Kristina Anevska

Pregnant growth restricted female rats have bone gains during late gestation which contributes to second generation adolescent and adult offspring having normal bone health

Low birth weight, due to uteroplacental insufficiency, results in programmed bone deficits in the first generation (F1). These deficits may be passed onto subsequent generations. We characterized the effects of being born small on maternal bone health during pregnancy; and aimed to characterize the contribution of the maternal environment and germ line effects to bone health in F2 offspring from mothers born small. Bilateral uterine vessel ligation (or sham) surgery was performed on female F0 WKY rats on gestational day 18 (term 22days) to induce uteroplacental insufficiency and fetal growth restriction. Control and Restricted F1 female offspring were allocated to a non-pregnant or pregnant group. To generate F2 offspring, F1 females were allocated to either non-embryo or embryo transfer groups. Embryo transfer was performed on gestational day 1, where second generation (F2) embryos were gestated (donor-in-recipient) in either a Control (Control-in-Control, Restricted-in-Control) or Restricted (Control-in-Restricted, Restricted-in-Restricted) mother. Restricted F1 females were born 10-15% lighter than Controls. Restricted non-pregnant females had shorter femurs, reduced trabecular and cortical bone mineral contents, trabecular density and bone geometry measures determined by peripheral quantitative computed tomography (pQCT) compared to non-pregnant Controls. Pregnancy restored the bone deficits that were present in F1 Restricted females. F2 non-embryo transfer male and female offspring were born of normal weight, while F2 embryo transfer males and females gestated in a Control mother (Control-in-Control, Restricted-in-Control) were heavier at birth compared to offspring gestated in a Restricted mother (Restricted-in-Restricted, Control-in-Restricted). Male F2 Restricted embryo groups (Restricted-in-Control and Restricted-in-Restricted) had accelerated postnatal growth. There was no transmission of bone deficits present at 35days or 6months in F2 offspring. Embryo transfer procedure had confounding effects preventing the separation of maternal environment and germ line contribution to outcomes. Deficits present in F1 non-pregnant Restricted females were absent during late gestation, indicating that pregnant F1 Restricted females experienced gains in bone. These beneficial maternal pregnancy adaptations may have prevented transmission of bone deficits to F2 offspring.

Maternal exercise in rats upregulates the placental insulin‐like growth factor system with diet‐ and sex‐specific responses: minimal effects in mothers born growth restricted

The placental insulin‐like growth factor (IGF) system is critical for normal fetoplacental growth, which is dysregulated following several pregnancy perturbations including uteroplacental insufficiency and maternal obesity. We report that the IGF system was altered in placentae of mothers born growth restricted compared to normal birth weight mothers, with maternal diet‐ and fetal sex‐specific responses. Additionally, we report increased body weight and plasma IGF1 concentrations in fetuses from chow‐fed normal birth weight mothers that exercised prior to and continued during pregnancy compared to sedentary mothers. Exercise initiated during pregnancy, on the other hand, resulted in placental morphological alterations and increased IGF1 and IGF1R protein expression, which may in part be modulated by reduced Let 7f‐1 miRNA abundance. Growth restriction of mothers before birth and exercise differentially regulate the placental IGF system with diet‐ and sex‐specific responses, probably as a means to improve fetoplacental growth and development, and hence neonatal survival. This increased neonatal survival may prevent adult disease onset.

Maternal Stress During Pregnancy Programs Nephron Deficits and Gender Specific Hypertension in Second Generation Offspring

### EXCESS PRENATAL CORTICOSTERONE EXPOSURE PROGRAMS HYPOTENSION, VASCULAR REMODELLING AND ALTERS THE RESPONSE TO RESTRAINT STRESS IN ADULT MALE MICE O’Sullivan L, Cuffe JSM, Koning A, Singh RR, Moritz KM, Paravicini TM School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia Background: Exposure to excess glucocorticoids in utero is known to program susceptibility to cardiovascular disease in later life. Endogenous levels of glucocorticoids are increased during periods of stressThe long-term cardiovascular implications for the offspring of women who suffer from stress during pregnancy are, however, poorly understood. Aim: To examine the direct effects of prenatal corticosterone (CORT) exposure on cardiovascular and renal outcomes in adult offspring. Methods: Pregnant C57Bl6 mice received CORT (33 g/kg/h) for 60 h from embryonic day 12.5 and allowed to litter naturally. Nephron number was determined in the offspring at postnatal day 30, and radiotelemetry was used to measure blood pressure and heart rate (both basal and during restraint stress) at 12 months. Pressurized myography was used to assess vascular function, structure and mechanics. Results: Excess prenatal CORT reduced nephron endowment by 33% and 20% in male and female offspring (respectively) compared to untreated controls (n=6–7; P <0.05). At 12 months, CORT-exposed male offspring were hypotensive: MAP 104.3 11.0 vs 115.6 5.5 mmHg in untreated controls (n=8–9; P <0.05). These mice also showed a blunted tachycardiac response to restraint stress. Power spectral density analysis of heart rate suggested that this may be due to an altered vagal/sympathetic balance. Prenatal CORT reduced activity levels of female offspring at night, but did not alter any cardiovascular parameters. In male offspring (but not females), prenatal CORT caused inward remodeling of mesenteric arteries (luminal diameter = 202 7 m vs 249 9 m in controls) without affecting vascular reactivity or the elasticity of vascular wall components. Conclusion: Prenatal CORT exposure programs hypotension in male offspring, despite the reduced nephron number and inward vascular remodeling in these animals. In …

Maternal stress does not exacerbate long-term bone deficits in female rats born growth restricted, with differential effects on offspring bone health

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 on Wistar-Kyoto rats. At 4 mo, 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 mo. Second-generation (F2) offspring generated four experimental groups: control unstressed, restricted unstressed, control stressed and restricted stressed. F2 offspring were studied at postnatal day 35 (PN35), 6, 12, and 16 mo. Peripheral quantitative computed tomography 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 mo. F2 offspring of stressed mothers were born lighter. F2 male offspring from stressed pregnancies had decreased trabecular content at 6 mo and decreased endosteal circumference at 16 mo. F2 female offspring from growth-restricted mothers had reduced cortical thickness at PN35 and reduced endosteal circumference at 6 mo. At 12 mo, 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.