To evaluate the in vivo effects of low-dose-rate (0.7 mGy h(-1)) gamma radiation, abnormal shapes of sperm in the caudal epidydimus of Apodemus agrarius coreae (A. a. coreae) were used. The six categories of abnormal forms (amorphous heads, blunt hooks, excessive hooks, two heads and tails, folded tails and short tails) of sperm were observed eight days after gamma irradiation (0, 0.5, 1 and 2 Gy) with a high dose rate (0.8 Gy min(-1)) and a low dose rate. The frequency of total abnormal sperm gradually increased starting from 0.5 Gy after high-dose-rate radiation. Blunt hooks and short tails shaped sperm, in particular, were gradually increasing in the high-dose-rate irradiated mice. Dose rate reduction effects for the frequency of abnormal sperms in low-dose-rate irradiated mice to high-dose-rate irradiated mice were 1 at 0.5 Gy, 0.7 at 1 Gy and 0.5 at 2 Gy. Our results indicate that low-dose-rate radiation is not detrimental to spermatogenic cells.

Compound 1 exhibited a better memory enhancing effect than tacrine, a positive agent, at the same dose in the passive avoidance test and a similar property in the water-maze test, and its action may be mediated, in part, by the acetylcholine enhancing cholinergic nervous system.

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