Abstract
Purpose :
A number of people live in a high-stress environment and it has become a serious problem in modern society. Dry eye disease (DED) is a highly prevalent disease and its incidence is rapidly increasing. We investigated whether tear secretion is associated with stress by environmental factors or not, in mice experiments.
Methods :
Male C57BL/6JJcl mice were exposed to environment enrichment (EE, n=30) and compared to mice living in a standard environment (SE, n=28) for 4 weeks. EE is defined as a living environment with a combination of complex inanimate and social stimulation. It has been reported that brain derived neurotrophic factor (BDNF) gene expression in the hippocampus increases by EE. After 4 weeks, mice were restrained once as an acute stress test for 4 hours. Tear secretion was measured once a week, and pre- and post-acute stress test.. Next we used BDNF STOPtetO mice which were suppressed of BDNF gene expression. We divided wild type mice, hetero mice and homo mice into two groups, SE and EE respectively, and compared tear secretion among all groups.
Results :
Tear secretion in the EE group was significantly higher (2.5±1.0 mm, 3.0±1.6mm, 4.2±1.3mm) than in the SE group (1.7±0.7 mm, 2.2±0.9mm, 2.8±1.2mm, P<0.01, P<0.05, P<0.01, respectively) at week 1, week 2 and week 3 in C57BL/6JJcl mice. After the acute stress test, tear secretion decreased only in the SE group (pre-: 3.8±1.9mm, post-: 2.3±1.7mm, P=0.06). Tear secretion in the EE group didn’t change after the acute stress. Tear secretion significantly decreased in BDNF STOPtetO hetero mice (1.9±1.0mm, P<0.05) and homo mice (0.5±0.5mm, P<0.01) compared to wild type mice (2.4±0.9mm). Tear secretion increased only in the EE group (4.0±1.6mm, P<0.01) compared to the SE group (2.4±1.1mm) in wild type mice at week 2. Tear secretion in hetero mice and homo mice didn’t change under EE compared to under SE.
Conclusions :
The results of this study suggest that environmental factors are related to tear secretion. Moreover, these results suggest an association between tear secretion and BDNF gene expression.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.