Effect Of Dexamethasone On Astrocytes Morphology Activated By Amphetamine In Mouse Hippocampus

ObjectiveTo observe influence of dexamethasone on astrocytes morphology activated by amphetamine in mouse hippocampal formation.MethodsClean male C57BL/6 mice were randomly divided into control group, saline group, amphetamine group and dexamethasone+amphetamine group. The chang of animal behavior were observed by behavioral observant method. Immunohisto-chemistry, western blot and electronic microscopic methods were used to the qualitative and quantitative test the changes in astrocytes morphology and level of GFAP expression.Results1. The results from behavior observation:The behavioral activity in normal group and the saline group does not appear anomaly. Compared with the normal group, Dexamethasone+amphetamine and amphetamine group mouse show signi-ficant behavioral anomalies, especially the score of behavior are obviously difference among groups (p<0.05).2. The result of immunohistochemistry:GFAP immun-opositive cells are mainly distributed in the polymorphic layer and molecular layer of the hippocampus and dentate gyrus in the normal control group and saline group. Compared with the normal group, the processes and branches of GFAP immu-nopositive cells are longer,larger and more than those in amphetamine group (p<0.05). but the number of GFAP immunopositive cells are not increased in CA3 subfield of hippo-campus at amphetamine group(p>0.05); In Dexamethasone+amphetamine group, distribution of GFAP immunopositive cells are similar as amphetamine group,but its processes were longer and larger than amphetamine group (p<0.05). the number of GFAP immunopositive cells are not increased in CA3 subfield of hippocampus (p>0.05); 3.The result of Western blotting method:There is no difference in the level of GFAP expression between the normal group, saline group, amphetamine group and dexamethasone+amphetamine group (p>0.05)o The level of GFAP expression in the amphetamine group and dexamethasone+amphetamine group is not obviously difference in varies dealing time but in dexamethasone+amphetamine group the level of GFAP expression appear less at 14 days than at 1 and 7days but it is not have statistical significance (p>0.05).4. The result of ultrastructure of electronic microscope:normal group and saline group of ultrastructure in hippocampal CA3 subfield show that astrocyte, mitochondria and medullary sheath are normal. The 14 d amphetamine group and 14 d dexamethasone+amphetamine group of ultrastructure in hippocampal CA3 region of mouse show that astrocytes become hyperplastic and hypertrophic, mitochondria become swollen, medullary sheath was loose and abrupt.ConclusionsUnder the experimental conditions, amphetamine cause activation of astrocytes in mouse hippocampal formation and dexamethasone did not reduce or inhibit the amphetamine induced activation of astrocytes but dexamethasone may reduce or inhibit GFAP expression of activated astrocytes.