Abstract
The roles of the pregnancy lactogens in the growth and development of the fetal rat are poorly understood. We measured the concentrations of placental lactogen II (rPL-II) in fetal rat serum and examined the distribution and mRNA expression of lactogenic receptors in embryonic and fetal tissues. The concentration of rPL-II in fetal serum (day 20 gestation) was 28.3 ± 0.8ng/ml (n = 6), = 1/10th that in maternal serum (398.3 ± 45.3 ng/ml). At physiological concentrations, rPL-II bound specifically to the fetal adrenal, kidney, intestine, liver and pancreas. rPL-1, expressed on days 10-12, bound to chorion and mesometrial decidua. The binding of rPL-1 & II were blocked by rat prolactin (PRL) but not by rat GH, suggesting a common PL/PRL receptor. Fetal tissues expressed four PRL receptor mRNA transcripts (12, 6.6, 4.2, 1.8 kb). The relative intensities with which fetal tissues bound rPL correlated with levels of the 4.2 and 1.8 kb transcripts. The observation that rPL-1 binds to chorion and decidua suggests a paracrine role for rPL-1 in the regulation of maternal decidual function. The demonstration that rPL-II circulates in fetal blood and binds to lactogenic receptors in fetal tissues implicates a role for the pregnancy lactogens in fetal development.
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Freemark, M., Kirk, K., Pihoker, K. et al. PREGNANCY LACTOGENS IN THE RAT CONCEPTUS: CIRCULATING LEVELS, DISTRIBUTION OF BINDING, AND EXPRESSION OF RECEPTOR mRNA. Pediatr Res 33 (Suppl 5), S71 (1993). https://doi.org/10.1203/00006450-199305001-00406
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DOI: https://doi.org/10.1203/00006450-199305001-00406