Links for Keyword: Obesity

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Microglia Cause Cognitive Decline in Obese Mice

Diana Kwon Obesity is on the rise across the globe. The worldwide prevalence of the condition has nearly tripled over the last four decades, and approximately 13 percent of adults were obese in 2016. This staggering rise poses a public health concern: not only is obesity tied to bodily ailments such as cardiovascular disease and diabetes, epidemiological investigations have revealed that it is also linked to cognitive decline—and higher chances of developing dementia and other brain-related disorders later in life. Researchers have recently started to shed light on how weight gain affects the brain, and over the last few years, microglia, the brain’s resident immune cells, have emerged as the key culprit. Several rodent studies paint a picture of activated microglia gobbling up dendritic spines that form synapses in obese animals’ brains as the cause of cognitive decline. A study published today (September 10) in the Journal of Neuroscience provides strong new support for this theory. While prior studies have drawn robust associations between microglia and obesity-related cognitive decline, Elise Cope, a postdoc at Princeton University, says none had yet addressed whether those cells were actually causing the behavioral changes. “The novelty of our study was where we decided to see if blocking microglia using three different methods could actually prevent the dendritic spine loss and improve cognitive function,” Cope says. © 1986 - 2018 The Scientist.

Related chapters from BN8e: Chapter 13: Homeostasis: Active Regulation of the Internal Environment; Chapter 17: Learning and Memory
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment; Chapter 13: Memory, Learning, and Development
Link ID: 25443 - Posted: 09.13.2018

How obesity may harm memory and learning

Laura Sanders Obesity can affect brainpower, and a study in mice may help explain how. In the brains of obese mice, rogue immune cells chomp nerve cell connections that are important for learning and memory, scientists report September 10 in the Journal of Neuroscience. Drugs that stop this synapse destruction may ultimately prove useful for protecting the brain against the immune cell assault. Like people, mice that eat lots of fat quickly pack on pounds. After 12 weeks of a high-fat diet, mice weighed almost 40 percent more than mice fed standard chow. These obese mice showed signs of diminished brainpower, neuroscientist Elizabeth Gould of Princeton University and colleagues found. Obese mice were worse at escaping mazes and remembering an object’s location than mice of a normal weight. On nerve cells, microscopic knobs called dendritic spines receive signals. Compared with normal-sized mice, obese mice had fewer dendritic spines in several parts of the mice’s hippocampi, brain structures important for learning and memory. The dendritic spine destruction comes from immune cells called microglia, the results suggest. In obese mice, higher numbers of active microglia lurked among these sparser nerve cell connections compared with mice of normal weights. When the researchers interfered with microglia in obese mice, dendritic spines were protected and the mice’s performance on thinking tests improved. |© Society for Science & the Public 2000 - 2018.

Longer daily fasting times improve health and longevity in mice

Increasing time between meals made male mice healthier overall and live longer compared to mice who ate more frequently, according to a new study published in the Sept. 6, 2018 issue of Cell Metabolism. Scientists from the National Institute on Aging (NIA) at the National Institutes of Health, the University of Wisconsin-Madison, and the Pennington Biomedical Research Center, Baton Rouge, Louisiana, reported that health and longevity improved with increased fasting time, regardless of what the mice ate or how many calories they consumed. “This study showed that mice who ate one meal per day, and thus had the longest fasting period, seemed to have a longer lifespan and better outcomes for common age-related liver disease and metabolic disorders,” said NIA Director Richard J. Hodes, M.D. “These intriguing results in an animal model show that the interplay of total caloric intake and the length of feeding and fasting periods deserves a closer look.” The scientists randomly divided 292 male mice into two diet groups. One group received a naturally sourced diet that was lower in purified sugars and fat, and higher in protein and fiber than the other diet. The mice in each diet group were then divided into three sub-groups based on how often they had access to food. The first group of mice had access to food around the clock. A second group of mice was fed 30 percent less calories per day than the first group. The third group was meal fed, getting a single meal that added up to the exact number of calories as the round-the-clock group. Both the meal-fed and calorie-restricted mice learned to eat quickly when food was available, resulting in longer daily fasting periods for both groups.

Related chapters from BN8e: Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 25421 - Posted: 09.07.2018

Limited Meal Times Prevent Obesity in Mice Prone to Gaining Weight

Abby Olena Mice with faulty circadian clocks are prone to obesity and diabetes. So are mice fed a diet high in fat. Remarkably, animals that have both of these obesity-driving conditions can stay lean and metabolically healthy by simply limiting the time of day when they eat. In a study published today (August 30) in Cell Metabolism, researchers report that restricting feeding times to mice’s active hours can overcome both defective clock genes and an unhealthy diet, a finding that may have an impact in the clinic. The work corroborates previous research showing how powerful restricted feeding can be to improve clock function, says Kristin Eckel-Mahan, a circadian biologist at the University of Texas Health Science Center at Houston who did not participate in the study. Over the last 20 years, biologists have found circadian clocks keeping physiologic time in almost every organ. They have also shown that mice with disrupted clocks often develop metabolic diseases, such as obesity, and that circadian clock proteins physically bind to the promoters of many metabolic regulators and instruct them when to turn on and off. For Satchidananda Panda of the Salk Institute, these lines of evidence came together in 2009, when his group published a study showing that in mice without the clock component Cryptochrome, feeding and fasting could drive the expression of some, but not all, of the metabolic regulators throughout the body. Other groups have also confirmed that even in the absence of the clock it is still possible to drive some genetic rhythms. In this latest study, he and colleagues wanted to look more closely at how the cycling of clock and metabolic transcripts induced by time-restricted feeding, rather than normal genetic rhythms, influences the health of mice. © 1986 - 2018 The Scientist

Weight-loss pill hailed as 'holy grail' in fight against obesity

A weight-loss pill has been hailed as a potential “holy grail” in the fight against obesity after a major study showed it did not increase the risk of serious heart problems. Researchers say lorcaserin is the first weight-loss drug to be deemed safe for heart health with long-term use. Taken twice a day, the drug is an appetite suppressant which works by stimulating brain chemicals to induce a feeling of fullness. A US study saw 12,000 people who were either obese or overweight given the pills or a placebo – with those who took the drug shedding an average of 4kg (9lbs) in 40 months. Further analysis showed no big differences in tests for heart valve damage. Tam Fry, of Britain’s National Obesity Forum, said the drug is potentially the “holy grail” of weight-loss medicine. “I think it is the thing everybody has been looking for,” he said. “I think there will be several holy grails, but this is a holy grail and one which has been certainly at the back of the mind of a lot of specialists for a long time. “But all of the other things apply – lifestyle change has got to be root and branch part of this.” Prof Jason Halford, an obesity expert at the University of Liverpool, told the Daily Telegraph newspaper that the drug’s availability in the UK would depend on whether it is approved by National Health Service regulators. “We don’t have any appetite suppressants available on the NHS. We have a massive great gap between lifestyle modification and surgery,” he said. © 2018 Guardian News and Media Limited

A Molecular Reason Why Obese People Have Trouble Losing Weight

By Bret Stetka Obesity rates in the U.S. and abroad have soared: The world now has more overweight people than those who weigh too little. One reason relates to the way the body reacts to its own fat stores by setting in motion a set of molecular events that impede the metabolic process that normally puts a damper on hunger. A new study published August 22 in Science Translational Medicine provides details of how this process occurs, giving new insight into why obese individuals have trouble shedding pounds. It also suggests a possible treatment approach that targets obesity in the brain, not in the belly. Scientists have long known that a hormone called leptin is instrumental in regulating the human diet. Produced by fat cells, the molecule communicates with a brain region called the hypothalamus, which reins in hunger cravings when our energy stores are full. Yet as we gain weight our bodies become less sensitive to leptin, and it becomes harder and harder to slim down. In other words, weight gain begets more weight gain. In an experiment using mice that became obese on a high-fat diet, an international team found obesity increases the activity of an enzyme called matrix metalloproteinase-2, or MMP-2. By using a technique called western blot analysis—separating and identifying all the proteins in a tissue sample—the authors found MMP-2 cleaves off a portion of the leptin receptor in the hypothalamus, impairing the hormone’s signaling and its ability to suppress appetite. © 2018 Scientific American

Low-carb diets could shorten life, study suggests

By Alex Therrien Health reporter, BBC News A low-carb diet could shorten life expectancy by up to four years, a study suggests. Low-carb diets, such as Atkins, have become increasingly popular for weight loss and have shown promise for lowering the risk of some illnesses. But a US study over 25 years indicates that moderate carb consumption - or switching meat for plant-based protein and fats - is healthier. The study relied on people remembering the amount of carbohydrates they ate. 'Gaining widespread popularity' In the study, published in The Lancet Public Health, 15,400 people from the US filled out questionnaires on the food and drink they consumed, along with portion sizes. From this, scientists estimated the proportion of calories they got from carbohydrates, fats, and protein. After following the group for an average of 25 years, researchers found that those who got 50-55% of their energy from carbohydrates (the moderate carb group and in line with UK dietary guidelines) had a slightly lower risk of death compared with the low and high-carb groups. Carbohydrates include vegetables, fruit and sugar but the main source of them is starchy foods, such as potatoes, bread, rice, pasta and cereals. The NHS Eatwell Guide provides details on how to achieve this kind of healthy, balanced diet and reduce the risk of serious illnesses in the long term. Researchers estimated that, from the age of 50, people in the moderate carb group were on average expected to live for another 33 years. © 2018 BBC

Any Weight Loss Can Be Healthful, but More Can Be Much Better

By Nicholas Bakalar When it comes to losing weight, more can be better. A lot better, according to a new study. Researchers studied 7,670 overweight or obese people who wanted to lose weight. Using data on current weight, weight a year ago and maximum lifetime weight, they tested the association of long-term weight loss with lowering the risk for metabolic syndrome — a constellation of unhealthy conditions that includes high blood pressure, insulin resistance, excess fat around the waist, high triglycerides and low HDL, or “good,” cholesterol. Compared to people who maintained less than a 5 percent weight loss for one year, those who lost 5 to 10 percent lowered their risk for metabolic syndrome by 22 percent. A 15 to 19 percent loss was associated with a 37 percent lower risk, and those who maintained a loss of 20 percent or more had a 53 percent lower risk. The study is in the Mayo Clinic Proceedings. Only 5.5 percent of the participants succeeded in holding a 20 percent or greater weight loss for one year. “Any weight loss is beneficial,” said the lead author, Gregory Knell of the University of Texas School of Public Health in Houston. “You don’t have to reach 20 percent to have a benefit. But if you are able to lose more weight, you get some really significant numbers related to metabolic health.” © 2018 The New York Times Company

Food cravings peak twice nightly, in countries all around the world

By Frankie Schembri Do you ever find yourself scouring the web for pizza delivery services to satisfy those late-night cravings? You’re not alone: A new study reveals that hungry web surfers around the world all start searching for food-related information at two peak times, 7 p.m. and 2 a.m. Wanting to see if they could spot trends in human behavior based on a massive database of Google searches, a team of scientists analyzed hourly food-related queries from five countries: the United States, Canada, India, Australia, and the United Kingdom. For two 1-week periods, they looked for general food-related keywords such as “pizza delivery” or “Chinese delivery” and country-specific delivery companies like India’s “Swiggy” and “Just Eat,” which serves the United Kingdom and Australia. They also analyzed 5 years of data to see if they could discover seasonal trends. The two spikes in food-related searches occurred across all countries, keywords, days of the week, and seasons, the researchers report today in Royal Society Open Science. They say the peaks likely represent two different groups of people searching for nighttime nourishment, one older (the early birds) and one younger (the night owls). Another hypothesis is that the two groups are simply running on different internal body clocks, which affects when they want their evening calories. © 2018 American Association for the Advancement of Science.

Related chapters from BN8e: Chapter 13: Homeostasis: Active Regulation of the Internal Environment; Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment; Chapter 10: Biological Rhythms and Sleep
Link ID: 25245 - Posted: 07.25.2018

Record number of severely obese children

A record number of primary school children are leaving school severely obese, according to new figures from Public Health England. Data for 2016/17 shows one in 25 10 to 11 year olds were severely obese. That's more than 22,000 children, and the highest level since records began. Levels of childhood obesity have remained fairly stable in recent years, but the new analysis shows that severe obesity has been on an upward trend over the last decade. The data from the National Child Measurement Programme (NCMP) for children for the year 2016/17 has detailed the trends in severe obesity for the first time. The programme found: More deprived areas have a much higher rate of overweight and obese children, compared to the most well-off areas. This disparity is happening at a faster rate in school leavers in year 6, than in reception age. The figures did however show a downward trend of reception age boys being overweight and obese. When records began in 2006/07, one in 32 primary school leavers were severely obese. Severe obesity is BMI on or above the 99.6th percentile for a child's age and sex. Dr Alison Tedstone, chief nutritionist at Public Health England, said the trends were "extremely worrying and have been decades in the making - reversing them will not happen overnight." She said "bold measures are needed to tackle this threat to our children's health". The Department of Health recently announced the second phase of its childhood obesity plan to help halve childhood obesity by 2030. As part of that, sweets and high-fat snacks will be banned from supermarket checkouts, and there will be tighter restrictions on junk food ads on TV. © 2018 BBC

Related chapters from BN8e: Chapter 13: Homeostasis: Active Regulation of the Internal Environment; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment; Chapter 13: Memory, Learning, and Development
Link ID: 25239 - Posted: 07.24.2018

Nerve cells that help control hunger have been ID’d in mice

Laura Sanders Newly identified nerve cells deep in the brains of mice compel them to eat. Similar cells exist in people, too, and may ultimately represent a new way to target eating disorders and obesity. These neurons, described in the July 6 Science, are not the first discovered to control appetite. But because of the mysterious brain region where they are found and the potential relevance to people, the mouse results “are worth pursuing,” says neurobiologist and physiologist Sabrina Diano of Yale University School of Medicine. Certain nerve cells in the human brain region called the nucleus tuberalis lateralis, or NTL, are known to malfunction in neurodegenerative diseases such as Huntington’s and Alzheimer’s. But “almost nothing is known about [the region],” says study coauthor Yu Fu of the Singapore Bioimaging Consortium, Agency for Science, Technology and Research. In people, the NTL is a small bump along the bottom edge of the hypothalamus, a brain structure known to regulate eating behavior. But in mice, a similar structure wasn’t thought to exist at all, until Fu and colleagues discovered it by chance. The researchers were studying cells that produce a hormone called somatostatin — a molecular signpost of some NTL cells in people. In mice, that cluster of cells in the hypothalamus seemed to correspond to the human NTL. Not only do these cells exist in mice, but they have a big role in eating behavior. The neurons sprang into action when the mice were hungry, or when the hunger-signaling hormone ghrelin was around, the team found. |© Society for Science & the Public 2000 - 201

Exercise May Aid in Weight Loss. Provided You Do Enough.

By Gretchen Reynolds Can working out help us to drop pounds after all? A provocative new study involving overweight men and women suggests that it probably can, undercutting a widespread notion that exercise, by itself, is worthless for weight loss. But the findings also indicate that, to benefit, we may need to exercise quite a bit. In theory, exercise should contribute substantially to weight loss. It burns calories. If we do not replace them, our bodies should achieve negative energy balance, use stored fat for fuel and shed pounds. But life and our metabolisms are not predictable or fair, as multiple exercise studies involving people and animals show. In these experiments, participants lose less weight than would be expected, given the energy they expend during exercise. The studies generally have concluded that the exercisers had compensated for the energy they had expended during exercise, either by eating more or moving less throughout the day. These compensations were often unwitting but effective. Some researchers had begun to wonder, though, if the amount of exercise might matter. Many of the past human experiments had involved about 30 minutes a day or so of moderate exercise, which is the amount generally recommended by current guidelines to improve health. But what if people exercised more, some researchers asked. Would they still compensate for all the calories that they burned? To find out, scientists from the University of North Dakota and other institutions decided to invite 31 overweight, sedentary men and women to a lab for measurements of their resting metabolic rate and body composition. The volunteers also recounted in detail what they had eaten the previous day and agreed to wear a sophisticated activity tracker for a week. © 2018 The New York Times Company

Gigantic study of Chinese babies yields slew of health data

David Cyranoski An ambitious Chinese study tracking tens of thousands of babies and their mothers has begun to bear fruit — just six years after the study’s leaders recruited their first sets of mothers and babies. Researchers have already published results based on the cohort study, which collects biological, environmental and social data, some with important public-health implications. And many more investigations are under way. One, in particular, will examine infants’ microbiomes, the collections of bacteria and other microorganisms that inhabit their bodies — a hot topic in health research and a key goal of the cohort study. The Born in Guangzhou Cohort Study has recruited about 33,000 babies and their mothers since 20121. The study’s leaders are hoping to reach 50,000 baby–mother sets by 2020. And this year, investigators started recruiting 5,000 maternal grandmothers to the project, enabling studies across multiple generations. “The data is vast, and there is space for many different groups globally to mine this information,” says Maria Gloria Dominguez-Bello, a microbiologist at Rutgers, The State University of New Jersey, in New Brunswick, who is not involved in the study. “I really admire this effort from the Chinese team. Very few countries can achieve this scale.” © 2018 Macmillan Publishers Limited,

Obesity Rates Higher in Country Than City

By Nicholas Bakalar Obesity is more common in rural areas than in cities in the United States, two new studies have found. The two analyses, one of adults and the other of children, used data on weight, height and where people lived that was gathered in a series of nationally representative surveys from 2001 to 2016. They were published online together in JAMA. The adult study included 10,792 men and women 20 and older. In the 2013-16 survey period, 39 percent were obese — defined as having a body mass index of 30 or above — including 8 percent who were severely obese, with a B.M.I. of 40 or more. Prevalence of obesity was 36.5 percent among men and 40.8 percent among women, including severe obesity of 5.5 percent for men and 9.8 percent for women. In the study of 6,863 children 2 to 19 years old, 17.8 percent were obese, including 5.8 percent who were severely obese. “I want to emphasize that this survey — the National Health and Nutrition Examination Survey — is the gold standard” in accuracy for obesity rates, said Cynthia L. Ogden, an epidemiologist with the Centers for Disease Control and Prevention and an author on both studies. “When people report their own measurements, they exaggerate their height and minimize their weight,” she said. “This survey has measured heights and weights.” About 38 percent of women living in urban areas with a population greater than a million were obese, as were 42.5 percent of those living in urban areas smaller than a million. But in rural areas, the obesity rate for women was 47.2 percent. Rates for men showed a similar, although not identical, pattern — 31.8 percent in large urban areas, 42.4 percent in small metropolitan areas, and 38.9 percent in rural regions. These differences could not be explained by age, education level, race, ethnicity or smoking status. © 2018 The New York Times Company

Could deep brain stimulation help zap diabetes?

By Emily Underwood When a 53-year-old man asked Dutch doctors to treat his obsessive-compulsive disorder (OCD) several years back, they suggested a new but promising surgical treatment: implanted electrodes that would stimulate deep brain tissue involved in decision-making, reward-seeking, and motivation. The treatment apparently helped him go off one of his psychiatric medications, but it came with a surprising side effect—it also seemed to improve his type 2 diabetes. Now, researchers think they know why. A new study suggests that a boost in the activity of dopamine, a neurotransmitter involved in motivation and pleasure, improves the body’s ability to process sugar. This is the first time such a pathway, previously seen in mice, has been found in humans, says Mike Michaelides, a neuroscientist at the National Institute on Drug Abuse in Baltimore, Maryland, who was not involved in the new research. That doesn’t make deep brain stimulation (DBS) realistic for most people with diabetes, but other, less invasive brain therapies that target dopamine might one day be feasible. Diabetes occurs when glucose, or sugar, in a person’s bloodstream remains in chronically high concentrations. Type 1, which typically begins in childhood, results when the immune system destroys the pancreatic cells that make insulin, the hormone that lets our cells use sugar as food. Type 2 diabetes, typically triggered by a combination of bad genes, poor eating habits, and a lack of exercise, also damages the body’s ability to produce its own insulin. As time goes on, cells are hard-pressed to remove sugar from the blood, and people require larger and larger amounts of insulin to keep their blood sugar stable. There is no cure for either disease. © 2018 American Association for the Advancement of Science

The truth about obesogens: can dust and chemicals make you fat?

Nicola Davis With 26% of adults classified as obese in the UK in 2016, the hunt for causes and solutions to expanding waistlines is on. While public health messages have focused largely on the food we eat, some scientists suspect there is another factor at play: substances being dubbed as “obesogens” – found in our packaging, household goods and furnishings that might affect our hormones and the buildup of fat in the body. However, experts are sceptical, particularly in the light of one report this week. It has made the bold claim that “removing shoes when entering the house and swapping carpet for wooden floors could help people stay slim”, citing a talk by researchers at the universities of Aveiro and Beira Interior in Portugal, who have suggested that preventing obesogens accumulating in the house by frequently sweeping and dusting could stop us gaining weight. As Prof Russell Viner, president of the Royal College of Paediatrics and Child Health, says: “For some medical reasons, such as protection against allergies, yes, it’s advised to keep a dust-free home and so, too, is removing shoes to avoid bringing in dirt from outside, but these things will not make you a healthy weight. Only a balanced diet and regular exercise will do that.” It is not the first study to moot the idea of the existence of obesogens. Earlier this year, researchers at Harvard University suggested compounds called perfluoroalkyl substances (PFAS) – widely used in products such as stain repellents and known to have a number of negative effects on human health – might lead to weight gain. © 2018 Guardian News and Media Limited

Fasting diets may raise risk of diabetes, researchers warn

Robin McKie, science editor Fasting every other day to lose weight could have damaging side effects. That is the conclusion of a group of scientists speaking this weekend at the European Society of Endocrinology’s annual meeting. Their findings suggest that fasting-based diets may impair the action of sugar-regulating hormone insulin, and lead to increased risk of diabetes. Care should be taken before starting such programmes, say researchers. Ana Bonassa, whose team from the University of São Paulo in Brazil carried out the study, said: “This is the first study to show that, despite weight loss, intermittent fasting diets may actually damage the pancreas and affect insulin function in normal healthy individuals, which could lead to diabetes and serious health issues.” Advertisement In recent years intermittent fasting diets have gained popularity. Participants fast for two days out of seven, or on alternate days. However, evidence of their success has been contradictory and there is debate among doctors about their potential to trigger harmful long-term effects. Previous research has also shown that short-term fasting can produce molecules called free radicals, highly reactive chemicals that can cause damage to cells in the body and which may be associated with impaired organ function, cancer risk and accelerated ageing. © 2018 Guardian News and Media Limited

Five things you might be surprised affect weight

By Kirstie Brewer BBC News People might think battling obesity is down to sheer willpower, but medical research says otherwise. Here are five potentially surprising factors that can affect your weight, as unearthed by The Truth About Obesity . 1. Gut microbes Gillian and Jackie are twins - but one weighs over six stone (41kg) more than the other. Prof Tim Spector has been tracking their progress over 25 years, as part of the Twins Research UK study. He believes a lot of their weight differences are down to the tiny organisms - microbes - that live deep in the gut. "Every time you eat anything, you're feeding a hundred trillion microbes. You're never dining alone," he says. A stool sample from each twin revealed Gillian, the thinner of the two, had a very diverse range of microbes, whereas Jackie had very few species living in her gut. "The greater the diversity, the skinnier the person. If you're carrying too much weight, your microbes aren't as diverse as they should be," says Prof Spector, who found the same pattern in a study of 5,000 people. Image copyright Science Photo Library Having a healthy and varied diet, rich in different sources of fibre, has been shown to create a more diverse range of gut microbes. Prof Spector warns most Britons eat only half the fibre they should. 2. The gene lottery Why do some people diligently follow diets and exercise regularly but still struggle to see results, while others do very little and don't pile on the pounds? Scientists at Cambridge University believe 40-70% of the effect on our weight is down to variation in the genes we inherit. © 2018 BBC

Exercise Warms the Brain, Causing Mice to Eat Less

By Kerry Grens Thermometers in the mouse brain are responsible for a lack of appetite the animals feel after a vigorous workout. Simply firing up heat-sensing receptors on cells in the mouse hypothalamus can reproduce the same appetite-suppressing effects of exercise, researchers report today (April 24) in PLOS Biology. “Our study provides evidence that body temperature can act as a biological signal that regulates feeding behavior, just like hormones and nutrients do,” says coauthor Young-Hwan Jo, a neuroscientist at Albert Einstein College of Medicine, in a press release. It’s a fairly common observation among people that working out staves off hunger for a short while afterward. And it turns out the same is true in mice. Jo’s group had mice run a treadmill for 40 minutes, and observed that their brains were warmer and they ate less for the next hour. To see what might be responsible for this effect, Jo and his colleagues centered in on the hypothalamus, given its role in regulating eating. They found that in mice, neurons in the hypothalamus—specifically, in the arcuate nucleus (ARC) of the hypothalamus—produce heat-sensitive receptors called TRPV1. Through a variety of methods, including the application of capsaicin, a compound found in hot chili peppers, the investigators revealed that flipping on TRPV1 could tamp down mice’s appetites. On the flip side, disrupting the receptor wiped out the appetite-suppressing effects of exercise. © 1986-2018 The Scientist

Related chapters from BN8e: Chapter 13: Homeostasis: Active Regulation of the Internal Environment; Chapter 8: General Principles of Sensory Processing, Touch, and Pain
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment; Chapter 5: The Sensorimotor System
Link ID: 24901 - Posted: 04.26.2018

Hunger is a gatekeeper of pain in the brain

Alexey Ponomarenko & Tatiana Korotkova The body’s basic needs include a timely supply of nutrients and the avoidance of tissue damage, which are signalled in the brain by hunger and pain, respectively. But these needs cannot be fulfilled simultaneously, because their resolution involves mutually exclusive behaviours. How does the brain prioritize the more urgent need? Writing in Cell, Alhadeff et al.1 report that the brain’s priorities are set depending on the type of pain involved. Hunger-mediating neurons suppress long-term inflammatory pain, but acute pain, which signals an immediate threat, dampens the activity of these neurons and thus deprioritizes feeding. Alhadeff and colleagues deprived mice of food for 24 hours, and analysed how the hungry animals responded to pain. The researchers found that responses to long-term inflammatory pain — of the type associated with chronic disease and recovery from injury — were reduced in the food-deprived animals compared with controls. By contrast, short-term responses to acute pain that was induced by chemicals, heat or force remained intact in hungry mice. The brain’s hypothalamus contains several structures involved in regulating food intake. One of these, the arcuate nucleus, harbours a population of neurons that express agouti-related protein (AgRP), and help to signal nutritional needs — activation of these neurons evokes voracious feeding2, whereas their ablation leads to starvation3,4. Alhadeff et al. found that stimulation of the AgRP-expressing neurons mimicked the pain-inhibiting effect of hunger in mice. By contrast, silencing of these cells blocked the reduction of inflammatory pain. © 2018 Macmillan Publishers Limited,

Related chapters from BN8e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain; Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 5: The Sensorimotor System; Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 24896 - Posted: 04.24.2018

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