"Tasting" the cerebrospinal fluid: Another function of the choroid plexus?

Area of Science:

• Neuroscience
• Molecular Biology
• Physiology

Background:

• The choroid plexus (CP) interfaces blood and cerebrospinal fluid (CSF), positioning it to monitor brain fluid composition.
• Mechanisms of CP surveillance are not fully understood, but taste pathways are known to sense chemical content in various body tissues.

Purpose of the Study:

• To investigate the hypothesis that the taste transduction pathway operates in the CP to assess CSF composition.
• To identify taste-related components and their functionality within CP epithelial cells (CPEC).

Main Methods:

• Analyzed gene and protein expression of taste receptors (Tas) and downstream signaling molecules in rat CP.
• Utilized calcium imaging to assess the functionality of T2R receptors in CPEC stimulated with bitter compounds.

Main Results:

• Transcripts and proteins for key taste pathway components (Tas1r1, Tas1r2, Tas1r3, Tas2r109, Tas2r144, α-Gustducin, Plcβ2, ItpR3, TrpM5) were found in CP.
• CP cells responded to bitter compound D-Salicin with increased intracellular calcium, which was blocked by Probenecid, confirming T2R receptor functionality.

Conclusions:

• The taste transduction pathway, including T2R receptors, is expressed and functional in the choroid plexus.
• This pathway likely enables CP epithelial cells to perform chemical surveillance of CSF, particularly detecting noxious bitter compounds.