31/12/2023
Natural sunlight containing Ultra Violet (UV)Radiation - so demonised , but it is critical to a vast number of metabolic processes in the body including appetite and glucose control, immune including autoimmune responses, mood disorders and more.
Time to ditch the sunglasses, sunscreen and slowly get a protective tan that allows moderate daily sun exposure.
How UV Light Touches the Brain and Endocrine System Through Skin, and Why
Andrzej T Slominski, Michal A Zmijewski, Przemyslaw M Plonka, Jerzy P Szaflarski, Ralf Paus
Endocrinology, Volume 159, Issue 5, May 2018, Pages 1992–2007, https://doi.org/10.1210/en.2017-03230
Published: 12 March 2018
Conclusions and Future Directions
Because UV energy has shaped both biological evolution and homeostatic responses, it is not surprising that UV regulates global homeostasis after absorption and transduction of its electromagnetic energy into chemical, hormonal, and neural signals in a wavelength-dependent fashion, defined by its tissue pe*******on and the nature of the chromophores UVR interacts with. This homeostatic activity includes activation of the CNS and/or endocrine glands through neural transmission or chemical messengers originating in the skin. This type of regulation, although representing relics from earlier periods of biological evolution, follows precise neuroendocrine regulatory mechanisms of which examples are represented by HPA, CRH-POMC, opioidogenic, serotonin/melatoninergic, secosteroid/steroidogenic, or NO systems.
In dermatology, phototherapy is used to treat inflammatory, pigmentary, and other skin disorders (23, 87). Phototherapy includes direct use of UVB or UVA, psoralens with UVA, or various combinations thereof. An increasing range of dermatoses and cosmetic skin conditions may also be amenable to phototherapy with VIS (232–234). Thus, with the increasing application of UVR and VIS to human skin, it becomes ever-more important to understand how exactly UV and VIS light “touch” the brain along the routes synthesized in this review, and to which extent the clinically desired outcomes of UV therapy reflect secondary phenomena that result from resetting the body homeostasis through activation of central neuroendocrine pathways.
That phototherapy also may hold promise in the treatment of selected systemic autoimmune diseases such as rheumatoid arthritis, inflammatory bowel diseases, multiple sclerosis, and scleroderma (59, 66, 68, 150, 152) all of which renders the need to better understand the UV-skin/eye-brain axis discussed here even more pressing. This is further underscored by emerging evidence that UV therapy may also be used in treatment of chemical addiction and in mood disorders due to its opioidogenic effects (1, 44, 65–67), and that UV may even be employed to regulate body metabolism, food intake, and appetite via its effects on POMC, CRH, and agouti-related protein signaling (67, 98).
Thus, we have long entered into an exciting new territory of endocrinological research that may perhaps best be termed “photo-neuroendocrinology” and is just waiting to be systematically explored and therapeutically targeted.
UV energy triggers skin-protective responses against stress, coordinated by the cutaneous-neuroendocrine system, and activates central neuroendocrine system pat