Expression and significance of estrogen receptor in bladder of experimental autoimmune encephalomyelitis mouse model

Abstract

Objective To study the changes of estrogen receptor (ER) expression in neurogenic bladder caused by multiple sclerosis (MS) and its significance by establishing an experimental autoimmune encephalomyelitis (EAE) model in mice. Methods The EAE models were induced by an antigen emulsion mixture that was well mixed with mog35-55 and complete Freund’s adjuvant. Twenty female C57Bl/6 mice were randomly divided into experimental group and control group. The clinical symptoms of mice were observed and recorded after immunization. Twenty-third days after immunization, micturition frequency and mean void weight were observed within 4 h. The spinal cord as well as the bladder was collected and the bladder was weighed. The pathological changes were observed by hematoxylin-eosin (HE) staining and Luxol fast blue (LFB) staining. The expression of ER in bladder of EAE mice was detected by Western blotting. Results The clinical score of neurological function in EAE mice increased, and typical MS symptoms appeared. The weight of the control group and experimental group was (23.0±1.1) g and (16.5±1.5) g respectively. As compared with the control group, the weight of the mice in the model group was obviously reduced. The average number of 4H urination in model group (8.7±1.4) was significantly greter than in the control group (4.2±1.1, P=0.001). The urine volume in the model group [(0.22±0.11) mg] was significantly less than that in the control group [(0.34±0.07) mg, P=0.008]. In the model group, the bladder weight ratio [(0.26±0.09)‰] was significantly higher than that in the model group [(0.11±0.03)‰, P=0.001]. HE-LFB staining showed obvious inflammatory cell infiltration and demyelination in the spinal cord of EAE model mice, and Western blotting showed that the relative expression of ER in the bladder of model group (0.38±0.08) was significantly lower than that in the control group (0.71±0.19, P=0.001). Conclusion Mog35-55 can successfully induce the EAE mice model. The EAE mice model can well simulate the MS neurogenic bladder symptoms. ER and estrogen may be the important factors in bladder dysfunction caused by multiple sclerosis. Key words: Estrogen receptor; Experimental autoimmune encephalomyelitis; Neurogenic bladder