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Possible brain hormone may unlock mystery of hibernation
April 06, 2006The discovery of a possible hibernation hormone in the brain may unlock the mystery behind the dormant state, researchers reported in the April 7, 2006 issue of Cell. Hibernation allows animals from bears to rodents to survive unscathed-in a state of suspended animation-under the harshest of winter conditions.
If the findings in chipmunks are confirmed, the hormone would represent the first essential brain signal governing the seasonal adaptation, according to the researchers.
As hibernation factors endow animals with an incredible ability to cope under otherwise lethal conditions-ratcheting down their metabolic rate to survive on limited energy reserves and withstanding extreme cardiovascular and oxygen stresses-the candidate hormone might also pave the way toward clinical therapies that lend humans the same kind of protection, they added.
The researchers earlier found that concentrations of "hibernation-specific protein" complex (HPc) decline in the blood of hibernating chipmunks. The team now reports evidence that the level of HPc in the brain increases at the onset of hibernation independently of changes in body temperature. Moreover, treatments that block HP activity in the animals' brains cuts hibernation short.
"One of the most curious biological phenomena in mammals is their ability to hibernate circannually, which allows them to survive unusually low body temperatures at or near freezing," said study author Takashi Ohtsu of Kanagawa Academy of Science and Technology in Japan. Scientists have attempted for decades to identify substances responsible for hibernation in the blood and organs of hibernating animals but have met with little success, the researchers said.
"Although the functions of HP remain to be clarified, the current observations lead us to propose the involvement of the protein complex in the regulation of energy metabolism and/or biological defenses during hibernation-crucial events for adapting to the severe physiological state," Ohtsu said.
In the current study, the researchers first demonstrated that hibernation in chipmunks is strictly controlled by an individual's internal circannual rhythm even under conditions of constant cold. In 20 hibernators examined throughout their lives, concentrations of HPc in the blood started to decrease prior to hibernation and remained low throughout the inactive state. Hibernation ended after blood HPc levels rose.
Further study revealed an inverse relationship between HPc levels in the blood and brain. While HPc levels dipped in blood, the putative hormone rose dramatically in cerebral spinal fluid, they reported. Likewise, HPc levels decreased abruptly in spinal fluid when hibernation terminated.
The researchers also found that blocking the activity of one of the HP complex proteins in the brain with antibody greatly decreased the hibernation time during which the chipmunks maintained a lowered body temperature, suggesting its critical role in the brain's capacity for dormancy.
The researchers propose that HPc in the blood is actively transported into the spinal fluid in response to the animals' natural rhythm. The hibernation complex might also play a role in the seasonal behavior changes of animal species that do not hibernate, the researchers suggested.
For example, the complex could moderate physiological events such as reproduction in seasonally breeding mammals and migration in birds, they said. Even humans can maintain seasonal rhythms as exhibited by seasonal affective disorder, a recurrent depression characterized by increased sleep, overeating, and weight gain-behaviors similar to those seen in hibernators, Ohtsu noted.
"Hibernation is an extreme response to a seasonal environment, yet we knew almost nothing about how it is timed, nor how vital cellular functions are sustained in the face of plummeting body temperature," wrote Michael Hastings in a preview. The researchers now "identify a liver-derived protein complex as an essential coordinator of this adaptation to the depredations of winter."
"The finding has more than passing biological interest because understanding how tissues cope with the cardiovascular and oxidative stresses associated with hibernation or torpor may have direct clinical relevance," he added.
For example, he wrote, such a protective program might be exploited in transplant and vascular surgery. Scientists have suggested that hibernation therapy might effectively preserve donor organs for weeks or months.
Hibernation has also been found to protect animals from a wide range of potential threats, from muscle disuse to cancer, the study authors said. Therefore, hibernation therapy might confer protective effects in other clinical arenas as well.
The new findings could lead to "potential pharmacological applications in humans to the prevention of lethal diseases, such as hypothermia, ischemia, muscle atrophy, bacterial infection, and tumorigenesis, which has been observed during hibernation in hibernators," the researchers said.
"These studies may further stimulate the exploration of new techniques for cryosurgery of the heart and brain, as well as the development of hypothermia treatment that is effective for preventing brain ischemic damage." In cryosurgery, physicians use extreme cold to destroy abnormal tissue, such as cancerous tumors.
Cell Press
The researchers earlier found that concentrations of "hibernation-specific protein" complex (HPc) decline in the blood of hibernating chipmunks. The team now reports evidence that the level of HPc in the brain increases at the onset of hibernation independently of changes in body temperature. Moreover, treatments that block HP activity in the animals' brains cuts hibernation short.
"One of the most curious biological phenomena in mammals is their ability to hibernate circannually, which allows them to survive unusually low body temperatures at or near freezing," said study author Takashi Ohtsu of Kanagawa Academy of Science and Technology in Japan. Scientists have attempted for decades to identify substances responsible for hibernation in the blood and organs of hibernating animals but have met with little success, the researchers said.
"Although the functions of HP remain to be clarified, the current observations lead us to propose the involvement of the protein complex in the regulation of energy metabolism and/or biological defenses during hibernation-crucial events for adapting to the severe physiological state," Ohtsu said.
In the current study, the researchers first demonstrated that hibernation in chipmunks is strictly controlled by an individual's internal circannual rhythm even under conditions of constant cold. In 20 hibernators examined throughout their lives, concentrations of HPc in the blood started to decrease prior to hibernation and remained low throughout the inactive state. Hibernation ended after blood HPc levels rose.
Further study revealed an inverse relationship between HPc levels in the blood and brain. While HPc levels dipped in blood, the putative hormone rose dramatically in cerebral spinal fluid, they reported. Likewise, HPc levels decreased abruptly in spinal fluid when hibernation terminated.
The researchers also found that blocking the activity of one of the HP complex proteins in the brain with antibody greatly decreased the hibernation time during which the chipmunks maintained a lowered body temperature, suggesting its critical role in the brain's capacity for dormancy.
The researchers propose that HPc in the blood is actively transported into the spinal fluid in response to the animals' natural rhythm. The hibernation complex might also play a role in the seasonal behavior changes of animal species that do not hibernate, the researchers suggested.
For example, the complex could moderate physiological events such as reproduction in seasonally breeding mammals and migration in birds, they said. Even humans can maintain seasonal rhythms as exhibited by seasonal affective disorder, a recurrent depression characterized by increased sleep, overeating, and weight gain-behaviors similar to those seen in hibernators, Ohtsu noted.
"Hibernation is an extreme response to a seasonal environment, yet we knew almost nothing about how it is timed, nor how vital cellular functions are sustained in the face of plummeting body temperature," wrote Michael Hastings in a preview. The researchers now "identify a liver-derived protein complex as an essential coordinator of this adaptation to the depredations of winter."
"The finding has more than passing biological interest because understanding how tissues cope with the cardiovascular and oxidative stresses associated with hibernation or torpor may have direct clinical relevance," he added.
For example, he wrote, such a protective program might be exploited in transplant and vascular surgery. Scientists have suggested that hibernation therapy might effectively preserve donor organs for weeks or months.
Hibernation has also been found to protect animals from a wide range of potential threats, from muscle disuse to cancer, the study authors said. Therefore, hibernation therapy might confer protective effects in other clinical arenas as well.
The new findings could lead to "potential pharmacological applications in humans to the prevention of lethal diseases, such as hypothermia, ischemia, muscle atrophy, bacterial infection, and tumorigenesis, which has been observed during hibernation in hibernators," the researchers said.
"These studies may further stimulate the exploration of new techniques for cryosurgery of the heart and brain, as well as the development of hypothermia treatment that is effective for preventing brain ischemic damage." In cryosurgery, physicians use extreme cold to destroy abnormal tissue, such as cancerous tumors.
Cell Press
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This morning, mission controllers confirmed that ESA's comet chaser Rosetta had swung by Earth at 8:45 CET as planned, skimming past our planet to pick up a gravitational boost for an epic journey to rendezvous with comet 67P/Churyumov-Gerasimenko in 2014.
Follow Rosetta's final Earth boost
ESA's comet chaser Rosetta will swing by Earth for the last time on 13 November to pick up energy and begin the final leg of its 10-year journey to comet 67P/Churyumov-Gerasimenko. ESA's European Space Operations Centre will host a media briefing on that day.
Biologist discovers pink-winged moth in Chiracahua Mountains
University of Arizona biologist Bruce Walsh has identified a new species of moth in southern Arizona. Normally, this is not a big deal.
Ecologists propose first prevention for white-nose syndrome death in bats
White-nose syndrome (WNS) is a poorly understood condition that, in the two years since its discovery, has spread to at least seven northeastern states and killed as many as half a million bats. Now researchers have suggested the first step toward a measure that may help save the affected bats: providing localized heat sources to the hibernating animals.
Mate or hibernate? That's the question worm pheromones answer
If worms could talk, they might tell potential suitors, "I like the way you wriggle," complete with that telltale come slither look.
'Hibernation-on-demand' drug significantly improves survival after extreme blood loss
For the first time, researchers have demonstrated that the administration of minute amounts of inhaled or intravenous hydrogen sulfide, or H2S - the molecule that gives rotten eggs their sulfurous stench - significantly improves survival from extreme blood loss in rats.
Foot-dragging Mars rover finds Yellowstone-like hot spring deposits
Deposits of nearly pure silica discovered by the Mars Exploration Rover Spirit in Gusev Crater formed when volcanic steam or hot water (or maybe both) percolated through the ground.
Dying bats in the Northeast remain a mystery
Investigations continue into the cause of a mysterious illness that has resulted in the deaths of thousands of bats since March 2008. At more than 25 caves and mines in the northeastern U.S, bats exhibiting a condition now referred to as "white-nosed syndrome" have been dying.
Vive the vole!
The gathering of data for research involving an animal usually involves invasive procedures or death for the experimental animals. But critical data may now be collected through a nonlethal procedure, according to a new paper for the forthcoming issue of Physiological and Biochemical Zoology.
Hibernation-like behavior in Antarctic fish -- on ice for winter
Scientists have discovered an Antarctic fish species that adopts a winter survival strategy similar to hibernation. Reporting this week in the journal PLoS ONE, the online journal from the Public Library of Science, scientists from British Antarctic Survey (BAS) and the University of Birmingham reveal, for the first time, that the Antarctic 'cod' Notothenia coriiceps effectively 'puts itself on ice' to survive the long Antarctic winter.
More Hibernation Current Events and Hibernation News Articles
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Hibernation (Patterns in Nature series) by Margaret Hall (Author) Simple text and photographs introduce hibernation and how some animals prepare for and experience hibernation each year. |
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What Is Hibernation? (Science of Living Things) by John Crossingham (Author), Bobbie Kalman (Author) This work is for ages 6-12. Hibernation is one of nature's greatest miracles, allowing animals to sleep through periods of extreme cold (and heat). From the tundra to the desert, this ability enables animals to live in some of Earth's harshest climates. Full-colour photographs and vivid text combine to give children a view of the many different ways that animals "sleep it off". Highlights include: how an animal's body uses fat to survive and even wake itself up; how an animal finds and prepares its den for hibernation; animals that estivate, or hibernate to escape heat; animals that give birth and care for their young during hibernation. |
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Time to Sleep (An Owlet Book) by Denise Fleming (Author), Denise Fleming (Illustrator) A warm, inviting bedtime book from a Caldecott winning illustrator. Bear sniffed once. She sniffed twice. "I smell winter in the air," said Bear. "It is time to crawl into my cave and sleep. But first I must tell Snail." Denise Fleming presents a warm-hearted story about animals of the forest settling down for their winter nap. But, like children who must go to bed for the night, they each find a way to put it off just a little bit longer. Richly illustrated in fall colors, Denise Fleming's story book world is right on target for preschoolers. |
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Hibernation (Cycles of Life) by Carolyn Scrace (Author), David Salariya (Author) Explains the process of hibernation, describing how a dormouse prepares for the long sleep. |
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Don't Wake Up the Bear! by Marjorie Dennis Murray (Author), Patricia Wittmann (Illustrator) On a cold, snowy evening, several animals snuggle up to a hibernating bear in order to keep warm. |
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Animals in Winter (Let's-Read-and-Find-Out Science 1) by Henrietta Bancroft (Author), Helen K. Davie (Illustrator) Have you ever seen a butterfly in the snow? Probably not. Butterflies can't survive cold weather, so when winter comes, many butterflies fly to warmer places. They migrate. Woodchucks don't like cold weather either but they don't migrate; they hibernate. Woodchucks sleep in their dens all winter long. Read and find out how other animals cope with winter's worst weather. |
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Some Things Never Change by Hibernation | |
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Do Not Disturb: The Mysteries of Animal Hibernation and Sleep by Margery Facklam (Author), Pamela Johnson (Illustrator) |
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How Do Bears Sleep (Carolrhoda Picture Books) by E. J. Bird (Author) Describes, in verse, what goes on in the bear's den during winter hibernation. |
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Some Things Never Change Hibernation (Primary Contributor) |
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