Objective   Through the investigations of the paralytic shellfish poisoning(PSP)on ability of learning and memory and motoractivity in rats to gain more information on toxicity of PSP.

  Methods   PSPwas extracted from the seafood in market, and the toxicity of the extract was deter mined by mouse bioassay.Atotal of 50 rats were divided into 5 groups: three PSP-treated groups were fed with the extracts in 18.4 μg STX/kg/d(hig h), 9.2 μg STX/kg/d(middle), 416 Lg STX/kg/d(low), respectively.Two controls were set, one group was fed with HC1 extracts from no toxic bivalves and the other with nature water.The extr acts in different tox icity were administrated tomrs through gastrotube once a day for 35 days.At the 28th and 29th day of exper iment, changes in ability of learning and memory of rots were investig ated by step-down test and that in motor activity were observed through exhaustive swimming test from the 31st to the 34th day of experiment.

  Results   For the male rats, a significant increase in number of errors of lear ning and a decrease in swimming time occurred in the hig h dose group.For the female rats, the number of errors in learning increased in the middle group and high group, in addition, the incubation period decreased greatly.

  Conclusion   PSPdid damage to the motor act ivity and ability in learning and memory in rats fed with certain PSP.