Mu-Opioid Receptor Polymorphisms and Breast Cancer in a Korean Female Adult Population: A Retrospective Study / 한국유방암학회지

Distribution of A118G single nucleotide polymorphism (SNP) in the mu-opioid receptor 1 gene (OPRM1) differs with ethnicity. We assessed the distribution of this SNP in Korean women with breast cancer and compared it with that in women of other ethnicities with breast cancer. Distribution of SNP genotypes was as follows: 49.8% for AG genotype, 40.6% for AA genotype, and 9.6% for GG genotype. Logistic regression analysis showed a negative association between the presence of the G allele at position 118 of OPRM1 and breast cancer in the studied population (odds ratios [OR], 0.635; p=0.002). However, the AG and GG genotypes were not associated with breast cancer in the studied population (OR, 0.719; p=0.130). The proportions of the AG and GG genotypes of the OPRM1 SNP were higher in Korean women with breast cancer than in those of other ethnicities.

Stable expression and function of rat mu-opioid receptor in PC12 cells by lentivirus vector / 国际药学研究杂志

Objective To stably express rat mu-opioid receptor (rMOR) in PC12 cells with characteristics of neurons. Methods After the lentiviral vector pBPLV-rMOR-eGFP was constructed, the lentivirus was packaged and used to infect the PC12 cells. PC12 cells stably expressing rMOR was screened by the flow cytometry and the limiting dilution assay. The affinity and quantity of rMOR protein expressed in the PC12 were verified by radio-ligand binding assay. The function of rMOR was analyzed by cAMP overshooting. Results The eGFP protein in PC12-rMOR cells infected by the lentivirus could be clearly shown by the fluorescence microscope. Cell lines grew normally after every clone was enlargedly cultured. The affinity (Kd) and quantity (Bmax) values of rMOR were (0.51 ± 0.07) nmol/L and (1.58 ± 0.15)pmol/mg protein respectively in 3H-diprenorphine binding assay. The cAMP content increased (255 ±25.2) % after naloxone precipitated in chronic morphine-treated cells. Exogenous agmatine could dose-dependently inhibit the overshooting of cAMP by naloxone precipitated. Conclusion We have successfully established the PC12 cell model co-expressing stably rMOR and I1 style imidazoline receptor(I1R) without α2 adrenergic receptor, expressing properties of neurons, which is a good cell model in vitro for investigating the neural molecular mechanism of opioid addition and regulating the opioid receptor function by the system of agmatine and I 1 Rin the future.

The Effect of Morphine on REST Expression in Human Neuroblastoma NMB Cells

The mu opioid receptor (MOR) has been regarded as the main site of interaction with analgesics in major clinical use, particularly morphine. The repressor element-1 silencing transcription factor (REST) functions as a transcriptional repressor of neuronal genes in non-neuronal cells. However, it is expressed in certain mature neurons, suggesting that it may have complex and novel roles. In addition, the interactions between MOR and REST and their functions remain unclear. In this study, we examined the effects of morphine on the expression of REST mRNA and protein in human neuroblastoma NMB cells to investigate the roles of REST induced by MOR activation in neuronal cells. To determine the effects of morphine on REST expression, we performed RT-PCR, real-time quantitative RT-PCR, western blot analysis and radioligand binding assays in NMB cells. By RT-PCR and real-time quantitative RT-PCR, the expression of REST was found to be unchanged by either the MOR agonist morphine or the MOR specific antagonist CTOP. By western blot, morphine was shown to significantly inhibit the expression of REST, but this suppression was completely blocked by treatment with CTOP. In the radioligand binding assay, the overexpression of REST led to an increased opioid ligand binding activity of endogenous MOR in the NMB cells. These results together suggest that morphine inhibits the expression of REST in human neuroblastoma cells through a post-transcriptional regulatory mechanism mediated through MOR.

Carrageenan-Induced Hyperalgesia Is Partially Alleviated by Endomorphin-1 Locally Delivered into Inflamed Paws In Rat

This study was performed to test whether endomorphin-1 has analgesic effect, when locally administrated into inflamed peripheral tissue. Carrageenan suspension (0.5%) was injected intraplantarly into the right paw of Sprague-Dawley male rats, and the rats were subjected to a series of mechanical stimuli with von Frei filaments before and after the injection. Carrageenan-injected rats showed typical inflammatory hyperalgesic signs and decrease of withdrawal threshold, peaked at 3 to 6 hours after the injection and lasted more than 3 days. Endomorphin-1 was intraplantarly injected with carrageenan, simultaneously or 3~4 hours after carrageenan. Simultaneous injection of endomorphin-1 with carrageenan significantly reduced hyperalgesia and thd analgesic effect was prolonged up to 8 hours. The delivery of endomorphin-1 (50 microgram) into the inflamed area after 3 to 4 hours of carrageenan injection significantly increased the threshold of hyperalgesic mechanical withdrawal response, but only partially. Intrathecal treatment of endomorphin-1 completely reversed carrageenan-induced hyperalgesia. This report is the first to show that peripherally delivered endomorphin-1 relieved inflammatory hyperalgesia. But a control through peripheral mu-opioid receptors appears to be not sufficient for complete pain treatment.