Daily Injection But Not Continuous Infusion of Apomorphine Inhibits Form-Deprivation Myopia in Mice.
OBJECTIVE
To compare the effects of daily injection versus continuous infusion of a nonspecific dopamine agonist, apomorphine (APO), on refraction and ocular growth in normal postnatal mice and mice with form-deprivation myopia (FDM).


METHODS
The C57BL/6 mice were subjected (or not) to monocular FD by covering the left eye with a frosted goggle and leaving the right (fellow) eye uncovered. During postnatal days 28 to 56, both groups received APO (5 mg/kg/d) or vehicle either as daily intraperitoneal injection or by continuous subcutaneous infusion with mini-pumps. After these treatments, binocular refractions were measured by photoretinoscopy and binocular ocular dimensions were measured by optical coherence tomography. Monocular photopic flash electroretinograms were recorded from non-FD mice.


RESULTS
In normal mice, daily injection or continuous infusion of APO did not affect normal postnatal development of refraction. However, in the FD group, daily APO-injection attenuated ocular growth and also myopia development, as reflected in the interocular differences for APO-injected mice compared with vehicle-injected mice: (1) refraction, -1.04 ± 0.37 diopter (D) (APO-injection) compared with -4.14 ± 0.77 D (vehicle-injection) (P < 0.05); (2) vitreous chamber depth: -0.002 ± 0.005 mm compared with 0.032 ± 0.009 mm (P < 0.05); and (3) axial length: 0.000 ± 0.005 mm compared with 0.057 ± 0.007 mm (P < 0.05). By contrast, continuous APO-infusion failed to affect these biometric parameters. Furthermore, daily APO-injection decreased the ERG a- and b-wave amplitudes, whereas continuous APO-infusion increased these responses.


CONCLUSIONS
In monocularly FD mice, daily APO-injection, but not continuous infusion, attenuated myopia development. Therefore, evaluating different dopamine agonist administration paradigms is important for identifying effective dopamine-based treatment for myopia.
School of Optometry and Ophthalmology and Eye Hospital, Wenzhou Medical College, Wenzhou, Zhejiang, China 2State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Health People's Republic of China and Zhejiang Provincial Ke.
Tingting
T
Yan
School of Optometry and Ophthalmology and Eye Hospital, Wenzhou Medical College, Wenzhou, Zhejiang, China 2State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Health People's Republic of China and Zhejiang Provincial Ke.
Weiwei
W
Xiong
School of Optometry and Ophthalmology and Eye Hospital, Wenzhou Medical College, Wenzhou, Zhejiang, China 2State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Health People's Republic of China and Zhejiang Provincial Ke.
Furong
F
Huang
School of Optometry and Ophthalmology and Eye Hospital, Wenzhou Medical College, Wenzhou, Zhejiang, China 2State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Health People's Republic of China and Zhejiang Provincial Ke.
Fan
F
Zheng
School of Optometry and Ophthalmology and Eye Hospital, Wenzhou Medical College, Wenzhou, Zhejiang, China 2State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Health People's Republic of China and Zhejiang Provincial Ke.
Huangfang
H
Ying
School of Optometry and Ophthalmology and Eye Hospital, Wenzhou Medical College, Wenzhou, Zhejiang, China 3Department of Neurology, Boston University School of Medicine, Boston, Massachusetts, United States.
Jiang-Fan
JF
Chen
School of Optometry and Ophthalmology and Eye Hospital, Wenzhou Medical College, Wenzhou, Zhejiang, China 2State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Health People's Republic of China and Zhejiang Provincial Ke.
Jia
J
Qu
School of Optometry and Ophthalmology and Eye Hospital, Wenzhou Medical College, Wenzhou, Zhejiang, China 2State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Health People's Republic of China and Zhejiang Provincial Ke.
Xiangtian
X
Zhou
D000818:Animals; D001058:Apomorphine / Q000008:administration & dosage*; D004195:Disease Models, Animal; D018491:Dopamine Agonists / Q000008:administration & dosage; D004334:Drug Administration Schedule; D007263:Infusions, Parenteral; D007274:Injections, Intraperitoneal; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009216:Myopia / Q000188:drug therapy* / Q000209:etiology / Q000503:physiopathology; D012029:Refraction, Ocular; D012683:Sensory Deprivation
D018491:Dopamine Agonists; D001058:Apomorphine