Orphanin FQ(OFQ) or Nociceptin is a newly discovered peptide identified as an en dogenous ligand of opioid receptor like (ORL 1) receptor. It has been observed that intracerebroventricular(icv) administration of OFQ could antagonize the im munosuppression induced by surgical trauma. The influence of icv administration O FQ on interleukin 1β(IL 1β) mRNA level in surgical traumatic rats was inves tigated . Using single base mutated template as inner standard, the quantitative reverse transcription polymerase chain reaction(RT PCR) technique was used to investigate the IL 1β mRNA level of hypothalamus in traumatic rats. The resul ts showed that the IL 1β mRNA level of hypothalamus of rats significantly incr eased after surgical trauma compared with the normal rats (normal : 2.51± 0.62 , trauma: 11.77±2.13 ,respectively, P<0.001). Icv 1μg OFQ had no ef fects on IL 1β mRNA level in normal rats (icv NS:4.34±0.89 ,icv OFQ:3.18± 1.06,respectively, P>0.05). Icv 1 μg OFQ could significantly decre ase IL 1β mRNA level in surgical traumatic rats (trauma + icv NS: 15.16 ±3. 17 , trauma + icv OFQ: 7.07±2.50,respectively, P<0.01). When traumati c rats were given with OFQ(icv 1 μg) first and OFQ receptor antagonist Phe 1Ψ (CH 2 NH)Gly 2 nociceptin(1 13) NH 2 (1 μg) later, the level of I L 1β mRNA in the hypothalamus increased to 17.26±2.48 which had no differen ce w ith that of trauma+icv NS(P>0.05). The above results suggested that t he effect of OFQ on the immunosuppression induced by surgical trauma may be medi ated via opioid receptor like(ORL1) receptor. The inhibition of IL 1β gene exp ression in hypothalamus may be related to the modulating effect of OFQ.
