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Philip Cohen
(All rights remain in the hands of New Scientist or the author, Philip Cohen. This work cannot be distributed or printed for profit without the permission of the aforesaid company or the author.)
'EXPECTANT mothers have long since been warned to avoid cigarettes, alcohol and many medicines. Now scientists have added another item to the list of taboos: space travel. Researchers in the US say female rats that flew into space suffered a difficult labor, and produced young that were disoriented by gravity.
The research, presented last week at a meeting of the American Psychological Society in San Francisco, is part of an ongoing study of the effects of microgravity by psychobiologists Jeff Alberts and April Ronca of Indiana University in Bloomington.
Nine days after conception, the pregnant rats were shot up in the space shuttle and spent nine days - or 40 per cent of their gestation time - in orbit. While circling the planet in June 1995, the pregnant rats gained weight normally, and appeared as active and healthy as a group of rats kept in an identical container at the same temperature and pressure back on Earth.
But differences became apparent once the rats landed. They were monitored with video cameras to catch the moment of birth and the pictures showed that spacefaring rats needed about 100 contractions to deliver their pups - twice that of the controls. Alberts and Ronca believe the extra squeezing was necessary because the animal's muscles had weakened during weightlessness.
The researchers had earlier detected other dramatic consequences of spaceflight on the unborn fetuses. Two hours after the rats had landed, Alberts and Ronca used hair-thin electrodes to measure the heart rate of the fetuses as each was tilted briefly, from lying on its side to a sitting posture and back again. For a normal rat fetus, this slight disorientation raises the heart rate by 1.5 per cent. But the heart rates of the fetuses in rats which had flown on the shuttle dropped by 8 per cent.
This extreme sensitivity to disturbance, says Alberts, probably reflects a difference in how the vestibular system of the inner ear, which controls balance, develops in space. "Their nervous system just isn't used to the constant pull of gravity," he says.
Even so, Alberts points out that the rats subsequently appeared to develop normally. This will be important if inhabitants of future lab stations want to keep colonies of lab animals for research, he says, or if pregnant women fly in space. Indeed, Alberts says that the real problem may not be living in space, but switching between microgravity and Earth. "We may find that if you grow up in space, it's best that you stay there for the rest of your life," he says.'
Philip Cohen, San Francisco
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