1. 'Smelling' the cerebrospinal fluid: olfactory signaling molecules are expressed in and mediate chemosensory signaling from the choroid plexus.
- Author
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Gonçalves I, Hubbard PC, Tomás J, Quintela T, Tavares G, Caria S, Barreiros D, and Santos CR
- Subjects
- Adenylyl Cyclases cerebrospinal fluid, Animals, Cadaverine cerebrospinal fluid, Cadaverine pharmacology, Cell Line, Choroid Plexus cytology, Choroid Plexus drug effects, Cyclic AMP cerebrospinal fluid, Cyclic Nucleotide-Gated Cation Channels antagonists & inhibitors, Cyclic Nucleotide-Gated Cation Channels cerebrospinal fluid, Epithelial Cells cytology, Epithelial Cells drug effects, GTP-Binding Protein alpha Subunits antagonists & inhibitors, GTP-Binding Protein alpha Subunits cerebrospinal fluid, Gene Expression Regulation, Inositol 1,4,5-Trisphosphate cerebrospinal fluid, Olfactory Pathways physiology, Olfactory Perception physiology, Polyamines cerebrospinal fluid, Polyamines pharmacology, Primary Cell Culture, Putrescine cerebrospinal fluid, Putrescine pharmacology, RNA, Small Interfering genetics, RNA, Small Interfering metabolism, Rats, Rats, Wistar, Signal Transduction, Spermidine cerebrospinal fluid, Spermidine pharmacology, Spermine cerebrospinal fluid, Spermine pharmacology, Type C Phospholipases cerebrospinal fluid, Type C Phospholipases genetics, Adenylyl Cyclases genetics, Choroid Plexus metabolism, Cyclic Nucleotide-Gated Cation Channels genetics, Epithelial Cells metabolism, GTP-Binding Protein alpha Subunits genetics
- Abstract
The olfactory-type signaling machinery has been known to be involved not only in odorant detection but also in other tissues with unsuspected sensory roles. As a barrier, the choroid plexus (CP) is an active participant in the monitoring of the cerebrospinal fluid (CSF), promptly responding to alterations in its composition. We hypothesized that olfactory signaling could be active in CP, contributing to the surveillance of the CSF composition. We determined the mRNA and protein expression of the major components of the olfactory transduction pathway in the rat CP, including odorant receptors, the olfactory G-protein (Gαolf), adenylate cyclase 3 and cyclic nucleotide-gated channel 2. The functionality of the transduction pathway and the intracellular mechanisms involved were analyzed by DC field potential recording electrophysiological analysis, in an ex vivo CP-brain setup, using polyamines as stimuli and blockers of the downstream signaling pathways. Concentration-dependent responses were obtained for the polyamines studied (cadaverine, putrescine, spermine and spermidine), all known to be present in the CSF. Transfection of a CP epithelial cell line with siRNA against Gαolf effectively knocked down protein expression and reduced the CP cells' response to spermine. Thus, the key components of the olfactory chemosensory apparatus are present and are functional in murine CP, and polyamines seem to trigger both the cAMP and the phospholipase C-inositol 1,4,5-trisphosphate pathways. Olfactory-like chemosensory signaling may be an essential component of the CP chemical surveillance apparatus to detect alterations in the CSF composition, and to elicit responses to modulate and maintain brain homeostasis., (© 2016 Federation of European Biochemical Societies.)
- Published
- 2016
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