NASA Scientific and Technical Aerospace Reports

Body weights of rat pups reared during exposure to hypergravity (hg) are significantly reduced relative to 1 g controls.
In the present study, we examined in hg-reared rat pups two major contributors to growth and development, namely growth
hormone (GH) and insulin-like growth factor-1 (IGF-1). Beginning on Gestational day (G)11 of the rats 22 day pregnancy,
rat dams and their litters were continuously exposed to either 1.5-g or 2.0-g. On Postnatal day (P)l0, plasma GH and IGF-1
were analyzed using radioimmunoassay (RIA). Both hormones were significantly elevated in hg pups relative to 1-g control
pups. Together, these findings suggest that GH and IGF-1 are not primary determinants of reduced body weights observed in
hg-reared pups. The significant elevations in pup GH and IGF-1 may be related to increased physical stimulation in
hypergravity.
Author
High Gravity Environments; Growth; Insulin; Rats; Pituitary Hormones
20040070926 NASA Ames Research Center, Moffett Field, CA, USA
Re-Adaptation to 1-G of Pregnant Rats Following Exposure to Spaceflight or Centrifugation
Johnson, K. E.; Ronca, A. E.; Alberts, J. R.; Journal of Gravitational Physiology; July 2003; ISSN 1077-9248; Volume 10, No.
1, pp. 69-70; In English; 24th Annual Gravitational Physiology Meeting, 4-9 May 2003, Santa Monica, CA, USA
Contract(s)/Grant(s): NAG2-6072; NCC2-870; NIH-MH46485; NIH-MH283555; RTOP 121-10-40; Copyright; Avail: Other
Sources
Late-pregnant rat dams were flown on a 9-day Space Shuttle mission or exposed to 1.5, 1.75 or 2-g centrifugation and
compared with 1 .O-g vivarium controls. Exposure to altered gravity began on the 11th day and recovery occurred on the 20th
day of the dams’ 22-day pregnancy. In the 1 st experiment, comparisons were made between Flight (FLT), Synchronous (SYN;
identically-housed) and Vivarium (VIV) controls. In the 2nd experiment, comparisons were made between dams centrifuged
at 2-G, 1.75-G, 1.5-G, Rotational controls (1.08-G) or Stationary controls (1 G). Within three hours of recovery from either
spaceflight or centrifugation, the dams’ locomotor behavior was videotaped for 2 min. FLT dams showed dramatically reduced
movement relative to both SYN and VIV control conditions, with significantly greater amounts of locomotor activity observed
in SYN as compared to VIV dams. Significantly greater locomotor activity was observed in SYN as compared to VIV controls.
In the second experiment, no differences were observed between dams exposed either 1, 1.5, 1.75, or 2-G. In both studies, the
dams showed similar patterns of hindlimb rearing. Together, these findings provide quantitative evidence for decreased
locomotor activity during re-adaptation to 1-g following spaceflight, but not centrifugation.
Author
Adaptation; Exposure; Pregnancy; Rats; Space Flight
20040070928 California Univ., Irvine, CA, USA
Effects of Hindlimb Unweighting on Arterial Contractile Responses in Mice
Ma, Jia; Ren, Xin-Ling; Purdy, Ralph E.; Journal of Gravitational Physiology; July 2003; ISSN 1077-9248; Volume 10, No.
1, pp. P79-P80; In English; 24th Annual Gravitational Physiology Meeting, 4-9 May 2003, Santa Monica, CA, USA; Original
contains black and white illustrations
Contract(s)/Grant(s): NAG2-6072; NAG9-1149; Copyright; Avail: Other Sources
The aim of this work was to determine if hindlimb unweighting in mice alters arterial contractile responses. Sixteen male
C57B/6 mice and 16 male Chinese Kunming mice were divided into control and 3 weeks hindlimb unweighting groups,
respectively. Using isolated arterial rings from different arteries of mouse, effects of 3 weeks hindlimb unweighting on arterial
contractile responsiveness were examined in vitro. The results showed that, in arterial rings from both C57B/6 and Chinese
Kunming mice, maximum isometric contractile tensions evoked by either KCl or phenylephrine were significantly lower in
abdominal aortic, mesenteric arterial and femoral arterial rings from hindlimb unweighting, compared to control mice.
However, the maximal contractile responses of common carotid rings to KCl and PE were not significantly different between
control and hindlimb unweighting groups. The sensitivity (EC(sub 50)) of all arteries to KCl or PE showed no significant
differences between control and hindlimb unweighting mice. These data indicated that 3 weeks hindlimb unweighting results
in a reduced capacity of the arterial smooth muscle of the hindquarter to develop tension. In addition, the alterations in arterial
contractile responses caused by hindlimb unweighting in mice are similar as those in rats. Our work suggested that hindlimb
unweighting mouse model may be used as a model for the study of postflight cardiovascular deconditioning.
Author
Abdomen; Arteries; Cardiovascular System; Deconditioning; Muscles; Neck (Anatomy)
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