EXPRESSION AND LOCALIZATION OF PROLACTIN RECEPTOR MESSENGER-RIBONUCLEIC-ACID IN RED DEER OVARY DURING THE ESTROUS-CYCLE AND PREGNANCY

In this study, expression of the prolactin receptor (PRL-R) gene in th e ovaries of cycling and pregnant red deer (Cervus elaphus) hinds was investigated. A 1.9-kilobase (kb) cDNA encoding the cervine long-form PRL-R was amplified by reverse transcriptase polymerase chain reaction from corpus luteum (CL) and liver poly(A)+ RNA. Northern hybridizatio n revealed a major mRNA transcript of 3.5 kb in both tissues. PRL-R mR NA transcripts were localized by in situ hybridization in 15-mu m froz en sections of red deer ovaries, collected during the estrous cycle an d early pregnancy, with homologous 45-mer [S-35]dATP-labeled sense and antisense oligonucleotide probes. Specific hybridization was assessed by measurement of autoradiograph optical density (OD) in CL, follicle s, and stroma. PRL-R mRNA expression was higher (p < 0.001) in the CL (OD = 22.2 +/- 3.77, 11 CL) than in follicles (OD = 2.8 +/- 0.10, n = 224 follicles) and was undetectable in the stroma (OD < 1, limit of de tection). No differences in abundance of PRL-R mRNA were observed betw een follicles divided on the basis of size, health vs. atresia, or sta ge of estrous cycle or pregnancy, or between CL from pregnant and nonp regnant hinds. In the follicles, PRL-R mRNA was localized to the theca layer. These results suggest a direct role for PRL in red deer ovaria n physiology during the estrous cycle and pregnancy.