Submitted on September 11, 2006
Accepted on February 20, 2007
In a hypergravity environment neonatal survival is adversely affected by alterations in dam tissue metabolism rather than reduced food intake
Laura M. Lintault1, Elzbieta I. Zakrzewska1, Rhonda L. Maple1, Lisa A. Baer2, Theresa Marie Casey3*, April E. Ronca4, Charles E. Wade2, and Karen I. Plaut5
1 Animal Science, University of Vermont, Burlington, Vermont, United States
2 US Army Institute for Surgical Research , Fort Sam Houston, Texas, United States; NASA/Ames Research Center, Moffet Field, California, United States
3 Animal Science, Michigan State Univrsity, Anthony Hall, East Lansing, Michigan, 48824, United States; Animal Science, Michigan State University, East Lansing, Michigan, United States
4 Obstetrics and Gynecology, Wake Forest University School of Medicine, Winston-Salem, North Carolina, United States; NASA/Ames Research Center, Moffet Field, California, United States
5 Animal Science, Michigan State University, East Lansing, Michigan, United States; NASA/Ames Research Center, Moffet Field, California, United States
* To whom correspondence should be addressed. E-mail: ande1218{at}msu.edu.
Exposure of rat dams to hypergravity during pregnancy is associated with increased pup mortality, reduced food intake and decreased rates of glucose oxidation and lipogenesis in mammary tissue. We hypothesized that increased pup mortality is due to changes in maternal metabolism and not reduced food intake of dams. Effects of hypergravity on rate of glucose oxidation and lipogenesis in mammary, liver and adipose tissue were measured in rat dams centrifuged at 2.0-g (HG), kept at 1.0-g (control), or fed to match the intake of HG rats (pair-fed) from Gestation day 11 (G11) until G21 or Postpartum d 3 (P3). Body weight, percent body fat, metabolizable energy (ME), and nitrogen balance were significantly less in HG dams compared to controls (p<0.05), however these factors were not different between HG and pair-fed dams. By P3 100% of control and pair-fed pups survived, while only 49% of HG pups survived. At G21, rate of glucose oxidation and lipogenesis in mammary and adipose were less in HG than in control and pair-fed dams (p<0.1 and p<0.05). In liver, at G21 ate of lipogenesis was greater in HG than control and pair-fed dams (p<0.01); at P3, lipogenesis was greater in control than HG and pair-fed (p<0.05). Gene expression of ATP citrate lyase, acetyl-CoA carboxylase and fatty acid synthase increased in liver from pregnancy to lactation in control and pair-fed dams, but not HG dams. Thus reduced food intake and body mass due to hypergravity exposure can not explain the dramatic decrease in HG pup survival.
