title: Diurnal variation in CREB phosphorylation and PER1 protein levels in lactotroph cells of melatonin-proficient C3H and melatonin-deficient C57BL mice: similarities and differences.
abstract: The pineal hormone melatonin plays an important role in the maintenance of rhythmic functions of the hypophyseal pars tuberalis, which controls the lactotroph cells of the pars distalis. To analyze the effects of melatonin deficiency on the activity state of these cells, we have investigated the levels of Ser133-phosphorylated (p)CREB and PER1 protein in immunocytochemically identified lactotroph cells of melatonin-proficient C3H and melatonin-deficient C57BL mice at four different time points of a 12/12 LD cycle. At night, the percentage of lactotroph cells showing a positive nuclear pCREB and PER1 immunoreaction is significantly smaller in C57BL than in C3H mice. In both mouse strains, the percentage of pCREB-immunoreactive cells is minimal in the early morning and gradually increases to reach a maximum in the late night. PER1 levels show a parallel temporal variation in C3H, but in C57BL, they are drastically reduced in the early afternoon. The observation that, during darkness, the percentage of lactotroph cells with nuclear pCREB immunoreaction is significantly higher in C3H than in C57BL mice suggests the existence of a distinct cell population that is under the control of melatonin-dependent intrapituitary signaling. Interestingly, the percentage of pCREB- and PER1-immunoreactive lactotroph cells reaches minimal and maximal values at the same time points. This suggests that the correlation between CREB phosphorylation and PER1 induction differs between these cells and other neuroendocrine centers, e.g., the pineal organ and suprachiasmatic nucleus, displaying a temporal gap between CREB phosphorylation and PER1 induction.
authors.affiliation: Dr. Senckenbergische Anatomie, Institut für Anatomie II, Fachbereich Medizin der J.W. Goethe-Universität Frankfurt, Germany.
authors.forename: Pjotr
authors.initials: P
authors.lastname: Sheynzon
authors.forename: Magdalena
authors.initials: M
authors.lastname: Karolczak
authors.forename: Faramarz
authors.initials: F
authors.lastname: Dehghani
authors.forename: Horst-Werner
authors.initials: HW
authors.lastname: Korf
mesh_terms: D000818:Animals; D001683:Biological Clocks / Q000502:physiology; D018797:Cell Cycle Proteins; D002467:Cell Nucleus / Q000378:metabolism; D002940:Circadian Rhythm / Q000502:physiology*; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism*; D015536:Down-Regulation / Q000502:physiology; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000502:physiology; D007150:Immunohistochemistry; D008297:Male; D008550:Melatonin / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D009490:Neurosecretory Systems / Q000502:physiology; D009687:Nuclear Proteins / Q000378:metabolism*; D056950:Period Circadian Proteins; D010766:Phosphorylation; D010902:Pituitary Gland / Q000166:cytology / Q000378:metabolism*; D011388:Prolactin / Q000378:metabolism; D012694:Serine / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D013045:Species Specificity
chemical_list: D018797:Cell Cycle Proteins; C492004:Creb1 protein, mouse; D017362:Cyclic AMP Response Element-Binding Protein; D009687:Nuclear Proteins; C539023:Per1 protein, mouse; D056950:Period Circadian Proteins; D012694:Serine; D011388:Prolactin; D008550:Melatonin