Purpose: To establish and characterize a dry eye model in New Zealand rabbits by subcutaneous injections of scopolamine hydrobromide (SCOP).
Methods: Twenty New Zealand male rabbits were injected subcutaneously SCOP for 14 consecutive days; subcutaneous saline was used as a negative control. The correlated clinical parameters of ocular surface dryness were detected in vivo using tear secretion and corneal fluorescein staining. The expression of IL-1β and TNF-α on the ocular surface and in lacrimal glands were analyzed by real-time PCR and western blot on the 14th day. The expression of Mucin-5 subtype AC (MUC5AC) was detected by Immunofluorescence staining in conjunctival tissue.
Results: The SCOP-treated rabbits exhibited significantly decreased aqueous tear secretion and increased corneal fluorescein staining scores over time. Both the mRNA expression levels and the protein expression levels of IL-1β and TNF-α were significantly increased after SCOP treatment compared with those after saline treatment. The loss of conjunctival MUC5AC was found in the SCOP-injected rabbits. Some infiltrated inflammatory cells and atrophic acinar cells were observed in the lacrimal gland after SCOP treatment. The disordered structures of the ocular surface and lacrimal glands were also observed.
Conclusions: This study showed that repeated subcutaneous SCOP injections successfully elicited some of the typical dry eye symptoms commonly seen in humans.
Keywords: Dry eye; IL-1β; MUC5AC; TNF-α; scopolamine.