Influence Of Amphetamine On Learning And Memory And Astrocytes In Hippocampal Formation Of Rats

ObjectiveTo explore the influence of amphetamine on the spatial discriminative learning and memory and astrocytes of the hippocampal formation in ratsMethodsSD male rats were randomly divided into three groups:the swimming group,the saline group and the amphetamine group.The amphetamine group were given intramuscular injection of amphetamine 0.5 mg/kg once daily;the saline group were treated with the same dose of saline. Water maze test were performed to test the spatial discriminative learning and memory.On days 14,28 and 42,rats in each group were sacrificed respectively.Then,immunohistochemical method,Western blotting method and electronic microscopic methods were used to identify the changes in astrocytes of the hippocampal formation in the three groups of rats.Results1.The results from the spatial discriminative learning and memory:At the training day of 7,the mean latency,the mean running time and the correct ratio in three groups reached the expected criteria.From day 1 to 14,the mean running time and the mean latency in the amphetamine group was shorter than that of the saline group(P＜0.05),from day 14 to 28, the correct ratio in the amphetamine group was much lower,and was further lower from day 29 to 42,the mean running time was increased compared with the saline group(P＜0.05).2.The result of immunohistochemical method:Astrocytes are mainly distributed in the polymorphic layer and molecular layer of the hippocampus and dentate gyrus in the swimming group.The distribution pattern in saline group was the same as that of the swimming group,but the number of astrocytes were increased in different subfield of hippocampus(P＜0.05),and the processes of astrocytes were longer and larger,with more branches in saline group.There was also an increase in the saline group(P＜0.05).The number of astrocytes in the amphetamine group rats were significantly increased compared with the saline group or the swimming group(P＜0.05),and the processes of astrocytes were more longer and larger,with more branches compared with the saline group.3.The result of Western blotting method:The level of GFAP in the amphetamine group was significantly high compared with the saline group or swimming group(P＜0.05),and its expression was gradually upregulated following the increase of time in the amphetamine group.4.The result of ultrastructure by electronic microscope:.Hyperplasia and hypertrophy of astrocytes were found,and the degenerative astrocytes were also found.ConclusionOur results suggested that amphetamine can injure the capability of the spatial discriminative learning and memory of rats,and cause proliferation and damage of astroeytes in the hippocampal formation.