[Studies of retinal dopamine transporter in experimental myopia]

To investigate the distribution of dopamine transporter (DAT) in the chicken eye and to explore the role of DAT in the occurrence of experimental myopia.

Thirty 2-day-old chickens were divided into four groups. Chicken eyes were fitted with lenses of -10 D (Group 1), -20 D (Group 2) and translucent goggles (Group 3) unilaterally. Chickens without any treatments were used as the control (Group 4). The refraction and the axial eye length of all chickens were measured after 3 weeks, then, all chickens were given an intramuscular injection of (125)I-beta-CIT [2beta-carbomethoxy-3beta-(4-iodophenyl) tropane] and sacrificed two hours after injection. Retinal pigment epithelium (RPE) and neural retina were dissected from the eye as a whole layer in Groups 1 and 4; and dissected separately in Groups 2 and 3. Radioactive DAT from each specimen was assayed by gamma-counter.

In Groups 2 and 3, the radioactive DAT value in the RPE from the experimental eyes was significantly greater than that in the neural retina and also greater than those in the RPE from the control eyes (P < 0.01). In Groups 1, 2, and 3, the radioactive DAT value in the whole retina or RPE from the experimental eyes was significantly greater than those from the control eyes (P < 0.01).

Retinal DAT is located mainly in the RPE and may be involved in the occurrence of both lens-induced myopia and form-deprivation myopia. These methods may provide a new approach for further studying the role of dopamine system in the occurrence of experimental myopia.