title: Upregulation of TrkA neurotrophin receptor expression in the thymic subcapsular, paraseptal, perivascular, and cortical epithelial cells during thymus regeneration.
abstract: Neuroimmune networks in the thymic microenvironment are thought to be involved in the regulation of T cell development. Here, we report upon an examination of the expression of the TrkA neurotrophin receptor, the high affinity receptor for nerve growth factor, during regeneration following acute involution induced by cyclophosphamide in the rat thymus. Light and electron microscopic immunocytochemistry demonstrated enhanced expression of the TrkA receptor in the subcapsular, paraseptal, perivascular, and cortical epithelial cells during thymus regeneration. In addition, various morphological alterations, suggestive of a hyperfunctional and dynamic state, of the subcapsular, paraseptal, and perivascular epithelial cells were also observed. The presence of TrkA protein in extracts from the control and regenerating rat thymus was confirmed by western blot. Furthermore, RT-PCR analysis supported these results by demonstrating that thymic extracts contain TrkA mRNA at higher levels during thymus regeneration. Thus, our results suggest that the TrkA receptor located on the thymic subcapsular, paraseptal, perivascular, and cortical epithelial cells could play a role in the development of new T cells to replace T cells damaged during thymus regeneration.
authors.affiliation: Department of Anatomy, College of Medicine, Pusan National University, 1-10 Ami-Dong, Seo-Gu, 602-739 Pusan, South Korea. sikyoon@pusan.ac.kr
authors.forename: Sik
authors.initials: S
authors.lastname: Yoon
authors.forename: Hee-Woo
authors.initials: HW
authors.lastname: Lee
authors.forename: Sun-Yong
authors.initials: SY
authors.lastname: Baek
authors.forename: Bong-Seon
authors.initials: BS
authors.lastname: Kim
authors.forename: Jae-Bong
authors.initials: JB
authors.lastname: Kim
authors.forename: Soon-Ae
authors.initials: SA
authors.lastname: Lee
mesh_terms: D000818:Animals; D015153:Blotting, Western; D003520:Cyclophosphamide / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D007124:Immunoenzyme Techniques; D007166:Immunosuppressive Agents / Q000494:pharmacology; D008297:Male; D008854:Microscopy, Electron; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D020917:Receptor, trkA / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D012038:Regeneration / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013047:Specific Pathogen-Free Organisms; D013950:Thymus Gland / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D014020:Tissue Extracts / Q000737:chemistry / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D007166:Immunosuppressive Agents; D012333:RNA, Messenger; D014020:Tissue Extracts; D003520:Cyclophosphamide; D020917:Receptor, trkA