Objective:To explore the expression and ultrastructure distribution of cofilin and its potential mecha-nisms in postsynaptic mitochondrial anchoring and synaptic plasticity in the pre-B?tzinger complex(pre-B?tC)in rats.Methods:Using neurokinin 1 receptor(NK1R)as a morphological marker of the pre-B?tC,we examined the expres-sion and ultrastructure distribution of cofilin in pre-B?tC neurons of normoxic(NOR)and acute intermittent hypoxic(AIH)rats by combining Western blot,RT-qPCR,immunofluorescence,and immunoelectron microscopy.Results:Cofilin was expressed in the nuclei,somata and dendrites of NK1R-positive neurons in the pre-B?tC and its expression decreased after AIH intervention in this region detected.The results of immunoelectron microscopy showed that cofilin was expressed in the dendritic spines and postsynaptic filamentous or flocculent structures of pre-B?tC neurons.A total of 317 synapses were detected in pre-B?tC(NOR:122;AIH:195).In the NOR group,65.6％of the postsynaptic had cofilin expression,while in the AIH group,the proportion decreased to 47.2％.Combining with the role of cofilin in the regulation of actin severing,it is suggested that the severing effect of cofilin on postsynaptic actin is weakened af-ter AIH intervention,which may further enhance the postsynaptic mitochondrial anchoring.Conclusion:Cofilin,an ac-tin binding protein,plays a crucial role in regulating shearing and depolymerization of actin.Decreased cofilin expres-sion induced by AIH suggests an enhanced actin polymerization,which may be involved in the postsynaptic anchoring of mitochondria and the regulation of synaptic plasticity in the pre-B?tC.

Objective:To explore the expression and ultrastructure distribution of cofilin and its potential mecha-nisms in postsynaptic mitochondrial anchoring and synaptic plasticity in the pre-B?tzinger complex(pre-B?tC)in rats.Methods:Using neurokinin 1 receptor(NK1R)as a morphological marker of the pre-B?tC,we examined the expres-sion and ultrastructure distribution of cofilin in pre-B?tC neurons of normoxic(NOR)and acute intermittent hypoxic(AIH)rats by combining Western blot,RT-qPCR,immunofluorescence,and immunoelectron microscopy.Results:Cofilin was expressed in the nuclei,somata and dendrites of NK1R-positive neurons in the pre-B?tC and its expression decreased after AIH intervention in this region detected.The results of immunoelectron microscopy showed that cofilin was expressed in the dendritic spines and postsynaptic filamentous or flocculent structures of pre-B?tC neurons.A total of 317 synapses were detected in pre-B?tC(NOR:122;AIH:195).In the NOR group,65.6％of the postsynaptic had cofilin expression,while in the AIH group,the proportion decreased to 47.2％.Combining with the role of cofilin in the regulation of actin severing,it is suggested that the severing effect of cofilin on postsynaptic actin is weakened af-ter AIH intervention,which may further enhance the postsynaptic mitochondrial anchoring.Conclusion:Cofilin,an ac-tin binding protein,plays a crucial role in regulating shearing and depolymerization of actin.Decreased cofilin expres-sion induced by AIH suggests an enhanced actin polymerization,which may be involved in the postsynaptic anchoring of mitochondria and the regulation of synaptic plasticity in the pre-B?tC.