IN-VIVO REGULATION OF RAT EPIDIDYMAL PROTEINS BY RETINOIDS - ANALYSISBY 2-DIMENSIONAL ELECTROPHORESIS

The role of retinoids in the regulation of epididymal fluid protein ex pression was investigated. We compared the patterns of two-dimensional electrophoretic gels of proteins from luminal fluids, cytosols and sp ermatozoa (from control rats only) of control, retinoid-depleted, reti noid-depleted retinoic acid-complemented and retinoid-depleted testost erone-supplemented rats. This study compared the luminal fluid pattern s from the 4 diets and observed 13 proteins whose expression was depen dent on nutritional status. Eight were either absent or very weakly ex pressed in retinoid-depleted animals only, while their presence was ob vious in control rats and in the retinoid-deficient retinoic acid- and testosterone-complemented groups. The expression of 8 proteins was gr eatly enhanced in retinoid-depleted testosterone-supplemented fluids a s compared to control fluids. Five of the regulated proteins seemed to be captured by spermatozoa as they were observed in sperm protein pat terns of control rats. These results clearly show that the synthesis o f several epididymal proteins is influenced by retinoids. Since testes terone-supplemented animals on retinoid-free diet elicited the same re sponse as retinol and retinoic acid ones, testosterone is likely to be the mediator of retinoid action on epididymal protein synthesis. Neve rtheless, the observation of one protein whose expression is stimulate d by retinoic acid only and is totally independent of testosterone als o favors the direct influence of this retinoid.