VISUALIZATION OF GENE-EXPRESSION OF PROLACTIN RECEPTORS (PRL-R) BY IN-SITU HYBRIDIZATION, IN TYPHLONECTES COMPRESSICAUDUS, A GYMNOPHIONAN AMPHIBIAN

The expression of the short and long forms of prolactin receptors (PRL -R) mRNA was studied in various types of tissues from Typhlonectes com pressicaudus, an amphibian, by quantitative in situ hybridization. Bot h forms were expressed in all the types of tissues studied. In the liv er, small intestine and hypophysis, the mRNA coding for the short form of PRL-R was more strongly expressed than the mRNA coding for the lon g form and vice-versa for the stomach, spleen and kidneys. In the fema le liver, quantification showed a higher value of mRNA expression mid- way through pregnancy than during the sexual inactivity period. This r esult was found to be correlated with the reserve function of the live r. In the kidney and small intestine, the presence of PRL-R was correl ated with the hydromineral function. A comparison with certain mammals was also established. These results confirm the ubiquity of PRL effec ts on metabolic regulation, and suggest a phylogenic conservation of i ts receptors.