title: Dexamethasone induces high-amplitude rhythms in preadipocytes, but hinders circadian expression in differentiated adipocytes.
abstract: Glucocorticoids induce circadian gene expression in cultured cells and change the phase of circadian gene expression in vivo. In addition, glucocorticoids induce differentiation of preadipocyte to adipocytes. We set out to test the effect of dexamethasone, a glucocorticoid receptor agonist, on circadian rhythms in 3T3-L1 differentiated adipocytes. Our results show that differentiated adipocytes exhibit robust circadian rhythms without dexamethasone. Dexamethasone induces phase changes and increases the amplitude of circadian gene expression in nondifferentiated 3T3-L1 preadipocytes. However, dexamethasone had an opposite effect on differentiated adipocytes, leading to low-amplitude circadian expression. In conclusion, although glucocorticoids reset circadian rhythms, once rhythms are reset, glucocorticoid administration hinders circadian expression.
authors.affiliation: Institute of Biochemistry, Food Science and Nutrition, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel.
authors.forename: Maayan
authors.initials: M
authors.lastname: Barnea
authors.forename: Zecharia
authors.initials: Z
authors.lastname: Madar
authors.forename: Oren
authors.initials: O
authors.lastname: Froy
mesh_terms: D041721:3T3-L1 Cells; D017667:Adipocytes / Q000166:cytology* / Q000187:drug effects*; D000818:Animals; D002454:Cell Differentiation; D002940:Circadian Rhythm / Q000187:drug effects*; D003907:Dexamethasone / Q000378:metabolism / Q000494:pharmacology*; D005938:Glucocorticoids / Q000378:metabolism / Q000494:pharmacology; D051379:Mice; D018485:Muscle Fibers, Skeletal / Q000187:drug effects; D010641:Phenotype; D012313:RNA / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D013997:Time Factors
chemical_list: D005938:Glucocorticoids; D012313:RNA; D003907:Dexamethasone