RT Journal Article SR Electronic T1 Suprachiasmatic Nucleus Interaction with the Arcuate Nucleus; Essential for Organizing Physiological Rhythms JF eneuro JO eNeuro FD Society for Neuroscience SP ENEURO.0028-17.2017 DO 10.1523/ENEURO.0028-17.2017 VO 4 IS 2 A1 Frederik N. Buijs A1 Mara Guzmán-Ruiz A1 Luis León-Mercado A1 Mari Carmen Basualdo A1 Carolina Escobar A1 Andries Kalsbeek A1 Ruud M. Buijs YR 2017 UL http://www.eneuro.org/content/4/2/ENEURO.0028-17.2017.abstract AB The suprachiasmatic nucleus (SCN) is generally considered the master clock, independently driving all circadian rhythms. We recently demonstrated the SCN receives metabolic and cardiovascular feedback adeptly altering its neuronal activity. In the present study, we show that microcuts effectively removing SCN-arcuate nucleus (ARC) interconnectivity in Wistar rats result in a loss of rhythmicity in locomotor activity, corticosterone levels, and body temperature in constant dark (DD) conditions. Elimination of these reciprocal connections did not affect SCN clock gene rhythmicity but did cause the ARC to desynchronize. Moreover, unilateral SCN lesions with contralateral retrochiasmatic microcuts resulted in identical arrhythmicity, proving that for the expression of physiological rhythms this reciprocal SCN-ARC interaction is essential. The unaltered SCN c-Fos expression following glucose administration in disconnected animals as compared to a significant decrease in controls demonstrates the importance of the ARC as metabolic modulator of SCN neuronal activity. Together, these results indicate that the SCN is more than an autonomous clock, and forms an essential component of a larger network controlling homeostasis. The present novel findings illustrate how an imbalance between SCN and ARC communication through circadian disruption could be involved in the etiology of metabolic disorders.