Mexican Aquatic Salamander Axolotl Brain Regenerates After Injury

In a recent study, researchers attempted to determine whether the aquatic salamander axolotl can completely rebuild its brain after suffering injury. The researchers looked at all the various cell types in their brains, as well as the pathways that connected various parts of them.

Aquatic Salamander Axolotl

According to myth, the axolotl is the Aztec god of lightning and fire. Yet, Xolotl took on the shape of a salamander to avoid being sacrificed.

In the scientific world, these Mexican amphibians have the ability to recover lost limbs and keep a youthful appearance throughout their lifetimes, according to National Geographic. Axolotls undergo neoteny, which means that the species never outgrows its larval or juvenile stage. This is in contrast to other salamanders that go through metamorphosis.

The aquatic salamander known as the axolotl has the capacity to regenerate its heart, spinal cord, and limbs. Throughout their lives, these amphibians also easily create new neurons. Researchers discovered in 1964 that adult axolotls' brains could regrow some of their tissues even when a sizable portion was entirely removed.

Atlas of the Axolotl Cells

In the recent study published in Science journal, the researchers developed an atlas of the cells that make up a portion of the axolotl brain. This provides light on both how it regenerates and how the brain has evolved across species. Identifying different brain cell types and their functions helps to explain the overall picture of how the brain operates. Additionally, it enables researchers to compare evolutionary developments and look for biological trends among various species.

Single-cell RNA sequencing is a method for determining which cells are expressing specific genes. Researchers can use this technique to count the active genes in each cell of a particular sample. This offers a snapshot of the tasks each cell was completing at the time of collection. It has been used on fish, reptiles, and mice.

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Research Process in Studying the Axolotl Cells

The telencephalon of the axolotl was the focus of the study. The neocortex is a part of it, which is the biggest division of the brain. This area is crucial for animal cognition and behavior. The several cell types that make up the axolotl telencephalon were identified by the researchers using scRNA-seq. Progenitor cells and many varieties of neurons are included.

They next determined which genes are turned on when progenitor cells develop into neurons. They discovered that before developing into adult neurons, many go through an intermediate cell type called neuroblasts.

The researchers identified three crucial phases of brain regeneration. A rapid rise in progenitor cells and the start of the wound-healing process mark the beginning of the first stage. Then neuroblasts start to form from progenitor cells. In the last stage, the neuroblasts evolve into the previously existing neurons.

The broken neuronal connections between the excised area and other regions of the brain were found to have been reconnected. This rewiring shows that the original function of the area was recovered and it is fully functional.

The researchers found that the hippocampus and the olfactory cortex in humans share striking similarities with cells in the telencephalon of axolotls. One axolotl cell type was also shown to share some similarities with the human neocortex, which is in charge of vision, cognition, and spatial reasoning. These similarities imply that the telencephalon of amphibians may be the ancestor cell type for the neocortex of mammals, and that these brain regions may have been evolutionarily maintained or have stayed comparable across time.