Ageing involves lots of changes throughout the body, but few organs broadcast the process quite as publicly as the skin.

Along with signs of intrinsic, chronological ageing, like fine wrinkles and thinning, skin also displays effects of 'extrinsic ageing ' bestowed by our environment, such as coarse wrinkles and sun spots. These can be caused by exposure to ultraviolet radiation, air pollution, or other external hazards.

Skin ageing is commonly framed as a cosmetic issue, but it can have health implications, too. As skin loses thickness and elasticity, for example, the risk of injury and infection may become more serious.

According to a new study, a variety of hormones might be able to help defend our skin from the ravages of time. Certain hormones show significant therapeutic potential for treating and preventing the outward effects of ageing, researchers report, including wrinkled skin and graying hair.

Some hormones are already used clinically to temper the effects of skin ageing, the authors note, but only a few so far, mainly estrogens and topical retinoids like retinol and tretinoin.

And given the overall importance of hormones for healthy skin – plus the importance of skin in producing and secreting hormones – scientists would likely benefit from a better understanding of dynamics between the two.

For their new review article, the researchers examined studies on a wide range of hormones and related chemicals in the body, looking for potential influences on skin ageing.

"Skin is not only a target for various hormones that control pathways of skin ageing, but itself is certainly the largest and richest site for hormone production besides classical endocrine glands," says lead author Markus Böhm, a professor of dermatology at the University of Münster in Germany.

Skin is increasingly recognized as a vital endocrine organ, due to its synthesis and secretion of hormones as well as other signaling molecules. That includes not just all layers of skin, but also all the hair follicles growing out of it, each of which is essentially "a fully functional neuroendocrine 'miniorgan,' the researchers write.

In hopes of shedding more light on the relationship between hormones and skin ageing, Böhm and his colleagues reviewed previous research on key hormones, including insulin-like growth factor 1, growth hormone, estrogens, retinoids, and melatonin.

Some of the hormones in the review showed dramatic effects on skin and hair ageing, suggesting they might wield powers we could harness for clinical purposes.

"Our paper highlights key hormone players that orchestrate pathways of skin ageing such as degradation of connective tissue (leading to wrinkling), stem cell survival, and loss of pigment (leading to hair graying)," Böhm says.

"Some of the hormones we studied have anti-ageing properties and may be used in the future as agents to prevent skin ageing."

Melatonin is one intriguing candidate, the researchers write, noting it's a small molecule, cheap, and generally well-tolerated. It acts as both a direct and indirect antioxidant, they add, and helps regulate mitochondrial metabolism.

It also suppresses DNA damage while providing anti-inflammatory effects and inhibiting apoptosis, a type of programmed cell death.

The review covered other hormones and endocrine actors, too, including alpha-melanocyte-stimulating hormone (α-MSH), oxytocin, endocannabinoids, and peroxisome proliferator-activated receptor modulators (PPARs).

Many of these also seem able to prevent or repair damage from skin ageing, the study found. For example, α-MSH offers valuable cytoprotective and antioxidant effects, and it reduces UV-induced DNA damage that has been linked with sun spots and pigment production in skin and hair.

"Further research into these hormones may offer opportunities to develop new therapeutics for treating and preventing skin ageing," Böhm says.