Changes in muscarinic acetylcholine receptor expression in formdeprivation myopia in guinea pigs

摘要

Purpose: Muscarinic receptor signaling is involved in oculardevelopment and implicated in myopia. The aims of this study were toidentify the presence of muscarinic acetylcholine receptors (mAChRs) innormal ocular tissues of guinea pigs and to determine if ocularexpression of mRNA and protein changes in guinea pigs with or withoutform-deprived myopia (FDM).Methods: One- to two-week-old guinea pigs were monocularly treatedwith a translucent lens. Twenty-one days after the induction of FDM, wecollected the retina, choroid, sclera, and iris-ciliary body. We used asemiquantitative reverse-transcription polymerase chain reaction(RT-PCR) to detect changes in mRNA expression for mAChRs. Westernblotting analysis was used to investigate changes in protein expressionfor mAChRs. Levels of mAChRs as well as mRNA and protein expression werestatistically compared among FDM, internal, and normal eyes.Results: We observed expression of mRNA for muscarinic subtypes M1to M5 in the retina, choroid, sclera, and iris-ciliary body. Proteinsfor the M1 to M5 subtypes were present in normal ocular tissues. Theirmolecular weights ranged from 80 kDa for M5 to 52 kDa for M1 as noted onWestern blotting. Twenty-one days after the induction of myopia, weobserved statistically significant increases in mRNA expression forsubtypes M1 (+18.67%) and M4 (+26.48%) as well as in protein expressionfor M1 (+24.65%) and M4 (+49.11%) in the posterior sclera ofFDM-affected eyes (p0.05 vs. internal control and normal eyes).Conclusions: The ocular tissues of guinea pigs express muscarinicsubtypes M1 to M5. In the posterior sclera, expression of the M1 and M4subtypes significantly increased in FDM eyes. This finding indicatesthat muscarinic antagonists may have the potential to act directly onthe sclera as a strategy to prevent myopia.