| Budget Amount *help |
¥2,400,000 (Direct Cost: ¥2,400,000)
Fiscal Year 1998: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1997: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Research Abstract |
Studies were performed to determine the relation between the morphological abnormalities of the hippocampus and the behavioral indices in rats exposed to prenatal methylazoxymethanol acetate (MAM) or with neonatal hippocampal lesions, in attempts to produce a model of attention-deficit hyperactive disorders (ADHD). Rats were subjected to a open-field, a shuttle-box avoidance and a radial maze learning tests during weaning or adult period.
Result were follows : 1) Rats treated MAM on the day 13 or 15 of gestation (G) showed hyperactivity at the weaning stage, but not at the adult period, 2) The G13 and G15 MAM rats showed a facilitated avoidance learning, whereas the G17 and G19 MAM rats showed a disability of avoidance learning compared to the controls, 3) The G13 and G15 MAM rats showed a learning deficit in the place-learning task but not in the cue-learning task on a 8-arm radial maze, 4) The G13 MAM rats showed an impairment of working memory when the retention interval was 10 min or more on a radial-arm maze retention task, 5) Rats lesioned the hippocampus on the day of birth showed a place-learning deficit on a 8-arm radial maze. Model animals which showed a hyperactivity, a facilitated avoidance and a spatial learning deficit in MAM rats tad mophological abnormalities of the hippocampus (occasional disruptions of the CAl pyramidal layer and/or numerous ectopic pyramidal neuron mass).
These behavioral disorders seem to be similar to those in ADHD children. Our findings indicate that the ADHD syndrome might be caused by hippocampal dysfunction which was occurred during perinatal period.
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