Being circadian or not: vasopressin release in cultured SCN mirrors behavior in adult voles

We studied vasopressin (AVP) release patterns from organotypic suprachiasma tic nucleus (SCN) cultures obtained from circadian rhythmic and non-rhythmi c voles. All eight SCN cultures made from non-rhythmic voles did not produc e any circadian pattern in AVP release, while five out of six SCN cultures of rhythmic voles produced significant (circadian) peak values. The total a mount of AVP released was 2-fold higher in SCN cultures from rhythmic vote. These data confirm our previously formulated AVP release deficit hypothesi s for nonrhythmic voles, and suggest that AVP in the vole SCN plays an impo rtant role in mediating output:of its circadian clock, regulating circadian organization of locomotor behavior, NeuroReport 11:3555-3558 (C) 2000 Lipp incott Williams & Wilkins.