Abstract
The terminal Schwann cells that accompany lanceolate sensory endings in the rat vibrissal follicle are known to display the small plasma membrane invaginations termed caveolae, which concentrate Ca(2+) signaling molecules. We have previously shown that these cells generate Ca(2+) signals at the lamellar processes covering the receptor axons through activation of the metabotropic purinoceptor P2Y(2). To investigate the roles of caveolae in the spatiotemporal organization of Ca(2+) signals, terminal Schwann cells were observed by immunohistochemistry for the caveola protein caveolin-1, and by transmission and scanning electron microscopy. In addition, immunohistochemical detection of P2Y(2) and its coupling partner G(q/11) along with confocal image analysis of the purinergically induced glial Ca(2+) responses was performed in isolated tissue preparations either treated or untreated with the caveolae eliminator methyl-β-cyclodextrin. Results showed the Schwann lamellae to be characterized by the presence of dense caveolae accompanying a fine tubular network of the endoplasmic reticulum Ca(2+) store and by intense expression of the signaling molecules P2Y(2) and G(q/11). Loss of caveolae diffusely redistributed these molecules throughout the entire cell and impaired the lamellar Ca(2+) signals, both in chronological priority (preceding the global cell response) and in spatial integrity (involving the entire length of the processes). To our knowledge, this is the first report of a subcellular accumulation of caveolae underlying compartmentalized glial Ca(2+) signals that can couple with local effects on the accompanying axon terminals.
Published Version
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