The circadian clock in the suprachiasmatic nucleus (SCN) regulates daily rhythms in physiology and behaviour and is an important part of the mammalian homeostatic system. Previously, we have shown that systemic inflammatory stimulation with lipopolysaccharide (LPS) induced the daytime-dependent phosphorylation of STAT3 in the SCN. Here, we demonstrate the LPS-induced Stat3 mRNA expression in the SCN and show also the circadian rhythm in Stat3 expression in the SCN, with high levels during the day. Moreover, we examined the effects of LPS (1mg/kg), applied either during the day or the night, on the rhythm in locomotor activity of male Wistar rats. We observed that recovery of normal locomotor activity patterns took longer when the animals were injected during the night. The clock genes Per1, Per2 and Nr1d1, and phosphorylation of kinases ERK1/2 and GSK3β are sensitive to external cues and function as the molecular entry for external signals into the circadian clockwork. We also studied the immediate changes in these clock genes expressions and the phosphorylation of ERK1/2 and GSK3β in the suprachiasmatic nucleus in response to daytime or night-time inflammatory stimulation. We revealed mild and transient changes with respect to the controls. Our data stress the role of STAT3 in the circadian clock response to the LPS and provide further evidence of the interaction between the circadian clock and immune system.

• MeSH
• cirkadiánní rytmus účinky léků   MeSH
• krysa rodu Rattus MeSH
• lipopolysacharidy toxicita   MeSH
• lokomoce účinky léků   MeSH
• MAP kinasový signální systém účinky léků   MeSH
• mitogenem aktivovaná proteinkinasa 3 metabolismus   MeSH
• nucleus suprachiasmaticus metabolismus   patologie   MeSH
• potkani Wistar MeSH
• regulace genové exprese účinky léků   MeSH
• transkripční faktor STAT3 biosyntéza   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• lipopolysacharidy MeSH
• mitogenem aktivovaná proteinkinasa 3 MeSH
• Stat3 protein, rat MeSH Prohlížeč
• transkripční faktor STAT3 MeSH

The intrinsic period of circadian clock in the suprachiasmatic nucleus is entrained to a 24-h cycle by external cues, mainly light. Previous studies have shown that light applied at night induces robust phosphorylation of extracellular-signal-regulated kinase that is necessary to process the light pulse into the phase shift of the clock phase. In this study, we show the persistent downregulation of phosphorylated extracellular-signal-regulated kinase and transient downregulation of phosphorylated glycogen synthase kinase-3beta in the ventrolateral part of the suprachiasmatic nucleus to photic stimuli starting at 2 h after the beginning of the light pulse. As both kinases are involved in regulation of circadian clockwork, we hypothesize that these changes may contribute to the phase-shifting effect of light at night.

• MeSH
• cirkadiánní hodiny * MeSH
• kinasa 3 glykogensynthasy metabolismus   MeSH
• kinasa glykogensynthasy 3beta MeSH
• krysa rodu Rattus MeSH
• MAP kinasový signální systém MeSH
• mitogenem aktivovaná proteinkinasa 1 metabolismus   MeSH
• mitogenem aktivovaná proteinkinasa 3 metabolismus   MeSH
• nucleus suprachiasmaticus metabolismus   fyziologie   MeSH
• potkani Wistar MeSH
• reakční čas * MeSH
• světelná stimulace MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• Gsk3b protein, rat MeSH Prohlížeč
• kinasa 3 glykogensynthasy MeSH
• kinasa glykogensynthasy 3beta MeSH
• mitogenem aktivovaná proteinkinasa 1 MeSH
• mitogenem aktivovaná proteinkinasa 3 MeSH