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
May 5,2020

The lockdown forced by the coronavirus in India has had some unexpected but positive fallouts: It has brought families together and reduced corporate politics, says an expert working in the field for the past decade.

"Today the whole world is on lockdown because of COVID-19, and all that we read, talk and hear is about life and death. We can't deny that the times are tough and the future is uncertain. But I would like to turn the coin and see the other side: the positive side," Shikha Mittal, Founder Director of Be.artsy told IANS in an interview.

Be.artsy is one of India's leading social awareness enterprises which deals with emotions at work and promotes arts as a communication tool for workplaces.

"In the 21st century, personally and professionally, people are practising politics over humanity, competition over collaboration, and have lost touch with themselves due to materialistic desires. During the lockdown, we are forced to confront our existing daily lives, and two interesting things that we can ponder upon, have emerged.

"First, have we ever looked at our family with the same lens as we are using today? What is it that we are doing differently with family today, and what can we do to carry our actions of today into our tomorrow? This is the premise of the #aajjaisakalcontest" that Be.artsy has launched across India.

The aim is "to encourage people to share one habit or life skill that they never practiced earlier, but post Covid-19 would like to continue and enjoy".

How did Be.artsy come about?

"I used to be in the corporate world, earning promotions and greater responsibility. However, the work conditions in those days were unfriendly to women and I had faced many instances of sexual harassment and workplace harassment in the six years of my corporate career. And that's when I had an epiphany."

Be.artsy's most popular programmes are on Prevention of Sexual Harassment (POSH) and on Financial Literacy which makes young people financially independent and better prepared to face the corporate world. "We know that a stitch in time (of planning for the future) saves nine (debt trap, dependence, health emergencies, expenses exceeding income, no savings, families without support, retirement in poverty, lost dreams, extravagance). This can only be achieved by sensitisation," Mittal explained.

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Agencies
June 24,2020

New Delhi, Jun 24: Expanding the testing criterion for coronavirus, the Indian Council of Medical Research has said it should be made widely available to all symptomatic individuals across the country.

"Since test, track and treat' is the only way to prevent spread of infection and save lives, it is imperative that testing should be made widely available to all symptomatic individuals in every part of the country and contact tracing mechanisms for containment of infection are further strengthened," it said in an advisory on 'Newer Additional Strategies for COVID-19 Testing' on Tuesday.

In its revised testing strategy for COVID-19 issued on May 18, the Indian Council of Medical Research (ICMR) had advised testing for all symptomatic Influenza-like illness (ILI) among returnees and migrants within seven days of illness.

All hospitalised patients who develop ILI symptoms, symptomatic individuals living within hotspots or containment zones and healthcare and frontline workers involved in containment and mitigation of coronavirus were also advised testing.

The apex health research body has also advised authorities to enable all government and private hospitals, offices and public sector units to perform antibody-based COVID-19 testing for surveillance to help allay fears and anxiety of healthcare workers and office employees.

The earlier advisories on rapid antibody testing advisories had focused on areas reporting clusters (containment zones), large migration gatherings/evacuees centers and testing of symptomatic ILI individuals at facility level.

Besides, the ICMR on Tuesday also recommended deployment of rapid antigen detection tests for COVID-19 in combination with RT-PCR tests in all containment zones, all central and state government medical colleges and government hospitals, all private hospitals approved by the National Accreditation Board for Hospitals and Healthcare (NABH), all NABL-accredited and ICMR approved private labs, for COVID-19 testing.

All hospitals, laboratories and state governments intending to perform the point-of-care antigen tests need to register with ICMR to obtain the login credentials for data entry.

"ICMR advises all state governments, public and private institutions concerned to take required steps to scale up testing for COVID-19 by deploying combination of various tests as advised," the advisory added.

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Agencies
January 5,2020

Washington D.C., Jan 5: After a woman filed a lawsuit against a diet soda company, the California court has declared that the beverage does not promise to help buyers in losing weight.

The woman had gulped down the drink for over a decade but did not lose inches as a result.

The three-judge panel declared during the hearing: "The prevalent understanding of the term in (the marketplace) is that the 'diet' version of a soft drink has fewer calories than its 'regular' counterpart."

However, the members of the US 9th circuit court have felt that the consumers tend to make out something of their own that is unreasonable and eventually hamper the reputation of brands through a deceptive allegation, reports Fox News.

The response was due to a misleading case filed against Diet Dr Pepper by Shana Becerra from Santa Rosa, California. Shana claimed that she has been addictively purchasing the low-calorie beverage for the past 13 years hoping for losing some fat but failed to lose even a single inch.

The woman also stated that the attractive and fit models misled her into believing that drink will help her in perfecting her body like them.

However, the court's decision was that advertisements are for representational purposes only. "Cannot be reasonably understood to convey any specific meaning at all," as written by Judge Jay Bybee.

Shana had last week made such allegation against Diet coke as well where the court came to a similar verdict. She claimed that she had found various studies where it is evident that the artificial sweetener aspartame used in diet beverages actually boosts weight gain.

But the artificial sweetener is approved in by the concerned administrative department and thus is used in most American drinks.

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