Objective To investigate the improving effect of low-dose estrogen on muscle function in ovariectomized sarcopenic rats and analyze its relationship with the expression of acetylcholinesterase (ACHE) in skeletal muscle. Methods Thirty female SD rats were randomly divided into three groups with 10 rats in each group: sham operation group (Sham group), ovariectomized group (OVX group), or ovariectomy + preventive estradiol injection group (OVX/E2 group). One week after postoperative feeding, the OVX/E2 group was subcutaneously injected with 10 μg/kg estradiol daily, while the Sham group and the OVX group were injected with an equal volume of the vehicle (0.9% sterile NaCl solution containing dimethyl sulfoxide) for 8 consecutive weeks. After the intervention, the inclined plane test and hanger test were conducted in sequence to evaluate muscle strength and motor coordination ability. Subsequently, the rats were euthanized, and the gastrocnemius muscle tissue was collected. Real-time fluorescence quantitative PCR and immunohistochemistry were used to detect the relative expression level of Ache mRNA and the positive expression rate of ACHE, respectively. Results The overall differences in the inclined plane retention time and hanger test scores among the three groups of rats were statistically significant (all P<0.05); the inclined plane retention time of the OVX/E2 group was longer than that of the OVX group, and the hanger test score of the OVX/E2 group was higher than those of the Sham group and OVX group (all P<0.05). The overall difference in the relative expression level of Ache mRNA in the gastrocnemius muscle among the three groups of rats was statistically significant (P<0.05), and the relative expression level of Ache mRNA in the gastrocnemius muscle decreased in the order of: OVX/E2 group > Sham group > OVX group (all P<0.05). The overall difference in the positive expression rate of ACHE in the gastrocnemius muscle among the three groups of rats was statistically significant (P<0.05); however, no statistically significant difference was observed in the pairwise comparisons between the groups (all P>0.05). Conclusion Low-dose estrogen supplementation can effectively improve the muscle function of ovariectomized sarcopenic rats, and its mechanism may be related to the up-regulation of Ache mRNA expression in skeletal muscle at the transcriptional level. However, at the protein translation level, the absence of consistent changes in ACHE indicates that this regulation involves complex post-transcriptional mechanisms.

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