The Cerebrospinal Fluid Secretion Rate Increases in Awake and Freely Moving Rats but Differs With Experimental Methodology.

Cerebrospinal fluid (CSF) dynamics hold implications for neurological health. Despite its importance, accurate quantification of the CSF secretion rate remains a challenge due to methodological controversies and the influence of anesthesia. A novel technique is established to determine CSF dynamics in awake and freely moving rats, and the CSF secretion is quantified with three different methodologies.

Day-night fluctuations in choroid plexus transcriptomics and cerebrospinal fluid metabolomics.

The cerebrospinal fluid (CSF) provides mechanical protection for the brain and serves as a brain dispersion route for nutrients, hormones, and metabolic waste. The CSF secretion rate is elevated in the dark phase in both humans and rats, which could support the CSF flow along the paravascular spaces that may be implicated in waste clearance. The similar diurnal CSF dynamics pattern observed in the day-active human and the nocturnal rat suggests a circadian regulation of this physiological variable, rather than sleep itself.

Nocturnal increase in cerebrospinal fluid secretion as a circadian regulator of intracranial pressure.

Background: It is crucial to maintain the intracranial pressure (ICP) within the physiological range to ensure proper brain function. The ICP may fluctuate during the light-dark phase cycle, complicating diagnosis and treatment choice in patients with pressure-related disorders. Such ICP fluctuations may originate in circadian or sleep-wake cycle-mediated modulation of cerebrospinal fluid (CSF) flow dynamics, which in addition could support diurnal regulation of brain waste clearance.