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Objective@#To investigate whether endogenous nociceptin/orphanin FQ (N/OFQ) can inhibit arrhythmia and expression of β1-adrenergic receptor (β1-AR) on the surface of myocardial cell membrane in acute myocardial ischemia rats by Raf kinase inhibitory protein (RKIP).@*Methods@#① Experiment one: according to random number table method, 30 adult male Sprague-Dawley (SD) rats with only 6 weeks of age were divided into Sham group (open the chest but do not ligate the coronary artery), myocardial ischemia model group (coronary ligation of left anterior descending branch), and endogenous N/OFQ antagonists UFP-101 pretreatment group (UFP-101 group, preoperative 10 minutes after tail vein injection of 1 mL/kg UFP-101), with 10 rats in each group. Arrhythmia was recorded within 15 minutes after operation. The expression of phosphorylated RKIP (p-RKIP) was detected by Western Blot. ② Experiment two: according to the random number table method, 30 4-week-old male SD rats were divided into UFP-101 control group, RKIP over expression group and RKIP antagonism group, with 10 rats in each group. The UFP-101 control group was intraperiton eally injected with corn oil every day, while the other two groups were injected with up adjuster of RKIP (Didymin). The rats in the three groups were all ligated after 4 weeks of feeding, and UFP-101 was injected through the tail vein 10 minutes before the operation. The RKIP antagonist group received intraperitoneal injection of the RKIP-specific antagonist locostatin 2 hours before surgery. Arrhythmia results were recorded within 15 minutes after operation. Western Blot was used to detect the expression of p-RKIP in myocardial tissue and expression of β1-AR on the surface of myocardial cell membrane 15 minutes after surgery.@*Results@#①Experiment one: compared with Sham group, ventricular ectopic beat (VEB), ventricular tachycardia (VT) and ventricular fibrillation (VF) increased significantly in the model group and UFP-101 group, and arrhythmia score increased significantly. In addition, compared with the Sham group, p-RKIP expression was increased in the model group and decreased in the UFP-101 group. Compared with the model group, preconditioning with UFP-101 significantly reduced the occurrence of arrhythmia [arrhythmia score: 1.5 (0.3, 5.0) vs. 4.0 (2.0, 5.0), P < 0.05], and the expression of p-RKIP in myocardial tissue significantly decreased (p-RKIP/total RKIP: 0.20±0.11 vs. 0.43±0.11, P < 0.05). This indicated that antagonistic N/OFQ could reduce the phosphorylation of RKIP and the occurrence of arrhythmia. ② Experiment two: compared with the UFP-101 control group, overexpression of RKIP significantly increased the occurrence of arrhythmia events, and the expression of β1-AR on the surface of the myocardial cell membrane significantly increased. And antagonism RKIP overexpression could make the occurrence of arrhythmia eased [arrhythmia score: 3.0 (2.0, 3.0) vs. 4.0 (2.0, 5.0), P < 0.05], and significantly reduce the expression of myocardial cell membrane surface β1-AR (β1-AR/Na+-K+-ATPase: 0.88±0.09 vs. 1.02±0.08, P < 0.05), while there was no significant difference in total RKIP expression (total RKIP/GAPDH: 5.40±0.21 vs. 5.36±0.19, P > 0.05). This indicated that endogenous N/OFQ affected the expression of plasma β1-AR on the surface of myocardial cell membrane and ischemic arrhythmia in rats through RKIP.@*Conclusion@#Endogenous N/OFQ can affect the expression of plasma β1-AR on the membrane surface of ischemic myocardium and arrhythmia in rats via increased expression of RKIP phosphorylation.
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Objective To investigate whether endogenous nociceptin/orphanin FQ (N/OFQ) can inhibit arrhythmia and expression of β1-adrenergic receptor (β1-AR) on the surface of myocardial cell membrane in acute myocardial ischemia rats by Raf kinase inhibitory protein (RKIP). Methods ① Experiment one: according to random number table method, 30 adult male Sprague-Dawley (SD) rats with only 6 weeks of age were divided into Sham group (open the chest but do not ligate the coronary artery), myocardial ischemia model group (coronary ligation of left anterior descending branch), and endogenous N/OFQ antagonists UFP-101 pretreatment group (UFP-101 group, preoperative 10 minutes after tail vein injection of 1 mL/kg UFP-101), with 10 rats in each group. Arrhythmia was recorded within 15 minutes after operation. The expression of phosphorylated RKIP (p-RKIP) was detected by Western Blot. ② Experiment two: according to the random number table method, 304-week-old male SD rats were divided into UFP-101 control group, RKIP over expression group and RKIP antagonism group, with 10 rats in each group. The UFP-101 control group was intraperiton eally injected with corn oil every day, while the other two groups were injected with up adjuster of RKIP (Didymin). The rats in the three groups were all ligated after 4 weeks of feeding, and UFP-101 was injected through the tail vein 10 minutes before the operation. The RKIP antagonist group received intraperitoneal injection of the RKIP-specific antagonist locostatin 2 hours before surgery. Arrhythmia results were recorded within 15 minutes after operation. Western Blot was used to detect the expression of p-RKIP in myocardial tissue and expression of β1-AR on the surface of myocardial cell membrane 15 minutes after surgery. Results ①Experiment one: compared with Sham group, ventricular ectopic beat (VEB), ventricular tachycardia (VT) and ventricular fibrillation (VF) increased significantly in the model group and UFP-101 group, and arrhythmia score increased significantly. In addition, compared with the Sham group, p-RKIP expression was increased in the model group and decreased in the UFP-101 group. Compared with the model group, preconditioning with UFP-101 significantly reduced the occurrence of arrhythmia [arrhythmia score: 1.5 (0.3, 5.0) vs. 4.0 (2.0, 5.0), P < 0.05], and the expression of p-RKIP in myocardial tissue significantly decreased (p-RKIP/total RKIP: 0.20±0.11 vs. 0.43±0.11, P < 0.05). This indicated that antagonistic N/OFQ could reduce the phosphorylation of RKIP and the occurrence of arrhythmia. ② Experiment two:compared with the UFP-101 control group, overexpression of RKIP significantly increased the occurrence of arrhythmia events, and the expression of β1-AR on the surface of the myocardial cell membrane significantly increased. And antagonism RKIP overexpression could make the occurrence of arrhythmia eased [arrhythmia score: 3.0 (2.0, 3.0) vs. 4.0 (2.0, 5.0), P < 0.05], and significantly reduce the expression of myocardial cell membrane surface β1-AR (β1-AR/Na+-K+-ATPase: 0.88±0.09 vs. 1.02±0.08, P < 0.05), while there was no significant difference in total RKIP expression (total RKIP/GAPDH: 5.40±0.21 vs. 5.36±0.19, P > 0.05). This indicated that endogenous N/OFQ affected the expression of plasma β1-AR on the surface of myocardial cell membrane and ischemic arrhythmia in rats through RKIP. Conclusion Endogenous N/OFQ can affect the expression of plasma β1-AR on the membrane surface of ischemic myocardium and arrhythmia in rats via increased expression of RKIP phosphorylation.
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Pain is not only a common syndrome in clinic,but also a disease harming people′s health and quality of life. Dis?covery of potent and low-or non-addictive analgesic agent is a great challenge and our expectation. Nociceptin/orphanin FQ opioid pep?tide (NOP)receptor,the fourth member of the opioid receptor family,was discovered in 1994. Growing evidence has revealed that NOP receptor plays an important role in pain transduction and modulation and becomes a potential target for novel analgesics develop?ment. This review focuses on the progresses in exploring the biological characteristics of NOP receptor and its complex role in pain modulation,as well as the discovery of novel analgesic agents targeting NOP receptor,which provides reference for understanding the mechanisms of pain and analgesia and finding ideal analgesics.
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Pain is not only a common syndrome in clinic, but also a disease harming people’s health and quality of life. Discovery of potent and low-or non-addictive analgesic agent is a great challenge and our expectation. Nociceptin/orphanin FQ opioid peptide (NOP)receptor, the fourth member of the opioid receptor family, was discovered in 1994. Growing evidence has revealed that NOP receptor plays an important role in pain transduction and modulation and becomes a potential target for novel analgesics development. This review focuses on the progresses in exploring the biological characteristics of NOP receptor and its complex role in pain modulation, as well as the discovery of novel analgesic agents targeting NOP receptor, which provides reference for understanding the mechanisms of pain and analgesia and finding ideal analgesics.
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PURPOSE: Nociceptin/orphanin FQ (N/OFQ) as an endogeneous hexadecapeptide is known to exert antinociceptive effects spinally. The aims of this study were to demonstrate the antinociceptive effects of i.t. N/OFQ and to investigate the possible interaction between N/OFQ and endogenous opioid systems using selective opioid receptor antagonists in rat formalin tests. MATERIALS AND METHODS: I.t. N/OFQ was injected in different doses (1-10 nmol) via a lumbar catheter prior to a 50 microL injection of 5% formalin into the right hindpaw of rats. Flinching responses were measured from 0-10 min (phase I, an initial acute state) and 11-60 min (phase II, a prolonged tonic state). To observe which opioid receptors are involved in the anti-nociceptive effect of i.t. N/OFQ in the rat-formalin tests, naltrindole (5-20 nmol), beta-funaltrexamine (1-10 nmol), and norbinaltorphimine (10 nmol), selective delta-, micro- and kappa-opioid receptor antagonists, respectively, were administered intrathecally 5 min after i.t. N/OFQ. RESULTS: I.t. N/OFQ attenuated the formalin-induced flinching responses in a dose-dependent manner in both phases I and II. I.t. administration of naltrindole and beta-funaltrexamine dose-dependently reversed the N/OFQ-induced attenuation of flinching responses in both phases; however, norbinaltorphimine did not. CONCLUSION: I.t. N/OFQ exerted an antinociceptive effect in both phases of the rat-formalin test through the nociceptin opioid peptide receptor. In addition, the results suggested that delta- and micro-opioid receptors, but not kappa-opioid receptors, are involved in the antinociceptive effects of N/OFQ in the spinal cord of rats.
Subject(s)
Animals , Male , Rats , Analgesics/administration & dosage , Formaldehyde/toxicity , Injections, Spinal , Naltrexone/administration & dosage , Narcotic Antagonists/administration & dosage , Opioid Peptides/administration & dosage , Pain Measurement , Rats, Sprague-Dawley , Receptors, Opioid/agonistsABSTRACT
Oyecave:To observe the influence of nociceptin/orphanin FQ(N/OFO)on cerebral infarction volume and somatosellsOry evoked potential(SEP)in focal cerebral ischemia in rats.Methods:Forty one SD rats were randomly alloomed into middle artery occlusion(MCAO)sham-operation(n=5),isehemic(n=8),N/OFQ 10μg(n=7),N/OFQ 1 μg(n=7),N/OFQ0.1 μg(n=7),and artificiai cerebrospinal fluid(ACSF)(n=7)groups.A model of middle cerebral artery occlusion(MCAO)in rats was induced using intraluminal suture method.Reperfusion was performed 2 hours after MCAO.One hour after MCAO,N/OFQ 10 μg,N/OFQ 1 μg,N/OFQ O. 1 μg,and the same volume of ACSF were injected intraventricularly in the N/OFQ 10 μg,N/OFQ 1 μg,N/OFQ 0. 1 μg,and ACSF groups,respectively. The cerebral infarction volurne was detected 24 hours after reperfusion,and SEP was recorded. Results:1he amplitude of SEP P1 decreased in the sham-operation group. There was no significant change in P1 peak latencies.There were no significant differences hetween the N/OFQ 0. 1 μg group and the ACSF group in SEP amplitudes,P1 peak lantecies and cerebral infarction volume. As compared with the ACSF group,the SEP amplitudes were further decreased in the N/OFQ 1 μg and N/OFQ 10 μg groups,but there were no significant change in P1 peak lantecies. One hour after reperfusion,the SEP amplitude in the ACSF group almost returned to the level of preischemia,the recovery slowed down in the N/OFQ 1 μg group,and it still did not recovered 3 hours after reperfusion in the N/OFQ 10 μg group. The dose of N/OFQ and SEP response showed dose-effect relationship,The higher the dose,the deeper the SEP depression and the slower the recovery. At 24 hours after reperfusion,the cerebral infarction vlumes in the shamoperation,ACSF,N/OFQ 0. 1 μg,N/OFQ 1 μg,and N/OFQ 10 μg groups were 0 mm3,24.180 ±4.088 mm3,23.090±4.523 mm3,35.304 ± 6. 824 mm3,and 40. 806±6. 716 mm3,respectively. There was no significant difference between N/OFQ 0. 1 and ACSF groups. There were significant differences between N/OFQ 1 μg and 10 μg groups and ACSF group (all P ＜ 0.01 ). Conclusions:Intracerebroventricular injection of N/OFQ in the early stage of cerebral ischemia decreases the SEP amplitude,prolongs the time of recovery,and increases cerebral infarction volume,which shoves that it may aggravate cerebral ischemic injury.
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