SUPPRESSION OF SPONTANEOUS ELECTRICAL ACTIVITY CHANGES THE DYNAMICS AND MATURATION OF AXONAL ARBORIZATION IN ZEBRAFISH LATERAL LINE AFFERENT NEURONS

LUCIA SALATINO; AB. ELGOYHEN; PAOLA PLAZAS

Congreso; Society for Neuroscience 53rd Annual Meeting, Washington DC, USA; 2023

Spontaneous electrical activity (SEA) is required for the proper assembly of sensory circuitsduring early stages of development, although the underlying mechanisms are still unknown. SEAis generated in sensory cells and propagated to the central nervous system. In order tounderstand 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 andamphibians to detect water motion and pressure changes and consists of clusters ofneuromasts, which contain mechanosensory hair cells (HC) that are innervated by afferent (Aff)and efferent neurons. These HC share structural, functional and molecular similarities with thosefound in the vertebrate inner ear. In Zebrafish LL Aff, SEA occurs between 5 and 7 days post-fertilization. To investigate the effectsof SEA on developing sensory circuits, we over-expressed inward rectifier K+ channels in orderto silence SEA in single LL Aff, and analyzed the phenotype and dynamics of axonal arbor growthand maturation. Our results indicate that suppression of SEA in single LL afferent neurons led toa decrease in innervation area in the hindbrain, as well as diff erences in axonal complexity.Moreover, silenced neurites displayed higher motility, formation, and elimination rates, and alower 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, andterritory in the hindbrain during the development of LL Aff. These findings shed light on theimportance of spontaneous electrical activity in the proper assembly of sensory circuits, and may have implications for understanding sensory disorders.