In most studies, the major supplement
docosahexaenoic acid (DHA) is administered orally or intraperitoneally. In this study, we proposed to assess the safety and efficacy of the
intravitreal injection of DHA in an
age-related macular degeneration (AMD) rat model. Different concentrations of DHA were injected into the vitreous body. Histopathology and
terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) analysis showed that there was no difference in thickness, observable structure, or apoptosis among the untreated,
normal saline, and DHA groups (0.2, 1.0, 5.0 and 10μg). However, GFAP expression was increased in the 10μg group. To investigate whether
intravitreal injection of DHA could protect photoreceptors, we developed a NaIO3-induced
retinal damage model in adult rats. Decreases in deformation and thickness were observed in the outer nuclear layer (ONL) after
NaIO3 administration but were improved with DHA injection. The
NaIO3 group showed a substantial reduction in the number of nuclei in ONL, whereas the DHA group showed an increase. Additionally, significant increases in SOD activity and Nrf2 expression were observed after DHA injection; GFAP and NF-κB expression levels were markedly decreased by DHA injection. Moreover, Western blotting showed that Bax, cleaved
caspase-3 and CHOP were notably increased in the
NaIO3 group but were significantly decreased by DHA injection. Collectively,
intravitreal injection of DHA is safe and effective in select doses in a NaIO3-induced AMD rat model. The current results suggest that
intravitreal injection of DHA may be a new avenue for the treatment of AMD.