title: Tumor necrosis factor {alpha} reversibly disrupts the blood-testis barrier and impairs Sertoli-germ cell adhesion in the seminiferous epithelium of adult rat testes.
abstract: The timely restructuring of the blood-testis barrier (BTB) that facilitates the migration of preleptotene and leptotene spermatocytes from the basal to the adluminal compartment in the seminiferous epithelium of adult rat testes, which occurs at late stage VII through early stage VIII of the epithelial cycle, is a crucial cellular event of spermatogenesis. However, the regulation of BTB dynamics at the biochemical level remains elusive. In this study, tumor necrosis factor alpha (TNFalpha), a secretory product of Sertoli and germ cells in rat testes, was shown to affect junction dynamics in vivo. Following an acute administration of recombinant TNFalpha directly to adult rat testes in vivo at 0.5 and 2 mug/testis (with a body weight ~300 g), this treatment significantly and transiently disrupted the BTB. It also transiently inhibited the steady-state protein levels of occludin, zonula occludens-1, and N-cadherin, but not junction adhesion molecule-A, alpha-, and beta-catenin in testes at the BTB site as illustrated by immunoblottings, immunohistochemistry, electron microscopy, and fluorescent microscopy. This transient disruption of the BTB integrity induced by TNFalpha treatment was further demonstrated by a functional test to assess the passage of a fluorescent dye (e.g. fluorescein-5-isothiocyanate) from the systemic circulation to the adluminal compartment. Additionally, both the phosphorylated-Ser/Thr protein kinase activated by MAP kinase kinase (p-p38) and phosphorylated-externally regulated kinase (p-ERK) mitogen -activated protein kinase-signaling pathways were transiently activated. Collectively, these data coupled with the recently published in vitro studies have illustrated that the BTB is likely utilizing a novel mechanism in which localized production of TNFalpha by Sertoli and germ cells into the microenvironment at the basal compartment facilitates the timely restructuring ('opening'?) of the BTB during spermatogenesis to facilitate germ cell migration.
authors.affiliation: Population Council, 1230 York Avenue, New York 10021, USA.
authors.forename: Michelle W M
authors.initials: MW
authors.lastname: Li
authors.forename: Weiliang
authors.initials: W
authors.lastname: Xia
authors.forename: Dolores D
authors.initials: DD
authors.lastname: Mruk
authors.forename: Claire Q F
authors.initials: CQ
authors.lastname: Wang
authors.forename: Helen H N
authors.initials: HH
authors.lastname: Yan
authors.forename: Michelle K Y
authors.initials: MK
authors.lastname: Siu
authors.forename: Wing-Yee
authors.initials: WY
authors.lastname: Lui
authors.forename: Will M
authors.initials: WM
authors.lastname: Lee
authors.forename: C Yan
authors.initials: CY
authors.lastname: Cheng
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000032:analysis; D001814:Blood-Testis Barrier / Q000187:drug effects*; D002448:Cell Adhesion / Q000187:drug effects; D015151:Immunoblotting; D008297:Male; D008565:Membrane Proteins / Q000032:analysis; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D023421:Models, Animal; D062793:Occludin; D010750:Phosphoproteins / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012670:Seminiferous Epithelium; D012708:Sertoli Cells / Q000166:cytology* / Q000187:drug effects; D013094:Spermatozoa / Q000166:cytology* / Q000187:drug effects; D013737:Testis / Q000737:chemistry / Q000648:ultrastructure; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis / Q000494:pharmacology*; D062826:Zonula Occludens-1 Protein
chemical_list: D015415:Biomarkers; D008565:Membrane Proteins; D062793:Occludin; C568987:Ocln protein, rat; D010750:Phosphoproteins; C569044:Tjp1 protein, rat; D014409:Tumor Necrosis Factor-alpha; D062826:Zonula Occludens-1 Protein