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APPETITE REGULATION

Hungry in the sun

Science Signaling
9 Aug 2022
Vol 15, Issue 746

Abstract

Ultraviolet exposure elicits the production of an appetite-stimulating hormone in males but not in females.
Sex differences occur in all aspects of physiology, including appetite regulation. Parikh et al. discovered a pathway in adipocytes in the hypodermis of the skin that stimulates appetite in males in response to UVB radiation and that is suppressed in females by estrogen (see also Dieguez and Nogueiras). Analysis of a nutritional survey revealed an increase in energy consumption in men in the summer but no seasonal variation in the energy consumption in women. Daily exposure to UVB radiation resulted in greater food intake and food-seeking behavior in male mice but not in female mice. Ghrelin is an appetite-stimulating hormone that is usually produced in the stomach but can be produced by other tissues. Daily UVB exposure increased the amount of ghrelin at the mRNA or protein level in hypodermal adipocytes in skin samples from male donors and in the circulation and skin of male mice, effects that were absent in their female counterparts. Increased food intake in male mice after UVB exposure was attenuated by an inhibitor of an enzyme in the ghrelin synthetic pathway or of the ghrelin receptor. UVB radiation activates the transcription factor p53, and the absence of p53 in adipocytes in male mice abrogated the UVB-induced increase in the hypodermal expression of ghrelin mRNA and in circulating ghrelin and food-seeking behavior. Estrogen reduced p53 occupancy of the ghrelin promoter, suggesting that the effects of UVB on p53-mediated transcriptional activation of ghrelin required the absence of estrogen. Accordingly, exposure to UVB radiation increased ghrelin amounts in adipose tissue in human female skin samples when treated with an estrogen-lowering drug. Likewise, UVB radiation increased food-seeking behavior and food intake in ovariectomized female mice. Solar exposure increased circulating amounts of ghrelin and feelings of hunger in male volunteers but not in female volunteers. Thus, UVB radiation stimulates food intake in males by inducing ghrelin production in adipocytes in the hypodermal layer of the skin through a p53-dependent pathway that is suppressed by estrogen.

Highlighted Articles

S. Parikh, R. Parikh, K. Michael, L. Bikovski, G. Barnabas, M. Mardamshina, R. Hemi, P. Manich, N. Goldstein, H. Malcov-Brog, T. Ben-Dov, O. Glaich, D. Liber, Y. Bornstein, K. Goltseker, R. Ben-Bezalel, M. Pavlovsky, T. Golan, L. Spitzer, H. Matz, P. Gonen, R. Percik, L. Leibou, T. Perluk, G. Ast, J. Frand, R. Brenner, T. Ziv, M. Khaled, S. Ben-Eliyahu, S. Barak, O. Karnieli-Miller, E. Levin, Y. Gepner, R. Weiss, P. Pfluger, A. Weller, C. Levy, Food-seeking behavior is triggered by skin ultraviolet exposure in males. Nat. Metab. 4, 883–900 (2022).
C.Dieguez, R.Nogueiras, Sun exposure stimulates appetite in males. Nat. Metab. 4, 796–797 (2022).

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Science Signaling
Volume 15 | Issue 746
August 2022

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Wei Wong
Science Signaling, AAAS, Washington, DC 20005, USA. Email: [email protected]

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