Distinct Inflammatory and Oxidative Effects of Diabetes Mellitus and Hypothyroidism in the Lacrimal Functional Unit

Diabetes mellitus (DM) and hypothyroidism (HT) are prevalent diseases associated with dry eye (DE). Their impact on the lacrimal functional unit (LFU) is poorly known. This work evaluates the changes in the LFU in DM and HT. Adult male rats had the disease induced as follows: (a) DM: streptozotocin and (b) HT: methimazole. The tear film (TF) and blood osmolarity were measured. Cytokine mRNA was compared in the lacrimal gland (LG), trigeminal ganglion (TG), and cornea (CO). Oxidative enzymes were evaluated in the LG. The DM group showed lower tear secretion ( = 0.02) and higher blood osmolarity ( < 0.001). The DM group presented lower mRNA expression of in the cornea ( = 0.03), higher mRNA expression ( = 0.03), and higher catalase activity in the LG ( < 0.001). The DM group presented higher mRNA expression in the TG ( = 0.02). The HT group showed higher TF osmolarity ( < 0.001), lower expression of mRNA in the CO ( < 0.001), higher catalase activity in the LG ( = 0.002), and higher expression of mRNA in the TG ( = 0.004). The findings revealed that DM and HT induce distinct compromises to the LG and the entire LFU.