Alterations of Glutamate and γ-Aminobutyric Acid Expressions in Normal and Myopic Eye Development in Guinea Pigs

Abstract

Purpose: The retina has an important role in the signal transmission related to eye development and myopia. Glutamate (Glu) and γ-aminobutyric acid (GABA) are the major excitatory and inhibitory neurotransmitters in the retina, which can affect the development of both the eye and myopia. Nevertheless, change in the balance between the excitatory and inhibitory neurotransmitters still is unclear during development of eyes and myopia. The purpose of this study was to explore the alterations of the ratio of Glu to GABA (RGG), which mediates the balance between the excitatory and inhibitory neurotransmitters in retina in the development of the eyes and lens-induced myopia (LIM) in a guinea pig model.

Method: An LIM guinea pig model was established using a -10 diopter (D) negative lens. The levels of Glu, GABA, and the dynamic change of RGG were measured in the retina in normal and myopia guinea pigs at four time points (i.e., 0, 2, 4, and 6 weeks after onset of LIM). Considering that Glu and GABA are related closely to the occurrence of myopia, we further studied the changes of RGG in the retina in LIM guinea pigs.

Result: Our results showed that the RGG was upregulated and was well correlated with diopter and axial length than either Glu or GABA during the development of normal eyes. Besides, we observed that the content of the RGG in the retina in myopia eyes was higher than that of Glu and GABA in normal subjects and was an obviously positive correlation.

Conclusions: Taken together, our findings suggest that the RGG has a pivotal role in eye development and myopia. The abnormal retina signal induced by the unbalanced ratio between Glu and GABA is related closely to the occurrence of myopia.