title: P0 mRNA expression increases during gradual nerve elongation in adult rats.
abstract: Leg lengthening with nerve elongation is a common clinical treatment. We investigated morphological and molecular changes in peripheral nerves associated with femoral lengthening using animal models. Sciatic nerves of 13 week old male Wistar rats (n = 35) were elongated indirectly by leg lengthening for 14 days at 1 mm/day. At 3, 7, 14, 21, and 35 days following initiation of elongation, sciatic nerves on the elongated side and contralateral (control) side were excised at the midpoint of the femur. Internodal length was increased by 17%. Light and electron microscopic observation of transverse sections at 14 days showed elongated nerves appearing similar to control nerves with no degenerating axons and normal myelin thickness. We next examined changes of mRNA expression of a major myelin glycoprotein, P0, in elongated nerves using a quantitative reverse transcription-polymerase chain reaction and in situ hybridization. P0 mRNA expression in elongated nerves was increased during the first 3 weeks, with expression reaching 160% of control nerve expression at 14 days. Results of in situ hybridization were confirmatory. We concluded that myelin synthesis occurred during gradual nerve elongation. In adulthood, Schwann cells retain ability to synthesize myelin in response to nerve stretching.
authors.affiliation: Department of Orthopaedic Surgery, Institute of Clinical Medicine, University of Tsukuba, Ibaraki, Japan. yukihara@mail1.accsnet.ne.jp
authors.forename: Yuki
authors.initials: Y
authors.lastname: Hara
authors.forename: Takashi
authors.initials: T
authors.lastname: Shiga
authors.forename: Ichiro
authors.initials: I
authors.lastname: Abe
authors.forename: Akihito
authors.initials: A
authors.lastname: Tsujino
authors.forename: Harumitsu
authors.initials: H
authors.lastname: Ichimura
authors.forename: Nobuo
authors.initials: N
authors.lastname: Okado
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Ochiai
mesh_terms: D000818:Animals; D001852:Bone Lengthening; D017403:In Situ Hybridization; D008297:Male; D018993:Myelin P0 Protein / Q000096:biosynthesis*; D009186:Myelin Sheath / Q000378:metabolism; D010525:Peripheral Nerves / Q000502:physiology*; D010812:Physical Stimulation; D012333:RNA, Messenger / Q000096:biosynthesis*; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D018993:Myelin P0 Protein; D012333:RNA, Messenger