Daily patterns of two brain chemicals in rat time-keeping cells do not rely on cell arrangement in culture

Cultured rat suprachiasmatic nucleus cells exhibited robust circadian rhythms of arginine vasopressin and vasoactive intestinal polypeptide starting 24 hours after dissociation.

• The circadian rhythms of arginine vasopressin and vasoactive intestinal polypeptide had similar periods, with vasoactive intestinal polypeptide peaks occurring approximately 1 hour before those of arginine vasopressin.
• These rhythms remained consistent two weeks post-culture, suggesting synchronization between the two peptide releases.
• Cell architecture exhibited significant variations based on the precoating matrices of culture dishes, yet this did not impact the circadian rhythms.
• Antimitotic treatment altered glial cell types and reduced their number but did not disrupt the synchronized rhythms of the peptides for up to 31 days.
• The early emergence of these rhythms implies that neural networks are not required for the synchronized release of the peptides.

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