title: TLR4 and CD14 receptors expressed in rat pineal gland trigger NFKB pathway.
abstract: Nuclear factor-kappa B (NFKB), a pivotal player in inflammatory responses, is constitutively expressed in the pineal gland. Corticosterone inhibits pineal NFKB leading to an enhancement of melatonin production, while tumor necrosis factor (TNF) leads to inhibition of Aa-nat transcription and the production of N-acetylserotonin in cultured glands. The reduction in nocturnal melatonin surge favors the mounting of the inflammatory response. Despite these data, there is no clear evidence of the ability of the pineal gland to recognize molecules that signal infection. This study investigated whether the rat pineal gland expresses receptors for lipopolysaccharide (LPS), the endotoxin from the membranes of Gram-negative bacteria, and to establish the mechanism of action of LPS. Here, we show that pineal glands possess both CD14 and toll-like receptor 4 (TLR4), membrane proteins that bind LPS and trigger the NFKB pathway. LPS induced the nuclear translocation of p50/p50 and p50/RELA dimers and the synthesis of TNF. The maximal expression of TNF in cultured glands coincides with an increase in the expression of TNF receptor 1 (TNFR1) in isolated pinealocytes. In addition, LPS inhibited the synthesis of N-acetylserotonin and melatonin. Therefore, the pineal gland transduces Gram-negative endotoxin stimulation by producing TNF and inhibiting melatonin synthesis. Here, we provide evidence to reinforce the idea of an immune-pineal axis, showing that the pineal gland is a constitutive player in the innate immune response.
authors.affiliation: Laboratory of Chronopharmacology, Department of Physiology, Institute of Biosciences, Universidade de São Paulo, São Paulo, Brasil.
authors.forename: Sanseray
authors.initials: S
authors.lastname: da Silveira Cruz-Machado
authors.forename: Claudia Emanuele
authors.initials: CE
authors.lastname: Carvalho-Sousa
authors.forename: Eduardo Koji
authors.initials: EK
authors.lastname: Tamura
authors.forename: Luciana
authors.initials: L
authors.lastname: Pinato
authors.forename: Erika
authors.initials: E
authors.lastname: Cecon
authors.forename: Pedro Augusto Carlos Magno
authors.initials: PA
authors.lastname: Fernandes
authors.forename: Maria Christina Werneck
authors.initials: MC
authors.lastname: de Avellar
authors.forename: Zulma Silva
authors.initials: ZS
authors.lastname: Ferreira
authors.forename: Regina Pekelmann
authors.initials: RP
authors.lastname: Markus
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002457:Cell Extracts / Q000737:chemistry; D002478:Cells, Cultured; D024202:Electrophoretic Mobility Shift Assay; D005260:Female; D007113:Immunity, Innate / Q000502:physiology; D007150:Immunohistochemistry; D018950:Lipopolysaccharide Receptors / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000378:metabolism; D008297:Male; D016328:NF-kappa B / Q000378:metabolism*; D010870:Pineal Gland / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D012333:RNA, Messenger; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D046509:Tissue Culture Techniques; D051197:Toll-Like Receptor 4 / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*
chemical_list: D002457:Cell Extracts; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; D016328:NF-kappa B; D012333:RNA, Messenger; C495347:Tlr4 protein, rat; D051197:Toll-Like Receptor 4