Essential fatty acid deficient hairless mouse: a model of chronic epidermal hyperproliferation.

Epidermal DNA synthesis has been shown to be increased approximately three-fold in hairless mice that were fed a diet deficient in essential fatty acids (EFA deficient) for 65 days, compared with animals fed a standard diet. Autoradiographic labelling indices showed a 330% increase in the EFA deficient mice over controls. The animals developed evidence of a diffuse thickening, scalping and loss of elasticity of the skin after 40 days on the EFA deficient diet. Histologically, the epiderma of the EFA deficient animals showed acanthosis, hypergranulosis, hyperkeratosis and increased intracellular epidermal spaces. Increased mitotic indices were found with Feulgen staining. This is further evidence that deficiencies of essential fatty acids are associated with disturbance of normal epidermal cell proliferation and control of keratinization. A single application of topical 0.1% betamethasone valerate to EFA deficient mice reduced the epidermal DNA synthesis to that of normal diet mice. Ten percent linoleic acid topically over 2 weeks also returned epidermal DNA synthesis to normal levels.