Hyperhomocysteinemia Induced Mitochondrial Dysfunction Disrupting the Eye Development.

Mitochondrial dynamics, including fusion and fission, are essential for neural cell function and survival during central nervous system development. These processes are vital for eye formation, which requires high energy to support cellular events, such as proliferation, differentiation, and apoptosis. However, different conditions can disrupt the normal development of the eye, such as hyperhomocysteinemia (HHcy), a metabolic disorder characterized by elevated homocysteine (Hcy) levels. This study aimed to evaluate the effects of HHcy on eye development of Gallus domesticus. Fertilized eggs were treated with 20 µmol Hcy at embryonic day 2 (E2), with analyses conducted at E6 and E10 using a combination of survival analysis, transmission electron microscopy, flow cytometry for mitochondrial proteins and autophagy markers, and cell viability assay, providing a comprehensive evaluation of HHcy toxicity. A significant 40% reduction in the survival rate relative to control was observed in HHcy-treated embryos. Although eye diameter remained unchanged, ultrastructural analyses revealed mitochondrial damage, including membrane rupture, loss, and disorganization of the cristae, induced by the exposure at both embryonic ages. Analysis of proteins involved in mitochondrial dynamics showed increased Drp1 (fission) and decreased Mfn1 and Mfn2 (fusion) in HHcy-treated embryos. At E10, these changes were accompanied by an increased number of mitochondrial profiles and reduced mitochondrial area. HHcy also induced a reduction in cell viability, highlighting its cytotoxic effects, particularly on mitochondria. Additionally, increased cytoplasmic vesicles and autophagy were observed in HHcy-treated embryos. These findings indicate that mitochondria are key targets of HHcy, with mitochondrial dynamics and ultrastructural integrity significantly impaired by the exposure. These changes highlight the harmful effects of high Hcy levels on embryonic development and eye formation, providing insights into its pathogenic effects.