Reduced fetal, placental, and amniotic fluid PTHrP in the growth-restricted spontaneously hypertensive rat

Abstract

Evidence implicates pivotal roles for parathyroid hormone-related protein (PTHrP) in stimulating cell growth and differentiation, placental calcium transport, and placental vasodilatation. As spontaneously hypertensive rat (SHR) fetuses are growth restricted compared with those of its normotensive control, the Wistar Kyoto (WKY) rat, we examined intrauterine PTHrP and total and ionic calcium concentrations in these rats. Fetal plasma PTHrP concentrations, but not total calcium concentrations, were lower in the SHR compared with WKY (P < 0.05). SHR placental concentrations of PTHrP were lower than in WKY (P < 0.03) and failed to show the increase observed in WKY near term (P < 0.05). PTHrP concentrations in amniotic fluid from SHR were not raised near term and were lower compared with WKY (P < 0.0005). The increased ionic calcium concentrations in amniotic fluid in the WKY near term (P < 0.05) were not detected in the SHR. Thus SHR fetal plasma, placental, and amniotic fluid PTHrP concentrations were reduced and associated with fetal growth restriction. We suggest that PTHrP may play a role in the etiology of both growth restriction during pregnancy and hypertension later in life.

Effects of Parathyroid Hormone Like Hormone (PTHLH) Antagonist, PTHLH7–34, on Fetoplacental Development and Growth During Midgestation in Rats1

“…In the placenta, PTHLH is expressed in syncytial trophoblasts [15], and is reported to stimulate Ca 2þ transport across the basal membrane [16], indicating a role for PTHLH in the nutrient exchange between the mother and fetus during pregnancy. Decreased PTHLH expression observed in the placenta of spontaneously hypertensive rats is associated with fetal growth restriction [17]. Together, these findings provide evidence that PTHLH may be involved in fetoplacental growth during pregnancy.…”

Uteroplacental insufficiency reduces rat plasma leptin concentrations and alters placental leptin transporters: ameliorated with enhanced milk intake and nutrition

“…Total calcium concentrations were determined using colorimetric spectrometry using the Synchron CX‐5 Clinical System (Beckman Coulter; Lane Cove, NSW, Australia) and ionic calcium (active or free calcium; regulated by PTHrP), sodium and potassium concentrations were determined using ion selective electrodes correcting for pH (Ciba‐Corning model 644; Cambridge, MA, USA) from milk as well as from pup and maternal plasma (Wlodek et al . , ). Total calcium concentration in the pup body was determined after ashing using the CX‐5 Analyser (Wlodek et al .…”

Effects of uteroplacental insufficiency and reducing litter size on maternal mammary function and postnatal offspring growth

“…Protein was extracted from mammary and uterine tissue using previously established techniques, and the extract was analyzed for PTHrP concentrations by radioimmunoassay (57)(58)(59). Plasma, milk, and tissue concentrations of PTHrP were quantified by a sensitive NH2-terminal radioimmunoassay that does not recognize parathyroid hormone (18,(57)(58)(59). Total calcium concentrations were determined using a Beckman Synchron CX-5 Clinical System with colorimetric spectrometry (Beckman Coulter, Fullerton, CA) and ionic calcium concentrations using ion-selective electrodes correcting for pH (Ciba-Corning model 644, Medfield, MA) from milk.…”