1. Light- and electron-microscopical study of phosphoprotein B-50 following denervation and reinnervation of the rat soleus muscle
- Author
-
PM Edwards, AB Oesteicher, J Verhaagen, H Veldman, FG Jennekens, and W.H. Gispen
- Subjects
Biology ,Neuromuscular junction ,GAP-43 Protein ,medicine ,Animals ,Axon ,Gap-43 protein ,Denervation ,Soleus muscle ,General Neuroscience ,Muscles ,Rats, Inbred Strains ,Articles ,Phosphoproteins ,Immunohistochemistry ,Muscle Denervation ,Cell biology ,Hindlimb ,Nerve Regeneration ,Rats ,Microscopy, Electron ,medicine.anatomical_structure ,Phosphoprotein ,biology.protein ,Acetylcholinesterase ,Immunologic Techniques ,Female ,Sciatic nerve ,Neuroscience ,Reinnervation - Abstract
The neuron-specific phosphoprotein B-50 was originally identified as a phosphoprotein in synaptic plasma membranes isolated from adult brain tissue. In this paper we study the reinnervation of the soleus muscle, a target muscle of sciatic nerve axons, using affinity-purified anti-B- 50 antibodies. Light-microscopical evaluation of the reinnervation process revealed that the period of muscle fiber reinnervation corresponds closely with the time in which high B-50 immunoreactivity was observed in the nerve fibers that invade the muscle and in the newly formed neuromuscular junctions. Upon completion of reinnervation, B-50 immunoreactivity decreased. In the newly innervating terminals, B- 50 was associated with presynaptic vesicular structures and with the presynaptic plasma membrane. In intact mature neuromuscular junctions, virtually no B-50 immunoreactivity could be detected with either light- or electron-microscopic procedures. These observations corroborate the association of high levels of B-50/GAP43 during axon outgrowth and support the concept that B-50 may be a key molecule in the reconstruction of axonal structures. We also observed an unexpected transient increase in B-50 immunoreactivity in the degenerating neuromuscular junctions. This observation cannot be explained in terms of increased neuronal synthesis of B-50, since the degenerating axon processes have been completely disconnected from their cell bodies. Thus, our evidence implies that a rise of B-50 immunoreactivity can be associated with stages of neuronal degeneration as well as with those of neuronal differentiation and axon outgrowth.
- Published
- 1988