Objective

2

To explore the potential mechanism of moxibustion at Guanyuan （CV 4） in delaying skin photoaging.

Methods

2

Thirty-two male Wistar rats were randomly

divided into four groups， namely blank group， model group， vitamin E group， and moxibustion group， with 8 rats in each group. Except for the blank group， dorsal skin of rats were exposed to ultraviolet （UV） radiation to establish a skin photoaging model. One week after modeling， the moxibustion group received moxibustion at "Guanyuan （CV 4）" once a day， five days per week； the vitamin E group received vitamin E （25 mg/kg·d） once a day by gavage， five days per week； the blank group， model group， and moxibustion group received an equivalent volume of normal saline via gavage； the intervention lasted for 7 weeks. After 7 weeks， dorsal skin tissues were collected to analyze the following indicators， such as skin tissue moisture content， histomorphological changes using hematoxylin-eosin （HE） staining， Collagen Ⅰ and collagen Ⅲ content using ELISA. Malondialdehyde （MDA）， glutathione peroxidase （GSH-Px）， superoxide dismutase （SOD）， hydrogen peroxide （H

2

O

2

）， and catalase （CAT） activity in skin tissue were dectected. Western Blot was used to determin autophagy-related proteins， including microtubule-associated protein 1A/1B-light chain 3 （LC3）， polyubiquitin-binding protein （p62）， and autophagy-specific gene （Beclin-1）；

LC3

，

p62

， and

Beclin

-

1

mRNA expression was detected via qRT-PCR， and autophagosome formation was observed using transmission electron microscopy （TEM）.

Results

2

HE staining showed that the epidermal structure in the blank group was orderly and evenly thick， while the model group exhibited uneven epidermal thickness. In the moxibustion group， the epidermis was well-structured， smooth， and uniform， with densely arranged dermal layers； the epidermis in the vitamin E group was thicker than that in the model group. Compared with the blank group， the model group exhibited decreased skin moisture content and reduced level of Collagen Ⅰ and collagen Ⅲ， reduced SOD， CAT， and GSH-Px activity in sk

in tissue， increased H

2

O

2

and MDA activity， elevated p62 protein and mRNA expression， reduced LC3 and Beclin-1 protein and mRNA expression （

P

＜0.05 or

P

＜0.01）. Compared with the model group， the moxibustion group showed significant improvement in all these indicators （

P

＜0.05 or

P

＜0.01）； whereas the vitamin E group did not show a statistically significant difference in Collagen Ⅰ and collagen Ⅲ levels （

P

＞0.05）. TEM results showed that， compared with the blank group， the model group had atrophic skin cells， extensive mitochondrial vacuolization， and degraded cellular structures； the moxibustion group exhibited crescent- or cup-shaped autophagosomes with a significantly increased number of autophagosomes per unit area， whereas the vitamin E group showed less improvement than the moxibustion group.

Conclusion

2

Moxibustion at "Guanyuan （CV 4）" may alleviate skin photoaging by regulating oxidative stress imba-lance， modulating cellular autophagy， and promoting collagen synthesis， thereby slowing the aging process of the skin.