Maternal stress does not exacerbate long-term bone deficits in female rats born growth restricted, with differential effects on offspring bone health
AJP Regulatory Integrative and Comparative Physiology
Published online on October 04, 2017
Abstract
Females born growth restricted have poor adult bone health. Stress exposure during pregnancy increases risk of pregnancy complications. We determined whether maternal stress exposure in growth restricted females exacerbates long-term maternal and offspring bone phenotypes. On gestational day 18, bilateral uterine vessel ligation (Restricted) or sham (Control) surgery was performed in WKY rats. At 4 months, Control and Restricted females were mated and allocated to Unstressed or Stressed pregnancies. Stressed pregnancies had physiological measurements performed, Unstressed females were not handled. After birth, mothers were aged to 13 months. Second-generation (F2) offspring generated 4 experimental groups; Control-Unstressed, Restricted-Unstressed, Control-Stressed and Restricted-Stressed. F2 offspring were studied at postnatal day 35 (PN35), 6, 12 and 16months. Peripheral quantitative computed tomography (pQCT) was performed on maternal and F2 offspring femurs. Restricted females, irrespective of stress during pregnancy, had decreased endosteal circumference, bending strength and increased osteocalcin concentrations after pregnancy at 13 months. F2 offspring of Stressed mothers were born lighter. F2 male offspring from Stressed pregnancies had decreased trabecular content at 6 months and decreased endosteal circumference at 16 months. F2 female offspring from growth restricted mothers had reduced cortical thickness at PN35 and reduced endosteal circumference at 6 months. At 12 months, females from Unstressed Restricted and Stressed Control mothers had decreased trabecular content. Low birth weight females had long-term bone changes, highlighting programming effects on bone health. Stress during pregnancy did not exacerbate these programmed effects. Male and female offspring responded differently to maternal growth restriction and stress, indicating gender-specific programming effects.