Secretory Profiles of Pregnancy‐Associated Glycoproteins at Different Stages of Pregnancy in the Goat

Abstract

ContentsPlasma concentrations of pregnancy‐associated glycoproteins (PAG) were determined in goats during pregnancy by two homologous radioimmunoassays that employed caprine PAG55+62 (caPAG55+62) and caprine PAG55+59 (caPAG55+59) and their specific antisera. The effects of fetal number on PAG concentrations were analysed. The concentrations of caPAG55+62 were higher than that of caPAG55+59 throughout pregnancy (p <0.05). Both caPAG55+62 and caPAG55+59 reached maximal levels in week 8 (48.6 ± 5.0 and 30.4 ± 4.3 ng/ml, respectively), decreased between weeks 12 and 14 (45.5 ± 2.5 to 31.9 ± 2.7 ng/ml and 30.6 ± 2.1 to 15.8 ± 2.8 ng/ml, respectively, p <0.01) and remained relatively constant until parturition. Twin‐bearing goats had higher PAG concentrations than single‐bearing animals, but the difference was only significant in week 4 (52.3 ± 3.7 versus 30.9 ± 3.9 ng/ml and 18.9 ± 1.7 versus 12.6 ± 2.0 ng/ml, for caPAG55+62 and caPAG55+59, respectively, p <.,0.05). This is the first study of PAG concentrations in goat throughout pregnancy by a homologous radioimmunoassay system. The profiles of caPAG55+62 and caPAG55+59 were closely parallel. Concentrations of PAG were lower than those obtained by a heterologous radioimmunoassay and their patterns were also different, due to a different specificity of the antisera used in heterologous system. Goats that delivered twins had higher PAG concentrations at the time of implantation than those that delivered a single fetus, indicating that PAG concentrations provide a useful measure of the trophoblast secretory activity.