Spontaneous electrical activity regulates axonal arbor growth and maturation in developing Zebrafish lateral line afferent neurons

LUCIA SALATINO; ANA BELÉN ELGOYHEN; PAOLA PLAZAS

Washington DC

Congreso; Neuroscience 2023; 2023

Society for Neuroscience

Spontaneous electrical activity (SEA) is required for the proper assembly of sensory circuits during early stages of development, although the underlying mechanisms are still unknown. SEA is generated in sensory cells and propagated to the central nervous system. In order to understand the mechanisms by which SEA affects the assembly of developing sensory circuits, we studied the Zebrafish (Danio rerio) lateral line system (LL). The LL allows fishes and amphibians to detect water motion and pressure changes and consists of clusters of neuromasts, which contain mechanosensory hair cells (HC) that are innervated by afferent (Aff) and efferent neurons. These HC share structural, functional and molecular similarities with those found in the vertebrate inner ear. In Zebrafish LL Aff, SEA occurs between 5 and 7 days post-fertilization. To investigate the effects of SEA on developing sensory circuits, we over-expressed inward rectifier K+ channels in order to silence SEA in single LL Aff, and analyzed the phenotype and dynamics of axonal arbor growth and maturation. Our results indicate that suppression of SEA in single LL afferent neurons led to a decrease in innervation area in the hindbrain, as well as differences in axonal complexity. Moreover, silenced neurites displayed higher motility, formation, and elimination rates, and a lower number of varicosities than wild-type neurons, which are features of immature neurons.Our study provides in vivo evidence that SEA regulates axonal arbor maturation, growth, and territory in the hindbrain during the development of LL Aff. These findings shed light on the importance of spontaneous electrical activity in the proper assembly of sensory circuits, and may have implications for understanding sensory disorders.