Rat gestation during space flight: Outcomes for dams and their offspring born after return to earth

Abstract

Abstract--Sprague-Dawley rats were studied to learn whether gestation in the near-zero gravity, high radiation environment of space impacts selected mammalian postnatal events.Ten rats spent days nine to twenty of pregnancy aboard the space shuttle orbiter Atlantis (STS-66). Their movement was studied shortly after return to Earth; subsequently, several of their offspring were cross-fostered and examined through postnatal day 81 (P81) for whole body growth and somatic motor development.Values for the flight animals were compared to ground-based control groups. Relative to controls, the pregnant flight rats showed a marked paucity of locomotion during the first few hours after returning to Earth.There was greater likelihood of perinatal morbidity for the offspring of flight dams when compared to the control groups. Whole body weight of surviving offspring, averaged for each group separately, showed typical sigmoidal growth curves when plotted against postnatal age. The flight group for our study had a larger ratio of female to male pups, and that was sufficient to account for the lower average daily weight gained by the flight animals when compared to the control groups. Walking was universally achieved by PI3 and preceded eye opening, which was complete in all pups by P17. Thus, both of these developmental horizons were attained on schedule in the flight as well as the control rats. Characteristic changes were observed in hind limb step length and gait width as the pups grew. These patterns occurred at the same time in each group of rats. Therefore, prenatal space flight from days nine to twenty of gestation did not interfere with the establishment of normal patterns for hind paw placement during walking.

Ontogeny of Mouse Vestibulo-Ocular Reflex Following Genetic or Environmental Alteration of Gravity Sensing

“…Experiments conducted on rats exposed to environmental deprivation of gravity during gestation concluded in a normal development in space. Hence, no change were found on ground in motor behavior such as walking (11 days µG between embryonic day E9–E20; [67]), righting response, negative geotaxis or rotating platform (5 days µG, E13–E18; [68], [69]). However, following 11 days in µG (E9–E20) vestibular-specific tests suggested a retarded ability to respond to gravistatic stimuli [70], abnormal water immersion responses [71], and increased bradychardia following roll stimulation [7].…”

The development of vestibular system and related functions in mammals: impact of gravity

“…Rats flown in a space flight prenatally (E8–E19) showed an early righting impairment that was recovered from PND5 (Ronca and Alberts, 1997, 2000; Ronca et al, 2000, 2008). Eventually, they did not show any change on successive timing of hind limb motor development over a period of 81 days after landing (Wong and Desantis, 1997). Rats exposed postnatally to the space environment (from PND15 to PND24 or from PND14 to PND 30) were able to swim (Temple et al, 2002; Walton et al, 2005a), and to perform surface righting at landing time.…”

Ground-Based Researches on the Effects of Altered Gravity on Mice Development

“…Flown rats showed an early impairment of vestibular reactions (righting test, horizontal rotation) that disappeared from P5, indicating a fast recovery (Ronca and Alberts 1997). Eventually, flown rats did not show any change on successive timing of hind limb locomotor development (Wong and DeSantis 1997). On the other hand, rat pups exposed shortly after birth (from the age of P5, P7 or P15) to 16 days of μG in a space shuttle showed deficits in their motor behaviour at their return (surface righting), with differences depending on the age and duration of exposure to the altered gravitational environment (Walton et al 2005).…”