5-HT(1A) Receptor Agonist Treatment Partially Ameliorates Rett Syndrome Phenotypes in mecp2-Null Mice by Rescuing Impairment of Neuron Transmission and the CREB/BDNF Signaling Pathway

Rett syndrome (RTT) is an X-linked neurodevelopmental disorder caused by mutations in the gene that encodes methyl CpG-binding protein 2 (MECP2) and is characterized by the loss of acquired motor and language skills, stereotypic movements, respiratory abnormalities and autistic features. There has been no effective treatment for this disorder until now. In this study, we used a Mecp2-null (KO) mouse model of RTT to investigate whether repeated intraperitoneal treatment with the 5-HT(1A) receptor agonist tandospirone could improve the RTT phenotype. The results showed that administration of tandospirone significantly extended the lifespan of Mecp2-KO mice and obviously ameliorated RTT phenotypes, including general condition, hindlimb clasping, gait, tremor and breathing in Mecp2-KO mice. Tandospirone treatment significantly improved the impairment in GABAergic, glutaminergic, dopaminergic and serotoninergic neurotransmission in the brainstem of Mecp2-KO mice. Decreased dopaminergic neurotransmission in the cerebellum of Mecp2-KO mice was also significantly increased by tandospirone treatment. Moreover, RNA-sequencing analysis found that tandospirone modulates the RTT phenotype, partially through the CREB1/BDNF signaling pathway in Mecp2-KO mice. These findings provide a new option for clinical treatment.