Ageing: Longevity hits a roadblock

Ageing: Longevity hits a roadblock:

Ageing: Longevity hits a roadblock

Nature 477, 7365 (2011). doi:10.1038/477410a

Authors: David B. Lombard, Scott D. Pletcher, Carles Cantó & Johan Auwerx

Increased expression of sirtuin proteins has been shown to enhance lifespan in several organisms. New data indicate that some of the reported effects may have been due to confounding factors in experimental design. Here, experts discuss the significance of these data for research into ageing. See Letter p.482

Equilibrium in the brain: Excitation and inhibition remain balanced, even when the brain undergoes reorganization

Equilibrium in the brain: Excitation and inhibition remain balanced, even when the brain undergoes reorganization: Every second, the brain's nerve cells exchange many billions of synaptic impulses. Two kinds of synapses ensure that this flow of data is regulated: Excitatory synapses relay information from one cell to the next, while inhibitory synapses restrict the flow of information. Scientists can now show that excitatory and inhibitory synapses remain balanced -- even if the brain undergoes reorganization.

Neuroscience: When lights take the circuits out

Neuroscience: When lights take the circuits out:

Neuroscience: When lights take the circuits out

Nature 477, 7363 (2011). doi:10.1038/477165a

Authors: João Peça & Guoping Feng

Circuit-level perturbations in the brain's electrical activity may underlie social-interaction deficits seen in people with schizophrenia and autism. A new optogenetic tool was instrumental in making this discovery. See Article p.171

The ageing systemic milieu negatively regulates neurogenesis and cognitive function

The ageing systemic milieu negatively regulates neurogenesis and cognitive function:

The ageing systemic milieu negatively regulates neurogenesis and cognitive function

Nature 477, 7362 (2011). doi:10.1038/nature10357

Authors: Saul A. Villeda, Jian Luo, Kira I. Mosher, Bende Zou, Markus Britschgi, Gregor Bieri, Trisha M. Stan, Nina Fainberg, Zhaoqing Ding, Alexander Eggel, Kurt M. Lucin, Eva Czirr, Jeong-Soo Park, Sebastien Couillard-Després, Ludwig Aigner, Ge Li, Elaine R. Peskind, Jeffrey A. Kaye, Joseph F. Quinn, Douglas R. Galasko, Xinmin S. Xie, Thomas A. Rando & Tony Wyss-Coray

In the central nervous system, ageing results in a precipitous decline in adult neural stem/progenitor cells and neurogenesis, with concomitant impairments in cognitive functions. Interestingly, such impairments can be ameliorated through systemic perturbations such as exercise. Here, using heterochronic parabiosis we show that blood-borne factors present in the systemic milieu can inhibit or promote adult neurogenesis in an age-dependent fashion in mice. Accordingly, exposing a young mouse to an old systemic environment or to plasma from old mice decreased synaptic plasticity, and impaired contextual fear conditioning and spatial learning and memory. We identify chemokines—including CCL11 (also known as eotaxin)—the plasma levels of which correlate with reduced neurogenesis in heterochronic parabionts and aged mice, and the levels of which are increased in the plasma and cerebrospinal fluid of healthy ageing humans. Lastly, increasing peripheral CCL11 chemokine levels in vivo in young mice decreased adult neurogenesis and impaired learning and memory. Together our data indicate that the decline in neurogenesis and cognitive impairments observed during ageing can be in part attributed to changes in blood-borne factors.