Sc-RNA seq Reveals the Protective Effects of Baoyuan Jieyu Formula on Spaceflight Depression Rats

Long-term spaceflight composite stress (LSCS) can induce detrimental impacts on the human central nervous system, leading to conditions such as depression. This study aimed to identify mechanisms of simulated LSCS-induced spaceflight depression and the protective effects of traditional Chinese medicine Baoyuan Jieyu Formula (BYJYF) on spaceflight depression rats. The present study simulated the real long-term space station environment by conducting a 6-week experiment that involved simulating microgravity, isolation, noise, circadian rhythm disruptions, and low pressure. Glutamatergic neuron firing in hippocampus of the rats was examined by patch clamp to explore the effects of simulated LSCS exposure and BYJYF intervention on neurons. Single-cell RNA sequencing was then conducted to reveal the underlying mechanisms of simulated LSCS-induced spaceflight depression and the efficiency of BYJYF intervention. Results showed that simulated LSCS caused glutamate overload, induced by an abnormally high release frequency (P < 0.05) from glutamatergic neurons. Single-cell sequencing revealed that the possible causes of glutamate overload lied in the reduction in hippocampal stromal cells, especially astrocytes, thereby delaying glutamate clearance, which could be mitigated by BYJYF intervention by up-regulating the proportion of stromal cells. Transcriptomics revealed that the target pathway of simulated LSCS-induced spaceflight depression was the calcium signaling pathway, and BYJYF functioned by regulating genes related to long-term potentiation pathway. Taken together, we demonstrate the target pathways of simulated LSCS-induced spaceflight depression and the potential clinical application of BYJYF, opening up broader prospects for the application of traditional Chinese medicine in space medicine.