Neuroscience lettersMar 28, 1994

Daily rhythms of two key signaling molecules in rat brain’s internal clock tissue

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Updated Mar 19, 2026

Abstract

The total vasoactive intestinal polypeptide (VIP) amount in the medium over 24 hours was six times larger than that of arginine-vasopressin (AVP).

VIP levels in the medium of organotypic suprachiasmatic nucleus (SCN) cultures exhibited a circadian rhythm with an approximate 22-hour period.
AVP levels also displayed similar circadian rhythms with the same period in the SCN culture.
The peak time of the VIP rhythm occurred slightly earlier than that of the AVP rhythm.
These findings indicate that VIP is released in a rhythmic pattern from the ventrolateral SCN.

Simplified

Temporal profiles of the amount of vasoactive intestinal polypeptide (VIP) were examined in the medium of organotypic suprachiasmatic nucleus (SCN) slice cultures over a 2-day period. Arginine-vasopressin (AVP) level was also measured in the same medium. The slices of the SCN were obtained from 7-8-day-old rats and cultured individually in tubes on a roller drum for 14 days. The VIP amount in the medium of SCN culture showed a circadian rhythm with a approximately 22-h period. Circadian rhythms with identical periods were also observed in AVP amount of the same culture. However, the peak time of the VIP rhythm was slightly ahead of that of the AVP rhythm. Furthermore, the total VIP amount in the medium over a 24-h period was six times as large as that of AVP. These results suggest that there is a circadian rhythm of VIP which is released from the ventrolateral SCN.

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Daily rhythms of two key signaling molecules in rat brain’s internal clock tissue

Abstract

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