Developmental expression of neuronal chloride transporters in different brain regions and sensory organs

Abstract The developmental changes in the expression of neuronal chloride transporters coincide closely with the dynamic sequences of postnatal brain development. The NKCC and KCC cation-chloride cotransporter families mediate excitatory-inhibitory balance by modulating neuronal excitability and the maturation of inhibitory GABAergic transmission. Additionally, they regulate neuronal activity, cell migration, cortical development and dendritic spine development—topics covered throughout this book. Understanding the developmental sequence in expression patterns during normal brain maturation helps elucidate the dysregulation that occurs across age-specific manifestations of neurological diseases, such as epilepsy, brain injury, autism spectrum disorders, schizophrenia, and more. Here, we review the developmental changes in the expression of neuronal chloride transporters with a particular focus on NKCC1 and KCC2 in rodents and humans. Starting from embryonic stages through postnatal development into adulthood, the specificity of neuronal chloride transporter expression in various regions and cell types across brain maturation will be highlighted, along with functional differences related to sex and the perinatal period. Additionally, we review expression patterns across sensory organs in relation to brain maturation and sensory function.