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EFFECTS OF HYPERGRAVITY AND FEED INTAKE ON MAMMARY, LIVER, AND ADIPOSE METABOLISM IN PREPARTUM RATS. L. Lintault¹, R. Maple¹, E. Zakrzewska¹, T. Mulvey¹, L. Baer², A. Ronca², C. Wade², K. Plaut¹. ¹University of Vermont, Burlington, ²NASA Ames Research Center, Moffett Field, CA.

   Previous studies have shown that pregnant rats subjected to hypergravity have lower rates of mammary metabolism. Prolactin and/or reduced feed intake may be factors involved in causing this response. To determine if other prolactin responsive tissues react in the same manner and if this response is due to changes in feed intake, prepartum rats were centrifuged at 2.0-g (HG; n=8) or kept at 1.0-g (SC; n=8). An additional 8 rats kept at 1.0-g were pair fed (PF) to match the feed intake of the HG group. HG dams were placed in the centrifuge on day 11 of their 22-23 day gestation, and removed on gestation day 21. Tissues were incubated in Kreb’s Ringer Bicarbonate buffer containing 10mM glucose and U-¹⁴C-glucose for 2, 3 and 4 hours for adipose, mammary and liver respectively. CO₂ was trapped as NaHCO₃ on filter paper suspended in center wells in the flasks. Tissue samples were saponified and lipids extracted with petroleum ether. Glucose oxidation to CO₂ in liver averaged 540 nmol glucose/100mg wet tissue and was not significantly different among treatments. In adipose, glucose oxidation to CO₂ was 88, 185 and 235 nmol/100mg for HG, SC and PF respectively, and was significantly less in HG compared to PF (P<0.01; SEM=33). In liver, glucose incorporation into lipids was very low yet significantly different among treatments (13, 5 and 2 nmol/100mg for HG, SC and PF respectively), with HG rats significantly greater than PF (P<0.01; SEM=2). Glucose incorporation into lipids in adipose tissue was not different among treatments (mean=74). Although glucose oxidation in mammary was 73% of SC (mean=540) and glucose incorporation into lipids was 33% of SC (mean=158), they were not significantly different from SC or PF due to variability among samples. Hypergravity affects tissue metabolism, however feed intake is not a major factor influencing these changes.

(Supported by NASA NCC2-1373 and NASA EPSCoR NCC5-581)