# Postnatal expression of Cat-315-positive perineuronal nets in the SAMP10 mouse primary somatosensory cortex

## TL;DR

The study finds that SAMP10 mice have reduced Cat-315-positive perineuronal nets early in life, which may explain age-related brain function decline.

## Contribution

The novel finding is that Cat-315 epitope expression is reduced during postnatal development in SAMP10 mice.

## Key findings

- Cat-315-positive perineuronal nets are expressed at lower levels in SAMP10 mice compared to SAMR1 mice during postnatal development.
- SAMP10 mice show early brain abnormalities that may contribute to age-related cognitive decline.
- Other PNN-related molecules remain unchanged between SAMP10 and SAMR1 mice.

## Abstract

Perineuronal nets (PNNs) form at the end of the critical period of plasticity in the mouse primary somatosensory cortex. PNNs are said to have functions that control neuroplasticity and provide neuroprotection. However, it is not clear which molecules in PNNs have these functions. We have previously reported that Cat-315-positive molecules were not expressed in the PNNs of the senescence-accelerated model (SAM)P10 strain model mice at 12 months of age. To confirm whether the loss of Cat-315-positive molecules occurred early in life in SAMP10 mice, we examined Cat-315-positive PNNs in the primary somatosensory cortex during postnatal development. This research helps to elucidate the function of PNNs and the mechanism of cognitive decline associated with ageing. To confirm whether Cat-315-positive PNNs changed in an age-dependent manner in SAMP10 mice, we examined the primary somatosensory cortex at 21, 28, and 56 days after birth. We compared these results with those of senescence-accelerated mouse-resistant (SAMR) mice. In SAMP10 mice, Cat-315-positive PNNs were expressed in the primary somatosensory cortex early after birth, but their expression was significantly lower than that in SAMR1 mice. Many other molecules that calibrated the PNN were unchanged between SAMP10 and SAMR1 mice. This study revealed that the expression of the Cat-315 epitope was decreased in the primary somatosensory cortex of SAMP10 mice during postnatal development. SAMP10 mice have had histological abnormalities in their brains since early life. Furthermore, using SAMP10 will be useful in elucidating the mechanism of age-related abnormalities in brain function as well as in elucidating the function and structure of PNNs.

•Senescence-accelerated model (SAM)P10 mice have early brain abnormalities.•Cat-315 epitope expression reduced during postnatal development in SAMP10.•SAMP10 may help elucidate mechanisms of age-related abnormalities in brain function.

Senescence-accelerated model (SAM)P10 mice have early brain abnormalities.

Cat-315 epitope expression reduced during postnatal development in SAMP10.

SAMP10 may help elucidate mechanisms of age-related abnormalities in brain function.