No consequence of dietary omega-3 polyunsaturated fatty acid deficiency on the severity of scopolamine-induced dry eye

Purpose Epidemiological studies suggest that dietary omega-3 polyunsaturated fatty acids (PUFAs) may protect against prevalence of dry eye. This work aimed to evaluate whether a dietary deficiency in omega-3 PUFAs may increase the severity of dry eye in a scopolamine-induced rat model. Methods Three consecutive generations of Lewis rats were bred under diets deprived of omega-3 PUFAs. Dry eye was experimentally induced by continuous scopolamine delivery in female animals from the third deficient generation and in female Lewis rats fed with a balanced diet. After 14 days of treatment, the clinical signs of ocular dryness were evaluated in vivo using fluorescein staining. MHCII and the mucin Muc5AC were immunostained on eyeball cryosections. Lipids were extracted from the exorbital lacrimal glands and phospholipid fatty acids were analyzed by gas chromatography. Results The percent of fluorescein stained area to total area of the cornea was significantly increased in scopolamine-treated animals when compared to not implanted animals. Scopolamine treatment decreased Muc5AC immunostaining and tended to increase MHCII immunostaining in the conjunctival epithelium for both diets. In exorbital lacrimal gland phospholipids, arachidonic acid (AA) and the delta5-desaturase index were significantly increased by scopolamine treatment for both diets. There was no significant diet-difference in scores of fluorescein staining, Muc5AC and MHCII immunostaining. The omega-3 PUFA deficiency induced a significant increase in AA in the exorbital lacrimal gland. Conclusion Our data suggest that, unexpectedly, an omega-3 PUFA deficiency did not increase the severity of dry eye in the rat.