Nerve growth factor receptor immunoreactivity in neurons of the normal adult rat spinal cord and its modulation after peripheral nerve lesions.
Motoneurons of the rat spinal cord express low-affinity nerve growth factor receptor (LNGFR) and corresponding mRNA during development, and re-express it after their axotomy by peripheral nerve injury. The present study establishes the anatomical and quantitative baseline of LNGFR immunoreactive (LNGFR-IR) neurons of the entire normal adult female rat and then investigates the temporal course for the re-expression of LNGFR-IR in lumbar motoneurons after either a crush lesion (which is followed by regeneration and reconnection to the muscle) or a cut lesion with removal of the distal stump (where a neuroma but no reconnection is formed). In the normal adult spinal cord, two types of LNGFR-IR neurons were recognized: (1) small populations of large motoneurons located in the ventral horn mainly in correspondence to the regions of the phrenic, cremasteric and dorsolateral nuclei, and (2) a more numerous and more dorsally located population of small neurons. With a sciatic cut lesion, the number of LNGFR-IR motoneurons at spinal levels L4-L6 rapidly and dramatically increased to a maximum between post-lesion days 1 and 7, apparently involving most axotomized motoneurons of the region, and returned to the baseline level by day 30. With a crush lesion, similar numbers and virtually the same time-course of LNGFR-IR appearance were seen, but the onset of progressive disappearance of LNGFR-IR neurons was delayed by one week, so that at 30 days, the most caudal motoneurons (which are last to reach their target) were still LNGFR-IR. Comparison of these two time courses gives clues to the kind of signals that may be involved in initiating and/or maintaining the LNGFR response.
Rende
M
M
Institute of Human Anatomy, Catholic University of Rome, Italy.
Hagg
T
T
Manthorpe
M
M
Varon
S
S
D000818:Animals; D005260:Female; D007839:Functional Laterality; D009046:Motor Neurons / Q000502:physiology*; D009132:Muscles / Q000294:innervation; D009409:Nerve Crush; D009414:Nerve Growth Factors / Q000378:metabolism*; D009416:Nerve Regeneration; D009474:Neurons / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D017475:Receptors, Nerve Growth Factor; D012584:Sciatic Nerve / Q000502:physiology*; D013116:Spinal Cord / Q000502:physiology* / Q000503:physiopathology
D009414:Nerve Growth Factors; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D017475:Receptors, Nerve Growth Factor