Daily rhythms of nerve cell and support cell glutamate transporters in the brain’s internal clock of mice

All three glutamate transporters—VGLUT1, VGLUT2, and GLAST—showed time-of-day-dependent rhythms in the suprachiasmatic nucleus of male C57Bl/6J mice.

• VGLUT1 and GLAST levels peaked during the light phase, while VGLUT2 levels peaked during the dark phase.
• The distinct timing of transporter peaks suggests that VGLUT1 and GLAST are more strongly coupled, whereas VGLUT2 serves a complementary role.
• The rhythmic expression of these transporters indicates that the efficiency of light information transmission may vary throughout the day.
• Transporter rhythms persisted under conditions of constant darkness and constant light, demonstrating robust circadian control.
• Findings support the idea that the circadian system may regulate its own glutamatergic input.

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