Osteocalcin as an index of osteoblast function during and after ovine pregnancy

Abstract

Fetal and neonatal calcium requirements impose heavy demands on maternal bone and mineral homeostasis. The functional response of maternal osteoblasts to this stress is poorly understood. Therefore, plasma osteocalcin (OC) levels were measured by homologous RIA in age-matched nonpregnant, pregnant, and postpartum ewes to evaluate osteoblast function. In pregnant ewes from day 35 of gestation to term, the plasma OC level was suppressed to 8.2 ± 0.5 μg/liter (mean ± SEM; n = 36) compared with age-matched nonpregnant ewes (18.3 ± 1.1 μg/liter; n = 39; P < 0.0005). Plasma OC rose to the nonpregnant value by day 20 postpartum and was elevated above this level for the following 40 days (e.g. 44.0 ..