Postnatal realignment of circadian PER2::LUC rhythms in the submandibular gland during oral feeding development

May 30, 2026Journal of oral biosciences

Changes in daily PER2 protein rhythms in the salivary gland after birth during feeding development

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Abstract

Circadian rhythms in the mouse submandibular gland undergo progressive phase realignment during postnatal development.

Robust circadian rhythms were consistently observed in the suprachiasmatic nucleus at all stages of development.
Salivary gland rhythms dampened rapidly in culture and shifted from the light phase to the middle of the dark phase as mice matured.
Circadian periods in both the suprachiasmatic nucleus and salivary glands remained close to 24 hours throughout the study.
Changes in maternal care and feeding activity correlated with the phase adjustments of salivary gland rhythms.
Post-weaning, salivary gland peak phases began to resemble those observed in adult mice.

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OBJECTIVES: Circadian rhythms in peripheral organs undergo dynamic reorganization during postnatal development. However, the mechanisms underlying the maturation of circadian clocks in the salivary glands, particularly in relation to feeding behavior, remain poorly understood. In this study, we aimed to characterize the developmental maturation of circadian rhythms in the mouse submandibular gland (SMG).

METHODS: PERIOD2::LUCIFERASE bioluminescence rhythms were recorded from cultured suprachiasmatic nucleus (SCN) and SMG tissues isolated from mice at postnatal days 0, 1, 7, 14, 21, and 28, and 8 weeks. Maternal behavior and pup feeding activity were continuously monitored using infrared video recording. Peak phases and circadian periods were analyzed to evaluate developmental changes.

RESULTS: Robust circadian oscillations were observed in the SCN tissue at all developmental stages, with stable periods and peak phases. In contrast, rhythms in the SMG were rapidly damped in culture, and exhibited a progressive phase shift from the light phase to the middle of the dark phase during postnatal development. Circadian periods in both tissues remained close to 24 h throughout development. Behavioral analyses revealed that developmental changes in maternal care and feeding activity were closely associated with the phase realignment of SMG rhythms. After weaning, SMG peak phases resembled those in adult mice.

CONCLUSIONS: Postnatal maturation of circadian rhythms in the SMG is characterized by progressive phase realignment that parallels the transition from suckling to independent feeding. These findings suggest that developmental coordination between feeding behavior and peripheral clock machinery contributes to the establishment of circadian regulation of salivary function.

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Postnatal realignment of circadian PER2::LUC rhythms in the submandibular gland during oral feeding development

Abstract

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