ARG@SU-AI.ARPA (Ron Goldman) (10/15/85)
a228 1314 14 Oct 85
AM-Shuttle Rats, Bjt,0630
Space Rats Suffered Dramatic Reductions in Growth Hormones
By MAUD S. BEELMAN
Associated Press Writer
STATE COLLEGE, Pa. (AP) - The 24 rats who rode into space on the
shuttle Challenger last April suffered dramatic reductions in the
release of growth hormone, a finding that could signal a serious
problem for astronauts, a researcher said Monday.
Wesley Hymer, a biochemist at Pennsylvania State University, was one
of 20 researchers nationwide who analyzed tissue samples from the
rats. His interest was what effect, if any, weightlessness had on the
ability of special cells in their pituitary glands to produce growth
hormones, which govern development and maintenance of muscle and bone
tissue.
Hymer's findings were the second indication of a potential space
flight hazard. Another National Aeronautics and Space Administration
researcher reported last month that the same rats lost bone and
muscle strength.
Richard Grindeland, a researcher at the Ames Research Center in
California, said that when the rats returned to Earth ''they were
limp, like dishrags,'' and that dissection revealed ''very dramatic
changes'' in bone and muscle strength.
Before beginning any long-term space flights, NASA needs to know if
humans suffer the same kind of changes.
Researchers need more test results before linking growth hormone
reduction to muscle and bone atrophy, Hymer said. But ''I think
there's probably a good chance that there's a relationship.''
Until scientists are certain that the lack of hormone release is
causing the muscle and bone atrophy, ''we can't, for example, suggest
extra doses of growth hormone as a possible way to prevent the
problem.''
After a battery of tests that included implanting normal rats with
growth hormone cells from the space rats, Hymer noted up to a 50
percent reduction in release of the hormone.
''Something is radically changed in those pituitary glands as a
result of the space flight,'' Hymer said.
''The cells from the flight-exposed animals were not able to release
as much growth hormone as the corresponding controls (rats on the
ground) - they worked about half as well,'' said Hymer, who will
discuss his findings Friday along with other researchers on the NASA
project at the Commission on Gravitational Physiology in Niagara
Falls, N.Y.
''I think the surprising thing was these changes occurred so
quickly,'' Hymer said. ''They happened in seven days in flight.''
Another unexpected finding, Hymer noted, was that although the space
rat cells only released half as much growth hormone as the cells of
control rats, they still contained two to three times more unreleased
hormone than did the cells of the control rats.
''We don't really know what's happening,'' he said.
''There could be more inhibitory chemicals coming from the brain
down to the pituitary and shutting off the release of hormone so that
the cells contain more hormone,'' Hymer said. Or there could be a
lack of stimulatory chemicals, which would also inhibit release of
the hormone.
But Hymer said he leans toward the possibility that the minute
gravity of near-Earth orbit is directly affecting the cells,
referring to a 1983 study of cultures of isolated growth hormone
cells that were taken into space.
''Those cells didn't release as much growth hormone in the test
tube. There you don't have any stimulatory or inhibitory molecules''
that could be causing the change, he said.
Hymer said researchers don't know yet if astronauts suffer the same
kind of changes.
''I can tell you that there are data that show that the blood levels
of growth hormone in the astronauts from Skylab were ... reduced by a
significant amount,'' Hymer said.
Hymer plans to send growth hormone cells, some of which will contain
the inhibitory and stimulatory chemicals, on a shuttle flight next
September for further tests. He said he also would like to see
similar experiments on primates.
AP-NY-10-14-85 1616EDT
***************fair@ucbarpa.BERKELEY.EDU (Erik E. &) (10/15/85)
Since there is (as I understand things) an agreement between the US and Soviet space research communities to share data, don't we have access to the physiological data collected on the various cosmonaut crews that have been in orbit for 200+ days at a time? I would expect that this data, along with that collected by the three Skylab crews would give a quite comprehensive picture of what happens to man in space over the medium to long term (of course, we may not *understand* the picture; I'm just suggesting a lot of useful data is already there). Erik E. Fair ucbvax!fair fair@ucbarpa.BERKELEY.EDU