Effect of irradiation at the early foetal stage on adult brain function of mouse: learning and memory.
OBJECTIVE
To study the long-term effect of early foetal irradiation on the learning and memory in the adult mouse.


METHODS
The abdominal area of pregnant Swiss albino mice was exposed to a single dose of 0.25-1.5Gy gamma-radiation on the 14th day of gestation and the mice were left to deliver their offspring. At 6 months of age, the learning and memory functions of the F(1) mice were tested by hole-board activity, conditioned avoidance response and radial arm maze performance. The animals were again subjected to the radial arm maze test at 12 and 18 months of age.


RESULTS
There was a significant dose-dependent decrease in the learning ability and memory retention of 6-month-old mice at doses > 0.25Gy. The significant changes persisted to 18 months of age in mice exposed to >or= 0.5Gy. All changes showed a linear dose-response at doses < 1Gy.


CONCLUSIONS
The gestational day 14 of Swiss albino mice is a sensitive stage in brain development to gamma-ray-induced impairment of learning and memory during the adult life. Permanent deficits in these functions can be induced by a dose of approximately 0.5Gy at this stage, when the developmental activity of the cerebral cortex is at its peak.
Hossain
M
M
Department of Radiobiology, Kasturba Medical College, Manipal 576 119, India.
Uma Devi
P
P
D000367:Age Factors; D000818:Animals; D001362:Avoidance Learning / Q000528:radiation effects*; D001522:Behavior, Animal / Q000528:radiation effects; D001921:Brain / Q000502:physiology / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D005260:Female; D007859:Learning Disabilities / Q000209:etiology; D008297:Male; D018782:Maze Learning / Q000528:radiation effects*; D008568:Memory / Q000528:radiation effects*; D008569:Memory Disorders / Q000209:etiology; D051379:Mice; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D011833:Radiation Injuries, Experimental / Q000209:etiology