title: Circadian rhythm in c-fos protein expression in the rat adrenal cortex.
abstract: The circadian variation in the expression of c-fos protein(s) in the adrenal cortex of adult rats was investigated immunocytochemically. The animals were maintained in standard laboratory facilities with a 12:12 h light:dark schedule (07.00-19.00 h) until sacrificed. The number of c-fos immunoreactive (c-fos IR) cells was statistically constant in the zona fasciculata and zona reticulata at 20.00 h and 24.00 h, and 04.00 h, but was decreased to 52% at 08.00 h and to 18% at 12.00 h, respectively, when compared to the 24.00 h value. At 16.00 h, the number of c-fos IR cells was increased again to 63% of the 24.00 h value. In the zona granulosa c-fos IR was observed only at 20.00 h and 24.00 h. Administration of dexamethasone, a potent inhibitor of ACTH release, significantly reduced the number of c-fos IR cells. As the circadian rhythm of c-fos expression in the adrenal cortex correlates to that reported for ACTH secretion from the pituitary, the results suggest that c-fos gene is involved in mediating physiological ACTH-induced responses in the adrenal cortical cells.
authors.affiliation: Department of Public Health, University of Tampere, Finland.
authors.forename: J
authors.initials: J
authors.lastname: Koistinaho
authors.forename: R
authors.initials: R
authors.lastname: Roivainen
authors.forename: G
authors.initials: G
authors.lastname: Yang
mesh_terms: D000302:Adrenal Cortex / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D002940:Circadian Rhythm; D003907:Dexamethasone / Q000494:pharmacology; D007124:Immunoenzyme Techniques; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D016760:Proto-Oncogene Proteins c-fos; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D011518:Proto-Oncogene Proteins; D016760:Proto-Oncogene Proteins c-fos; D003907:Dexamethasone