Use of linseed oil to treat experimentally induced keratoconjunctivitis sicca in rabbits

There were significant improvements in the parameters analyzed (STT, FT, and RBT) and in the histopathological finding in all of the groups using LO.The analyzed results demonstrate that LO, administered orally or topically, was effective in treating experimentally induced KCS in rabbits, although combined oral and topical LO did not show additional benefits greater than those with a single route of administration.Keratoconjunctivitis sicca (KCS), or dry eye syndrome, is characterized by chronic inflammation of the cornea, conjunctiva, and lacrimal glands caused by quantitative and/or qualitative tear changes [1]. Recently, several studies have proven that essential fatty acids (EFAs), omega-3 (ω-3) and omega-6 (ω-6), administered orally are an alternative therapy for patients with various types of tear deficiency, including Sj？gren's syndrome and KCS [2-6]. Additionally, the topical use of ω-3 and ω-6 effectively controlled the signs of experimentally induced inflammation in rats with KCS [7].Eicosanoids are biologically active substances that regulate physiological processes and are lipid mediators of inflammation. From the ω-6 EFA-derived prostanoids, arachidonic acid, via cyclooxygenase 1 (COX1) pro-inflammatory mediators, is synthesized, including prostaglandin (PGE2), thromboxane (TXA2), prostacyclin (PGI2), and the leukotrienes (LTA4, LTB4, LTC4, and LTD4). However, non-inflammatory mediators (PGE1 and TXA1) are also synthesized from the EFA series of ω-6 by the action of COX1 on dihomo-γ-linoleic acid (DGLA) and from the EFA series of ω-3 by the action of COX1 on eicosapentaenoic acid (PGE3, PGI3, and TXA3) as well as by the actions of lipoxygenase (LTA5, LTB5, LTC5, and LTD5) and of docosahexaenoic acid [2,4].The ω-3 and ω-6 EFAs are found in many foods, such as nuts, cold-water fish, soybeans, rapeseed oil, and linseed oil. Linseed, Linum usitatissimum, is composed of 57% ω-3, 16% ω-6, 28% monounsaturated fatty acids, and only 9% unsaturated fatty acids, a