Anticataractogenic effect of betaine in chick embryo hydrocortisone-induced cataract model

Investigation of the antioxidant effect of Chrysin in an experimental cataract model created in chick embryos

PURPOSE

Cataract, which occurs as a result of lens opacification, is one of the most common causes of vision loss. In the literature, deterioration of the antioxidant system due to the increase in reactive oxygen species and oxidant levels is shown among the causes of cataract formation. The aim of this study was to investigate the antioxidant effect of chrysin on steroid-induced cataract development in an experimental chick embryo model using morphological, histological and biochemical parameters.

METHODS

Within the scope of the study, 150 specific pathogen free (SPF) fertilized eggs were used. Eggs were divided into 6 groups as control (group 1), corn oil (group 2), hydrocortisone hemisuccinate sodium (HC) (group 3), low dose chrysin (group 4), medium dose chrysin (group 5) and high dose chrysin (group 6). On the 15th day of incubation, Chrysin and HC were applicated to the air sac of the eggs with Hamilton and/or insulin injector. On day 17, the chick embryos were removed from the eggs and the bulbus oculi of the embryos were dissected. Lenses of 9 embryos were used for morpholigical cataract grading in each group, lens of 8 embryos for biochemical analysis and intact eyes of 7 embryos for histological evaluation (TUNEL method).

RESULTS

No opacity was observed in any of the lenses in Group 1 and 2. Cataract was observed in all lenses in Group 3. The mean opacity grades in group 3 were statistically significantly higher when compared to group 1 and 2 (p<0.05). The difference between group 6 and group 3 was statistically significant (p<0.05). GSH and TAS levels in the lenses were statistically significantly decreased compared to the control group due to HC application (p<0.05). It was determined that the decreased GSH and TAS levels in the lenses increased in relation to the Chrysin application doses. The increased levels of MDA, TOS, caspase 3 and caspase 9 in the HC group decreased significantly depending to the chrysin doses (p<0.05). In addition, while the rate of apoptotic cells determined by the TUNEL method was statistically significantly higher in the HC administered group than in the control group (p<0.05), it was statistically significantly decreased in the chrysin-administered groups, in relation to the dose of chrysin (p<0.05).

CONCLUSIONS

We think that anti-cataract effect of crhysin may be due to the antioxidant and antiapoptotic properties of chrysin. However, more research is needed to clarify the anti-cataract effects of chrysin.

The Chick Embryo and Its Structures as a Model System for Experimental Ophthalmology

The possibilities of using the chick embryo and its individual structures as a model system in experimental ophthalmology are considered. Cultures of the retina and spinal ganglia from chick embryos are used in the development of new methods for the treatment of glaucomatous optic neuropathy and ischemic optic neuropathy. The chorioallantoic membrane is used for modelling vascular pathologies of the eye, screening of anti-VEGF drugs, and assessing biocompatibility of implants. Co-culturing of chick embryo nervous tissue and human corneal cells makes it possible to study the processes of corneal reinnervation. The use of chick embryo cells and tissues in the "organ-on-a-chip" system opens up wide opportunities for fundamental and applied ophthalmological studies.

Development of a potent embryonic chick lens model for studying congenital cataracts in vivo

Congenital cataracts are associated with gene mutations, yet the underlying mechanism remains largely unknown. Here we reported an embryonic chick lens model that closely recapitulates the process of cataract formation. We adopted dominant-negative site mutations that cause congenital cataracts, connexin, Cx50E48K, aquaporin 0, AQP0R33C, αA-crystallin, CRYAA R12C and R54C. The recombinant retroviruses containing these mutants were microinjected into the occlusive lumen of chick lenses at early embryonic development. Cx50E48K expression developed cataracts associated with disorganized nuclei and enlarged extracellular spaces. Expression of AQP0R33C resulted in cortical cataracts, enlarged extracellular spaces and distorted fiber cell organization. αA crystallin mutations distorted lens light transmission and increased crystalline protein aggregation. Together, retroviral expression of congenital mutant genes in embryonic chick lenses closely mimics characteristics of human congenital cataracts. This model will provide an effective, reliable in vivo system to investigate the development and underlying mechanism of cataracts and other genetic diseases.