Original article Development and evaluation of animal models for sex steroid deficient dry eye Smrita Singh a , Laxmi Moksha a , Namrata Sharma b , Jeevan Singh Titiyal b , Nirhar Ranjan Biswas c , Thirumurthy Velpandian a, ⁎ a Department of Ocular Pharmacology and Pharmacy, Dr. R. P. Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110029, India b Department of Cornea and Refractory Surgery, Dr. R. P. Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110029, India c Department of Pharmacology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110029, India abstract article info Article history: Received 6 January 2014 Accepted 4 March 2014 Available online 13 March 2014 Keywords: Androgen deficiency dry eye Postmenopausal dry eye Sex steroids Experimental models Purpose: The present study was conducted to develop animal models to mimic postmenopausal/androgen deficiency dry eye and to evaluate the expression of sex steroid receptors (NR3A1, NR3A2 and NR3C4) in the ocular tissues of the developed models. Methods: The study was conducted in healthy Wistar rats of either sex weighing 180–250 g. Bilateral ovariectomy was performed in female rats and oral finasteride (dose of 1.16 mg/kg/day) challenge was given to both male and female rats. Along with time tear film stability was assessed by using cotton thread method and tear breakup time (TBUT). Dew point calculation was done using August–Roche–Magnus approximation during the tear assessments to correlate environmental factors affecting the tear function tests. At the end, animals were sacrificed and ocular tissues (lacrimal gland and cornea) were subjected for the quantification of the expression of NR3A1 (ER-α), NR3A2 (ER-β) and androgen (NR3C4) receptors. Results: The impact of ovariectomy caused a significant tear film deficiency from the 20th day onwards in all female rats. The ten day finasteride administration also showed a significant tear film deficiency in both male and female rats. However, subjecting 60 days post ovariectomy rats to finasteride challenge did not show any further decrease in tear flow. Gene expression analysis also revealed a significant downregulation of sex steroid receptors in ocular tissues after ovariectomy and finasteride challenge. Discussion and conclusion: From this study, it has been concluded that ovariectomized and finasteride treated antiandrogenic models pro- duced a significant tear deficiency in the rats which can be explored for pharmacological screening of topical agents and understanding the disease process in postmenopausal and androgen deficiency dry eye disorders. © 2014 Elsevier Inc. All rights reserved. 1. Introduction Dry eye syndrome (DES) is an ocular surface disorder with multiple etiologies. Decrease in tear aqueous production, abnormality of the tear lipid, protein and mucin profiles are the important factors contributing towards the loss of tear film integrity thereby causing DES. Despite the significant incidence, appropriate drug treatment for DES in postmeno- pausal women or in aging men is largely ignored. The epidemiological studies such as large women's health study and physician's health study indicate that the prevalence of symptomatic dry eye is about 7% in women and 4% in men in the US amongst those N 50 years of age (Schaumberg, Sullivan, Buring, & Dana, 2003). Presence of sex steroid receptors in various structures of the eye has been reported (Gupta, Johar, Nagpal, & Vasavada, 2005). It has also been correlated that lacrimal gland insufficiency affects postmenopausal women more frequently than men due to decreased production of sex hormones (Serrander & Peek, 1993) that play a major role in the regulation of the lacrimal gland secretary functions. If untreated, postmenopausal DES affects the quality of life in the later stage and rationalized therapeutic options are lacking as of now. For the development of successful therapeutic intervention, an appropriate animal model for this condition was felt as important. Therefore, the present study was conducted to develop rat models of sex steroid deficient dry eye and quantification of their receptor expression in the lacrimal gland and cornea. 2. Material & methods Healthy Wistar female and male rats of seven months old weighing 180–250 g were included in the experiment. The protocol of the study was approved by the standing Institute Animal Ethics Committee. The animals were used in accordance with the institute's guidelines and Journal of Pharmacological and Toxicological Methods 70 (2014) 29–34 Abbreviations: TBUT, tear breakup time; DES, dry eye syndrome; OVX, ovariectomized female rats; FINF, finasteride treated female rats; OVX + FIN, ovariectomized rats treated with finasteride; FINM, male rats treated with finasteride. ⁎ Corresponding author. Tel.: +91 11 26593162; fax: +91 11 26588919. E-mail address: tvelpandian@hotmail.com (T. Velpandian). http://dx.doi.org/10.1016/j.vascn.2014.03.004 1056-8719/© 2014 Elsevier Inc. All rights reserved. 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