Motor nerve terminal loss from degenerating muscle fibers

Rich, Mark M.; Lichtman, Jeff W.

doi:10.1016/0896-6273(89)90236-5

Cited by 71 publications

(67 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Those authors interpreted the sprouting to be due to a local disinhibition of nerve growth induced by killing the muscle fiber underlying the nerve terminal. However, our attempts to induce sprouting in repeatedly damaged muscle fibers failed; indeed, we found just the opposite, a significant retraction of nerve branches when the muscle fiber died (see also Rich and Lichtman, 1989b). Furthermore, the incidence of sprouting increased in our studies (and in the previous work) over several days, reaching a maximum at 5-6 d when in every case we found that the nerve terminal was once again sitting on a healthy muscle fiber.…”

Section: Discussionsupporting

confidence: 55%

“…Our aim was to study if and how newly forming muscle fibers become innervated in living animals. We have found that when a muscle fiber is damaged by laser irradiation, away from its neuromuscular junction (to spare the motor axon from damage), the regenerated muscle fiber is innervated by the same axon and at the same site as the previous muscle fiber (see also Rich and Lichtman, 1989b). We also observed that muscle fiber regeneration is accompanied not only by sprouting from the nerve terminal on the regenerating muscle fiber but, interestingly, also sprouting from immediately adjacent neuromuscular junctions.…”

Section: Discussionmentioning

confidence: 52%

“…6A, compare d0 with d5) after muscle fiber damage and then sprouted after a new fiber appeared (see also Rich and Lichtman, 1989b). Interestingly, however, in some of the muscles we observed that nerve terminals on muscle fibers near the new fiber also showed terminal sprouts (Fig.…”

Section: Resultsmentioning

confidence: 61%

“…To test whether the sprouting from nearby nerve terminals was caused by muscle damage and regeneration rather than through inadvertent laser damage to the nerve terminals adjacent to the irradiated muscle fiber, in six mice approximately half the muscle fibers in the stemomastoid were damaged in a different way by pinching them with forceps at the ends of the fibers far away from the axons or the nerve terminals. This technique causes degeneration and regeneration of many muscle fibers (Rich and Lichtman, 1989b). Five to six days after muscle pinching, sprouting was evident from nerve terminals on several normal muscle fibers near the regenerating muscle fiber region in two of six examined muscles.…”

Section: Resultsmentioning

confidence: 99%

“…The left panel shows muscle appearance just prior to laser irradiation. Note that the nerve terminal on the regenerating fiber at day 5 is much smaller than it was prior to laser irradiation on day 0, indicating that during muscle degeneration many of the nerve terminal branches were retracted (for a fuller description see Rich and Lichtman, 1989b). B, Sprouting (arrow) from an adjacent nerve terminal on an undumuged muscle fiber 6 d after laser irradiating the muscle fiber to the left of it.…”

Section: Resultsmentioning

confidence: 99%

See 4 more Smart Citations

Regenerating muscle fibers induce directional sprouting from nearby nerve terminals: studies in living mice

Mier

Lichtman

1994

J. Neurosci.

View full text Add to dashboard Cite

The principal aim of this work was to better understand how regenerating muscle fibers become innervated in adult animals. To induce muscle regeneration, individual identified muscle fibers in a mouse were damaged with a laser focused through a microscope. The muscle fiber that degenerated and the muscle fiber that was formed in its place were followed by viewing the same site repeatedly over a period of 2 d to 40 weeks. Commonly, the nerve terminal innervating the irradiated muscle fiber partially retracted during muscle fiber degeneration, and then sprouted to innervate the regenerating muscle fiber at the same site it had previously innervated the muscle fiber that was damaged. During the early phase of muscle regeneration we also observed sprouts originating from nerve terminals on adjacent muscle fibers. The new nerve growth was a response to the regenerating muscle fiber rather than to the degenerated fiber it replaced because repeated damage of the same site every 2–3 d over a 10 d period (to prevent regeneration) did not cause any sprouting. The direction of the sprouts on adjacent muscle fibers showed a bias toward the regenerating muscle fiber, although they avoided the region occupied by the original nerve terminal. Forty percent of the sprouts managed to reach the regenerated fiber. Nonetheless, by 11 d after muscle fiber damage, all sprouts had regressed, leaving the new fiber innervated by the same motor axon that innervated the fiber that was damaged. On the other hand, when the overlying nerve terminal as well as the muscle fiber was damaged, the sprouts from nearby muscle fibers were both more numerous and more stable, and in five cases we observed two or more new synaptic junctions on the regenerating fiber originating from different axons. In one case we witnessed a protracted competition between the original motor axon as it sprouted back and the sprouts from nearby junctions for sole innervation of the regenerate. Ultimately, the surviving sprouts myelinated and became the permanent and exclusive input to the new fiber. These results indicate that regenerating muscle fibers emit a signal that induces directional sprouting from nearby undamaged nerve terminals. Reinnervation of the regenerating muscle fiber by one axon apparently prevents the maintenance of such neurites. Because the process of muscle regeneration shares many features in common with myogenesis during embryonic development, it is likely that developing muscle fibers present an analogous stimulus to ingrowing motor axons.(ABSTRACT TRUNCATED AT 400 WORDS)

show abstract

Section: Discussionsupporting

confidence: 55%

Section: Discussionmentioning

confidence: 52%

Section: Resultsmentioning

confidence: 61%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 3 more Smart Citations