Brain's on-off thirst switch identified

January 27, 2015

Brains on-off

Washington, Jan 27: Scientists have identified neurons that trigger our sense of thirst and those that turn it off.

For years, researchers have suspected that thirst is regulated by neurons in the subfornical organ (SFO), in the hypothalamus. But it has been difficult to pinpoint exactly which neurons are involved.

“When researchers used electrical current to stimulate different parts of the SFO of mice, they got confusing results,” said lead author Yuki Oka, a postdoctoral research scientist in the laboratory of Charles S Zuker, a Howard Hughes Medical Institute Investigator at Columbia University Medical Center (CUMC).

The CUMC team hypothesised that there are at least two types of neurons in the SFO, including ones that drive thirst and others that suppress it.

“Those electrostimulation experiments were probably activating both types of neurons at once, so they were bound to get conflicting results,” said Oka.

To test their hypothesis, Oka and Zuker turned to optogenetics, a more precise technique for controlling brain activity. With optogenetics, researchers can control specific sets of neurons in the brain after inserting light-activated molecules into them.

Shining light onto these molecules turns on the neurons without affecting other types of neurons nearby.

These “mind-control” experiments revealed two types of neurons in the SFO that control thirst: CAMKII neurons, which turn thirst on, and VGAT neurons, which turn it off.

When the researchers turned on CAMK11 neurons, mice immediately began to seek water and to drink intensively.

This behaviour was as strong in well-hydrated mice as in dehydrated ones. Once the neurons were shut off – by turning off the light – the mice immediately stopped drinking.

The researchers also found that light-stimulation of the CAMKII neurons did not induce feeding behaviour. In addition, light-induced thirst was specific for water and did not increase the animals’ consumption of other fluids, including glycerol and honey.

Similar experiments with VGAT neurons showed that these neurons act to turn off thirst. When the researchers turned on these neurons with light, dehydrated mice immediately stopped drinking, even if they were drinking water.

“Together, these findings show that the SFO is a dedicated brain system for thirst,” said Oka.

“The SFO is one of few neurological structures that is not blocked by the blood-brain barrier – it’s completely exposed to the general circulation,” said Oka.

“This raises the possibility that it may be possible to develop drugs for conditions related to thirst,” Oka added.

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Agencies
March 27,2020

New Delhi, Mar 27: The Centre has restricted sale and distribution of "hydroxychloroquine" declaring it as an essential drug to treat the COVID-19 patients and meet the requirements of emergency arising due to the pandemic.

The Ministry of Health and Family Welfare on Thursday made the announcement making it clear that the order "shall come into force on the date of its publication in the official Gazette".

In the order, the government declared that the Central government is "satisfied that the drug hydroxychloroquine is essential to meet the requirements of emergency arising due to pandemic COVID-19 and in the public interest, it is necessary and expedient to regulate and restrict the sale and distribution of the drug 'hydroxychloroquine' and preparation based thereon for preventing their misuse".

"Now, therefore, in exercise of the powers conferred by Section 26B of the Drugs and Cosmetics Act, 1940 (23 of 1940), the Central government hereby directs that sale by retail of any preparation containing the drug Hydroxychloroquine shall be in accordance with the conditions for sale of drugs specified in Schedule H1 to the Drugs and Cosmetics Rules, 1945."

The order came at a time when the novel coronavirus claimed 16 lives and infected over 600 people across India.

The announcement regarding ban of sale and distribution of the drug was made by the government earlier but it issued an official Gazette notification on Thursday signalling that hydroxychloroquine -- an anti-Malaria drug -- will work as a medicine for treating coronavirus infected patients as well.

Recently, the national task force for COVID-19 constituted by Indian Council for Medical Research (ICMR) has recommended hydroxy-chloroquine as a preventive medication.

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Agencies
January 12,2020

Washington D.C., Jan 12: Disruption in one night's sleep can lead to getting Alzheimer's disease, a recent study has stated.

The interruption in the sound sleep for a single night aggravates the level of tau protein in any young male's body, thus gives rise to the chances of developing the disease.

According to CNN, the report was published on Wednesday in neurology, the medical journal of the American Academy of Neurology.

"Our study focuses on the fact that even in young, healthy individuals, missing one night of sleep increases the level of tau in blood suggesting that over time, such sleep deprivation could possibly have detrimental effects," says study author Dr Jonathan Cedernaes, a neurologist at Uppsala University in Sweden.

As defined by the Alzheimer's Association, tau is the name of a protein that helps in stabilizing the internal structure of the brain's nerve cells. An abnormal build-up of tau protein in the body can end up in causing interior cells to fall apart and eventually developing Alzheimer's.

"When you get more of that deep sleep and you get the REM sleep in the normal amounts, that improves clearance of abnormal proteins which we think is good," said Mayo Clinic neurologist Dr Donn Dexter, not the study author but a fellow of the American Academy of Neurology.

Earlier studies have also shown that getting deprived of sleep can allow higher tau development and accumulation. Thus that poor sleep can hasten the development of cognitive issues.

Researchers caution that the study is small and inconclusive, and acknowledged they were not able to determine what the increased levels might mean.

"This study raises more questions than answers," agreed Dexter on a concluding note, sharing, "What this is telling us is that we have to dig more deeply. Despite something we do for a third of our lives, we know so little about sleep and we're learning every day, particularly when it comes to sleep and dementia."

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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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