Development of spinal motoneurons in rats after a neonatal hypoxic insult.
To determine the developmental changes of cervical and lumbar motoneurons (MNs) during normal development and after a neonatal hypoxic insult, cervical and lumbar MNs were studied in rats of various postnatal ages using a retrograde neurotracing technique combined with immunohistochemistry. The results regarding normal development could be summarized as follows: (1) the dendrites elongated mainly during the first 5 postnatal days (PNDs), being longer and more extensive in cervical MNs than in lumbar MNs; (2) the average cell body area increased from PND 5 to 14; and (3) the distribution of cell body areas changed from a unimodal to a bimodal pattern between PND 5 and 14. The temporal differences in morphologic development between cervical and lumbar MNs may influence the motor development in a rostrocaudal manner. The dendrites of lumbar MNs were shorter and less extensive in rats with a neonatal hypoxic insult than in rats without one; no significant difference was observed in cervical MNs between the two groups. The developmental difference between cervical and lumbar MNs after a neonatal hypoxic insult may contribute to motor deficits, with greater effect on the lower than the upper limbs.
Takahashi
S
S
Department of Pediatrics, Asahikawa Medical College, Japan.
Tanaka
H
H
Oki
J
J
D000818:Animals; D048429:Cell Size; D002574:Cervical Vertebrae; D003712:Dendrites / Q000473:pathology; D002534:Hypoxia, Brain / Q000150:complications* / Q000473:pathology*; D008159:Lumbar Vertebrae; D009046:Motor Neurons / Q000473:pathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013116:Spinal Cord / Q000254:growth & development / Q000473:pathology*