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RESEARCH PRODUCT

Expression Profile of Stress Proteins, Intermediate Filaments, and Adhesion Molecules in Experimentally Denervated and Reinnervated Rat Facial Muscle

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The immunohistochemical profiles of ubiquitin, heat shock protein 70, alpha-B-crystallin, desmin, vimentin, neural cell adhesion molecule (N-CAM), and tenascin in rat facial muscle were studied after permanent denervation by transection of the facial plexus on one side and compared with findings after immediate reinnervation by hypoglossal-facial nerve anastomosis subsequent to transection on the contralateral side. Levator labii muscle samples were collected sequentially at 2, 6, 7, 10, 20, and 24 weeks after surgery. Normal levator labii muscle fibers showed physiological expression of desmin and alpha-B-crystallin. Denervated rat facial muscle displayed distinct up-regulation of ubiquitin, alpha-B-crystallin, N-CAM, and tenascin. While alpha-B-crystallin and N-CAM decreased in long-standing denervation, tenascin had completely disappeared at 6 weeks. Like-wise, reinnervated muscles displayed enhanced expression of ubiquitin, alpha-B-crystallin, N-CAM, tenascin, and, additionally, desmin. Strong expression of desmin and ubiquitin was found up to the 10th week as well as of alpha-B-crystallin, N-CAM, and tenascin up to the 7th week of reinnervation. Afterward, expression of stress proteins, intermediate filaments, and adhesion molecules returned to expression profiles of normal controls, indicating that enhancement of these proteins was restricted to the "atrophic and regenerative" states with a decline to physiological levels after successful reinnervation and restoration of muscle fibers. Furthermore part of regeneration from damage seems to resemble reactivated developmental mechanisms by reappearance of developmentally expressed proteins like desmin, N-CAM, and tenascin.