Skin ?-endorphin mediates addiction to ultraviolet light #MMPMID24949966
Fell GL; Robinson KC; Mao J; Woolf CJ; Fisher DE
Cell 2014[Jun]; 157 (7): 1527-34 PMID24949966show ga
Ultraviolet light is an established carcinogen yet evidence suggests that UV-seeking behavior has addictive features. Following UV exposure, epidermal keratinocytes synthesize Proopiomelanocortin that is processed to Melanocyte Stimulating Hormone, inducing tanning. We show that in rodents another POMC-derived peptide, ?-endorphin, is coordinately synthesized in skin, elevating plasma levels after low-dose UV. Increases in pain-related thresholds are observed, and reversed by pharmacologic opioid antagonism. Opioid blockade also elicits withdrawal signs after chronic UV exposure. This effect was sufficient to guide operant behavioral choices to avoidance of opioid withdrawal (conditioned place aversion). These UV-induced nociceptive and behavioral effects were absent in ?-endorphin knockout mice and in mice lacking p53-mediated POMC induction in epidermal keratinocytes. While primordial UV addiction, mediated by the hedonic action of ?-endorphin and anhedonic effects of withdrawal, may theoretically have enhanced evolutionary vitamin D biosynthesis, it now may contribute to the relentless rise in skin cancer incidence in man.
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Cell 2014 ; 157 (7): 1527-34
