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Maternal reproductive experience enhances early postnatal outcome following gestation and birth of rats in hypergravityA major goal of space life sciences research is to broaden scientific knowledge of the influence of gravity on living systems. Recent spaceflight and centrifugation studies demonstrate that reproduction and ontogenesis in mammals are amenable to study under gravitational conditions that deviate considerably from those typically experienced on Earth (1 x g). In the present study, we tested the hypothesis that maternal reproductive experience determines neonatal outcome following gestation and birth under increased (hyper) gravity. Primigravid and bigravid female rats and their offspring were exposed to 1.5 x g centrifugation from Gestational Day 11 either through birth or through the first postnatal week. On the day of birth, litter sizes were identical across gravity and parity conditions, although significantly fewer live neonates were observed among hypergravity-reared litters born to primigravid dams than among those born to bigravid dams (82% and 94%, respectively; 1.0 x g controls, 99%). Within the hypergravity groups, neonatal mortality was comparable across parity conditions from Postnatal Day 1 through Day 7, at which time litter sizes stabilized. Maternal reproductive experience ameliorated neonatal losses during the first 24 h after birth but not on subsequent days, and neonatal mortality was associated with changes in maternal care patterns. These results indicate that repeated maternal reproductive experience affords protection against neonatal losses during exposure to increased gravity. Differential mortality of neonates born to primigravid versus bigravid dams denotes gravitational load as one environmental mechanism enabling the expression of parity-related variations in birth outcome.
Document ID
20040112317
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Ronca, A. E.
(NASA Ames Research Center Moffett Field CA United States)
Baer, L. A.
Daunton, N. G.
Wade, C. E.
Date Acquired
August 21, 2013
Publication Date
September 1, 2001
Publication Information
Publication: Biology of reproduction
Volume: 65
Issue: 3
ISSN: 0006-3363
Subject Category
Aerospace Medicine
Funding Number(s)
CONTRACT_GRANT: MH46485
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Developmental Biology
NASA Center ARC

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