Dermatologists are discovering UV-induced mechanisms for regulating body weight and metabolic health

Obesity and metabolic disorders are becoming increasingly important public health problems worldwide. In a novel study, a team of dermatologists assessed the effects of exposure to ultraviolet (UV) radiation on appetite and weight regulation. They found that exposure to UV radiation increased norepinephrine levels, decreased leptin levels, and browned subcutaneous fat, thereby increasing energy expenditure. These results potentially pave the way for new approaches to preventing and treating obesity and metabolic disorders. Their discoveries appear in Journal of Investigative Dermatologypublished by Elsevier.

UV radiation is a common environmental factor that has a multi-faceted effect on the skin, which covers a large area of ​​the body. UV radiation causes harmful effects such as sunburn, photoaging and skin cancer; however, it is also associated with beneficial effects such as vitamin D synthesis.

Co-authors Dr. Qing-Ling Quan and Dr. Eun Ju Kim from the Department of Dermatology, Seoul National University Hospital, explained: “Recent evidence suggests that UV exposure limits weight gain in mouse models of obesity. Subcutaneous fat is a critical organ in the regulation of energy homeostasis. In addition to previous research on the effects of UV exposure on obesity and metabolic disorders, our team was inspired by our previous discovery that although UV rays do not directly reach subcutaneous tissue after exposure to the skin, they can regulate subcutaneous fat metabolism. This led us to hypothesize that skin exposure to UV rays may play a significant role in systemic energy homeostasis, which led us to undertake this research.”

Researchers found that mice fed a normal diet and mice fed a high-fat diet exposed to continuous UV radiation showed increased appetite due to a decrease in levels of leptin, a hormone key in appetite regulation. However, no increase in body weight was observed. They found that UV radiation inhibited weight gain by increasing the secretion of the neurotransmitter noradrenaline, which not only reduces leptin levels but also increases energy expenditure by “browning” subcutaneous fat tissue.

Increased energy intake, caused by increased appetite, is converted into heat and burned before it can be stored in subcutaneous fat, thus preventing weight gain.

This research provides new information on the effects of UV exposure on the regulation of appetite and body weight, opening opportunities for new approaches in the prevention and treatment of obesity and metabolic disorders. In particular, discovering the mechanism by which UV radiation prevents weight gain could offer a new approach to regulating diet and weight loss, providing innovative insights into health and obesity management that could have a positive impact on human health.

Principal Investigator Jin Ho Chung, MD, PhD, Department of Dermatology, Seoul University Hospital, Seoul National University College of Medicine, explained: “This study explains the mechanism by which UV exposure can increase appetite while inhibiting weight gain. These findings contribute significantly to the understanding of the effects of UV radiation on energy metabolism and homeostasis and open new avenues for investigating strategies to prevent and treat obesity and metabolic disorders. Notably, the fact that UV radiation lowers leptin levels and increases norepinephrine levels, thereby promoting the browning of subcutaneous adipose tissue and increasing energy expenditure, provides a breakthrough clue for the development of obesity treatment strategies. This study shows that exposure to UV radiation not only affects the skin, but that the skin also plays a profound role in our body’s energy metabolism and homeostasis processes. However, further research is needed on the long-term effects and safety of UV exposure, and there should be significant interest in developing new therapeutic approaches that take advantage of the effectiveness of UV radiation. “

However, as corresponding co-author Dong Hun Lee, MD, PhD, Institute of Human-Environment Interface Biology, Seoul National University, noted: “Because UV exposure can accelerate skin aging and promote skin cancer, it is recommended to minimize UV ​​exposure and protect the skin with sunscreen. Therefore, our research team plans to conduct further research to develop new strategies that could mimic the effects of UV radiation in treating obesity and regulating metabolism.”