Estrogen‐mediated coupling via gap junctions in the suprachiasmatic nucleus

Schlaeger, Lina; Olejniczak, Iwona; Lehmann, Marianne; Schmidt, Cosima Xenia; Astiz, Mariana; Oster, Henrik; Pilorz, Violetta

doi:10.1111/ejn.16270

Cited by 2 publications

(1 citation statement)

References 91 publications

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“…GAP26 inhibits Connexin 43 (Cn43), a gap junction protein only expressed in astrocytes in the SCN as shown by the colocalization with GFAP + cells (Fig. 4c) and as also shown by others 40,41 .…”

Section: Resultssupporting

confidence: 69%

Astrocytes in the mouse suprachiasmatic nuclei respond directly to glucocorticoids feedback

Händler,

Sreenivasan,

Pilorz

et al. 2024

Preprint

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The circadian timing system anticipates daily recurring changes in the environment to synchronize physiology. In mammals, the master pacemaker is the hypothalamic suprachiasmatic nuclei (SCN), which synchronizes "wake" functions by inducing the circadian release of Glucocorticoids (GCs) from the adrenal gland. GCs peak right before the active phase and set the time of peripheral clocks, however, it is still unclear whether the SCN respond to GCs feedback. While GCs influence directly the SCN during the perinatal period, the adult circuit is considered to be resistant to them, suggesting a reduction of GCs-sensitivity along development. To understand this mechanism, we followed the expression of GC receptor (GR) along mouse SCN development with single-cell resolution and show that GR is up-regulated in astrocytes as the circuit matures. We provide in vivo and in vitro evidence that the adult SCN stays responsive to circulating GCs through the activation of GR in astrocytes. Astrocytes' communication is necessary to induce the GC-dependent shift on the SCN clock. Our data provides insight into the development of the SCN and highlight a new role of astrocytes as time-keepers in the adult. This finding might shed light on how the circadian system adapts to jetlag or shift work.

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Section: Resultssupporting

confidence: 69%

Astrocytes in the mouse suprachiasmatic nuclei respond directly to glucocorticoids feedback

Händler,

Sreenivasan,

Pilorz

et al. 2024

Preprint

Self Cite

View full text Add to dashboard Cite

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Experimentally Elevated Levels of Testosterone Advance Daily Onset of Activity in Short‐Day Housed Male House Sparrows (Passer domesticus)

Galante,

Lane,

Elderbrock

et al. 2024

J Exp Zool Pt A

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Seasonal changes in sleep/wake cycles and behaviors related to reproduction often co‐occur with seasonal fluctuations in sex hormones. Experimental studies have established that fluctuations in circulating testosterone mediate circadian rhythms. However, most studies are performed under constant lighting conditions and fail to investigate the effects of testosterone on the phenotypic output of circadian rhythms, that is, chronotype (daily activity patterns under light:dark cycles). Here, we experimentally elevated testosterone with implants during short nonbreeding daylengths in male house sparrows (Passer domesticus) to test if observed seasonal changes in chronotype are directly in response to photoperiod or to testosterone. We fitted individuals with accelerometers to track activity across treatment periods. Birds experienced three treatments periods: short day photoperiods before manipulation (SD), followed by testosterone implants while still on short days (SD + T). Implants were then removed. After a decrease in cloacal protuberance size, an indicator of low testosterone levels, birds were then photostimulated on long days (LD). Blood samples were collected at night, when testosterone peaks, to compare testosterone levels to daily onset/offset activity for experimental periods. Our results indicate that experimentally elevated testosterone under short nonbreeding photoperiods significantly advanced daily onset of activity and total daily activity relative to daylength. This suggests that testosterone, independent of photoperiod, is responsible for seasonal shifts in chronotypes and daily activity rhythms. These findings suggest that sex steroid hormone actions regulate timing of daily behaviors, likely coordinating expression of reproductive behaviors to appropriate times of the day.

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Estrogen‐mediated coupling via gap junctions in the suprachiasmatic nucleus

Cited by 2 publications

References 91 publications

Astrocytes in the mouse suprachiasmatic nuclei respond directly to glucocorticoids feedback

Astrocytes in the mouse suprachiasmatic nuclei respond directly to glucocorticoids feedback

Experimentally Elevated Levels of Testosterone Advance Daily Onset of Activity in Short‐Day Housed Male House Sparrows (Passer domesticus)

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