Tag Archives: central nervous system

The nervous system is like an electrical wiring. Credit: GuidesHealth.com

Scientists coax mice with injured spinal cords to regrow nerve fibers, something deemed impossible not too long ago

The nervous system is like an electrical wiring. Credit: GuidesHealth.com

The nervous system is like electrical wiring for your body. Credit: GuidesHealth.com

German researchers proved that nerve cells can regenerate in mice who suffered spinal cord injuries. These sort of injuries cause permanent disabilities like paralysis because the nerves do not regenerate by themselves. Though thought impossible, the researchers showed that they could coax one of the rodents’ molecular mechanisms to start producing new nerve cells in the site of injury using a drug called Pregabalin.

Helping neurons reach out their arms again

The human nervous system is comprised of an intricate network of nerve cells that transmit signals between different parts of the body, from head to toe. It helps to imagine this network like the body’s electrical wiring, which starts at the brain then branches out throughout the entire body. Damages to this wiring system can be catastrophic — an injury to the spinal cord, for instance, might cut the sensory input from the damaged site down. That’s because, again like an electrical wire, the neurons of the central nervous systems are connected by long projections called axons. When the axons are severed, these are unable to regrow leaving the connection discontinued permanently.

Scientists know that these axons grow during the embryonic development stage. They stop extending their arms past this stage, though. But if there’s a molecular mechanism that instructs the neuron’s axons to grow and to stop later at some point, then there’s a chance we can re-activate this re-growth process by targetting its underlying molecular brake.

This is what researchers at the German Center for Neurodegenerative Diseases (DZNE) set out to do. They quickly realized it was like looking for a needle in a haystack. That’s because there are literally hundreds of active genes in every nerve cell, says neurobiologist Frank Bradke who is one the lead authors of the study.

If it weren’t for computers and algorithms that can comb through vast databases, Bradke and colleagues might have still been at it. Thanks to bioinformatics, though, they managed to zero in on a promising candidate — a gene called Cacna2d2, which is known to play an important role in synapse formation and function.

Cacna2d2 has the blueprint for the production of a protein that anchors ion channels in the cell membrane. This mechanism regulates the flow of calcium ions into the nerve cell which is integral to the release of neurotransmitters, be them serotonin or dopamine.

Investigating further, Bradke and colleagues found that a drug called Pregabalin (PGB) can bind to these calcium channel molecular anchors. They gave PGB to mice who had undergone spinal cord trauma and later found this treatment spurred new nerve connections to grow, as reported in the journal Neuron.

“Our study shows that synapse formation acts as a powerful switch that restrains axonal growth. A clinically-relevant drug can manipulate this effect,” says Bradke.

Hopefully, the first human trials with PGB might start soon, considering the drug is already prescribed to spinal cord injured patients. PGB is prescribed for its pain relieving properties and often late, a long time after the injury occurred. Until then, there are other intriguing developments. Previously, another group from Germany grew spinal cords in a petri dish and, elsewhere in Switzerland, researchers used a flexible ribbon-like implant that attaches itself to a paralyzed rat’s spinal cord allowing the rodent to walk again.

“PGB might have a regenerative effect in patients, if it is given soon enough. In the long term this could lead to a new treatment approach. However, we don’t know yet,” Bradke added.

Evidence that RMST is necessary for neuronal differentiation: overexpression of RMST led to a 3-fold increase in neuron-specific beta tubulin (bottom) compared to control (top). Scale bars represent 100 microns. (Credit: Shi-Yan Ng et al./Molecular Cell)

Gene key in neuron generation discovered

Scientists have discovered an atypical gene that is thought to be crucial for the generation of new neurons in the brain, a process called neurogenesis. The discovery and further study of the gene might help scientists better understand how neurodegenerative diseases such as Alzheimer’s affect the brain and, in term, how to address them.

Evidence that RMST is necessary for neuronal differentiation: overexpression of RMST led to a 3-fold increase in neuron-specific beta tubulin (bottom) compared to control (top). Scale bars represent 100 microns. (Credit: Shi-Yan Ng et al./Molecular Cell)

Evidence that RMST is necessary for neuronal differentiation: overexpression of RMST led to a 3-fold increase in neuron-specific beta tubulin (bottom) compared to control (top). Scale bars represent 100 microns. (Credit: Shi-Yan Ng et al./Molecular Cell)

New neurons are born through a complex temporal and spatial control of hundreds of genes. The expression of these genes is controlled by regulatory networks, usually involving proteins, indispensable for the well functioning of the central nervous system. When one or some of these genes are inhibited or over expressed,  neurological disorders develop. Understanding the mechanisms that govern neurogenesis becomes thus of the utmost importance when developing treatments for such serious diseases.

A major breakthrough in this respect was recently made by scientists at A*STAR’s Genome Institute of Singapore (GIS), who discovered a key component within a gene regulatory network that controls the birth of new neurons, called RMST. This component isn’t a protein like most people, even the researchers involved in the study, thought. RMST is an atypical, long non-coding RNA, a newly discovered class of RNA whose functions remain largely unknown

In this latest study, one of the components in this new class has been at least demystified. They found that RMST acts directly within a gene regulatory network.

“Stanton and colleagues show how RMST, a human lncRNA, directly regulates SOX2, a key transcription factor protein that is instrumental for directing the birth of new neurons,” said Associate Prof Leonard Lipovich, from the Center for Molecular Medicine and Genetics at the Wayne State University and a member of GENCODE. Even more intriguingly, they highlight that RMST controls SOX2 by directly interacting with the protein.

Their work is important not only because it sheds light on the process of neurogenesis, but also new insight into how lncRNA works together with protein components to regulate the important biological processes of gene expression.

“The paper is therefore an important advance in the still nascent and controversial field of riboregulators, or RNAs that regulate proteins in our cells. DNA-binding proteins that turn genes on and off were traditionally thought to be distinct from RNA-binding proteins. Stanton et al, however, illuminate the cryptic, yet crucial, RNA-binding roles for DNA-binding transcription factors: lncRNAs just might be the definitive regulatory switch that controls these factors’ activity.”

Findings were reported in the journal Molecular Cell.

[via KurzweilAI]

An eye growing on the tail of a tadpole.

Tadpoles can see through eyes implanted in their tails

An eye growing on the tail of a tadpole.

An eye growing on the tail of a tadpole.

Most animals have eyes in the vicinity of their brains, typically inside the head, since these are very sensible organs that require a very sophisticated neural link. Recently, biologists at Tufts University have shown that they could implant working eyes in other locations as well, after they granted blind tadpoles vision after they implanted eyes in their tails. The findings might offer further insight into artificial visions and regenerative medicine.

The scientists experimented with 134 tadpoles of the African clawed frog Xenopus laevis, a popular lab pet for researchers worldwide. These had their eyes surgically removed, after which the scientists painstakingly implanted eyes in their torsos and tails.

An experimental set-up was devised with quadrants of water illuminated by either red or blue LED light. The arena, half illuminated in red, half illuminated in blue, would regularly switch between colors via software. The trick lied in the fact that whenever tadpoles when enter the red district, they would receive a mild electrical shock. A motion-tracking camera kept tabs on where the tadpoles were at all times.

Remarkably, it was observed that six of the tadpoles always kept away from the red half of the arena, hinting that they could see with the eyes implanted in their tails. These eyes came from other genetically engineered tadpoles that were instructed to grow a red florescent protein. This allowed the researchers to see whether the eyes sent red nerves outward in the body. Half the 134 recipient tadpoles had no such nerves grow, while about a quarter had nerves projecting toward the gut and the other quarter had nerves extending toward their spine. All of the six tadpoles that showed signs of vision had nerves plugged into their spine, meaning their new eyes were now linked to their nervous system.

“One of the things that this study showed us is that connecting a sense organ as complex as the eye to the spinal cord is sufficient to confer vision,” Dr. Michael Levin said. “So you don’t have to plug in to the actual brain.”

Does this mean that the tadpoles can see just as well as they used to with their original eyes? In reply to this vexing questions, the scientists’ answer is straightforward – they don’t know. “We have no idea what a tadpole is experiencing. This is a philosophical question that is not immediately tractable,” the researchers write in their paper published in the Journal of Experimental Biology.

It’s well worth noting that applications for this kind of research aren’t limited to regenerative medicine only, augmented technology for instance would have a lot to benefit.

“You may want to increase your sensory capacity with sensors that normal people usually don’t have,” he said. “This opens the possibility for attaching all sorts of peripherals to your body.”

Robot designers could also learn a thing or two from the findings, in terms of adaptive flexibility.

“You can imagine that information that comes from any sensory structure – any part of the body – is tagged in some way that uses a unique identifier,” said Dr. Douglas Blackiston, a post-doctoral associate. “So, the source of that information is not nearly as important as what the brain is sensing.”

boiled crab feel pain

Crabs and other shellfish feel pain. Opens ethical discussion

boiled crab feel painA new study from researchers at Queen’s University Belfast, UK, found that indeed shellfish, like crabs or lobsters that are typically cooked alive in horrid conditions, feel pain as well. The findings raise significant ethical discussions, warning the food and fish industry of its ill ways of killing live seafood.

“On a philosophical point, it is impossible to demonstrate absolutely that an animal experiences pain,” researcher Bob Elwood of the Queen’s School of Biological Sciences, was quoted as saying in a press release. “However, various criteria have been suggested regarding what we would expect if pain were to be experienced. The research at Queen’s has tested those criteria and the data is consistent with the idea of pain. Thus, we conclude that there is a strong probability of pain and the need to consider the welfare of these animals.”

Crabs are typically boiled alive in a tank, however since the crustaceans have a very primitive central nervous system, it has always been thought that they do not experience pain. The panic and struggle crabs experience when dived in boiled water has always been attributed to a reflex behavior, not at all to pain-induced self preservation.

“In contrast to mammals, crustaceans are given little or no protection as the presumption is that they cannot experience pain. Our research suggests otherwise,” Professor Elwood said.

“More consideration of the treatment of these animals is needed as a potentially very large problem is being ignored.”

To distinguish between reflex and actual pain the researchers devised a simple, but ingenious experiment. The scientists took 90 crabs and put them in a tank with two dark shelters. After most crabs selected their shelter of choice, one of the shelters was electrically charged. The scientists pulled out the crabs from the tank and after some rest inserted them back. Most stuck with what they knew best, returning to the shelter they had chosen first time around, where those that had been shocked on first choice again experienced a shock. When introduced to the tank for the third time, however, the vast majority of shocked crabs now went to the alternative safe shelter. Those not shocked continued to use their preferred shelter.

“Having experienced two rounds of shocks the crabs learned to avoid the shelter where they received the shock,” Professor Elwood said.

“They were willing to give up their hideaway in order to avoid the source of their probable pain.”

With this in mind, crabs, lobsters and other shellfish and crustaceans may experience the world more like us than we might have thought. Findings were reported in a paper published in the Journal of Experimental Biology.

via Discovery