Lipopolysaccharide induces preprotachykinin gene expression.
This study was performed to test whether biosynthesis of tachykinins plays a pivotal role in lipopolysaccharide (LPS)-induced airway alteration by analyzing preprotachykinin-I (PPT-I, a precursor of tachykinins) gene expression. Brown-Norway rats (11-12 wk old) were divided into four groups: control; LPS; dimethylthiourea (DMTU, an effective hydroxyl radical scavenger); and DMTU+LPS. Each animal in the control group received saline treatment. Forty-nine animals in the LPS group were further divided into seven subgroups to test effects of doses and length of the LPS treatment. Total RNA extracted from nodose ganglia and lungs was used to assay relative amount of PPT-I mRNA using the real-time quantitative reverse transcriptase-polymerase chain reaction. In addition, LPS-induced alterations in airway responses to bronchial constrictors, neutral endopeptidase (NEP) gene expression, leukocyte counts, and SP and calcitonin gene-related peptide (CGRP) levels were determined. LPS (4 mg/kg, intraperitoneal) raised significantly PPT-I mRNA level after 4 h in nodose ganglia and 12 h in the lung, and this elevation sustained for 5 d. Also, LPS caused significant increases in NEP mRNA, SP and CGRP levels, airway reactivity to capsaicin and SP, and neutrophil counts, but a significant decrease in macrophage count. Our data support that LPS-induced bronchial hyperreactivity to capsaicin is related closely to the upregulation of tachykinin gene expression, but not the upregulation of NEP.
Department of Physiology, College of Medicine, National Taiwan University, No. 1, Sec. 1, Jen-Ai Road, Taipei 100, Taiwan.
Hsueh-Yin
HY
Huang
Yih-Loong
YL
Lai
D000818:Animals; D001980:Bronchi / Q000187:drug effects; D016166:Free Radical Scavengers / Q000494:pharmacology; D005786:Gene Expression Regulation; D008070:Lipopolysaccharides / Q000378:metabolism*; D008168:Lung / Q000378:metabolism; D009620:Nodose Ganglion / Q000378:metabolism; D011498:Protein Precursors / Q000096:biosynthesis / Q000187:drug effects / Q000235:genetics*; D051381:Rats; D011914:Rats, Inbred BN; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015320:Tachykinins / Q000096:biosynthesis / Q000187:drug effects / Q000235:genetics*; D013890:Thiourea / Q000031:analogs & derivatives* / Q000494:pharmacology
D016166:Free Radical Scavengers; D008070:Lipopolysaccharides; D011498:Protein Precursors; D015320:Tachykinins; C044206:preprotachykinin; C038983:1,3-dimethylthiourea; D020794:Receptor Protein-Tyrosine Kinases; D013890:Thiourea