Effects of retinal dopamine depletion on the growth of the fish eye |
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Authors: | R H H Kröger B Hirt H-J Wagner |
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Institution: | Eberhard-Karls-Universit?t Tübingen, Anatomisches Institut, Abt. Zellul?re Neurobiologie, ?sterbergstra?e 3, D-72074 Tübingen, Germany e-mail: kroeger@anatu.uni-tuebingen.de Tel.:+49-7071-2973022; Fax: +49-7071-294014, DE
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Abstract: | We investigated the suitability of fishes as animal models to study the involvement of the retinal dopaminergic system in
the visually guided control of eye growth (emmetropization). Advantages of such a model system are (i) that all dopaminergic
cells in the retina can be destroyed without apparent damage to other neurons, (ii) simple optical design and short depth
of field of the eye, and (iii) continuous growth throughout life. Depleting the retina of dopamine in Aequidens pulcher (Cichlidae) had no apparent effect on refractive state, since size and focal length of the eye were reduced by the same amount.
Furthermore, imposed defocus was compensated at a normal rate in spite of the absence of retinal dopamine. In A. pulcher, the dopaminergic system of the retina thus appears not to have an essential role in emmetropization. Our results furthermore
suggest that in eyes of more complicated optical design, manipulation of the retinal dopaminergic system may lead to unrelated
effects indistinguishable from direct interference with emmetropization. A major disadvantage of the fish model was that refractive
state of the eye could not be measured accurately in vivo with standard methods.
Accepted: 9 January 1999 |
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Keywords: | Emmetropization Myopia Dopamine 6-Hydroxy-dopamine Crystalline lens |
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