Sub-erythemal ultraviolet radiation reduces metabolic dysfunction in already overweight mice.
Exposure to sunlight may limit cardiometabolic risk. In our previous studies, regular exposure to sub-erythemal (non-burning) ultraviolet radiation (UVR) reduced signs of adiposity and cardiometabolic dysfunction in mice fed a high-fat diet. Some of the observed effects were dependent on skin release of nitric oxide after UVR exposure. Here, we examine the effects of sub-erythemal UVR on signs of adiposity and metabolic dysfunction in already overweight mice, comparing the effects of two sunlamps with distinct emitted light spectra. Mice were fed a high-fat diet from 8 weeks of age, with UVR administered twice a week from 14 weeks of age until they were killed at 20 weeks of age. Mice were irradiated with the same dose of UVB radiation (1 kJ/m2) from either FS40 (65% UVB, 35% UVA) or CLEO (4% UVB, 96% UVA) sunlamps, but substantially more UVA from the latter. FS40 UVR (but not CLEO UVR) significantly reduced mouse weights and weight gain, compared to mice fed a high-fat diet (only). These effects were dependent on nitric oxide. Conversely, CLEO UVR (but not FS40 UVR) significantly reduced circulating LDL cholesterol. Both light sources reduced fasting insulin levels, and the extent of hepatic steatosis; the latter was reversed by topical application of cPTIO, suggesting an important role for skin release of nitric oxide in preventing hepatic lipid accumulation. These results suggest that there may be a number of benefits achieved by regular exposure to safe (non-burning) levels of sunlight or UV-containing phototherapy, with effects potentially dependent on the predominance of the wavelengths of UVR administered.
Telethon Kids InstituteUniversity of Western Australia, Perth, Australia.
Naomi
N
Fleury
Clinical and Experimental SciencesFaculty of Medicine, University of Southampton, Southampton General Hospital, Southampton, UK.
Martin
M
Feelisch
Telethon Kids InstituteUniversity of Western Australia, Perth, Australia.
Prue H
PH
Hart
University of EdinburghMRC Centre for Inflammation Research, Edinburgh, Scotland.
Richard B
RB
Weller
Telethon Kids InstituteUniversity of Western Australia, Perth, Australia.
Jordan
J
Smoothy
School of Medicine and Pharmacology - Royal Perth Hospital UnitThe University of Western Australia, Perth, Australia.
Vance B
VB
Matthews
Telethon Kids InstituteUniversity of Western Australia, Perth, Australia shelley.gorman@telethonkids.org.au.
Shelley
S
Gorman
D052242:Adiponectin / Q000097:blood; D050154:Adiposity / Q000528:radiation effects*; D000818:Animals; D002784:Cholesterol / Q000097:blood; D059305:Diet, High-Fat; D005234:Fatty Liver / Q000378:metabolism; D007328:Insulin / Q000097:blood; D020738:Leptin / Q000097:blood; D008297:Male; D051379:Mice; D009569:Nitric Oxide / Q000378:metabolism; D009765:Obesity / Q000378:metabolism*; D012867:Skin / Q000378:metabolism / Q000528:radiation effects; D014466:Ultraviolet Rays
D052242:Adiponectin; D007328:Insulin; D020738:Leptin; D009569:Nitric Oxide; D002784:Cholesterol
cardiometabolic dysfunction; high-fat diet; mice; nitric oxide; obesity; ultraviolet radiation