Absorption et distribution de l'acide ?-linolenique14C administre par voie percutanee chez le rat et l'homme

Publisher Website
Google Scholar
Abstract
Deficiency of .gamma.-linolenic acid (.gamma.-LA), an essential fatty acid (EFA) in animals, provokes cutaneous disorders such as scaly lesions of the skin, acanthosis, loss of elasticity of the skin and irregularities in cutaneous barrier function. These disorders disappear with restitution of EFA. Although the deficiency does not exist in man, EFA could be of interest in cosmetology and dermatology, particularly in the treatment of dryness of the skin and some other cutaneous disorders observed in skin aging. The efficiency of this treatment depends on an adequate cutaneous absorption of the acids. Experiments were performed with 4% 14C-.gamma.-LA incorporated in an oil/water emulsion and applied to the skin. Detection of .gamma.-LA was only in the superficial epidermal structures and in the sebaceous glands, as shown by autoradiography obtained with hairless rat skin sections. On human skin in vitro, by using the stripping technique, very slow diffusion into cutaneous structures was observed during the first 2 h. Of skin radioactivity, 18% was found in Malpighian layers after 8 h. Permeability constants Kp were measured in vitro with diffusion cells. In hairless rats 18 mo. old, Kp was 4.6 .times. 10-6 cm/h. This value was 31 .times. 10-6 cm/h in rats of the same age deficient in EFA. With human skin, the permeability constant after 24 h was in the same range as that in normal rats (4.67 .times. 10-6 cm/h). During this time, 0.5% of .gamma.-LA was absorbed. In anesthetized hairless 18 mo. old rats, the radioactivity in plasma, liver, kidney, muscular and fatty tissues remained negligible up to 8 h after cutaneous administration of .gamma.-LA. Radioactivity was high under the area of application and increased with time in subcutaneous conjunctive tissue (9 .mu.g/g after 8 h) and muscular tissue. These results show the potential importance of the use of .gamma.-LA in dermatology and cosmetology.