Proceedings of the National Academy of Sciences of the United States of America
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Proc. Natl. Acad. Sci. U.S.A. · Mar 2011
Analgesia mediated by soluble epoxide hydrolase inhibitors is dependent on cAMP.
Pain is a major health concern even though numerous analgesic agents are available. Side effects and lack of wide-spectrum efficacy of current drugs justify efforts to better understand pain mechanisms. Stabilization of natural epoxy-fatty acids (EFAs) through inhibition of the soluble epoxide hydrolase (sEH) reduces pain. ⋯ Our findings demonstrate a mechanism of action of cAMP and EFAs in the pathophysiology of pain. Furthermore, we demonstrate that inhibition of various PDE isozymes, including PDE4, lead to significant increases in EFA levels through a mechanism independent of sEH, suggesting that the efficacy of commercial PDE inhibitors could result in part from increasing EFAs. The cross-talk between the two major pathways-one mediated by cAMP and the other by EFAs-paves the way to new approaches to understand and control pain.
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Proc. Natl. Acad. Sci. U.S.A. · Mar 2011
Signaling by vitamin A and retinol-binding protein regulates gene expression to inhibit insulin responses.
It currently is believed that vitamin A, retinol, functions through active metabolites: the visual chromophore 11-cis-retinal, and retinoic acids, which regulate gene transcription. Retinol circulates in blood bound to retinol-binding protein (RBP) and is transported into cells by a membrane protein termed "stimulated by retinoic acid 6" (STRA6). ⋯ The RBP-retinol/STRA6/JAK2/STAT5 signaling cascade induces the expression of STAT target genes, including suppressor of cytokine signaling 3 (SOCS3), which inhibits insulin signaling, and peroxisome proliferator-activated receptor gamma (PPARγ), which enhances lipid accumulation. These observations establish that the parental vitamin A molecule is a transcriptional regulator in its own right, reveal that the scope of biological functions of the vitamin is broader than previously suspected, and provide a rationale for understanding how RBP and retinol regulate energy homeostasis and insulin responses.
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Proc. Natl. Acad. Sci. U.S.A. · Mar 2011
Incomplete recovery and individualized responses of the human distal gut microbiota to repeated antibiotic perturbation.
The indigenous human microbiota is essential to the health of the host. Although the microbiota can be affected by many features of modern life, we know little about its responses to disturbance, especially repeated disturbances, and how these changes compare with baseline temporal variation. We examined the distal gut microbiota of three individuals over 10 mo that spanned two courses of the antibiotic ciprofloxacin, analyzing more than 1.7 million bacterial 16S rRNA hypervariable region sequences from 52 to 56 samples per subject. ⋯ In all subjects, the composition of the gut microbiota stabilized by the end of the experiment but was altered from its initial state. As with other ecosystems, the human distal gut microbiome at baseline is a dynamic regimen with a stable average state. Antibiotic perturbation may cause a shift to an alternative stable state, the full consequences of which remain unknown.