title: Effects of 6-meals-a-day feeding and 6-meals-a-day feeding combined with adrenalectomy on daily gene expression rhythms in rat epididymal white adipose tissue.
abstract: The master clock in the hypothalamic suprachiasmatic nucleus (SCN) is assumed to synchronize the tissue-specific rhythms of the peripheral clocks with the environmental day/night changes via neural, humoral and/or behavioral connections. The feeding rhythm is considered an important Zeitgeber for peripheral clocks, as daytime feeding reverses (clock) gene rhythms in the periphery, but not in the SCN. In this study, we investigated the necessity of a daily feeding rhythm for maintaining gene expression rhythms in epididymal white adipose tissue (eWAT). We showed that 7 of 9 rhythmic metabolic/adipokine genes, but not clock genes, lost their rhythmicity upon exposure to 6-meals-a-day feeding. Previously, we showed comparable effects of adrenalectomy on eWAT; therefore, subsequently we investigated the effect of simultaneous disruption of these humoral and behavioral signaling pathways, by exposing adrenalectomized animals to 6-meals-a-day feeding. Interestingly, under these conditions, all the clock genes and 10 of 11 rhythmic metabolic/adipokine genes lost their rhythmicity. These data indicate that adrenal hormones and feeding rhythm are indispensable for maintaining daily rhythms in metabolic/adipokine gene, but not clock gene, expression in eWAT. In contrast, at least one of these two signals should be present in order for eWAT clock gene rhythms to be maintained.
authors.affiliation: Hypothalamic Integration Mechanisms, Netherlands Institute for Neuroscience, Meibergdreef 47, 1105 BA, Amsterdam, The Netherlands.
authors.forename: Yan
authors.initials: Y
authors.lastname: Su
authors.affiliation: Department of Endocrinology and Metabolism, Academic Medical Center (AMC), University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.
authors.forename: Ewout
authors.initials: E
authors.lastname: Foppen
authors.affiliation: Department of Endocrinology and Metabolism, Academic Medical Center (AMC), University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.
authors.forename: Zhi
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Department of Endocrinology and Metabolism, Academic Medical Center (AMC), University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.
authors.forename: Eric
authors.initials: E
authors.lastname: Fliers
authors.affiliation: Hypothalamic Integration Mechanisms, Netherlands Institute for Neuroscience, Meibergdreef 47, 1105 BA, Amsterdam, The Netherlands.|Department of Endocrinology and Metabolism, Academic Medical Center (AMC), University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.
authors.forename: Andries
authors.initials: A
authors.lastname: Kalsbeek
mesh_terms: D054392:Adipokines / Q000235:genetics / Q000378:metabolism; D052436:Adipose Tissue, White / Q000378:metabolism*; D000315:Adrenalectomy; D000818:Animals; D001683:Biological Clocks / Q000235:genetics; D001835:Body Weight / Q000235:genetics; D002940:Circadian Rhythm / Q000235:genetics; D003345:Corticosterone / Q000097:blood; D004822:Epididymis / Q000378:metabolism*; D005247:Feeding Behavior; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D007328:Insulin / Q000097:blood; D008297:Male; D062407:Meals; D051381:Rats; D014280:Triglycerides / Q000097:blood
chemical_list: D054392:Adipokines; D007328:Insulin; D014280:Triglycerides; D003345:Corticosterone