NUCLEAR FACTOR–kß IN LACRIMAL GLAND AND TEAR FILM CHANGES IN DIABETIC RATS

Abstract

Abstract: : Purpose: Previous studies from our laboratory have shown that insulin action is impaired in the lacrimal gland (LG) of diabetic rats and have identified insulin in rat tears as well as insulin receptors in ocular surface tissues. Nuclear Factor–kß (NF–kß) is an intracellular protein that participates in the control of gene transcription and has been implicated as a mediator of Diabetes Mellitus (DM) complications through the activation of pro inflammatory cytokines as IL–1ß. And TNF–µ To further understand the role of Diabetes Mellitus (DM) on the ocular surface (OS), the present study: (1) evaluated the presence of (NF–kß) in LG, cornea and conjunctiva, (2) compared the expression of NF–kß and IL–1ß in LG of diabetic and control rats, and (3) measured the volume and protein concentration in the tear film of both groups. Methods: Western Blot (WB) and imunohistochemistry with confocal microscopy were used to evaluate NF––kß expression in LG, cornea and conjunctiva of 8–week old male Wistar rats. DM was induced with streptozotocin (60mg/Kg). After 12 weeks, tear and plasma samples of diabetic and control rats (n=6 animals/group) were analyzed by spectrophotometry for protein and glucose levels, respectively. LG from both groups were compared by WB for the expression of NF–kß and IL–1ß. Results: NF–B proteins were identified in rat cornea and conjunctiva. LG NF––kß and IL–1ß expression was significantly higher in diabetic than in control rats. The tear volume was 2.96±1.19 µl in controls and 1.27±0.66 µl in diabetic rats (p<0,05) and protein concentration in tears was 3.12±0.88 µg/ml in controls and 1.84±0.24 µg/µl in diabetic rats (p=0.02). Conclusions: DM induces significant alterations in the lacrimal secretion of rats. The higher expression of NF––kß and IL–1ß proteins in LG of diabetic rats suggests that these factors may be involved in OS dysfunction of DM. This information enables the investigation of specific therapeutics for dry eye and OS alterations related to DM.

Keywords: cornea: tears/tear film/dry eye • diabetes • signal transduction