Abstract
Purpose: :
We have provided the evidence that not only excess evaporation of tear fluid but also hypofunction of the lacrimal gland contributes to the pathogenesis of VDT-associated dry eye (Plos one 2010). Calorie restriction extends life span and retards age-related chronic diseases including cancer, atherosclerosis, and dry eye. In this study we investigate the effect of intermittent fasting, reduced meal frequency, on lacrimal function in VDT associated dry eye using rat model.
Methods: :
8-week-old female Sprague-Dawley rats were used for this study. A series of treatments were performed under continuous exposure to low-humidity airflow (25 ± 5%, 2 - 4 m/s). Rats were placed on a swing made of a plastic pipe for 7.5 h/d, and for 16.5 hours, they were placed in individual cages without swing treatment. This series of treatments was repeated for up to 10 days. Rats were assigned to two groups: AL, ad libitum-fed animals, and IF, intermittent fasting rats, which were provided unlimited access to food every other day. Change in tear secretion was measured by the cotton thread test. Lacrimal gland mitochondria were isolated and ROS production and membrane potential were measured.
Results: :
A significant decrease in tear secretion was observed in the AL compared with the initial value. In the IF, slight decreases in the tear secretion were observed, although the differences were not significant compared with the initial values. Change in tear secretion was significantly suppressed in the IF compare to the AL (2.79 ± 1.02 mm/min, p < 0.001) at day 10. The ROS production from isolated mitochondria were significantly lowered in the IF compare to the AL (83.5 ±11.5 % vs. AL, p < 0.01). The mitochondrial membrane potential loss was significantly suppressed in the IF compare to the AL (89.4 ± 2.4 % vs. AL).
Conclusions: :
Our findings suggest that mitochondrial functions play an important role of tear secretion which can be improved by IF in VDT associated dry eye.
Keywords: lacrimal gland • cornea: tears/tear film/dry eye • mitochondria