Kligman L H, Mezick J A, Capetola R J, Thorne E G
Department of Dermatology, University of Pennsylvania School of Medicine, Philadelphia 19104.
Acta Derm Venereol. 1992 Nov;72(6):418-22.
The discovery that topical tretinoin can reverse some of the effects of photodamage may lead to its chronic application. Examination of long-term effects was of interest. Three groups of hairless mice (age 6-8 weeks) were treated dorsally with 1) tretinoin (0.025%), 2) cream vehicle, 3) sham treatment. Applications were 3 times weekly and continued for up to 2 years until all mice were sacrificed or had died. Biweekly examinations showed no sign of retinoid toxicity, with growth and longevity similar in all groups. Tretinoin-treated skin was smooth and pink, resembling that of younger mice. Controls had yellowed, irregularly thickened skin. Histologically, tretinoin-treated skin had a hyperplastic epidermis consisting of plump, cytologically normal cells. Control skin had 3-4 compressed cell layers. Foci of new normally staining collagen were present in the subepidermal dermis of tretinoin-treated skin; fibroblasts were large and abundant in these areas. These foci were absent in controls. Mice treated with tretinoin also appeared to have increased amounts of elastic fibers and glycosaminoglycans.
外用维甲酸可逆转部分光损伤效应这一发现可能会促使其长期应用。对长期效应的研究很有意义。将三组6 - 8周龄的无毛小鼠背部进行如下处理：1）维甲酸（0.025%），2）乳膏基质，3）假处理。每周涂抹3次，持续长达2年，直至所有小鼠被处死或死亡。每两周检查一次，未发现类维生素A毒性迹象，所有组的生长和寿命相似。维甲酸处理的皮肤光滑且呈粉红色，类似于年轻小鼠的皮肤。对照组的皮肤发黄且不规则增厚。组织学上，维甲酸处理的皮肤有增生的表皮，由饱满、细胞学上正常的细胞组成。对照皮肤有3 - 4层压缩细胞层。在维甲酸处理皮肤的表皮下真皮中有新的正常染色的胶原灶；这些区域的成纤维细胞大且丰富。对照组中没有这些病灶。用维甲酸处理的小鼠似乎弹性纤维和糖胺聚糖的含量也有所增加。
