Résumé
ORL1(Opioid receptor-like 1)receptor and its endogenous ligand,nociceptin/orphanin FQ,belong to G protein-coupled receptor super family with multiple functions.ORL1 is not only endowed with anti-opioid properties(it suppresses opioid-mediated analgesia),but also involved in cognitive processes,emotion,cardioprotection and neuroendocrine secretion.The research on ORL1 and N/OFQ will certainly be helpful to develop new therapeutic drugs and to find drug targets of clinical application.
Résumé
Objective: To investigate the effects of endotoxin stimulation on the expression of orphan opioid receptor (ORL-1) gene in peripheral blood lymphocyte in vivo. Methods: Total RNA was extracted from peripheral blood lymphocytes, which have been incubated with variable lipopolysaccharide concentrations(0, 0.1, 10,100ng/ml) for different periods of time(0, 3, 6, 12, 24h). The level of mRNA was measured with the method of semi-quantitative reverse transcription polymerase chain reaction(RT-PCR) using GAPDH as an internal standard. The specificity of the amplified DNA fragments was verified by Southern blot. Results: The level of ORL- 1 mRNA in peripheral blood lymphocyte was 1.060±0. 390 under the basal condition. An endotoxin dose-and time-dependent inhibition of ex vivo ORL-1 gene expression in lymphocyte was observed. A significant descrease of the ORL-1 mRNA was detected in lymphocyte at 3 hrs with the stimulation of 100ng/ml of endotoxin, at 6 hrs with the stimulation of 10ng/ml of endotoxin, at 12 hrs with the stimulation of 0.1ng/ml of endotoxin.No significant change of ORL-1 mRNA level was found without the stimulation of endotoxin. Conclusions: Endotoxin inhibits the expression of ORL-1 gene in normal human peripheral blood lymphocyte. The level of ORL-1 mRNA is related to the functional state of lymphocyte. Nociceptin(OFQ) may have an important immunological function.