AI Insight
This study investigates the role of tachykinin neuropeptides in the development of motor neurons in zebrafish embryos, specifically examining how these neurons simultaneously extend axons and form synapses. Researchers found that disrupting the tac1 gene, which produces tachykinin neuropeptides, causes motor axons to develop abnormally long branches, subtle defects in synapse structure, and approximately 1.5-fold increased motor neuron activity leading to excessive spontaneous muscle contractions. Pharmacological blocking of tachykinin receptors reproduced similar axonal defects, confirming that tachykinin signaling normally restrains excessive branching and modulates synapse formation during motor axon growth.
Why it matters
Understanding how neurons coordinate axon growth with synapse formation has implications for developmental disorders affecting motor control and potentially for regenerative medicine approaches aimed at repairing damaged neural connections. The findings could inform strategies for treating conditions involving abnormal motor neuron development or function.
Understand the Science
⚠️ Preprint – Noch nicht peer-reviewed
Dieser Artikel wurde noch nicht von unabhängigen Experten begutachtet. Die Ergebnisse sind vorläufig und sollten mit Vorsicht interpretiert werden.
In contrast to many other developing systems, in which axon pathfinding and synaptogenesis are separated in time, the pioneering axon of the individually identifiable caudal primary motor neuron in embryonic zebrafish forms en passant synapses during its stereotypical ventral growth. How simultaneous synaptic differentiation and axon pathfinding are coordinated is not fully understood. Here we ask what the role of the tac1 gene, coding for the synaptic tachykinin neuropeptides, is in this unique axon differentiation process. The gene is expressed during axon outgrowth and its disruption results in increased branch length of CaP axons and subtle morphological defects of the pre-synapse. These abnormalities are accompanied by a robust ~1.5-fold increase in motor neuron activity and in spontaneous early contractions in tac1-deficient embryos. Furthermore, pharmacological inhibition of the tachykinin receptor (Tacr1) leads to altered CaP axonal morphology, mimicking the axonal phenotype observed in tac1-deficient zebrafish. These findings suggest that tachykinin neuropeptides modulate formation and activity of en passant synapses and prevent aberrant axon branching during growth of zebrafish motor axons.