Diurnal changes in perineuronal nets and parvalbumin neurons in the rat medial prefrontal cortex

Feb 15, 2021Brain structure & function

Daily changes in protective neuron structures and fast-firing neurons in the rat thinking area

AI simplified

Circadian Biology on OpenScience ↗PubMed ↗DOI ↗

Abstract

The intensity of perineuronal nets (PNNs) and parvalbumin (PV) interneurons increased during the dark phase compared to the light phase.

Relative to the light phase (ZT0), PNN and PV labeling intensities were higher during the dark phase.
The oxidative stress marker 8-oxo-dG decreased across all measured times compared to ZT0.
More excitatory puncta were observed on PV cells with PNNs at ZT18 compared to ZT6, with no changes noted for PV cells without PNNs.
An increased ratio of AMPA to NMDA receptor activity was found in fast-spiking PV cells with PNNs at ZT18 compared to ZT6.
A strong trend toward an increase in the number of PV cells containing orthodenticle homeobox 2 (OTX2) was noted from ZT6 to ZT18.

AI simplified

Perineuronal nets (PNNs) surrounding fast-spiking, parvalbumin (PV) interneurons provide excitatory:inhibitory balance, which is impaired in several disorders associated with altered diurnal rhythms, yet few studies have examined diurnal rhythms of PNNs or PV cells. We measured the intensity and number of PV cells and PNNs labeled with Wisteria floribunda agglutinin (WFA) and also the oxidative stress marker 8-oxo-deoxyguanosine (8-oxo-dG) in rat prelimbic medial prefrontal cortex (mPFC) at Zeitgeber times (ZT) ZT0 (lights-on, inactive phase), ZT6 (mid-inactive phase), ZT12 (lights-off, active phase), and ZT18 (mid-active phase). Relative to ZT0, the intensities of PNN and PV labeling were increased in the dark (active) phase compared with the light (inactive) phase. The intensity of 8-oxo-dG was decreased from ZT0 at all times (ZT6,12,18). We also measured GAD 65/67 and vGLUT1 puncta apposed to PV cells with and without PNNs. There were more excitatory puncta on PV cells with PNNs at ZT18 vs. ZT6, but no changes in PV cells without PNNs and no changes in inhibitory puncta. Whole-cell slice recordings in fast-spiking (PV) cells with PNNs showed an increased ratio of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor:N-methyl-D-aspartate receptor (AMPA: NMDA) at ZT18 vs. ZT6. The number of PV cells and PV/PNN cells containing orthodenticle homeobox 2 (OTX2), which maintains PNNs, showed a strong trend toward an increase from ZT6 to ZT18. Diurnal fluctuations in PNNs and PV cells are expected to alter cortical excitatory:inhibitory balance and provide new insights into treatments for diseases impacted by disturbances in sleep and circadian rhythms.

Full Text

Full text is available at the source.

View full text (PDF) ↗View full text (HTML) ↗

Diurnal changes in perineuronal nets and parvalbumin neurons in the rat medial prefrontal cortex

Abstract

Full Text

You found one interesting study. We’ll send the next 7.

what lands in your inbox each week:

Recent issues from the circadian biology brief