gamma-linolenic-acid and Dry-Eye-Syndromes

The etiology of diet-related disorders is closely associated with dietary factors. A special role is attributed to intake of fat and fatty acid profile, both quantitative and qualitative. For prevention and treatment of the abovementioned diseases a proper supply of unsaturated fatty acids plays a significant role, because of their particular importance to health. γ-Linolenic acid (GLA), with three double bonds in the carbon chain, also known as all-cis 6,9,12-octadecatrienoic acid, belongs to the n-6 family of fatty acids. It plays biologically important functions in the human body, such as being a substrate for eicosanoids synthesis, involvement in the transport and oxidation of cholesterol, and being one of the components of lipid membrane. Its inadequate dietary intake or impaired formation is the cause of many inflammatory and degenerative diseases. A rich source of this fatty acid is vegetable oils, until recently used mainly in folk medicine. Nowadays, studies conducted both in animal models and in humans suggest its health-promoting properties in the prevention and treatment of atopic dermatitis, cardiovascular diseases, diabetes, cancers and rheumatoid arthritis.

Topics: Animals; Antineoplastic Agents; Arthritis, Rheumatoid; Cardiovascular Diseases; Dermatitis, Atopic; Dry Eye Syndromes; gamma-Linolenic Acid; Humans; Metabolic Diseases; Neoplasms

This study was conducted to evaluate the efficacy of dietary n-6 and n-3 polyunsaturated fatty acids (PUFAs) in dry eye in a rat model.. Female Lewis rats were fed with diets containing (1) gamma-linolenic acid (GLA), (2) eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA), or (3) GLA + EPA + DHA, for 2 months before the induction of dry eye using a continuous delivery of scopolamine and during scopolamine treatment. Two, 10 and 28 days after dry-eye induction, clinical signs of corneal dryness were evaluated in vivo using fluorescein staining. MHC II expression and mucin rMuc5AC production in the conjunctival epithelium were evaluated by immunostaining. Lipids and prostaglandins (PGs) E(1) and E(2) were analysed from the exorbital lacrimal gland (LG).. Dietary PUFAs minimised the occurrence of corneal keratitis 28 days after induction of dry eye. The decrease in mucin production observed on the conjunctival epithelium was partially prevented by EPA + DHA supplementation after 2 days of scopolamine treatment, as well as by GLA and GLA + EPA + DHA diets after 10 days of treatment. The overexpression of MHC II in the conjunctival epithelium caused by dry eye induction was significantly reduced only with the GLA + EPA + DHA diet after 28 days of treatment. Dietary PUFAs were incorporated into phospholipids of the exorbital LG. Induction of dry eye was associated with a significant increase in PGE(1) and PGE(2) levels in the exorbital LG, which was inhibited by dietary EPA + DHA at 10 days (for PGE(2)) and 28 days (for PGE(1)).. Dietary GLA, EPA and DHA significantly interfered with lipid homeostasis in the exorbital LG and partially prevented the course of dry eye. In particular, our results demonstrate the efficacy of the combination of n-6 and n-3 PUFAs.

Topics: Animals; Conjunctiva; Dietary Fats, Unsaturated; Dietary Supplements; Disease Models, Animal; Docosahexaenoic Acids; Dry Eye Syndromes; Eicosapentaenoic Acid; Epithelium; Fatty Acids, Unsaturated; Female; gamma-Linolenic Acid; Histocompatibility Antigens Class II; Immunoenzyme Techniques; Lacrimal Apparatus; Lipid Metabolism; Mucin 5AC; Rats; Rats, Inbred Lew; Scopolamine; Treatment Outcome