Abbreviations D diotic dissonant DD dichotic dissonant GMD gray matter density IC inferior colliculus O original VBM voxel-based morphometry “
“Division of Diabetes, Endocrinology & Metabolism, Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN, USA Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX, USA The methamphetamine-sensitive circadian oscillator (MASCO) is an enigmatic circadian clock whose output is observed during continuous consumption

of low-dose methamphetamine. The MASCO rhythm persists when the light-entrainable pacemaker in the suprachiasmatic nucleus (SCN) is lesioned, but check details the anatomical location of MASCO is unknown. We recently found that the period of the MASCO rhythm is unusually short (21 h) in mice with disruption of all three paralogs of the canonical clock Selleckchem U0126 gene, Period. In this study, we investigated the contribution of each Period paralog to timekeeping in MASCO. We measured wheel-running activity rhythms in intact and SCN-lesioned Per1-, 2- and 3-mutant mice administered methamphetamine, and found that none of the

mice displayed a short (21-h) period, demonstrating that no single Period gene is responsible for the short-period MASCO rhythm of Per1−/−/Per2−/−/Per3−/− mice. We also found that the periods of activity Cediranib (AZD2171) rhythms in constant darkness were lengthened by methamphetamine treatment in intact wild-type, Per1−/− and Per3−/− mice but not Per2−/− mice, and Per2−/− mice had two distinct activity rhythms upon release to constant light. These data suggest that the SCN and MASCO are not coupled in Per2−/− mice. The

MASCO rhythm in Per1−/−/Per2−/− mice in constant darkness alternated between a short (22-h) and a long (27-h) period. This pattern could result from two coupled oscillators that are not synchronised to each other, or from a single oscillator displaying birhythmicity. Finally, we propose a working model of the in vivo relationship between MASCO and the SCN that poses testable hypotheses for future studies. “
“Cleavage of amyloid-β precursor protein (APP) at the Asp1 β-secretase site of the amyloid-β protein (Aβ) domain by β-site Aβ precursor protein-cleaving enzyme 1 (BACE1) is required for the generation of Aβ, a central component of neuritic plaques in the Alzheimer’s disease (AD) brain. In this study, we found that Aβ Glu11 is the major β-secretase site for cleavage of APP by BACE1 to generate soluble secreted APP (sAPPβ)606 and the C-terminal membrane-bound fragment (CTF)β product C89. Cleavage of C89 by γ-secretase resulted in truncated Aβ generation in a non-amyloidogenic pathway.