The Expression Of Aromatase In Lumbar Spinal Cord Of SOD1^G93A Transgenic Mice At Different Stages

Objective: Amyotrophic lateral sclerosis?ALS?was a devastating central nervous system neurodegenerative disease,which involved central cortex,brain stem and spinal cord,leading to loss of upper and lower motor neurons and progressive muscular dystrophy,paralysis,bulbar symptoms,finally died of respiratory failure.Epidemiology researches about ALS demonstrated that men was higher than premenopausal women in morbidity rate,however,there was no obvious difference between men and postmenopausal women.A behavior study of ALS animal model suggested that the life time of intact female mice was longer than that of ovariectomized female mice.These results indicated that estrogen was related with the cause and progression of ALS.Estrogen,as a neuroprotective agent,can promote synaptic plasticity and survival of neurons,protecting the integrity of tissue.Aromatase,the key enzyme for estrogen synthesis,converts androstenedione,testosterone and 16-hydroxytestosterone to oestrone,oestrodiol and oestriol.Under physiological conditions,multiple tissues could express aromatase,such as ovaries,placenta,testis,prostate,adipose tissue,bone and brain.Some studies demonstrated that aromatase in brain is expressed only in neurons under physiological conditions.However,after various of acute injury,activated astrocytes started to express aromatase,accompanied by increase of activity and finally exerted neuroprotective effects through synthesizing estrogen.In the cerebrospinal fluid and blood of patients with Alzheimer's disease,estradiol is reduced and aromatase in hypothalamus is also decreased.However,the relationship between aromatase and ALS is rarely reported.The purpose of this experiment is to observe expression change of aromatase at different stages in spinal cord of lumbar segments in familial ALS animal model,providing a basis for the study of estrogen's neuroprotective role in ALS.Methods:1 Animal modelBreeding female and male familial amyotrophic lateral sclerosis transgenic mice animal models(SOD1^G93A).SOD1^G93Atransgenic were divided into three groups as pre-symptomatic stage,disease onset stage and end stage,the SOD1^G93Atransgenic negative mice of the same nest,same age and same gender were the control.Each group includes 3 mice.2 Immunoblotting analysisMice were anesthetized with 10% chloral hydrate by 350 mg/kg.Then the lumbar spinal cord of mice were selected immediately and put into liquid nitrogen freezing,-80? storage.We extracted total protein and then detected the expression level of aromatase by Western-blotting.3 Statistical AnalysisWe used SPSS version 13.0 for Windows?SPSS?for all statistical analyses.The data are depicted as mean values and standard errors of the mean?SEM?.One-way ANOVA test and paired-samples t-text was used.P < 0.05 was considered as statistically significant.Results: At pre-symptomatic stage,there was no statistical significance about the expression of aromatase in lumbar spinal cord between SOD1^G93Atransgenic mice group and littermate group.At onset stage,aromatase was decreased in lumbar spinal cord of SOD1^G93Atransgenic mice group compared with littermate group.At end stage,aromatase was obviously decreased in lumbar spinal cord of SOD1^G93Atransgenic mice group compared with littermate group.The expression of aromatase in lumbar spinal cord was gradually decreased at pre-symptomatic stage,onset stage and end stage.And there was no statistical significance about the expression of aromatase in nonSOD1^G93Atransgenic mice group at these three stages.Conclusions:Aromatase were expressed in lumbar spinal cord of female and male SOD1^G93Atransgenic mice and littermates.The comparison of aromatase in lumbar spinal cord between SOD1^G93Atransgenic mice and non-SOD1^G93Atransgenic was different at different stages.Compared with littermate group,aromatase in SOD1^G93Atransgenic mice group was reduced at onset stage and end stage.At pre-symptomatic stage,there was no obvious difference between these two groups.With progression of ALS,the expression of aromatase in lumbar spinal cord of female and male SOD1^G93Atransgenic mice was gradually decreased.