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 21,2020

The Lockdown is not a cure but a critical strategy to prevent the geographical spread of COVID-19.

While pandemics at this level involves actual life threatening situations for individual's or significant others in one's immediate circle, it envisages a marked disruption in routine life. Even after the pandemic has been contained and will come to pass; it's aftermath will leave a trailblazer which demands planning and implementation of a post pandemic reconstruction of society with potentially traumatic experiences varying in intensity, multiplicity and duration.

Degree of Trauma

It would do well for each one of us to realise that the pandemic is "potentially traumatic", since not everyone will experience COVID -19 as a traumatic event in their lives. Yet, there will be those who may develop post pandemic stress reactions, depression and related dysfunction and pathological reactions while still other exhibit healthy reactions to the same set of circumstances.

"Psychological reactions to the pandemic can be distilled into four distinct prototypical patterns, namely, Resilience, Recovery, Chronic and Delayed patterns which may vary in intensity, multiplicity, and duration. Resilient individual have an ability to bounce back from adversity and experience modest or little disruption in normal functioning and are able to maintain a relatively stable, healthy levels of psychological functioning even after enduring the pandemic. Recovery pattern is characterised by relatively rapid reduction in symptoms and return to normal functioning whereas chronic pattern is characterised by symptoms and dysfunction of a long duration," says Pune-based military psychologist Lt Col Dr Samir Rawat.

Challenges at the Individual and Community Levels

From a psychological perspective, post pandemic reconstruction would entail catering to the problems, concerns and needs of those adversely impacted by the COVID -19 with stress symptoms typically characterised by individual's experiencing an overwhelming trauma of the pandemic (for example, recurring nightmares/ breaking into a cold sweat, flashback of stressful events, increasing irritability, low frustration tolerance or emotional numbing).

It could also manifest in depressive symptoms which may result in lack of interest or diminished pleasure in activities and things which you earlier liked to do, feelings of worthlessness or even survivor guilt in case of a loss of a loved one due to COVID-19, fleeting thoughts of death and suicidal ideation. Physical symptoms, on the other hand could be a decrease in appetite, weight and sleep problems, inability to focus and lack of concentration.

Undoubtedly, the pandemic will cause a financial loss of varying magnitude to many, especially the marginalised and economically disadvantaged strata of daily wage earners; it will also lead to loss of jobs (already beginning to show), homelessness, occupational difficulties and new challenges in interpersonal relations at work and on the home front, besides physical health problems and psychological barriers with new norms of accepted social behaviour (social distancing, handshakes, an obsession for cleanliness to name a few).

Emotional battles

Many factors may influence whether individuals come out stronger and more resilient or surrender to the pandemic. Emotion Regulation is one such long term critical factor that can play an important role in contributing to varying degrees of adaptation with negative or positive outcomes. While we know that primary emotions are fear, anger, disgust, joy, anticipation, acceptance, sadness and surprise, other basic emotions include wonder, love, desire, joy, hatred, sadness, attachment, disgust, rage and even expectancy .

To be able to regulate these emotions and avoid negativity , especially on social media platforms is likely to increase efforts in emotion regulation which involves initiating, increasing or maintaining an emotional response.

This means by regulating or on the other hand by stopping, decreasing or avoiding an emotional response, that is, by down-regulating, depending on the individual's objectives and goals or his /her ability to regulate emotions in the valued and given direction.

"One of the best ways to regulate emotions is through cognitive restructuring wherein we change the way we think; after all it is not the event but the interpretation of the event which is perceived as stressful and finding meaning promotes resilience and reduces risk and vulnerability to stress," advises Dr Rawat.

Adding, "Clearly, we need to have a psychological plan to prevent, mitigate and minimise negative outcomes by post pandemic reconstruction of society at an individual and community level all over the country; this has to be integrated by all leaders across verticals in diverse domains."

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Agencies
July 2,2020

London, Jul 2: The World Health Organisation says smoking is linked to a higher risk of severe illness and death from the coronavirus in hospitalised patients, although it was unable to specify exactly how much greater those risks might be.

In a scientific brief published this week, the U.N. health agency reviewed 34 published studies on the association between smoking and Covid-19, including the probability of infection, hospitalisation, severity of disease and death.

WHO noted that smokers represent up to 18% of hospitalised coronavirus patients and that there appeared to be a significant link between whether or not patients smoked and the severity of disease they suffered, the type of hospital interventions required and patients' risk of dying.

In April, French researchers released a small study suggesting smokers were at less risk of catching Covid-19 and planned to test nicotine patches on patients and health workers — but their findings were questioned by many scientists at the time who cited the lack of definitive data.

WHO says "the available evidence suggests that smoking is associated with increased severity of disease and death in hospitalized Covid-19 patients. It recommends that smokers quit.

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Agencies
July 3,2020

Apart from the many benefits of doing exercise, new research has now found that exercise can slow down or prevent the development of macular degeneration and may benefit other common causes of vision loss, such as glaucoma and diabetic retinopathy.

The new study from the University of Virginia School of Medicine found that exercise reduced the harmful overgrowth of blood vessels in the eyes of lab mice by up to 45 per cent. This tangle of blood vessels is a key contributor to macular degeneration and several other eye diseases.

The study represents the first experimental evidence showing that exercise can reduce the severity of macular degeneration, a leading cause of vision loss, the scientists report. Ten million Americans are estimated to have the condition.

"There has long been a question about whether maintaining a healthy lifestyle can delay or prevent the development of macular degeneration. The way that question has historically been answered has been by taking surveys of people, asking them what they are eating and how much exercise they are performing," said researcher Bradley Gelfand, PhD, of UVA's Center for Advanced Vision Science.

"That is basically the most sophisticated study that has been done. The problem with that is that people are notoriously bad self-reporters ... and that can lead to conclusions that may or not be true. This [study] offers hard evidence from the lab for the very first time," Gelfand added.

Enticingly, the research found that the bar for receiving the benefits from exercise was relatively low - more exercise didn't mean more benefit.

"Mice are kind of like people in that they will do a spectrum of exercise. As long as they had a wheel and ran on it, there was a benefit. The benefit that they obtained is saturated at low levels of exercise," Gelfand said.

An initial test comparing mice that voluntarily exercised versus those that did not found that exercise reduced the blood vessel overgrowth by 45%. A second test, to confirm the findings, found a reduction of 32 per cent.

The scientists aren't certain exactly how exercise is preventing the blood vessel overgrowth. There could be a variety of factors at play, they say, including increased blood flow to the eyes.

Gelfand, of UVA's Department of Ophthalmology and Department of Biomedical Engineering, noted that the onset of vision loss is often associated with a decrease in exercise.

"It is fairly well known that as people's eyes and vision deteriorate, their tendency to engage in physical activity also goes down. It can be a challenging thing to study with older people. ... How much of that is one causing the other?" he said.
The researchers already have submitted grant proposals in hopes of obtaining funding to pursue their findings further.

"The next step is to look at how and why this happens, and to see if we can develop a pill or method that will give you the benefits of exercise without having to exercise," Gelfand said.

He explained, "We're talking about a fairly elderly population [of people with macular degeneration], many of whom may not be capable of conducting the type of exercise regimen that may be required to see some kind of benefit." (He urged people to consult their doctors before beginning any aggressive exercise program.)
Gelfand, a self-described couch potato, disclosed a secret motivation for the research: "One reason I wanted to do this study was sort of selfish. I was hoping to find some reason not to exercise," he joked. "It turned out exercise really is good for you."

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