Suprachiasmatic nucleus-mediated glucose entry into the arcuate nucleus determines the daily rhythm in blood glycemia

Rodríguez-Cortés, Betty; Hurtado‐Alvarado, Gabriela; Martínez-Gómez, Ricardo; León-Mercado, Luis A.; Prager‐Khoutorsky, Masha; Buijs, R.M.

doi:10.1016/j.cub.2021.12.039

Cited by 24 publications

(21 citation statements)

References 67 publications

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“…In addition, there are several brain regions that show a circadian rhythm in glucose utilization (Crane et al, 1980 ; Newman et al, 1992 ). Recently, Rodríguez‐Cortes et al demonstrated a circadian rhythm in the entry of glucose into the hypothalamic arcuate nucleus (Rodríguez‐Cortés et al, 2022 ), suggesting that the daily variations in glucose levels in different brain areas could also be a cyclic signal modulating microglial function.…”

Section: Possible Mechanisms Imposing a Time Stamp On Microgliamentioning

confidence: 99%

Circadian modulation of microglial physiological processes and immune responses

Guzmán-Ruiz

Guerrero‐Vargas

Lagunes‐Cruz

et al. 2022

Glia

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Microglia is considered the central nervous system (CNS) resident macrophages that establish an innate immune response against pathogens and toxins. However, the recent studies have shown that microglial gene and protein expression follows a circadian pattern; several immune activation markers and clock genes are expressed rhythmically without the need for an immune stimulus. Furthermore, microglia responds to an immune challenge with different magnitudes depending on the time of the day. This review examines the circadian control of microglia function and the possible physiological implications. For example, we discuss that synaptic prune is performed in the cortex at a certain moment of the day. We also consider the implications of daily microglial function for maintaining biological rhythms like general activity, body temperature, and food intake. We conclude that the developmental stage, brain region, and pathological state are not the only factors to consider for the evaluation of microglial functions; instead, emerging evidence indicates that circadian time as an essential aspect for a better understanding of the role of microglia in CNS physiology.

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Section: Possible Mechanisms Imposing a Time Stamp On Microgliamentioning

confidence: 99%

Circadian modulation of microglial physiological processes and immune responses

Guzmán-Ruiz

Guerrero‐Vargas

Lagunes‐Cruz

et al. 2022

Glia

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“…The Arc region has been shown to have its own functional circadian system ( Cedernaes et al, 2019 ). It is also indirectly influenced by signals from the SCN, which changed the glucose concentration in the CSF to adapt glucose levels to the daily needs ( Rodriguez-Cortes et al, 2022 ). We found that the homeostatic component of feeding contributed a substantial amount of the signal to search for food, which became apparent if we blocked the SCN to PVN communication ( Figures 2 – 5 ).…”

Section: Discussionmentioning

confidence: 99%

“…As speculation, the signal could come from either the Arc or intergeniculate leaflet region ( Yi et al, 2006 ; Saderi et al, 2013 ), or directly from the CSF filling the third ventricle. While the SCN activates the tanycytes lining the third ventricle to facilitate glucose secretion into the CSF ( Rodriguez-Cortes et al, 2022 ), signals could also come back from these cells to the SCN ( Langlet 2014 ; Bolborea et al, 2020 ). Further analysis is clearly necessary to find the place of the SCN within the regulatory network to motivate or inhibit the search for food.…”

Section: Discussionmentioning

confidence: 99%

“…The graft of SCN tissue into mice with lesioned SCN could restore rhythms in the PVN, indicating a humoral synchronizing signal derived from the SCN ( Tousson and Meissl 2004 ). This signal could be related to the same signal used by the SCN to influence the Arc ( Rodriguez-Cortes et al, 2022 ). Furthermore, light inhibition of food searching was mediated by the Avp neurons in the SCN inhibiting the oxytocin neurons in the PVN ( Santoso et al, 2018 ), while activation of food searching was mediated by AgRP neurons in the Arc inhibiting the oxytocin neurons in the Paraventricular hypothalamus ( Atasoy et al, 2012 ).…”

Section: Discussionmentioning

confidence: 99%

“…The activation of these neurons could then stop the food uptake and movement of the rats. A completely different mechanism was recently described for the interaction of the SCN with the Arc region ( Rodriguez-Cortes et al, 2022 ). In this scenario, at the time of transition to the rest phase, vasopressin released from the SCN increased the transport of glucose into the CSF of the third ventricle.…”

Section: Introductionmentioning

confidence: 96%

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Suprachiasmatic to paraventricular nuclei interaction generates normal food searching rhythms in mice

et al. 2022

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Searching for food follows a well-organized decision process in mammals to take up food only if necessary. Moreover, scavenging is preferred during their activity phase. Various time-dependent regulatory processes have been identified originating from the suprachiasmatic nuclei (SCN), which convert external light information into synchronizing output signals. However, a direct impact of the SCN on the timing of normal food searching has not yet been found. Here, we revisited the function of the SCN to affect when mice look for food. We found that this process was independent of light but modified by the palatability of the food source. Surprisingly, reducing the output from the SCN, in particular from the vasopressin releasing neurons, reduced the amount of scavenging during the early activity phase. The SCN appeared to transmit a signal to the paraventricular nuclei (PVN) via GABA receptor A1. Finally, the interaction of SCN and PVN was verified by retrograde transport-mediated complementation. None of the genetic manipulations affected the uptake of more palatable food. The data indicate that the PVN are sufficient to produce blunted food searching rhythms and are responsive to hedonistic feeding. Nevertheless, the search for normal food during the early activity phase is significantly enhanced by the SCN.

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