title: Platelet-derived growth factor-b expression induced after rat peripheral nerve injuries.
abstract: Schwann cells are crucially important for peripheral nerve regeneration. These cells synthesize several factors that are supposed to enhance axonal regeneration when injured. Platelet-derived growth factor (PDGF) B-chain and its beta-receptor are expressed in Schwann cells in both normal peripheral nerves and culture. To elucidate the role of PDGF-B in peripheral nerve regeneration, we investigated its expression in cut or crush-injured rat sciatic nerves for up to 28 days. Northern blotting identified substantial increase of PDGF B-chain transcripts in injured nerves. Immunohistochemistry demonstrated that protein products of the transcripts were augmented at the distal tip of swollen axons in proximal nerve segments and in regenerating axons. Soon after both types of injury, considerable amounts of PDGF-B accumulated in numerous Schwann cells in distal segments of both models. With restoration of the axon-Schwann cell relationship in the crush model, levels of PDGF-B tended to decrease, eventually returning to normal. In the cut model in which the relationship cannot be restored, the PDGF-B was depleted to a very low level. The spatiotemporal correlation between PDGF-B and cell proliferation was very close throughout the study. These results differed strikingly from those of our previous study of rat optic nerve transection, in which PDGF-B was expressed only in a few recruited macrophages and glial cells. Augmented PDGF-B expression after sciatic nerve injury might contribute to peripheral nerve regeneration because PDGF-B is a mitogen and survival factor for Schwann cells and because it has trophic activity on neurons.
authors: Department of Pathology II, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Toyama, Japan.
authors: Takeshi
authors: T
authors: Oya
authors: Ying-Luan
authors: YL
authors: Zhao
authors: Kiyoshi
authors: K
authors: Takagawa
authors: Makoto
authors: M
authors: Kawaguchi
authors: Kamon
authors: K
authors: Shirakawa
authors: Tadakazu
authors: T
authors: Yamauchi
authors: Masakiyo
authors: M
authors: Sasahara
mesh_terms: D000818:Animals; D001369:Axons / Q000378:metabolism* / Q000648:ultrastructure; D000077214:Becaplermin; D015152:Blotting, Northern; D002455:Cell Division / Q000502:physiology; D005786:Gene Expression Regulation / Q000502:physiology; D007150:Immunohistochemistry; D008297:Male; D009409:Nerve Crush; D009416:Nerve Regeneration / Q000502:physiology*; D059348:Peripheral Nerve Injuries; D010525:Peripheral Nerves / Q000166:cytology / Q000378:metabolism*; D010982:Platelet-Derived Growth Factor / Q000235:genetics*; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D020574:Proto-Oncogene Proteins c-sis; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D020797:Receptor, Platelet-Derived Growth Factor beta / Q000378:metabolism; D012583:Schwann Cells / Q000166:cytology / Q000378:metabolism*; D015854:Up-Regulation / Q000235:genetics*
chemical_list: D010982:Platelet-Derived Growth Factor; D018809:Proliferating Cell Nuclear Antigen; D020574:Proto-Oncogene Proteins c-sis; D012333:RNA, Messenger; D000077214:Becaplermin; D020797:Receptor, Platelet-Derived Growth Factor beta