Ovariectomy Increases Circulating Retinol-Binding Protein Concentrations Independently of Sex-Dependent Differences in Retinol Concentrations in Rats

Hiroko Moriya; Yuki Yokobori; Taichi Furukawa; Taku Kato; Ryota Sato; Asako Takenaka

doi:10.1016/j.tjnut.2023.02.033

Ovariectomy Increases Circulating Retinol-Binding Protein Concentrations Independently of Sex-Dependent Differences in Retinol Concentrations in Rats

J Nutr. 2023 Apr;153(4):1019-1028. doi: 10.1016/j.tjnut.2023.02.033. Epub 2023 Mar 2.

Authors

Hiroko Moriya¹, Yuki Yokobori¹, Taichi Furukawa¹, Taku Kato¹, Ryota Sato¹, Asako Takenaka²

Affiliations

¹ Department of Agricultural Chemistry, School of Agriculture, Meiji University, Kawasaki, Kanagawa, Japan.
² Department of Agricultural Chemistry, School of Agriculture, Meiji University, Kawasaki, Kanagawa, Japan. Electronic address: takenaka@meiji.ac.jp.

PMID: 36870537
DOI: 10.1016/j.tjnut.2023.02.033

Abstract

Background: There is a sex-dependent difference in blood retinol and RBP concentrations, and plasma RBP is associated with insulin resistance.

Objectives: We aimed to clarify sex-dependent variations in body concentrations of retinol and RBPs and their association with sex hormones in rats.

Methods: Plasma and liver retinol concentrations and hepatic mRNA and plasma concentrations of RBP4 were analyzed in 3- and 8-wk-old male and female Wistar rats before and after sexual maturity (experiment 1) and in orchiectomized male Wistar rats (experiment 2) and ovariectomized female Wistar rats (experiment 3). Furthermore, the mRNA and protein concentrations of RBP4 in adipose tissue were measured in ovariectomized female rats (experiment 3).

Results: There were no sex-dependent differences in liver retinyl palmitate and retinol concentrations; however, the plasma retinol concentration was significantly higher in male rats than that in female rats after sexual maturity. Furthermore, the plasma retinol concentrations did not differ between the ovariectomized or orchiectomized rats and the control rats. Plasma Rbp4 mRNA concentrations were higher in male rats than those in female rats but not in castrated and control rats, a change consistent with plasma retinol concentration. Plasma RBP4 concentrations were also higher in male rats than those in female rats; however, unlike liver Rbp4 gene expression, plasma RBP4 concentrations were 7-fold higher in the ovariectomized rats than those in the control rats. Moreover, the Rbp4 mRNA concentrations in inguinal white adipose tissue was significantly higher in the ovariectomized rats than those in the control rats and correlated with plasma RBP4 concentrations.

Conclusions: Hepatic Rbp4 mRNA is higher in male rats through a sex hormone-independent mechanism, which may contribute to sex differences in blood retinol concentrations. Furthermore, ovariectomy leads to an increase in adipose tissue Rbp4 mRNA and blood RBP4 concentrations, which may contribute to insulin resistance in ovariectomized rats and postmenopausal women.

Keywords: RBP4; ovariectomy; retinol; retinol-binding protein; vitamin A.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Adipose Tissue / metabolism
Animals
Female
Insulin Resistance*
Male
Rats
Rats, Wistar
Retinol-Binding Proteins, Plasma / genetics
Retinol-Binding Proteins, Plasma / metabolism
Sex Characteristics
Vitamin A

Substances

Vitamin A
Retinol-Binding Proteins, Plasma