Daily electrical activity in the master circadian clock of a diurnal mammal

Baño-Otálora, Beatriz; Moye, Matthew; Brown, Timothy M.; Lucas, Robert J.; Diekman, Casey O.; Belle, Mino D. C.

doi:10.7554/elife.68179

Cited by 17 publications

(7 citation statements)

References 95 publications

(193 reference statements)

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“…Additionally, 6 out of 24 (25.0%) persistent inhibitions appeared to consist of a GABAergic and a non‐GABAergic component and showed biphasic responses in the AP5 + CNQX+GZ condition. Recently, a patch‐clamp study in Rhabdomys SCN slices reported a delayed recovery of firing after a hyperpolarizing current injection 37 . This delay has not been previously identified in nocturnal species and therefore may reflect an intrinsic characteristic of the diurnal SCN.…”

Section: Discussionmentioning

confidence: 84%

Inhibitory responses to retinohypothalamic tract stimulation in the circadian clock of the diurnal rodent Rhabdomys pumilio

et al. 2022

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In both diurnal and nocturnal mammals, the timing of activity is regulated by the central circadian clock of the suprachiasmatic nucleus (SCN). The SCN is synchronized to the external light cycle via the retinohypothalamic tract (RHT). To investigate potential differences in light processing between nocturnal mice and the diurnal rodent Rhabdomys pumilio, we mimicked retinal input by stimulation of the RHT ex vivo. Using Ca2+ imaging, we observed excitations as well as inhibitions of SCN neurons in response to electrical RHT stimulation. In mice, the vast majority of responses were excitatory (85%), whereas in Rhabdomys, the proportion of excitatory and inhibitory responses was similar (51% excitatory, 49% inhibitory). Glutamate blockers AP5 and CNQX blocked the excitatory responses to RHT stimulation but did not abolish the inhibitory responses in mice or Rhabdomys, indicating that the inhibitions were monosynaptically transmitted via the RHT. Simultaneous application of glutamate blockers with the GABAA antagonist gabazine blocked all inhibitory responses in mice, but not in Rhabdomys. Collectively, our results indicate that in Rhabdomys, considerably more inhibitory responses to light are present and that these responses are driven directly by the RHT. We propose that this increased proportion of inhibitory input could reflect a difference in the entrainment mechanism employed by diurnal rodents.

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Section: Discussionmentioning

confidence: 84%

Inhibitory responses to retinohypothalamic tract stimulation in the circadian clock of the diurnal rodent Rhabdomys pumilio

et al. 2022

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“…The SCN then regulates a timekeeping molecular loop of clock genes (Lincoln et al ., 2002) and synchronizes other tissue activities through the systemic release of hormones and polypeptides (Astiz, Heyde & Oster, 2019). SCN activity is similar between nocturnal and diurnal animals, with higher neuronal excitability during the daytime in both chronotypes (Bano‐Otalora et al ., 2021). The mechanisms responsible for the chronotype or temporal niche preference, while still misunderstood, are most likely located downstream from the SCN (Yan, Smale & Nunez, 2018).…”

Section: Introductionmentioning

confidence: 99%

Circadian rhythms and glial cells of the central nervous system

Brécier

Smith

et al. 2022

Biological Reviews

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Glial cells are the most abundant cells in the central nervous system and play crucial roles in neural development, homeostasis, immunity, and conductivity. Over the past few decades, glial cell activity in mammals has been linked to circadian rhythms, the 24‐h chronobiological clocks that regulate many physiological processes. Indeed, glial cells rhythmically express clock genes that cell‐autonomously regulate glial function. In addition, recent findings in rodents have revealed that disruption of the glial molecular clock could impact the entire organism. In this review, we discuss the impact of circadian rhythms on the function of the three major glial cell types – astrocytes, microglia, and oligodendrocytes – across different locations within the central nervous system. We also review recent evidence uncovering the impact of glial cells on the body's circadian rhythm. Together, this sheds new light on the involvement of glial clock machinery in various diseases.

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“…The majority of PFC pyramidal neurons are intrinsically quiescent in their resting state and regulate information throughput via a wide array of ion channels, such as cyclic-nucleotide-gated non-selective cation (HCN) channels, sodium (Na + ), calcium (Ca 2+ ) and potassium (K + ) channels, including g-protein inward rectifying K + (GIRK) channels that mediate postsynaptic throughput of synaptic currents (11, 14–16). In the suprachiasmatic nucleus (SCN) brain clock, changes in sodium (Na + ), K + , and Ca 2+ ion channel function mediate daily rhythms in the spontaneous activity, and action potential dynamics of neurons (17, 18). How these channels might impact daily rhythms in PFC function and the gating of information throughput remains an important gap in our knowledge.…”

Section: Introductionmentioning

confidence: 99%

Circadian desynchronization attenuates information throughput of prefrontal cortex pyramidal neurons in mice

Roberts

Karatsoreos

2022

Preprint

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Circadian rhythms are ubiquitous in biology, from the molecular to behavioral levels. There is growing interest in understanding the functional implications of circadian oscillations in different cells and systems, including the brain. The prefrontal cortex (PFC) is heavily involved in myriad processes, including working memory, cognition, stress responses, and fear associated behaviors. Many PFC associated behaviors are time-of-day dependent, yet how time-of-day impacts the basic function of neurons in the PFC is not known. Here we use patch-clamp electrophysiology to record from layer 2/3 pyramidal neurons in the prelimbic (pl) PFC of male and female C57BL/6J mice at 4 separate bins of zeitgeber time (ZT): 0-4, 6-10, 12-16, and 18-22. We measured changes in membrane properties, inhibitory and excitatory inputs, ion channel function, and action potential kinetics. We demonstrate that the activity of plPFC neurons, their inhibitory inputs, and action potential dynamics are regulated by time-of-day. Further, we show that in males postsynaptic K+ channels play a central role in mediating these rhythms, suggesting the potential for an intrinsic gating mechanism mediating information throughput. These key discoveries in PFC physiology demonstrate the importance of understanding how daily rhythms contribute to the mechanisms underlying the basic functions of PFC circuitry.

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Daily electrical activity in the master circadian clock of a diurnal mammal

Cited by 17 publications

References 95 publications

Inhibitory responses to retinohypothalamic tract stimulation in the circadian clock of the diurnal rodent Rhabdomys pumilio

Inhibitory responses to retinohypothalamic tract stimulation in the circadian clock of the diurnal rodent Rhabdomys pumilio

Circadian rhythms and glial cells of the central nervous system

Circadian desynchronization attenuates information throughput of prefrontal cortex pyramidal neurons in mice

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