Neonatal Meishan pigs show POU1F1 genotype effects on plasma GH and PRL concentration

Chinese Meishan pigs develop rapidly with onset of puberty at less than 100 days of age, and have a smaller placental size and larger litter size as compared with British/Continental breeds. POU1F1 is a member of the POU-domain family gene and is a positive regulator for growth hormone (GH), prolactin (PRL), and thyroid-stimulating hormone beta (TSHbeta) in several mammalian species. To investigate the role of POU1F1 in controlling pig growth and reproduction traits, Meishan (MS) pigs segregating a MspI POU1F1 polymorphism were used to determine differences of GH and PRL at both mRNA and circulating hormone concentrations. Animals from nine litters were used to collect pituitary (n=60) and/or blood samples (n=80) at day 0, 15, and 30 after birth, and all animals were genotyped (CC, CD, DD) for the MspI POU1F1 polymorphism. Reverse transcriptase-polymerase chain reaction (RT-PCR) with standard curve quantification was used to quantify mRNA levels for GH, PRL, and two alternative POU1F1 transcripts, POU1F1-alpha, and POU1F1-beta. Radioimmunoassays were done to determine the circulating concentration of GH and PRL in blood plasma. Our results indicated a significant effect of POU1F1 genotype on circulating levels of both GH and PRL at birth, but not thereafter. The DD neonates had lower levels of GH, but higher levels of PRL, than other genotypes. POU1F1-alpha mRNA decreased (P<0.05) from days 0 to 30, which paralleled decreases (P<0.05) in GH mRNA as well as PRL and GH plasma levels over the same period. POU1F1-beta mRNA levels did not significantly change over this period. Correlations were significant between POU1F1-alpha mRNA and both GH mRNA and GH plasma concentration levels, as well as between the two POU1F1 mRNA isoforms. Results from this study add to our understanding of the role of POU1F1 in controlling pig development and reproduction.