Retinoid effects on photodamaged skin.

The effects of retinoid treatment on wrinkling in the hairless mouse can be understood in the context of the repair of the dermal elastosis. The two isomers of retinoic acid do not differ qualitatively in their effects on the histological appearance of the tissue or on the wrinkling patterns produced. The all-trans isomer is slightly more potent in this system than the 13-cis isomer but substantially more irritating, which may limit the maximum degree of repair attainable. The "reconstructed" dermis is thickened, it contains new collagen as a result of the stimulation of gene expression, and the tangled, disorganized elastin is packed into a thin layer in the lower dermis. Thus, the framework within which a wrinkle had been established is eliminated, and the skin assumes a normal state, as observed. That the effacement is apparently permanent is additional evidence of the relationship between the integrity of the elastic fiber network and the surface appearance. The only difference in the repaired skin is the absence of filamentous surface features. The thickening effect of UVB and subsequent retinoid treatment on the epidermis does not contribute substantially to the overall thickness of the repaired skin. Nevertheless, despite having a minor role in the effacement of deep wrinkles, these epidermal changes evidently preclude the formation of fine surface features. The model is a valid one for the repair of photodamaged skin. From what is known about the role of elastin in maintaining skin integrity and from the association of wrinkling with excessive sun exposure, it is encouraging to observe the dual effect of retinoic acids.(ABSTRACT TRUNCATED AT 250 WORDS)