Hormones and AD miceJenna C. Carroll, Emily R. Rosario, Lilly Chang, Frank Z click to see full text . Stanczyk, Salvatore Oddo, Frank M. Laferla and Christian J. PikeThis week, Carroll et al. Investigated the effect of progesterone to the known benefits of estrogen in Alzheimer’s disease . Estrogen depletion in postmenopausal women is a risk factor for AD. In female mice, 3xTg AD,-amyloid accumulate with age in neurons of hormone-responsive brain areas including the hippocampus, subiculum and frontal cortex. Hyperphosphorylation of tau decreased with age and increased performance on a working memory task. The authors then ovariectomized 3xTg – AD mice aged 3 months and treated them with estrogen or placebo. As expected, the A? Load and behavioral level worsened OVX mice, effects that were attenuated by E2. Progesterone treatment does not protect against A? accumumulation after OVX, but it did reduce tau phosphorylation in ovariectomized animals. Progesterone blocked the beneficial effect of E2 on A? Accumulation, but not on behavior, suggesting that the two hormones have independent functions in this process.
Cdc42, cofilin and Neuronal PolarityBoyan K. Garvalov, Kevin C. Dorothee Neukirchen, Liane Meyn, Nicole Teusch Xunwei Wu, Cord Brakebusch, James R. Bamburg , and Frank BradkeNothing is more fundamental to Cell biology of the neuron than the polarization of its processes in dendrites and axons, a process that apparently requires a small cast of signaling and cytoskeletal molecules. This week Garvalov et al. Examined neuronal polarity in mice in which the Rho GTPase Cdc42 was knocked conditionally. Cdc42 was axonal growth axonal outgrowth and neuronal polarity. True to form axons were in the null mice in vivo, fewer, shorter and sparser. In cultured hippocampal neurons from Cdc42-/ – mice, the initial growth of neurites appeared normal, but the growth of the longest neurite, the axon the axon, slowed dramatically. Growth cones of the future axon were enlarged, A – abnormalities and reduced filopodial dynamics. Cofilin, a downstream effector of Cdc42 appeared this pathway this pathway. Neurons from Cdc42 null mice had increased cofilin phosphorylation and thus reduced cofilin activity in axonal growth cones. – The functional anatomy of the auditory streaming. Read more