 and 8.7 per 1,000 patient-days, respectively) during the study period. Among ADEs, 1.6%, 4.9% and 33% were fatal, lifethreatening and serious, respectively. Among ADEs, 14% were preventable. The rate per admission was 29 per 100 admissions, higher than in U.S. studies because associated with of the long length of hospital stay in Japan (mean, 17 days). CONCLUSIONS: The epidemiology and nature of ADEs and medication errors in Japan were similar to other countries, although more frequent per admission. Solutions that worked in these countries might thus improve medication safety in Japan, as could shortening hospital length of stay.KEY WORDS: adverse drug events; epidemiology; medication errors; patient safety.

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The vitamin D receptor (VDR) is believed to mediate different biologic actions of vitamin D3, an active metabolite of vitamin D, through regulation of gene expression after binding to specific DNA-response element (VDRE) on target genes. To further understand roles of both vitamin D3 and VDR in the central nervous system, we examined VDRE binding in nuclear extracts prepared from discrete rat brain regions and cultured rat cortical neurons by electrophoretic mobility shift assay. The highest activity of VDRE binding was found in the cerebellum among other brain regions examined, but sequence specific by taking into consideration the efficient competition with excess unlabeled VDRE but not with mutated VDRE. On in situ hybridization analysis, cells stained for VDR mRNA were abundant in neuron-enriched areas of cerebral cortex, hippocampus and cerebellar cortex in the mouse brain. Chronic treatment of vitamin D3 increased the expression of microtubule-associated protein-2, growth-associated protein-43 and synapsin-1 in cultured rat cortical neurons, suggesting a trophic role of vitamin D3 in differentiation and maturation of neurons. Neuronal cell death by brief glutamate exposure was significantly protected in cultured cortical neurons chronically treated with vitamin D3. Parallel studies showed that VDR mRNA was significantly upregulated 12-24 hr after brief glutamate exposure in cultured neurons chronically treated with vitamin D3, but not in those with vehicle alone. Our results suggest that vitamin D3 may play a role in mechanisms relevant to protective properties against the neurotoxicity of glutamate through upregulation of VDR expression in cultured rat cortical neurons.