Abstract
Purpose: :
The study was to use simplified methods to evaluate a dry eye murine model induced by rimabotulinum toxin B (BTX-B) for testing the efficacy of potential anti-dry eye compounds for novel dry eye treatments.
Methods: :
Thirty-six (36) CBA/J mice were used in the study divided equally into blank, saline, and BTX-B groups. Twelve (12) animals were injected with saline or with BTX-B into both lacrimal glands on Day 0. The half animals per group were sacrificed at the time-point of two weeks or four weeks after the lacrimal gland injections. During the study, all animals were measured for tear production (TP); corneal front membrane fluorescein break-up time (FBUT); and corneal fluorescein staining (CFS) at pre-study, twice/week and at pre-sacrifice. TP was measured with standardized phenol red-impregnated cotton threads (mm). FBUT was recorded (Sec.) and CFS was scored (grading 0-4) under a Slit-Lamp with blue cobalt light. Histopathological analysis was evaluated after staining with hematoxylin and eosin (H & E). All animals were clinically observed daily and were weighed at pre-study and at pre-sacrifice.
Results: :
The average TP of animals in the BTX-B group was 1.7 mm ± 0.3 mm (two weeks) and 1.4 ± 0.4 mm (four weeks), displayed a statistically significant time-dependent decrease compared to animals in the blank group with 3.1± 0.6 mm (two weeks) and 3.7 ± 0.8 mm (four weeks) and in the saline group with 3.4 ± 0.8 mm (two weeks) and 3.6 ± 0.7 mm (four weeks) (p < 0.05). The average FBUT of animals in the BTX-B group was 6.0 ± 0.9 Sec. (two weeks) and 4.2 ± 0.7 Sec. (four weeks), displayed a statistically significant time-dependent decrease compared to animals in the blank group with 9.4 ± 1.0 Sec. (two weeks) and 10.0 ± 1.1 Sec. (four weeks) and in the saline group with 9.8 ± 1.1 Sec. (two weeks) and 9.5 ± 1.4 Sec. (four weeks) (p < 0.05). The average CFS of animals in the BTX-B group was 2.3 ± 0.9 Grading (two weeks) and 3.3 ± 0.5 Grading (four weeks), displayed a statistically significant time-dependent increase compared to animals in the blank or the saline group with 0.2 ± 0.4 Grading (two or four weeks) (p < 0.05). Histopathological analysis revealed no remarkable differences in any groups at either the time-point of two or four weeks. However, a small acinus focal area was found in the right lacrimal gland of one animal in the BTX-B group at the time-point of four weeks.
Conclusions: :
Based simply on ocular examinations by TP, FBUT, CFS, and histopathology to evaluate the dry eye mouse model induced by BTX-B through injections of lacrimal glands, the data accurately revealed that BTX-B decreased TP and FBUT, but increased CFS. Therefore, a valid dry eye mouse model has been successfully created for testing and developing the efficacy of potential anti-dry eye compounds.
Keywords: cornea: tears/tear film/dry eye • drug toxicity/drug effects • lacrimal gland