title: Diurnal, circadian and photic regulation of calcium/calmodulin-dependent kinase II and neuronal nitric oxide synthase in the hamster suprachiasmatic nuclei.
abstract: Mammalian circadian rhythms are entrained by light pulses that induce phosphorylation events in the suprachiasmatic nuclei (SCN). Ca(2+)-dependent enzymes are known to be involved in circadian phase shifting. In this paper, we show that calcium/calmodulin-dependent kinase II (CaMKII) is rhythmically phosphorylated in the SCN both under entrained and free-running (constant dark) conditions while neuronal nitric oxide synthase (nNOS) is rhythmically phosphorylated in the SCN only under entrained conditions. Both p-CaMKII and p-NOS (specifically phosphorylated by CaMKII) levels peak during the day or subjective day. Light pulses administered during the subjective night, but not during the day, induced rapid phosphorylation of both enzymes. Moreover, we found an inhibitory effect of KN-62 and KN-93, both CaMKII inhibitors, on light-induced nNOS activity and nNOS phosphorylation respectively, suggesting a direct pathway between both enzymes which is at least partially responsible of photic circadian entrainment.
authors.affiliation: Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Roque Saenz Peña 180, Bernal 1876, Buenos Aires, Argentina.
authors.forename: Patricia V
authors.initials: PV
authors.lastname: Agostino
authors.forename: Gabriela A
authors.initials: GA
authors.lastname: Ferreyra
authors.forename: Alejandro D
authors.initials: AD
authors.lastname: Murad
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Watanabe
authors.forename: Diego A
authors.initials: DA
authors.lastname: Golombek
mesh_terms: D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D001596:Benzylamines / Q000494:pharmacology; D015153:Blotting, Western; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D002940:Circadian Rhythm / Q000502:physiology*; D006224:Cricetinae; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007276:Injections, Intraventricular; D008027:Light; D008647:Mesocricetus; D019001:Nitric Oxide Synthase / Q000096:biosynthesis*; D052248:Nitric Oxide Synthase Type I; D010766:Phosphorylation; D017440:Photoperiod; D013449:Sulfonamides / Q000494:pharmacology; D013493:Suprachiasmatic Nucleus / Q000187:drug effects / Q000201:enzymology* / Q000502:physiology*; D000096926:Benzenesulfonamides
chemical_list: D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D001596:Benzylamines; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D004791:Enzyme Inhibitors; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; D013449:Sulfonamides; C072105:KN 93; D000096926:Benzenesulfonamides; C063302:KN 62