A new study in mice concludes that light-sensitive proteins on fat cells can detect sunlight
Islamabad (Pakistan Point News / Online - 06th February, 2020) A new study in mice concludes that light-sensitive proteins on fat cells can detect sunlight. It also finds that too little natural light can alter how fat cells behave and may increase the risk of metabolic syndrome.Sunlight may influence fat metabolism, according to a recent study.Throughout the evolution of life on Earth, much has changed. One notable constant, however, is the light from our sun.
We cannot overstate our reliance on this huge ball of plasma 93 million miles away.Because life in all its forms evolved under the glow of our nearest star, animals have evolved to utilize its emissions. Most obviously, the eyes contain photoreceptors that detect light and share the information with the brain, which then generates an image of a person's surroundings.Light beyond the eyesAnimals can detect light using proteins called opsins.
Two of the most well-known in humans are melanopsin and neuropsin, which are expressed in some retinal cells.In other animals, light-detecting compounds are present outside of the visual system. For example, frogs can detect light through cells in their skin called chromatophores.Until quite recently, scientists believed that mammals only detected light through their eyes. However, several studies have now overturned this notion.For instance, one study from 2019 found that neuropsin in the skin of rats can detect light and help them maintain their circadian rhythms.
Still, evidence of so-called extraocular photoreception in mammals is scarce.For the first time, a new study has investigated whether or not certain proteins on fat cells that lie beneath the skin might also detect light.Opsin 3 in fat cellsThe researchers focused on opsin 3 (OPN3). This protein is present throughout the body, including in the brain, testis, liver, and kidneys.They demonstrated that OPN3 is also present in both human and mouse fat cells, or adipocytes.
Also, importantly, they showed that light can travel deep enough through a rat's skin to trigger OPN3 in adipocytes.In the refrigeratorWhen mammals, including humans, are in a cold environment, the body adapts. Aside from shivering, the body burns fat to create heat. White adipose tissue is the Primary energy store, and brown adipose tissue is mainly responsible for generating heat (without shivering) when we are cold.Testing the refrigerator lightIn another experiment, the researchers placed normal adult mice in a cold environment with full-spectrum lighting and monitored their core body temperatures.
After 3 hours, they switched off the blue light of the wavelength that triggers OPN3 but left the rest of the spectrum. Without the blue wavelength, the animals' core temperatures dropped, providing further evidence that natural, full-spectrum light influences metabolism.Looking forwardAlthough the scientists conducted this study in mice, they believe that a similar mechanism probably exists in humans. Of course, they will need to carry out more research to explore whether or not this is the case.
They write:"If the light-OPN3 adipocyte pathway exists in humans, there are potentially broad implications for human health. Our modern lifestyle subjects us to unnatural lighting spectra, exposure to light at night, shift work, and jet lag, all of which result in metabolic disruption."Although scientists are at the very start of this line of investigation, the study authors theorize that "insufficient stimulation of the light-OPN3 adipocyte pathway is part of an explanation for the prevalence of metabolic deregulation in industrialized nations where unnatural lighting has become the norm."
