Affiliations: Department of Anatomy, Faculty of Medicine, Kyushu
University, Fukuoka 812, Japan | Department of Medical Technology, Kyushu University
School of Health Sciences, Fukuoka 812, Japan
Note: [] Correspondence: Dr. Masaru Kawabuchi, M.D., Ph.D., Department of
Anatomy, Faculty of Medicine, Kyushu University, Higashi-ku, Maidashi 3-1-1,
Fukuoka 812-82, Japan. Phone: +81-92-642-6045; Fax.: +81-92-642- 6050; E-mail:
[email protected]
Abstract: The extent of the muscle endplate reinnervation that followed crush
injury of the sciatic nerve was compared between young adult (4 and 5 months
old) and aged (24 months old) animals. The time course of regeneration in the
muscular nerve bundle, its ramification, and the nerve terminal was
immunohistochemically estimated using an antibody against the neuron specific
enolase (NSE), a neuronal marker. During early phases of regeneration (7, 21
and 28 days post-crush) in the young adult animal, there were tortuosity,
vacuolation and/or unfasciculation in the nerve bundle and its ramification,
along with immature nerve terminals and multiple innervation. Following a
subsequent advancement in reinnervation to the denervated motor endplates, the
adult type of single motor innervation was common on the day 56. The old
muscles basically followed the course of reversible axotomy alike the young
adult ones. The age difference accounted for as fol-lows: a reduced rate of
reinnervation as indicated by a greater frequency of abnormal nerve bundles and
immature nerve terminals at 28 days and 56 days post-crush, as well as unusual
pathways or striking tortuosity represented by the NSE-labeled processes
between day 7 and 56; late in the reinnervation period, abnormal regeneration
characterized by damage of the nerve bundle, and poorly developed terminal
architec-tures. These results suggest that despite the capability of the nerve
from the old animals to extend its process, re-establishment of normal single
motor innervation is reduced due to some age-related deficits, which may be
related to the impaired Schwann cell-axon interactions.
Keywords: Denervation, Rat, Regeneration, Immunohistochemistry, Neuron specific enolase, Aging, peripheral nervous system (PNS), nerve crush
