Hypertrophy of adipose tissues in quail embryos by in ovo all-trans retinoic acid injection

Authors: KIM, DONG HWAN - The Ohio State University; LEE, JOONBUM - The Ohio State University; KIM, SANGGU - The Ohio State University; Lillehoj, Hyun; LEE, KICHOON - The Ohio State University

Submitted to: Nutrients
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/14/2021
Publication Date: 5/21/2021
Citation: Kim, D., Lee, J., Kim, S., Lillehoj, H.S., Lee, K. 2021. Hypertrophy of adipose tissues in quail embryos by in ovo all-trans retinoic acid injection. Nutrients. https://doi.org/10.3389/fphys.2021.681562.
DOI: https://doi.org/10.3389/fphys.2021.681562

Interpretive Summary: Excessive adipose accretion causes health issues in humans and decreases feed efficiency in poultry. This study was conducted to investigate the role of vitamin A which has been shown to enhance fat formation in mammals. Although vitamin A has been known to be involved in adipogenesis, the effects of all-trans retinoic acid (atRA), a metabolite of vitamin A, on embryonic adipose development in the avian species have not been studied yet. In this paper, ARS scientists collaborated with scientists at Ohio State University to use quail embryos as a biological model system to study the effect of atRA on fat tissue development since quail embryos develop in confined egg shell which can be directly modified to study the effects of nutrients on embryonic fat cell development. Using quail embryos, the injection of atRA at embryonic day 9 (E9) showed that fat tissues significantly increased in size when measured at E14. Furthermore, the injection of atRA at E7 time point showed the most significant increase in weight and percentage of inguinal fat. These results demonstrate the important role of vtA in fat cell accretion in quail embryos and imply an important role of atRA in embryonic development of adipose tissues in mammals.

Technical Abstract: Excessive adipose accretion causes health issues in human and decreases feed efficiency in poultry. Although vitamin A has been known to be involved in adipogenesis, effects of all-trans retinoic acid (atRA), as a metabolite of vitamin A, on embryonic adipose development have not been studied yet. Avian embryos are developing in confined egg environment which can be directly modified to study effects of nutrients on embryonic adipogenesis. Using quail embryos, different concentrations of atRA (0 M to 10 'M) were injected in ovo at embryonic day (E) 9 and adipose tissues were sampled at E14. Percentages of fat pad weights in embryo weights were significantly in-creased in the group injected with 300 nM of atRA. Also, among three injection time points, E5, 7 or 9, the E7 showed most significant increase in weights and percentages of inguinal fat at E14. In-jection of atRA at E7 increased fat cell size in E14 embryos. These data demonstrate that atRA promotes hypertrophic fat accretion in quail embryos, implying important role of atRA in embryonic development of adipose tissues.