Impaired mammary function and parathyroid hormone-related protein during lactation in growth-restricted spontaneously hypertensive rats

Wlodek, Mary E.; Westcott, Kerryn T.; Serruto, A.; O'Dowd, Rachael; Wassef, Lesley; Ho, Patricia W. M.; Moseley, J. M.

doi:10.1677/joe.0.1780233

Cited by 21 publications

(34 citation statements)

References 41 publications

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“…Morbidity associated with the relatively low birth weights may have resulted in inadequate suckling, possibly influencing supply. Cross-fostering, used in rodents to eliminate such neonatal confounding (Wlodek et al 2003), is not feasible in sheep. However, the onset of copious milk secretion occurs independently of milk removal in all species (Kulski et al 1978, and our finding of reduced concentration of lactose in milk and postpartum maternal plasma in the BETA group supports the conclusion that secretory activation was delayed in these sheep.…”

Section: Discussionmentioning

confidence: 99%

Disrupted secretory activation of the mammary gland after antenatal glucocorticoid treatment in sheep

Henderson¹,

Hartmann²,

Moss³

et al. 2008

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Antenatal glucocorticoids are administered to women at risk of preterm delivery to prevent neonatal respiratory morbidity. The effects of exogenous glucocorticoids on the development of lactation are unknown. This study investigated the effects of a single dose of antenatal glucocorticoids on secretory activation in sheep before and after parturition. Pregnant ewes (NZ36) were randomised to receive either medroxyprogesterone acetate (MPA) at 118 days of pregnancy and betamethasone at 125 days (BETA group), MPA at 118 days and saline at 125 days (MPA group) or saline at 118 and 125 days (SALINE group). The concentration of lactose, progesterone, cortisol and prolactin in maternal plasma was measured during pregnancy. After term parturition, the concentration of lactose in milk and maternal plasma was measured daily for 5 days. Lambs were weighed at birth and at 5 days of age; milk volume was measured on day 5. The concentration of lactose in maternal plasma increased significantly after betamethasone administration, corresponding to a fall in plasma progesterone. No changes in lactose were observed in MPA or SALINE ewes. Transient decreases in cortisol and increases in prolactin were observed in the BETA group, but not in either the MPA or SALINE group. After parturition, BETA ewes experienced reduced milk yield and lamb weight gain, and delayed increases in milk lactose levels compared with MPA and saline controls. This study demonstrated that, in sheep, antenatal glucocorticoid administration disrupted secretory activation, causing precocious mammary secretion before parturition and compromising postpartum milk production and lamb growth.

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Section: Discussionmentioning

confidence: 99%

Disrupted secretory activation of the mammary gland after antenatal glucocorticoid treatment in sheep

Henderson¹,

Hartmann²,

Moss³

et al. 2008

Reproduction

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“…Systolic blood pressure was measured in preconditioned conscious rats at 6 mo of age by a tail-cuff method, prior to necropsy (46,49). Rats were anesthetized with an intraperitoneal injection of a mixed solution containing ketamine (Parnell Laboratories, Pty., Alexandria, NSW, Australia, 50 mg/kg of body wt) and Ilium Xylazil -20 (Troy Laboratories, Pty., Smithfield, NSW, Australia, 10 mg/kg of body wt).…”

Section: Methodsmentioning

confidence: 99%

Normal lactational environment restores cardiomyocyte number after uteroplacental insufficiency: implications for the preterm neonate

Black

Siebel

Gezmish

et al. 2012

American Journal of Physiology-Regulatory, Integrative and Comp

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A reduced complement of cardiomyocytes in early life can adversely affect life-long cardiac functional reserve. In the present study, using a cross-fostering approach in rats, we examined the contributions of the prenatal and postnatal environments in the programming of cardiomyocyte growth. Rat dams underwent either bilateral uterine vessel ligation (Restricted) or sham surgery (Control) on day 18 of gestation. One day after birth, Control and Restricted pups were cross-fostered onto Control (normal lactation) or Restricted (impaired lactation due to impaired mammary gland formation) mothers. In male offspring, genes involved in cardiomyocyte differentiation, proliferation, hypertrophy and apoptosis were examined at gestational day 20 and postnatal days 1 and 7 to assess effects on cardiomyocyte growth. At postnatal day 7 cardiomyocyte number was determined stereologically. Offspring were examined at age 6 mo for evidence of hypertension and pathological cardiac gene expression. There was an increase in Igf1 and Igf2 mRNA expression in hearts of Restricted pups at gestational day 20. At postnatal day 7, Agtr1a and Agtr1b mRNA expression as well as Bcl2 and Cmyc were elevated in all hearts from offspring that were prenatally or postnatally growth restricted. There was a significant reduction (-29%) in cardiomyocyte number in the Restricted-on-Restricted group. Importantly, this deficit was prevented by optimization of postnatal nutrition (in the Restricted-on-Control group). At 6 mo, blood pressure was significantly elevated in the Restricted-on-Restricted group, but there was no difference in expression of the cardiac hypertrophy, remodeling or angiogenic genes across groups. In conclusion, the findings reveal a critical developmental window, when cardiomyocytes are still proliferating, whereby improved neonatal nutrition has the capacity to restore cardiomyocyte number to normal levels. These findings are of particular relevance to the preterm infant who is born at a time when cardiomyocytes are immature and still dividing.

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“…The serum calcium of lactating rats has been quite variable in published reports, and not clearly explained by the calcium content of the diet: hypercalcemia on 1.5 or 1.2% calcium (86,318); normocalcemia on 1.6% (568), 1% (991), 0.5% (114), 0.4% calcium (91,318,569), and an unspecified diet (337); low blood calcium on 1.2, 0.9, 0.8, and 0.4% calcium (76,90,320,321,568,718,920,927,989); and marked hypocalcemia on 0.1, 0.04, and 0.01% calcium (32,320,321,568,991). The ionized calcium has been low on a 1.6% calcium diet (568), high on a 1.2% calcium diet (318), low on a 0.8% calcium diet (989), normal (318) and low on a 0.4% calcium diet (90,568,569), and low on a 0.1% calcium diet (32, 568).…”

Section: Calcium and Phosphorusmentioning

confidence: 99%

Maternal Mineral and Bone Metabolism During Pregnancy, Lactation, and Post-Weaning Recovery

Kovacs

2016

Physiological Reviews

383

524

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During pregnancy and lactation, female physiology adapts to meet the added nutritional demands of fetuses and neonates. An average full-term fetus contains ϳ30 g calcium, 20 g phosphorus, and 0.8 g magnesium. About 80% of mineral is accreted during the third trimester; calcium transfers at 300-350 mg/day during the final 6 wk. The neonate requires 200 mg calcium daily from milk during the first 6 mo, and 120 mg calcium from milk during the second 6 mo (additional calcium comes from solid foods). Calcium transfers can be more than double and triple these values, respectively, in women who nurse twins and triplets. About 25% of dietary calcium is normally absorbed in healthy adults. Average maternal calcium intakes in American and Canadian women are insufficient to meet the fetal and neonatal calcium requirements if normal efficiency of intestinal calcium absorption is relied upon. However, several adaptations are invoked to meet the fetal and neonatal demands for mineral without requiring increased intakes by the mother. During pregnancy the efficiency of intestinal calcium absorption doubles, whereas during lactation the maternal skeleton is resorbed to provide calcium for milk. This review addresses our current knowledge regarding maternal adaptations in mineral and skeletal homeostasis that occur during pregnancy, lactation, and post-weaning recovery. Also considered are the impacts that these adaptations have on biochemical and hormonal parameters of mineral homeostasis, the consequences for long-term skeletal health, and the presentation and management of disorders of mineral and bone metabolism.

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Impaired mammary function and parathyroid hormone-related protein during lactation in growth-restricted spontaneously hypertensive rats

Cited by 21 publications

References 41 publications

Disrupted secretory activation of the mammary gland after antenatal glucocorticoid treatment in sheep

Disrupted secretory activation of the mammary gland after antenatal glucocorticoid treatment in sheep

Normal lactational environment restores cardiomyocyte number after uteroplacental insufficiency: implications for the preterm neonate

Maternal Mineral and Bone Metabolism During Pregnancy, Lactation, and Post-Weaning Recovery

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