Hypertrophy of Adipose Tissues in Quail Embryos by in ovo Injection of All- Trans Retinoic Acid

Dong-Hwan Kim; Joonbum Lee; Sanggu Kim; Hyun S Lillehoj; Kichoon Lee

doi:10.3389/fphys.2021.681562

Hypertrophy of Adipose Tissues in Quail Embryos by in ovo Injection of All- Trans Retinoic Acid

Front Physiol. 2021 May 21:12:681562. doi: 10.3389/fphys.2021.681562. eCollection 2021.

Authors

Dong-Hwan Kim¹, Joonbum Lee^{1

2}, Sanggu Kim³, Hyun S Lillehoj⁴, Kichoon Lee^{1

2}

Affiliations

¹ Department of Animal Sciences, The Ohio State University, Columbus, OH, United States.
² The Ohio State University Interdisciplinary Human Nutrition Program, The Ohio State University, Columbus, OH, United States.
³ Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH, United States.
⁴ Animal Bioscience and Biotechnology Laboratory, Beltsville Agricultural Research Center, Agricultural Research Service, United States Department of Agriculture, Beltsville, MD, United States.

Abstract

Excessive adipose accretion causes health issues in humans 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 environments, which can be directly modified to study effects of nutrients on embryonic adipogenesis. With the use of quail embryos, different concentrations of atRA (0 M to 10 μM) 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 increased in the group injected with 300 nM of atRA. Also, among three injection time points, E5, E7, or E9, E7 showed the most significant increase in weight and percentage of inguinal fat at E14. Injection of atRA at E7 increased fat cell size in E14 embryos with up-regulation of pro-adipogenic marker genes (Pparγ and Fabp4) and down-regulation of a preadipocyte marker gene (Dlk1) in adipose tissues. These data demonstrate that atRA promotes hypertrophic fat accretion in quail embryos, implying important roles of atRA in embryonic development of adipose tissues.

Keywords: adipocyte hypertrophy; all-trans retinoic acid; embryonic development; fat accretion; in ovo injection; quail.