Abstract Background: Peroxisome proliferator-activated receptor alpha (PPARα) is associated with diabetic retinopathy (DR), and the underlying mechanism is still unclear. Aim of this work was to investigate the mechanism of PPARα in DR. Methods: Human retinal capillary pericytes (HRCPs) were treated with high glucose (HG) to induce DR cell model. DR mouse model was established by streptozotocin injection, and then received 5-Aza-2-deoxycytidine (DAC; DNA methyltransferase inhibitor) treatment. Hematoxylin–eosin staining was performed to assess retinal tissue damage. PPARα methylation was examined by Methylation-Specific PCR. Flow cytometry and DCFH-DA fluorescent probe was used to estimate apoptosis and reactive oxygen species (ROS). The interaction between DNA methyltransferase-1 (DNMT1) and PPARα promoter was examined by Chromatin Immunoprecipitation. Quantitative real-time PCR and western blot were performed to assess gene and protein expression. Results: HG treatment enhanced the methylation levels of PPARα, and repressed PPARα expression in HRCPs. The levels of apoptotic cells and ROS were significantly increased in HRCPs in the presence of HG. Moreover, DNMT1 was highly expressed in HG-treated HRCPs, and DNMT1 interacted with PPARα promoter. PPARα overexpression suppressed apoptosis and ROS levels of HRCPs, which was rescued by DNMT1 up-regulation. In DR mice, DAC treatment inhibited PPARα methylation and reduced damage of retinal tissues. Conclusion: DNMT1-mediated PPARα methylation promotes apoptosis and ROS levels of HRCPs and aggravates damage of retinal tissues in DR mice. Thus, this study may highlight novel insights into DR pathogenesis.

ABSTRACT The topmouth gudgeon, Pseudorasbora parva (Temminck & Schlegel, 1842), is a small cyprinid fish that inhabits the littoral zones of freshwater habitats throughout Asia and Europe. It is regarded as an invasive species in Europe, but in its native range, in China, as food and as an environmental bio-indicator. In this study, the embryonic and larval development of P. parva was investigated for the first time. The eggs of P. parva are transparent, adhesive and elliptical. The mean size of fertilized eggs was (1.63×1.31) ± 0.04 mm. From fertilization to hatching, embryonic development could be divided into eight stages and 34 phases, and the incubation period lasted for 109.25 hours at 24 ± 1 °C. Newly hatched larvae were 4.1 ± 3 mm in length, and the yolk absorption was completed within six days after hatching. The first and second swim bladders formed at the third and ninth day, respectively. The pectoral fin formed before the hatching stage, followed by the caudal, dorsal, anal and ventral fin formation after hatching. About 20 days after hatching, the morphology of the fry was similar to the adult fish. These findings provide a basis for determining the complete ontogeny of P. parva, as well as facilitate the management and utilization of this fish.