Stretch receptor-associated expression of alpha sub(3) isoform of the Na super(+),K super(+)-ATPase in rat peripheral nervous system

• Published in: Neuroscience Vol. 116; no. 4; pp. 1069 - 1080
• Main Authors: Dobretsov, M, Hastings, S L, Sims, T J, Stimers, J R, Romanovsky, D
• Format: Journal Article
• Language: English
• Published: 01.02.2003
• ISSN: 0306-4522
• DOI: 10.1016/S0306-4522(02)00922-3

Expression of the neuronal alpha sub(3) isoform of the Na super(+),K super(+)-ATPase ( alpha sub(3) Na super(+),K super(+)-ATPase) was studied in the rat peripheral nervous system using histological and immunohistochemical techniques. Non-uniform expression of the alpha sub(3) Na super(+),K super(+)-ATPase was observed in L5 ventral and dorsal roots, dorsal root ganglion, sciatic nerve and its branches into skeletal muscle. The alpha sub(3) Na super(+),K super(+)-ATPase was not detected in nerve fibers in skin, saphenous and sural nerves. In dorsal root ganglion 12 plus or minus 2% of neurons were immunopositive for alpha sub(3) Na super(+),K super(+)-ATPase and all these neurons were large primary afferents that were not labeled by Griffonia simplicifolia isolectin B4 (marker of small primary sensory neurons). In dorsal and ventral roots 27 plus or minus 3% and 40 plus or minus 3%, respectively, of myelinated axons displayed immunoreactivity for alpha sub(3) Na super(+),K super(+)-ATPase. In contrast to the dorsal roots, strong immunoreactivity in ventral roots was observed only in myelinated axons of small caliber, presumably gamma -efferents. In the mixed sciatic nerve alpha sub(3) Na super(+),K super(+)-ATPase was detected in 26 plus or minus 5% of myelinated axons (both small and large caliber). In extensor hallicus proprius and lumbricales hind limb muscles alpha sub(3) Na super(+),K super(+)-ATPase was detected in some intramuscular axons and axonal terminals on intrafusal muscle fibers in the spindle equatorial and polar regions (regions of afferent and efferent innervation of the muscle stretch receptor, respectively). No alpha sub(3) Na super(+),K super(+)-ATPase was found in association with innervation of extrafusal muscle fibers or in tendon-muscle fusion regions. These data demonstrate non-uniform expression of the alpha sub(3) isoform of the Na super(+),K super(+)-ATPase in rat peripheral nervous system and suggest that alpha sub(3) Na super(+),K super(+)-ATPase is specifically expressed in afferent and efferent axons innervating skeletal muscle stretch receptors.