Expressions of retinal γ-aminobutyric acid and its receptors in retina of guinea pig eyes after lens induction

Abstract

Background Researches showed that gamma aminobutyric acid (GABA),an inhibitory amino acid neurotransmitter,plays a critical role in myopia refractive development.The inhibitory roles of GABA and its receptors antagonists have been confirmed.However,the study on whether GABA participates in the mechanisms of lens-induced myopia (LIM) in guinea pigs is rare. Objective The aim of this study was to explore the alteration of expression of GABA and its three receptor subtypes in the retinas of guinea pigs with LIM. Methods Three-week-old healthy guinea pigs were randomized into the normal control group and the model group.The right eyes of the guinea pigs in the normal control group served as the normal control eyes,and the right eyes of the guinea pigs in the model group monocularly fitted with -10 D lens as the experimental eyes,and the fellow eyes of the model group were used as the self-control eyes.The refraction and axial length of eyes were measured by A-sonography and streak retinoscopy before and 4 weeks after modeling.The guinea pigs were sacrificed at the fourth week after modeling,and the retinas were isolated.GABA content in the retinas was assayed by high performance liquid chromatography (HPLC) and the relative expression levels of subtypes of GABA receptors were detected by real-time PCR.All the results were compared among the groups.All experimental protocols and animal handling procedures were approved by the Animal Care and Use Committee of Shandong University of Traditional Chinese Medicine,and were in accordance with the statement of the Association for Research in Vision and Ophthalmology for the use of animals. Results At the fourth week after modeling,the mean diopter of the model eyes was (-3.39±0.70)D,which was significantly higher than (1.03±0.68)D of the normal control eyes and (0.77±0.64)D of the self-control eyes in the model group (t=-16.382,-17.113,both at P 0.05). Conclusions The expressions of GABA as well as the mRNA of GABAA and GABAC receptor up-regulate, but there is no obvious alteration in the expression of mRNA of GABAB receptor in the LIM eyes. Key words: Myopia/lens-induced; Gamma aminobutyric acid; Gamma aminobutyric acid receptor; Retina