bims-ciryme 2024-03-24 papers

Issue of 2024‒03‒24
two papers selected by
Gabriela Da Silva Xavier, University of Birmingham

Proc Natl Acad Sci U S A. 2024 Mar 26. 121(13): e2316841121

The circadian molecular clock in the suprachiasmatic nucleus is necessary but not sufficient for fear entrainment.

Ivana L Bussi, Miriam Ben-Hamo, Luis E Salazar Leon, Leandro P Casiraghi, Victor Y Zhang, Alexandra F Neitz, Jeffrey Lee, Joseph S Takahashi, Jeansok J Kim, Horacio O de la Iglesia.

We show that nocturnal aversive stimuli presented to mice while they are eating and drinking outside of their safe nest can entrain circadian behaviors, leading to a shift toward daytime activity. We also show that the canonical molecular circadian clock is necessary for fear entrainment and that an intact molecular clockwork in the suprachiasmatic nucleus, the site of the central circadian pacemaker, is necessary but not sufficient to sustain fear entrainment of circadian rhythms. Our results demonstrate that entrainment of a circadian clock by cyclic fearful stimuli can lead to severely mistimed circadian behavior that persists even after the aversive stimulus is removed. Together, our findings support the interpretation that circadian and sleep symptoms associated with fear and anxiety disorders are, in part, the output of a fear-entrained clock, and provide a mechanistic insight into this clock.

Keywords: PTSD; circadian; fear; sleep; suprachiasmatic

DOI: https://doi.org/10.1073/pnas.2316841121

Cell Rep. 2024 Mar 12. pii: S2211-1247(24)00279-1. [Epub ahead of print] 113951

Energy balance drives diurnal and nocturnal brain transcriptome rhythms.

Laura van Rosmalen, Shaunak Deota, Geraldine Maier, Hiep D Le, Terry Lin, Ramesh K Ramasamy, Roelof A Hut, Satchidananda Panda.

Plasticity in daily timing of activity has been observed in many species, yet the underlying mechanisms driving nocturnality and diurnality are unknown. By regulating how much wheel-running activity will be rewarded with a food pellet, we can manipulate energy balance and switch mice to be nocturnal or diurnal. Here, we present the rhythmic transcriptome of 21 tissues, including 17 brain regions, sampled every 4 h over a 24-h period from nocturnal and diurnal male CBA/CaJ mice. Rhythmic gene expression across tissues comprised different sets of genes with minimal overlap between nocturnal and diurnal mice. We show that non-clock genes in the suprachiasmatic nucleus (SCN) change, and the habenula was most affected. Our results indicate that adaptive flexibility in daily timing of behavior is supported by gene expression dynamics in many tissues and brain regions, especially in the habenula, which suggests a crucial role for the observed nocturnal-diurnal switch.

Keywords: CP: Metabolism; CP: Neuroscience; SCN; behavioral plasticity; circadian rhythms; diurnal; habenula; hypothalamus; negative energy balance; nocturnal; running wheel activity; temporal niche switching

DOI: https://doi.org/10.1016/j.celrep.2024.113951