title: Immunocytochemical demonstration of day/night changes of clock gene protein levels in the murine adrenal gland: differences between melatonin-proficient (C3H) and melatonin-deficient (C57BL) mice.
abstract: The circadian system comprises several peripheral oscillators and a central rhythm generator that, in mammals, is located in the suprachiasmatic nucleus of the hypothalamus. Expression of clock genes is a characteristic feature of the central rhythm generator and the peripheral oscillators. With regard to the rhythmic production of glucocorticoids, the adrenal gland can be considered as peripheral oscillator, but little is known about clock gene expression in this tissue. Therefore, the present study investigates the levels of three clock gene proteins PER1, BMAL1 and CRY2 in the murine adrenal cortex and medulla at seven different time points of a 12-hr light/12-hr dark cycle. To determine a potential role of melatonin we compared the patterns of clock gene proteins in the adrenal gland of melatonin-proficient mice (C3H) with those of melatonin-deficient mice (C57BL). In C3H mice, both, the adrenal cortex and medulla displayed day/night variation in PER1-, CRY2- and BMAL1-protein levels. PER1 and CRY2 peaked in the middle of the light phase, whereas BMAL1 peaked in the dark phase. This pattern was also observed in the adrenal medulla of C57BL, but in the adrenal cortex of C57BL clock gene protein levels did not change with time and were consistently lower than in C3H mice. These results support the hypothesis that the adrenal gland is a peripheral oscillator and raise the possibility that melatonin may be involved in the control of clock gene protein levels in the adrenal cortex of mice.
authors.affiliation: Institut für Anatomie II, Dr. Senckenbergische Anatomie, Johann Wolfgang Goethe-Universität, Frankfurt, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Torres-Farfan
authors.forename: María
authors.initials: M
authors.lastname: Serón-Ferré
authors.forename: Virginie
authors.initials: V
authors.lastname: Dinet
authors.forename: Horst-Werner
authors.initials: HW
authors.lastname: Korf
mesh_terms: D056930:ARNTL Transcription Factors; D000311:Adrenal Glands / Q000502:physiology*; D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism*; D001683:Biological Clocks; D018797:Cell Cycle Proteins; D002940:Circadian Rhythm / Q000502:physiology*; D056931:Cryptochromes; D005420:Flavoproteins / Q000378:metabolism*; D005786:Gene Expression Regulation; D007150:Immunohistochemistry; D008297:Male; D008550:Melatonin / Q000172:deficiency / Q000502:physiology*; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D009687:Nuclear Proteins / Q000378:metabolism*; D056950:Period Circadian Proteins
chemical_list: D056930:ARNTL Transcription Factors; D051792:Basic Helix-Loop-Helix Proteins; D018797:Cell Cycle Proteins; D056931:Cryptochromes; D005420:Flavoproteins; D008550:Melatonin; D009687:Nuclear Proteins; D056950:Period Circadian Proteins; C538961:Bmal1 protein, mouse; C538967:Cry2 protein, mouse; C539023:Per1 protein, mouse