Timekeeping in the hindbrain: a multi-oscillatory circadian centre in the mouse dorsal vagal complex

Metabolic and cardiovascular processes controlled by the hindbrain exhibit circadian rhythms. Here we provide compelling evidence from ex vivo and in vivo studies that genetic, neuronal, and vascular activities of the brainstem’s dorsal vagal complex are subject to intrinsic circadian control with a crucial role for the connection between its components in regulating their rhythmic properties. Robust 24h variation in clock gene expression in vivo and neuronal firing ex vivo were observed in the area postrema (AP) and nucleus of the solitary tract (NTS), together with enhanced nocturnal responsiveness to metabolic cues. Unexpectedly, we also find functional and molecular evidence for increased penetration of blood borne molecules into the NTS at night. Our findings reveal that the hindbrain houses a local network complex of neuronal and non-neuronal autonomous circadian oscillators. These provide a basis for daily variation in molecular and cellular homeostasis and raise clear implications for understanding local temporal control of physiology in the brainstem.