| ObjectiveIn this study,Morris water maze neurobehavioral tests were performed on rats exposed to styrene,and Through the nitric oxide(NO)in hippocampus content,nitric oxide synthase(NOS)activity,N-methyl-D-aspartate receptor(NMDAR)subunit NR1,NR2A,NR2B protein expression and mRNA transcription level effects to further explore the effect and mechanism of styrene on learning and memory.Has an important social significance to protect the health and safety of workersMethodsSixty-four healthy adult Wistar rats,weighing 180g or 220g,were randomly divided into 4 groups:control group and low,medium and high dose groups,with 16 rats in each group.The dose of styrene was divided into 1/16 LD50(0.31g/kg)?1/8 LD50(0.62g/kg)?1/4LD50(1.25g/kg).The way of exposure was oral gavage(0.01ml/g mouse weight),the control group was given the same amount of corn oil,1 time/d for 4 weeks.The effects of styrene exposure on learning and memory ability of rats were measured by Morris water maze test.The brain was taken and the hippocampus was isolated.The content of NO and NOS in hippocampus of rat were determined by kit method.Real-time PCR was used to detect the mRNA transcription levels of NMDAR subunits NR1,NR2A and NR2B in the hippocampus of 8 rats.Western blot was used to detect the expression of NMDAR subunits NR1,NR2A and NR2B in hippocampus of the remaining 8 rats in the same group.Results1.The results of Morris water maze in rats exposed to styrene showed that on the 4th day of the navigation experiment,the time of finding the platform in the high dose group was significantly longer than that in the control group(P<0.05).On the 5th day of navigation,the time of finding platform in the medium and high dose group way significantly longer than that in the control group(P<0.05).In the space exploration experiment,the number of effective platform rats in high dose group was significantly less than that of the control group,the difference was statistically significant(P<0.01).The retention time in the 4th quadrant of the rats in the high dose group was significantly less than that in the control group(P<0.05).2.The results of NO content and NOS activity in the hippocampus of rats exposed to styrene showed that,compared with the control group,the NO content and NOS activity in the rats of styrene-poisoned rats at the low,middle dose groups all decreased,but there was no statistical difference(P>0.05).The content of NO and activity of NOS in hippocampus of rats exposed to high dose of styrene were significantly different from those in the control group(P<0.05).3.The results of Western blot showed that there was no significant difference in the expression of NR1 protein in hippocampus of rats exposed to styrene in low and middle dose groups compared with the control group(P>0.05).The expression of NR1 protein in hippocampus of rats exposed to styrene in high dose group was significantly lower than that in control group(P<0.05).The expression of NR2A protein in hippocampus of rats exposed to styrene in low and middle dose groups was not significantly different from that in control group(P>0.05).The expression of NR2A protein in hippocampus of rats exposed to styrene in high dose group was significantly lower than that in control group(P<0.05).The expression of NR2B protein in hippocampus of styrene-exposed rats in low and middle dose groups was significantly lower than that in control group(P<0.05).The expression of NR2B protein in hippocampus of rats exposed to styrene in high dose group was significantly lower than that in control group(P<0.05).4.The results of Real-Time PCR showed that the expression of NR1 mRNA in the hippocampus of the low-dose group and the middle-dose group was not significantly different from that of the control group(P>0.05).The expression of NR1 mRNA in the hippocampus of the high-dose group was lower than that of the control group.The difference was statistically significant(P<0.05).The expression of NR2A mRNA in the hippocampus of rats in the low,medium and high dose groups was significantly lower than that in the control group(P<0.01).The expression of NR2B mRNA in the hippocampus of rats in the low,medium dose groups was not significantly different from that of the control group(P>0.05).The expression of NR2B mRNA in the hippocampus of rats in the high-dose group was lower than that in the control group,and the difference was statistically significant(P<0.05).Conclusions1.The time of finding the platform was prolonged,the number of effective platform and the time of staying in the fourth quadrant were significantly decreased in the high dose group of styrene,which indicated that styrene could induce the decrease of learning and memory ability of rats.2.styrene exposure decreased NO content and NOS activity in hippocampus of rats,which due to the fact that styrene can enter the brain tissue of rats,which leads to the decrease of NOS activity,resulting in the decrease of no content in hippocampus of rats.3.Styrene exposure decreased the expression of NR1,NR2A and NR2B protein and the transcription of mRNA in hippocampus of rats,which may be due to the change of NOS activity in rats induced by styrene exposure,which was related to the decrease of NOS activity and NO content in styrene-exposed rats,Thus affecting the learning and memory ability of rats. |
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