High fat diet may cause changes in the brain: study

October 24, 2016

Washington, Oct 24: In a recent study, scientists have discovered a new mechanism that regulates obesity. The study shows that this new mechanism can potentially be targeted to treat obesity.

highfatSenior author of the study Makoto Fukuda said, "It's well known that the brain is involved in the development of obesity, but how a high-fat diet changes the brain so it triggers the accumulation of body fat is still unclear."

The team studied the mouse Rap1 gene, which is expressed in a variety of tissues, including the brain where it is involved in functions such as memory and learning. Little was known, however, of the role brain Rap1 plays in energy balance.

To explore the role Rap1 plays in a mouse model, the scientists selectively deleted the Rap1 gene in a group of neurons in the hypothalamus, a region of the brain that is involved in regulating whole-body metabolism.

The scientists had two groups of mice. In one group, the mice were genetically engineered to lack the Rap1 gene, while the control group had a functional Rap 1 gene. Then, the scientists fed the mice in both groups a high-fat diet in which 60 percent of the calories came from fat.

As expected, the control mice with a working Rap1 gene gained weight, but, in comparison, the mice that lacked Rap 1 had markedly reduced body weight and less body fat. Interestingly, when both groups of mice were fed a normal diet, both showed similar weights and body fat.

The scientists then looked closer at why the mice lacking the Rap1 gene had not gained weight despite eating a high-fat diet.

"We observed that the mice lacking Rap1 were not more physically active. However, they ate less and burned more body fat than mice with Rap1," said Fukuda.

Adding, "These observations were associated with the hypothalamus producing more of a hormone that reduces appetite, called POMC, and less of hormones that stimulate appetite, called NPY and AgRP." These mice also had lower levels of blood glucose and insulin than controls.

The scientists also were interested in studying whether leptin changed in mice lacking Rap1.

Leptin, the 'satiety hormone' produced by fatty tissue, helps regulate body weight by inhibiting appetite. Obese people, however, do not respond to leptin's signals of satiety, and the blood levels of leptin are higher than those in non-obese people. Leptin resistance is a hallmark of human obesity.

Mice that lacked Rap1 and ate a high-fat diet, on the other hand, did not develop leptin resistance; they were able to respond to leptin and this was reflected in the hormone's lower blood levels.

The team also tested the effect of inhibiting Rap1 with drugs instead of deleting the gene on mice on a high-fat diet. The scientists inhibited RAP1 action with inhibitor ESI-05.

"When we administered ESI-05 to obese mice, we restored their sensitivity to leptin to a level similar to that in mice eating a normal diet. The mice ate less and lost weight," he said.

The scientists have shown a new mechanism by which the brain can affect the development of obesity triggered by consuming a high-fat diet.

Consuming a high-fat diet results in changes in the brain that increase Rap1 activity, which in turn leads to a decreased sensitivity to leptin, and this sets the body on a path to obesity.

"This new mechanism involving Rap1 in the brain may represent a potential therapeutic target for treating human obesity in the future," said Fukuda.

The study appeared in Cell Reports today.

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Agencies
April 15,2020

Dear parents, if you want your children to have proper sleep, read this carefully. Joining a growing list of studies that tell parents to shun devices at bed-time, researchers say that children who use devices and decide what time they go to sleep, achieve less sleep and feel more sleepier the following day than their peers.

The study of children in this age-group (aged 11 to 13 years), published in the New Zealand Medical Journal, found most (72 per cent) of the 163 students interviewed by University of Otago researchers achieved recommended guidelines of an average 9 to 11 hours sleep nightly over one week.

"But that also means that almost one in four students did not achieve sleep within these guidelines, which highlights an area for improvement," said study researcher Kate Ford.

However, consistent with previous research in 15 to 17-year-old New Zealanders, the study results show less sleep on the nights where devices are used in the hour before bed.

According to the researchers, students who used devices before going to sleep were also more likely to report that they felt sleepy the following morning. Watching television before bed had no significant effect on sleep length.

There were also some interesting observations over the weekends where students went to bed later but woke later achieving similar sleep length to the school days, the researchers said.

A small group of students (six per cent) who reported less than seven hours of sleep, including a small number reporting not sleeping at all, according to the study,

Therefore, while the average across the week of 72 per cent of students reporting adequate sleep is reassuring, it is far from the goal of every child achieving sleep within the recommended guidelines," Ford said.

Dr Paul Kelly, head of the Sleep Health Service at Canterbury District Health Board, supervised the study and explained that the foundations for good health are based on proper nutrition, regular exercise and good sleep quality.

Sleep quality is often overlooked as a contributory factor to poor health.

"The study findings suggest the need for parental guidance around bedtimings and moderation of the use and availability of electronic devices before bed," Kelly said.

"Respect and protect your sleep, as good daytime functioning is reliant on adequate sleep," Kelly added.

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News Network
June 20,2020

Washington, Jun 20: Pregnant and postpartum women are usually at a high risk of depression and anxiety - one in seven women struggle with symptoms in the perinatal period and the coronavirus pandemic is exacerbating those struggles according to a recent study.

The study was published in Frontiers in Global Women's Health, which found that the likelihood of maternal depression and anxiety has substantially increased during the health crisis.

"The social and physical isolation measures that are critically needed to reduce the spread of the virus are taking a toll on the physical and mental health of many of us," said Dr. Margie Davenport of the University of Alberta, Canada, who co-authored the study.

For new moms, those stresses come with side effects.

"We know that experiencing depression and anxiety during pregnancy and the postpartum period can have detrimental effects on the mental and physical health of both mother and baby that can persist for years," said Davenport.

Such effects can include premature delivery, reduced mother-infant bonding, and developmental delays in infants.

The study surveyed 900 women - 520 of whom were pregnant and 380 of whom had given birth in the past year - and asked about their depression and anxiety symptoms before and during the pandemic.

Before the pandemic began, 29 percent of those women experienced moderate to high anxiety symptoms, and 15 percent experienced depressive symptoms. During the pandemic, those numbers increased - 72 percent experienced anxiety and 41percent experienced depression.

Because lockdown measures have affected daily routines and access to gyms, researchers also asked women whether their exercise habits had changed. Of the women surveyed, 64 percent reduced their physical activity since the pandemic began, while 15 percent increased and 21 percent experienced no change.

Exercise is a known way to ease depression symptoms, so limited physical activity may result in an uptick in depressive symptoms. Indeed, the study found that women who engaged in at least 150 minutes of moderate physical activity a week had significantly lower symptoms of depression and anxiety.

The findings are somewhat limited given the fact that researchers could not survey women before the pandemic began (since they could not know a pandemic would occur). The women surveyed could only offer their pre-pandemic symptoms in hindsight.

Also, while the researchers asked women about their symptoms using validated measures, only mental health care professionals can validly diagnose an individual with depression or anxiety.

The study was specifically interested in the impact of COVID-19 on new moms, but Davenport says maternal mental health is a critical issue no matter the time.

"Even when we are not in a global pandemic, many pregnant and postpartum women frequently feel isolated whether due to being hospitalized, not having family or friends around or other reasons," she said.

"It is critical to increase awareness of the impact of social (and physical) isolation on the mental health of pregnant and postpartum women," Davenport added.

Increased awareness makes diagnosis and treatment - the ultimate goal - more likely.

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Agencies
May 19,2020

New York, May 19: Cigarette smoke spurs the lungs to make more of the receptor protein which the novel coronavirus uses to enter human cells, according to a study which suggests that quitting smoking might reduce the risk of a severe coronavirus infection.

The findings, published in the journal Developmental Cell, may explain why smokers appear to be particularly vulnerable to severe COVID-19 disease.

"Our results provide a clue as to why smokers who develop COVID-19 tend to have poor clinical outcomes," said study senior author Jason Sheltzer, a cancer geneticist at Cold Spring Harbor Laboratory in the US.

"We found that smoking caused a significant increase in the expression of ACE2, the protein that SARS-CoV-2 uses to enter human cells," Sheltzer said.

According to the scientists, quitting smoking might reduce the risk of a severe coronavirus infection.

They said most individuals infected with the virus suffer only mild illness, if they experience any at all.

However, some require intensive care when the sometimes-fatal virus attacks, the researchers said.

In particular, they said three groups have been significantly more likely than others to develop severe illness -- men, the elderly, and smokers.

Turning to previously published data for possible explanations for these disparities, the scientists assessed if vulnerable groups share some key features related to the human proteins that the coronavirus relies on for infection.

First, they said, they focused on comparing gene activity in the lungs across different ages, between the sexes, and between smokers and nonsmokers.

The scientists said both mice that had been exposed to smoke in a laboratory, and humans who were current smokers had significant upregulation of ACE2.

According to Sheltzer, smokers produced 30-55 per cent more ACE2 than their non-smoking counterparts.

While the researchers found no evidence that age or sex impacts ACE2 levels in the lungs, they said the influence of smoke exposure was surprisingly strong.

However, they said, the change seemed to be temporary.

According to the data, the level of the receptors ACE2 in the lungs of people who had quit smoking was similar to that of non-smokers.

The study noted that the most prolific producers of ACE2 in the airways are mucus-producing cells called goblet cells.

Smoking is known to increase the prevalence of such cells, the scientists said.

"Goblet cells produce mucous to protect the respiratory tract from inhaled irritants. Thus, the increased expression of ACE2 in smokers' lungs could be a byproduct of smoking-induced secretory cell hyperplasia," Sheltzer explained.

However, Sheltzer said other studies on the effects of cigarette smoke have shown mixed results.

"Cigarette smoke contains hundreds of different chemicals. It's possible that certain ingredients like nicotine have a different effect than whole smoke does," he said.

The researchers cautioned that the actual ACE2 protein may be regulated in ways not addressed in the current study.

"One could imagine that having more cells that express ACE2 could make it easier for SARS-CoV-2 to spread in someone's lungs, but there is still a lot more we need to explore," Sheltzer said.

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