Biologists from the University of Bayreuth have discovered an exceptionally rapid form of regeneration in injured neurons and their function in the central nervous system of the zebrafish. Scientists have published their findings in the journal Communications Biology.

In the central nervous systems of other animal species, such complete regeneration of neurons has not yet been definitively demonstrated.

Mauthner cells

The mauthner cells They are the largest cells found in the brains of animals. They are part of the central nervous system of most species of fish and amphibians and trigger life-saving escape responses when predators approach.

Signal transmission in Mauthner cells to their motor neurons is only guaranteed if a certain part of these cells, the axon, is intact. The axon is an elongated structure that limits the cell body with its cell nucleus at one of its two ends. If the axon injury occurs near the cell body, the Mauthner cell dies. If the axon is damaged at its opposite end, lost functions are not restored at all or only slowly and limitedly.

However, the Mauthner cell reacts to a lesion in the middle of the axon with rapid and complete regeneration. In fact, within a week after injury, the axon and its function are completely restored, and the fish can escape again from the approaching predators.

It could be possible that other neurons in the zebrafish can induce this life-saving escape behavior and thus take over the lost function of Mauthner cells. However, precisely this possibility was ruled out by the previously published findings. According to one of the main researchers, Hecker:

Mauthner cells now offer us the possibility of investigating very different responses to the lesions of individual cells within the same nervous system: an absence or insufficient regeneration processes on the one hand, and a solid and complete regeneration on the other. Surprisingly, axon injuries, which led to such conflicting responses, were not far behind. Elucidating the causes is an exciting field of investigation, which also includes the identification of genes that are active in the regeneration of neurons. And if we discover why the regeneration processes in Mauthner cells do not occur, we could also better understand the mechanisms that prevent the regeneration of neurons in humans.

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