It is the first time scientists have shown that inhibiting an enzyme involved in programmed cell death can protect a brain region in a living animal from neurodegeneration following the withdrawal of steroids.
In addition, the University of Washington research being published in tomorrow’s edition of the Journal of Neuroscience reports that the infusion of this enzyme inhibitor into one brain region also kept another connected brain structure from degenerating.
The research has potential to help scientists develop clinical strategies for treating strokes and such human age-related degenerative diseases as Alzheimer’s, Parkinson’s and dementia, all of which may involve the death of brain cells.
Previous work by the co-authors Christopher Thompson and Eliot Brenowitz showed that neurons in a brain region called the HVC begin regressing within 12 hours after the withdrawal of the steroid hormone testosterone, followed soon thereafter by cell death. The new study indicates that enzymes called caspases, which play a key role in a cell suicide process called apoptosis, are involved in this process of neurodegeneration and that inactivation of caspases protects brain cells for at least a week.
Thompson, who just earned his doctorate in neurobiology and behavior at the UW and is now a postdoctoral researcher at the Freie Univeristät in Berlin, and Brenowitz, a UW professor of psychology and biology, study the brain regions controlling the singing behavior of a white-crowned sparrow.
“In the future, physicians might be able to stabilize people who have suffered a stroke using these inhibitors,” said Brenowitz. “The basic mechanisms of cell death are the same in people and birds. With a stroke we often act as if it only affects the one area stricken by the loss of blood supply. But neuroscience has shown that different brain regions are connected in neural circuits. By using inhibitors like these to preserve neurons in the affected area, we might be able to preserve neurons in other connected brain areas.”
The researchers received federal and state permits to capture 15 male sparrows in Eastern Washington after the breeding season as the birds were returning from Alaska to their winter home in California. The birds were housed indoors for 12 weeks under short-day lighting conditions to ensure their song and reproductive systems were regressed to a non-breeding state. Song-control regions in the brains of these sparrows and other songbirds naturally expand and shrink during the year depending on whether or not the birds are in a breeding state.
Next, the birds were exposed to 16 hours of light a day in long-day conditions, castrated and implanted with a high level of testosterone for 28 days to induce full growth of the song-control system. At that point, testosterone was withdrawn, the caspase inhibitors were infused near the HVC region on one side of the brain in 12 of the birds and the sparrows were returned to short-day lighting conditions. Three of the sparrows received a control substance that is chemically similar but did not have inhibitory properties. Groups of birds were euthanized after 1, 3 and 7 days. These procedures were done with the approval of the UW’s Institutional Animal Care and Use Committee and the National Institute of Mental Health. The latter funded the research.
Examination of brain tissue showed that the caspase inhibitors prevented cell death in the HVC on the side of birds’ brain that received these chemicals while this region began to degenerate on the opposite side of the brain. In addition, neurons in another connected song-control region called the RA on the side of the brain receiving the caspase inhibitors did not regress after seven days. Neurons in the HVC in the birds that did not get caspase inhibitors exhibited cell death, and RA neurons regressed.
“The normal role of hormones during the breeding season is to stimulate and maintain growth of these neural systems. We don’t yet know all the ways in which hormones prevent brain cell death, but this study shows that hormones block caspases and so preserve neurons,” said Brenowitz. “We are extending the life of these cells and halting the rapid degeneration of the song system.”
For more information, contact Brenowitz at (206) 543-8534 or email@example.com or Thompson at firstname.lastname@example.org.
Joel Schwarz | Newswise Science News
Multi-institutional collaboration uncovers how molecular machines assemble
02.12.2016 | Salk Institute
Fertilized egg cells trigger and monitor loss of sperm’s epigenetic memory
02.12.2016 | IMBA - Institut für Molekulare Biotechnologie der Österreichischen Akademie der Wissenschaften GmbH
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water
In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...
The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.
Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
02.12.2016 | Medical Engineering
02.12.2016 | Agricultural and Forestry Science
02.12.2016 | Physics and Astronomy