Abstract: Objective To explore the relationship between exposure to the nitric oxide synthesis inhibitor N①-nitro-L-arginine methyl ester (L-NAME) and the impairment of cognitive ability in offspring rats. Methods Maternal rats are randomly divided into 3 groups: (1) high dose group: maternal rats are subcutaneously injected with 125 mg/kg L-NAME in the 13th gestational day, and persisting in 7 days;(2) low dose group: maternal rats are subcutaneously injected with 75mg/kg L-NAME in the 13th gestational day，and persisting in 7 days;(3) control group: maternal rats are subcutaneously injected with 1 ml of 0.9% NaCl in the 13th gestational day, and persisting in 7 days. Afler the maternal rats is spontaneous delivery, the offspring rats are fed till they are 8 weeks old. The offspring rats were tested for visual-spatial learning and memory and spatial localization abilities in Morris water maze. Results In the animal model of preeclampsia, in the 1st day of place navigation test, the escape latent period of high dose group and low dose group is significant longer than that of control group (P＜0.05). In the 4th day, the escape latent period of high dose group is significant longer than that of control group (P＜0.05). In spatial exploration test, the percent of IV quadrant distance of low dose group is significant lower than that of control group(P＜0.05). Conclusion Exposure to the L-NAME results in the impairment of intelligence of the offspring rats. The study pattern has not significant difference. And the memory and space direction ability of offspring rats is impaired.

Key words: Hypertension disorder complicating pregnancy, offspring rat, L-NAME, Morris water maze, cognitive ability