SPONTANEOUS ELECTRICAL ACTIVITY REGULATES AXONAL ARBOR GROWTH IN DEVELOPING ZEBRAFISH LATERAL LINE AFFERENT NEURONS

LUCIA SALATINO; ANA BELÉN ELGOYHEN; PAOLA PLAZAS

Congreso; XXXIV Congreso Anual de la Sociedad Argentina de Investigaciones en Neurociencias; 2019

Neuronal circuits responsible for processing sensory information are established early in development through a combination of genetic programs and (spontaneous electrical) activity-dependent processes. In order to decipher the mechanisms by which spontaneous electrical activity (SEA) affects the assembly of developing sensory circuits, we used the Zebrafish (Danio rerio) lateral line system (LL). The LL allows fishes and amphibians to detect water motion and pressure changes and it consists of clusters of mechanosensory hair cells called neuromasts, which are innervated by afferent and efferent neurons, and non-sensory supporting cells. LL hair cells share structural, functional and molecular similarities with the hair cells in the vertebrate inner ear. Zebrafish LL afferent neurons exhibit SEA between 5 and 7 days post-fertilization (dpf), however its role in the assembly of LL circuit is still unknown. To answer this question, we silenced SEA in single LL afferent neurons by stochastic over-expression of inward rectifier K+ channels. At 5 dpf, suppression of SEA in single LL afferent neurons led to a decrease in both axonal arbor length and innervation area in the hindbrain. Our results provide an in vivo demonstration that SEA regulates axonal arbor growth and territory in the hindbrain, in developing LL afferent neurons.