Published ahead of print on December 14, 2006, doi:10.1165/rcmb.2006-0256OC Am. J. Respir. Cell Mol. Biol., Volume 36, Number 5, May 2007, 541-551 A more recent version of this article appeared on May 1, 2007
Submitted on July 14, 2006 Sensory Receptors in the Visceral Pleura: Neurochemical Coding and Live Staining in Whole MountsIsabel Pintelon1,1 Laboratory of Cell Biology and Histology, University of Antwerp, Antwerp, Belgium * To whom correspondence should be addressed. E-mail: dirk.adriaensen{at}ua.ac.be.
Today, diagnosis and treatment of chest pain related to pathological changes in the visceral pleura are often difficult. Literature data on the sensory innervation of the visceral pleura are sparse. The present study aimed at identifying sensory end-organs in the visceral pleura, and at obtaining more information about their neurochemical coding. The immunocytochemcial data are mainly based on whole mounts of the visceral pleura of control and vagally denervated rats. It was shown that innervation of the rat visceral pleura is characterized by nerve bundles that enter in the hilus region and gradually split into slender bundles with a few nerve fibers. Separate nerve fibers regularly give rise to characteristic laminar terminals. Because of their unique association with the elastic fibers of the visceral pleura, we decided to refer to them as 'visceral pleura receptors' (VPRs). Cryostat sections of rat lungs confirmed a predominant location on mediastinal and interlobar lung surfaces. VPRs can specifically be visualized by PGP9.5 immunostaining, and were shown to express vesicular glutamate transporters, calbindin D28K, Na+/K+-ATPase, and P2X3 ATP-receptors. The sensory nerve fibres giving rise to VPRs appeared to be myelinated and to have a spinal origin. Since several of the investigated proteins have been reported as markers for sensory terminals in other organs, the present study revealed that VPRs display the neurochemical characteristics of mechanosensory and/or nociceptive terminals. The development of a live staining method, using AM1-43, showed that VPRs can be visualized in living tissue, offering an interesting model for future physiological studies.
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