News Release

News tips from the Journal of Neuroscience

Peer-Reviewed Publication

Society for Neuroscience

1. Slow, Stop-and-Go Axonal Traffic
Subhojit Roy, Matthew J. Winton, Mark M. Black, John Q. Trojanowski, and Virginia M.-Y. Lee

This week, Roy et al. monitored traffic in the fast and slow lanes of axons. Proteins are transported to distal axons in three distinct groups: fast component (FC), slow component-a (SCa), and slow component-b (SCb). The well described FC and SCa mechanisms move vesicular and structural cargoes, respectively, to axons at vastly different speeds. SCb hauls loads such as proteins involved in axon growth at about 2¨C10 times the speed of SCa. The authors visualized SCb transport in live hippocampal neurons transfected with combinations of three fluorescently tagged SCb proteins: ¦Á-synuclein, synapsin-I, and glyceraldehyde-3-phosphate dehydrogenase, as well as the FC protein synaptophysin. A direct comparison of ¦Á-synuclein and synaptophysin transport revealed that SCb transport was much slower overall, but it had a herky-jerky quality, and its instantaneous velocity was surprisingly comparable with FC. Like SCa transport, the stop-and-go movement of the multiprotein SCb complexes slows traffic.

2. Maternal Separation and Gene Expression in Monkeys
Michael J. Sabatini, Philip Ebert, David A. Lewis, Pat Levitt, Judy L. Cameron, and K¨¢roly Mirnics

Even most dads will admit there¡¯s nothing quite like mom when you are young. In this week¡¯s Journal, Sabatini et al. investigated the neural substrate of behaviors caused by maternal separation of monkeys at either 1 week or 1 month of age. Using DNA microarrays, the authors identified a single gene that was differentially regulated in 1 week and 1 month separation animals: the nitric oxide signaling molecule GUCY1A3, an analog of rat guanylate cyclase 1 ¦Á 1. In maternally reared control monkeys, in situ hybridization showed that GUCY1A3 was expressed at highest levels in the amygdala, and was expressed maximally by 1 week of age. Expression was significantly lower in 1 week maternally separated animals and was intermediate in 1 month separated monkeys. GUCY1A3 expression correlated with acute and long-term self- and social-comforting behaviors. Whether GUCY1A3 is simply a marker of this behavior or plays a causal role remains to be determined.

3. Input Fluctuations in Layer 5 Pyramidal Neurons
Maura Arsiero, Hans-Rudolf L¨¹scher, Brian Nils Lundstrom, and Michele Giugliano

Cortical neurons fire asynchronously, thus producing membrane voltage fluctuations in the synaptic potentials in downstream neurons. This week, Arsiero et al. asked how important these membrane fluctuations are to information processing. They recorded from layer 5 pyramidal neurons of rat medial prefrontal cortex (mPFC) in vitro. Using a fluctuating stimulus during voltage recording, the authors simulated input from a population of neurons and measured the mean firing rate response from single neurons. The mPFC neurons displayed a sigmoidal increase in firing rate with a maximal frequency of ~40¨C60 Hz. The neurons remained highly sensitive to input current fluctuations, suggesting that they can encode irregular inputs, not just integrate the mean input. The authors suggest that the adaptation to input mean, but not to the variance, may be explained by slow voltage-dependent inactivation of the sodium current. Seems these neurons can stay on task even in a noisy environment.

4. Minocycline, Microglia, and Amyloidosis
Rong Fan, Feng Xu, Mary Lou Previti, Judianne Davis, Alicia M. Grande, John K. Robinson, and William E. Van Nostrand

Amyloid-¦Â (A¦Â) can accumulate not only as parenchymal plaques in brain, but also the fibrillary deposits in cerebral vasculature. Early and severe vascular deposits in cerebral amyloid angiopathy (CAA) result from inherited A¦Â mutations and are associated with a strong local neuroinflammatory reaction. The latter seems to correlate with amyloid extending from vessels into brain parenchyma. This week, Fan et al. measured the effects of a neural anti-inflammatory drug in Tg-SwDI mice. Decoding the name, the mouse is a transgenic strain that expresses human amyloid precursor protein carrying the Dutch- and Iowa-type familial CAA mutations. The anti-inflammatory drug minocycline did not affect fibrillar amyloid deposits in the microvasculature of Tg-SwDI mice, nor was total soluble or insoluble A¦Â reduced. Minocycline also did not alter the number of reactive astrocytes. However, minocycline did reduce the number and activation state of microglia. After 4 weeks of treatment, 1-year-old mice displayed improved learning memory performance in a maze task.

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