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Effects of prenatal irradiation with accelerated heavy-ion beams on postnatal development in rats : III.Testicular development and breeding activity
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With a significant increase in human activities dealing with space
missions, potential teratogenic effects on the mammalian reproductive system
from prenatal exposure to space radiation have become a hot topic that needs
to be addressed. However, even for the ground experiments, such effects from
exposure to high LET ionizing radiation are not as well studied as those for
low LET ionizing radiations such as X-rays. Using the Heavy Ion Medical
Accelerator in Chiba (HIMAC) and Wistar rats, effects on gonads in prenatal
male fetuses, on postnatal testicular development and on breeding activity
of male offspring were studied following exposure of the pregnant animals to
either accelerated carbon-ion beams with a LET value of about 13 keV/microm or
neon-ion beams with a LET value of about 30 keV/microm at a dose range from 0.1
Gy to 2.0 Gy on gestation day 15. The effects of X-rays at 200 kVp estimated
for the same biological end points were studied for comparison. A
significantly dose-dependent increase of apoptosis in gonocytes appeared 6
hours after irradiations with a dose of 0.5 Gy or more. Measured delayed
testis descent and malformed testicular seminiferous tubules were observed
to be significantly different from the control animals at a dose of 0.5 Gy.
These effects are observed to be dose- and LET- dependent. Markedly reduced
testicular weight and testicular weight to body weight ratio were scored at
postnatal day 30 even in the offspring that were prenatally irradiated with
eon ions at a dose of 0.1 Gy. A dose of 0.5 Gy from neon-ion beams induced a
marked decrease in breeding activity in the prenatally irradiated male rats,
while for the carbon-ion beams or X-rays, the significantly reduced breeding
activity was observed only when the prenatal dose was at 1.0 Gy or more.
These findings indicated that prenatal irradiations with heavy ion beams on
gestation day 15 generally induced markedly detrimental effects on prenatal
gonads, postnatal testicular development and male breeding activity in rats,
which seemed to be a dose and LET-related event.
Effects of prenatal irradiation with accelerated heavy-ion beams on postnatal development in rats : III.Testicular development and breeding activity
