title: Relationship between ribosomal RNA gene transcription activity and motoneuron death: observations of avulsion and axotomy of the facial nerve in rats.
abstract: Motoneuron number and expression of cytoplasmic RNA and ribosomal RNA (rRNA) gene transcription activity in the facial nucleus were examined quantitatively and chronologically for up to 4 weeks in rats after facial nerve axotomy and avulsion in order to elucidate interrelationships in axonal changes. The right facial nerves of adult Fischer rats were avulsed at a portion of the outlet or axotomized at a portion of the foramen stylomastoideus. The number of large motoneurons in the facial nucleus was reduced by 40% 2 weeks after avulsion and by 70% 4 weeks after avulsion but displayed a 19% loss even 4 weeks after axotomy. The amount of cytoplasmic RNA decreased significantly and progressively from 1 day after avulsion. rRNA gene transcription activity in the large motoneurons of the facial nucleus decreased significantly beginning 30 min after both axotomy and avulsion, but the severity of the decrease was far more marked in the avulsion group, showing a 59% loss from the control value 4 weeks after avulsion. These findings indicate that rRNA gene transcription activity, expression of cytoplasmic RNA, and the number of motoneurons that survive are interrelated and that the decrease in rRNA gene transcription activity is a very early event in the phenomena observed in the axonal reactions of motoneurons.
authors.affiliation: Japan Foundation for Neuroscience and Mental Health, Tokyo, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Nagasao
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Hayashi
authors.forename: Yoko
authors.initials: Y
authors.lastname: Kawazoe
authors.forename: Emiko
authors.initials: E
authors.lastname: Kawakami
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Watabe
authors.forename: Kiyomitsu
authors.initials: K
authors.lastname: Oyanagi
mesh_terms: D000818:Animals; D019771:Axotomy; D001933:Brain Stem / Q000378:metabolism / Q000473:pathology; D002452:Cell Count; D016923:Cell Death; D003593:Cytoplasm / Q000235:genetics; D005154:Facial Nerve / Q000502:physiology*; D020220:Facial Nerve Injuries / Q000503:physiopathology*; D015870:Gene Expression / Q000502:physiology; D005786:Gene Expression Regulation / Q000502:physiology; D020459:Genes, rRNA / Q000502:physiology*; D008297:Male; D009046:Motor Neurons / Q000378:metabolism / Q000473:pathology*; D012313:RNA / Q000032:analysis; D051381:Rats; D011916:Rats, Inbred F344; D014158:Transcription, Genetic
chemical_list: D012313:RNA