title: Effects of dopaminergic agents on progression of naturally occurring myopia in albino guinea pigs (Cavia porcellus).
abstract: OBJECTIVE
  Disruption of dopaminergic signaling has been implicated in the abnormalities of ocular development in albinism, and many experiments have shown that retinal dopamine is a major regulator of postnatal eye growth and myopia in animal models. Therefore, in the present study we investigated whether progressive myopia, which can occur in albino guinea pigs without experimental manipulation of visual conditions, is affected by dopaminergic agents.
  
  
  METHODS
  Two-week-old albino guinea pigs, selected for being myopic (range refractive error [RE], -2 to -10 diopters [D]), received unilateral peribulbar injections of apomorphine (nonselective dopamine receptor agonist; 0, 7.5, 25, 75, 250, 750, and 2500 ng; n = 112), SKF38393 (D1-like agonist; 0, 10, 100, 1000 ng; n = 63), SCH23390 (D1-like antagonist; 0, 2500 ng; n = 27), quinpirole (D2-like agonist; 0, 10, 100, 1000 ng; n = 58), or sulpiride (D2-like antagonist; 0, 2500 ng; n = 24) once a day for four weeks. One noninjected group (n = 19) served as untreated control. Refractive states and axial dimensions of the eyes were measured without cycloplegia or general anesthetic, using eccentric infrared photoretinoscopy and A-scan ultrasonography, respectively, before treatment, and after 2 and 4 weeks of treatment. The main drug effects were analyzed by paired t-test or 2-way repeated measures ANOVA, as required.
  
  
  RESULTS
  The naturally occurring progression of myopic RE was inhibited by apomorphine at relatively high doses (250 and 750 ng), SKF38393 at 100 ng (D1-like agonist), and sulpiride at 2500 ng (D2-like antagonist), but promoted by apomorphine at a lower dose (25 ng), quinpirole at 100 ng (D2-like agonist), and SCH23390 at 2500 ng (D1-like antagonist). All drugs affected primarily vitreous chamber depth, rather than anterior segment dimensions.
  
  
  CONCLUSIONS
  Our data suggest that the activation of D1-like receptors inhibits, whereas activation of D2-like receptors promotes, progressive myopia in this animal model. The robust effects of antagonists suggest that ocular dopamine receptors in these albinos may be in a chronic state of partial excitation. The precise location and identity of the receptors responsible for these effects remain to be determined.
authors.affiliation: School of Optometry and Ophthalmology and Eye Hospital, Wenzhou Medical University; and State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Health, Wenzhou, Zhejiang, China.
authors.forename: Liqin
authors.initials: L
authors.lastname: Jiang
authors.affiliation: School of Optometry and Ophthalmology and Eye Hospital, Wenzhou Medical University; and State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Health, Wenzhou, Zhejiang, China Xuzhou Eye Institute, Xuzhou, Jiangsu Province, China.
authors.forename: Keli
authors.initials: K
authors.lastname: Long
authors.affiliation: Section of Neurobiology of the Eye, Ophthalmic Research Institute, Tübingen, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Schaeffel
authors.affiliation: School of Optometry and Ophthalmology and Eye Hospital, Wenzhou Medical University; and State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Health, Wenzhou, Zhejiang, China.
authors.forename: Xiangtian
authors.initials: X
authors.lastname: Zhou
authors.affiliation: School of Optometry and Ophthalmology and Eye Hospital, Wenzhou Medical University; and State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Health, Wenzhou, Zhejiang, China.
authors.forename: Yibo
authors.initials: Y
authors.lastname: Zheng
authors.affiliation: School of Optometry and Ophthalmology and Eye Hospital, Wenzhou Medical University; and State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Health, Wenzhou, Zhejiang, China.
authors.forename: Huangfang
authors.initials: H
authors.lastname: Ying
authors.affiliation: School of Optometry and Ophthalmology and Eye Hospital, Wenzhou Medical University; and State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Health, Wenzhou, Zhejiang, China.
authors.forename: Fan
authors.initials: F
authors.lastname: Lu
authors.affiliation: Departments of Cell Biology and Anatomy, and Surgery, and Hotchkiss Brain Institute, University of Calgary Faculty of Medicine, Calgary, Alberta, Canada.
authors.forename: William K
authors.initials: WK
authors.lastname: Stell
authors.affiliation: School of Optometry and Ophthalmology and Eye Hospital, Wenzhou Medical University; and State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Health, Wenzhou, Zhejiang, China.
authors.forename: Jia
authors.initials: J
authors.lastname: Qu
mesh_terms: D000818:Animals; D001058:Apomorphine / Q000494:pharmacology*; D001552:Benzazepines / Q000494:pharmacology*; D004195:Disease Models, Animal; D018450:Disease Progression; D018491:Dopamine Agonists / Q000494:pharmacology; D018492:Dopamine Antagonists / Q000494:pharmacology; D005500:Follow-Up Studies; D006168:Guinea Pigs; D009216:Myopia / Q000188:drug therapy* / Q000503:physiopathology; D012029:Refraction, Ocular / Q000187:drug effects*; D013469:Sulpiride / Q000494:pharmacology*; D016896:Treatment Outcome
chemical_list: D001552:Benzazepines; D018491:Dopamine Agonists; D018492:Dopamine Antagonists; C534628:SCH 23390; D013469:Sulpiride; D001058:Apomorphine
keywords: SCH23390; SKF38393; apomorphine; axial length; dopamine receptor; quinpirole; refractive error; sulpiride