Nat Metab: Does the sun make men eat more? The skin also regulates appetite

Introduction: On April 13, 2011, the World Health Organization classified all classes of ultraviolet (UV) radiation as Class 1 carcinogens
.

On July 11, 2022, a study published in Nature Metabolism titled "Food-seeking behavior is triggered by skin ultraviolet exposure in males" noted that UVB irradiation will lead to p53 transcriptional activation in skin fat cells, increased mRNA levels of ghrelin, and increased concentrations of ghrelin in plasma.

Figure 1 Results of the study (Source: [1])

There are many hormones involved in appetite regulation, such as insulin, leptin and other peripheral hormones can suppress appetite, but ghrelin is currently the only peripheral peptide
known to stimulate appetite.

Sun exposure enhances male energy intake and metabolism

By analyzing data from a 3-year national nutrition survey of about 3,000 people, the researchers found that men's energy intake and metabolism were significantly associated
with solar radiation and its seasonal fluctuations.

Fig.

UVB exposure enhances foraging behavior in males

The researchers treated mice with UVB exposure for 10 weeks and observed food intake and behavioral activity during periods, and found that male mice experienced significant increases in food intake and eating behavior when exposed to UVB, but the maximum VO2 uptake and fat content in the stool showed that basal metabolic rate was not regulated
.

UVB exposure induces the production and secretion of ghrelin in skin fat cells

UVB exposure activates p53 and its downstream to produce adrenocorticotropic hormone (ACTH), melanin-stimulating hormone (α-melanocyte-stimulating hormone, α-MSH), and β-endorphins
.

Fig.

P53 mediates the expression of ghrelin in UVB-induced adipocytes

The researchers found that ghrelin-induced peaked 8 h after UVB exposure, suggesting the presence of
transcriptional regulation.

Figure 4 Deletion of p53 in skin fat cells eliminates UVB-induced appetite enhancement (Source: [1])

Estrogen blocks the p53 transcriptional activation of ghrelin under UVB exposure

The researchers found testosterone and estrogen as potential regulators of UVB effects and stimulated cells
with dihydrotestosterone (DHT) or 17β-estradiol (17β-estradiol, β-E2).

P53 is a well-known tumor suppressor gene, plays an important role in the DNA damage response, also known as the guardian of the genome, this study found that p53 is also a key mediator of food intake, all external factors that can affect p53 activity, may be through p53 to regulate appetite, and UVB exposure so caused by p53 mediated effect also depends on the amount
of exposed skin.

Original Source:

Parikh， S.