Free Access
Reprod. Nutr. Dev.
Volume 42, Number 4, July-August 2002
Page(s) 285 - 294
Reprod. Nutr. Dev. 42 (2002) 285-294
DOI: 10.1051/rnd:2002025

Distribution of endogenous retinoids, retinoid binding proteins (RBP, CRABPI) and nuclear retinoid X receptor $\beta$ (RXR $\beta$) in the porcine embryo

Florian J. Schweigerta, Christiane Sieglinga, Georg Tzimasb, Johannes Seegerc and Heinz Naud

a  Institute of Nutritional Science, University of Potsdam, Arthur-Scheunert-Allee 114-116, 14558 Potsdam-Rehbrücke, Germany
b  Brigitte Cosmetics, Tzimas-Dimolios, Co., Thessaloniki, Greece
c  Department of Anatomy and Histology, University of Leipzig, Germany
d  Institute of Food Toxicology, University of Veterinary Medicine, Hannover, Germany

(Received 7 December 2001; accepted 15 May 2002)

Retinoids are important signalling molecules in the development of limbs and in the determination of the anterior-posterior orientation of the embryo. The present study examined the content and distribution of retinoic acid, retinol and retinyl esters in porcine embryos during early gestation (gestation days 22-30) macroscopically and microscopically by its autofluorescence and by HPLC. Macroscopically, the yellowish-greenish autofluorescence characteristic of vitamin A was observed in tissues affected by morphogenesis, such as the limbs, in a spatial and temporal manner. Changes in the intensity of autofluorescence in the limbs paralleled changes in the concentration of retinoids in these structures. In the limbs and the body, retinol, retinyl palmitate, and all-trans-retinoic acid but neither the isomers of all-trans retinoic acid nor other retinoid metabolites were detected. In addition, the distribution of specific retinoid-binding proteins was investigated; these are involved in vitamin A transport, metabolism and signal transduction. Immunoreactive retinol-binding protein as well as cellular retinoic acid binding protein type I were only localised in the mesonephros, while the retinoid X receptor $\beta$ was widely distributed in most of the tissues and organs of the embryo throughout the time period investigated. The combination of autofluorescence and HPLC analysis allowed for the first time to attribute the yellowish-greenish autofluorescence in specific regions of the embryo to vitamin A, and offers a method to study the local cellular distribution of retinol and/or retinyl esters as well as their concentrations in embryonic tissues.

Key words: retinoid / vitamin A / binding protein / nuclear receptor / autofluorescence / embryo / pig

Correspondence and reprints: Florian J. Schweigert

© INRA, EDP Sciences 2002