Age-related changes in layer II immature neurons of the murine piriform cortex

Front. Cell. Neurosci., 2023 · DOI: 10.3389/fncel.2023.1205173 · Published: July 28, 2023

Simple Explanation

The study investigates how a specific type of brain cell, called cortical immature neurons (cINs), changes with age in mice. These cINs are unique because they are formed before birth but remain in an immature state until later in life, when they can mature and integrate into brain circuits. Researchers examined the number and characteristics of cINs in the piriform cortex, a brain region involved in processing smells, at different ages, from young to old mice. They used special staining techniques to identify these cells and markers to assess their maturity. The findings suggest that while the number of cINs decreases as mice age, some immature cells persist even in old age. This raises the possibility that these remaining cINs could serve as a reserve of young, adaptable cells in the aging brain.

Study Duration

1 to 15 months

Participants

Mice C57/BL6, male, aged 1, 3, 5, 7, 12, 15 months (4 animals for each age)

Evidence Level

Original Research

Key Findings

1
The study found a significant decrease in the number of cINs in the piriform cortex as mice aged, particularly between 1 and 12-15 months.
2
There was a decrease in the proportion of type 2 cINs (more mature) compared to type 1 cINs (highly immature) with age progression, suggesting a shift towards a higher proportion of immature cells in older animals.
3
Co-expression analysis of DCX with PSA-NCAM and NeuN revealed that while the co-expression of DCX and PSA-NCAM remained relatively stable with age, the co-expression of DCX and NeuN increased with age, possibly indicating a slowing down of the maturation process.

Research Summary

This study investigates the age-related changes in cortical immature neurons (cINs) within the piriform cortex of mice, focusing on their numbers, morphology, and marker expression from postnatal stages to old age. The key finding is that while the number of cINs decreases with age, a small population of highly immature cINs persists into advanced ages, suggesting a potential reservoir for brain plasticity in the aging brain. The study also compares the age-related decline of cINs with that of hippocampal neurogenesis, noting similarities and differences, and discusses the implications of these findings in the context of brain plasticity and aging in mammals, including humans.

Practical Implications

Understanding Brain Aging

The study sheds light on how specific types of brain cells change with age, contributing to a better understanding of the aging process in the brain.

Potential Therapeutic Targets

The findings suggest that preserving or stimulating the immature neurons in the aging brain could be a potential therapeutic strategy for maintaining cognitive function.

Evolutionary Perspective

The research highlights the differences in brain plasticity between species, suggesting that the maintenance of immature neurons may be more important in long-lived, large-brained animals.

Study Limitations

1
The number of sections considered in the counting was not high (three sections/animal) may explain the variability observed between animals, what could represent a limit of this study.
2
The study focuses solely on male mice, limiting the generalizability of the findings to female mice.
3
The quantiﬁcation of DCX+ cells was performed using a direct cell counting on ImageJ software instead of stereological methods with Stereoinvestigator

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