INTRODUCTION: Parkinson's disease is one of the most common age-related disease in the modern times. Motor symptoms observed in patients are related with the degeneration of dopaminergic cells in substantia nigra. Recent studies have shown that one of the first symptoms are those related to vision, caused by decreased dopamine signaling in the retina. The fruit fly (Drosophila melanogaster) is the good alternative for modeling Parkinson’s disease. The presence of receptor Dop1R1 in the Drosophila eye has been identified, but its function in this location has not been identified.

AIM(S): The main aim of the study was to show the effect of the reduction of the Dop1R1 receptor expression in the retinal cells of Drosophila melanogaster.

METHOD(S): The shape and structure of the retina was examined to describe potential effect of decreased dopamine signaling on the ommatidia degeneration. We checked also possible changes in the sleep level, as it was shown previously that proper retina functioning is necessary to maintain the normal pattern and level of sleep and activity.

RESULTS: Our results indicate that even no changes in ommatidia degeneration were detected between the experimental and the control groups, increased locomotor activity during the dark phase was observed. There was also statistically significant difference in the time of the period of circadian activity.

CONCLUSIONS: The Dop1R1 receptor present in the eye plays a significant role in the regulation of circadian activity in the dark phase, suggesting that dopamine has a significant impact on circadian clock signaling already at the level of ommatidia. This study helps to understand the mechanism involved in dopamine signaling in the visual system of the fruit fly and it may help to understand the mechanisms of eye degeneration in parkinson's disease.