The study was to investigate the proliferation and apoptosis effect of nociceptin/orphanin FQ (OFQ) on 562 cells in vitro. Inhibition of K562 cells proliferation was measured by MTT assay. Morphological assessment of apoptosis was performed with Wright staining and transmission electron microscope. The apoptosis peak was measured by flow cytometry. DNA fragmentation was visualized by agarose gel electrophoresis. The results showed that OFQ time-dependently and no-dose-dependently inhibited the proliferation of K562 cells at concentrations of 10(-6) - 10(-13) mol/L. Discrete maximum of cytolytic activity was detected at concentrations of 10(-6) - 10(-7), 10(-9), 10(-12) mol/L. Compared with the control group K562 cells, the cells treated with OFQ at concentration of 10(-9) mol/L for 72 hours showed typical characteristics of apoptosis under transmission electron microscope. Apoptosis peak was found by FCM at concentration of 0, 10(-7), 10(-8), 10(-9) mol/L of OFQ for 72 hours, apoptosis rates were 0%, 22.8%, 23.8% and 26.5% respectively. DNA agarose gel electrophoresis revealed nuclear fragmentation (DNA ladder). It is concluded that OFQ can inhibit the proliferation of K562 cells and induce the apoptosis in K562 cells.
Apoptosis ; drug effects ; Cell Proliferation ; drug effects ; Humans ; K562 Cells ; Opioid Peptides ; pharmacology ; Receptors, Opioid ; agonists

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.
Analgesics/administration & dosage/*pharmacology ; Animals ; Formaldehyde/toxicity ; Injections, Spinal ; Male ; Naltrexone/administration & dosage/analogs & derivatives/pharmacology ; Narcotic Antagonists/administration & dosage/*pharmacology ; Opioid Peptides/administration & dosage/*pharmacology ; Pain Measurement ; Rats ; Rats, Sprague-Dawley ; Receptors, Opioid/*agonists/drug effects

AIMTo study upon to serum deprivation if delta-opioid receptor activation has direct effect on cultured impaired cardiomyocytes survival.

METHODSMyocardial cells of neonatal rats were cultured in vitro. The cell viability was determined with crystal violet staining uptake. The percentage of S + G2 + M in cell cycle was determined by flow cytometry. Apoptosis rates were determined by flow cytometry (FCM). The expression of Caspase-3 were investigated by Western blotting.

RESULTSMyocardial cells of neonatal rats were cultured of serum-free in vitro, apoptotic index was significantly increased, the expression of Caspase-3 was significantly increased, free-serum induced apoptosis in cardiac myocytes after 48 h. At concentrations of 10 nmol x L(-1) - 10 micromol x L(-1), a delta opoid receptor agonist [D-Ala2, D-Leu5]-enkephalin DADLE promoted the myocardial cells survival, in a concentration-dependent manner. The optimal response was achieved at 0.1 micromol x L(-1), which increase survival index of cardiac myocyte, percentage of S + G2 + M in cell cycle, decrease apoptotic index of cardiac myocyte, and the expression activate caspase-3. Delta-opioid receptor antagonist naltrindole at 10 micromol x L(-1) inhibited the promoting effects of DADLE, which decrease survival index of cardiac myocyte, and percentage of S + G2 + M in cell cycle, increase apoptotic index of cardiac myocyte and the expression of Caspase-3.

CONCLUSIONThe protective of delta-opioid receptor activation can promote survival in cultured impaired myocardial cells.

Animals ; Animals, Newborn ; Apoptosis ; drug effects ; Caspase 3 ; metabolism ; Cell Survival ; drug effects ; Cells, Cultured ; Culture Media, Serum-Free ; Enkephalin, Leucine-2-Alanine ; pharmacology ; Female ; Male ; Myocytes, Cardiac ; cytology ; Rats ; Rats, Sprague-Dawley ; Receptors, Opioid, delta ; agonists

In the present study, whole-cell patch-clamp technique was used to observe the effects of SNC162, a selective agonist of δ-opioid receptors, on L-type Ca(2+) current (I(Ca-L)) and transient outward K(+) current (I(to)) in rat ventricular myocytes. The results showed that SNC162 significantly inhibited I(Ca-L) and I(to) in rat ventricular myocytes. The maximal inhibition rate of I(Ca-L) and I(to) reached (46.13±4.12)% and (36.53±10.57)%, respectively. SNC162 at 1×10(-4) mol/L inhibited the current density of I(Ca-L) from (8.98±0.40) pA/pF to (4.84±0.44) pA/pF (P<0.01, n=5) and inhibited that of I(to) from (18.69±2.42) pA/pF to (11.73±1.67) pA/pF (P<0.01, n=5). Furthermore, the effects of naltrindole, a highly selective antagonist of δ-opioid receptors, on I(Ca-L) and I(to) were also observed. The results showed that naltrindole alone had no effects on I(Ca-L) and I(to), while it abolished the inhibitory effects of SNC162 on I(Ca-L) and I(to). In conclusion, SNC162 concentration-dependently inhibited I(Ca-L) and I(to) in rat ventricular myocytes via activation of the δ-opioid receptors, which may be a fundamental mechanism underlying the antiarrhythmic effect of activating δ-opioid receptors.
Animals ; Anti-Arrhythmia Agents ; Benzamides ; pharmacology ; Calcium Channels, L-Type ; metabolism ; Cells, Cultured ; Heart Ventricles ; cytology ; Myocytes, Cardiac ; drug effects ; metabolism ; Naltrexone ; analogs & derivatives ; pharmacology ; Patch-Clamp Techniques ; Piperazines ; pharmacology ; Potassium Channels ; metabolism ; Rats ; Receptors, Opioid, delta ; agonists

OBJECTIVETo investigate the effect of DADLE, a δ-opioid receptor agonist, on the proliferation of human liver cancer HepG2 cells and explore the mechanism involving PKC pathway.

METHODSHepG2 cells were treated with DADLE at different doses (0.01, 0.1, 1.0 and 10 µmol/L). Cell viability was determined using methyl thiazolyl terazolium (MTT) assay. The expression of PKC mRNA and p-PKC protein were examined by RT-PCR and Western blot assay. After treated separately with DADLE plusing NAL or PMA, the cell cycle of HepG2 cells was analyzed by flow cytometer. MTT was used to detect their proliferation capacity and Western blot was used to examine the p-PKC expression. The growth inhibitory rate of HepG2 cells treated with DADLE and cis-diammine dichloridoplatinum (CDDP) was analyzed.

RESULTSDADLE at different concentrations showed an inhibitory effect on the proliferation of HepG2 cells though inhibiting the expression of PKC mRNA and p-PKC protein. The results of flow cytometry showed that compared with the control group, the percentage of S + G(2)/M cells in DADLE-treated group was lowered by 3.94% (P < 0.01). Meanwhile, after treated with NAL and PMA, the percentage was elevated by 3.22% and 3.63%, respectively (P < 0.01). The MTT and Western blot assays showed that compared with the control group, the values of A570 and p-PKC protein levels in the HepG2 cells of DADLE-treated group were significantly decreased (P < 0.01). After treatment with NAL and PMA, the values of A570 and p-PKC protein levels were elevated significantly (P < 0.01). The growth inhibitory rate of DADLE + CDDP group was 79.9%, significantly lower than 25.2% and 43.2% of the DADLE and CDDP groups, respectively.

CONCLUSIONSActivation of δ-opioid receptor by DADLE inhibits the apoptosis of human liver cancer HepG2 cells. The underlying mechanism may be correlated with PKC pathway. DADLE can enhance the chemosensitivity of HepG2 cells to CDDP.

Antineoplastic Agents ; pharmacology ; Cell Cycle ; drug effects ; Cell Proliferation ; drug effects ; Cisplatin ; pharmacology ; Dose-Response Relationship, Drug ; Drug Resistance, Neoplasm ; Enkephalin, Leucine-2-Alanine ; administration & dosage ; pharmacology ; Hep G2 Cells ; Humans ; Naltrexone ; analogs & derivatives ; pharmacology ; Phosphorylation ; Protein Kinase C ; genetics ; metabolism ; RNA, Messenger ; metabolism ; Receptors, Opioid, delta ; agonists ; Signal Transduction ; Tetradecanoylphorbol Acetate ; analogs & derivatives ; pharmacology

OBJECTIVETo demonstrate the inhibitory effect of kappa-opioid receptor activation by U50488H on hypertrophy induced by NE in cultured neonatal rat cardiac myocytes and compare its effect with that of prazosin and propranolol.

METHODSThe cellular proliferation was determined with crystal violet staining. The protein content was assayed with Lowry's method. The cardiomyocytes volumes were measured by computer photograph analysis system. The protein synthesis was assayed with [3H]-lencine incorporation method.

RESULTS(1) NE significantly induced the increase of protein content, [3H]-leucine incorporation and cell size without a concomitant increase in cell number in low serum medium. OThese responses were partially suppressed by prazosin or propranolol alone and completely abolished by both in combination. U50488H significantly inhibited the NE-induced increase of protein content, [3H]-leucine incorporation and cell size. The inhibitory effects of U50488H on NE-induced cardiac hypertrophy were greater than either prazosin or propranolol, but comparable to combination of both.

CONCLUSIONNE, acting via both alpha1- and beta-adrenergic pathway, stimulates myocyte hypertrophy. Stimulating kappa-opioid receptor significantly inhibits NE-induced cardiac hypertrophy, which may be related with alpha1- and beta1-adrenergic pathway.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer ; pharmacology ; Adrenergic alpha-1 Receptor Antagonists ; pharmacology ; Adrenergic beta-Antagonists ; pharmacology ; Animals ; Animals, Newborn ; Cardiomegaly ; chemically induced ; pathology ; prevention & control ; Cell Enlargement ; drug effects ; Cells, Cultured ; Female ; Male ; Myocytes, Cardiac ; cytology ; Norepinephrine ; Prazosin ; pharmacology ; Propranolol ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Receptors, Opioid, kappa ; agonists

AIMTo determine whether activation of kappa-opioid receptor with U50,488H, a selective kappa-opioid receptor agonist, produces any changes in electrical uncoupling during prolonged ischemia and whether these changes in electrical uncoupling is associated with the cardioprotection induced by kappa-opioid receptor activation, and to explore the possible mechanism.

METHODS(1) To observe the effect of U50,488H (10(-7), 10(-6), 3 x10(-6) and 10(-5) mol/L), a selective kappa-opioid receptor agonist, or with a selective kappa-opioid receptor antagonist nor-BNI (5 x 10(-6) mol/L), or with a mitochondrial K(ATP) channel inhibitor 5-HD on myocardium during ischemia/reperfusion in isolated perfused rat heart. Parameters of measurements include hemodynamic data, formazan content, heart rate, coronary flow, and lactate dehydrogenase (LDH). (2) To examine the effect of U50,488H of different concentration on electrical coupling parameters (including onset of uncoupling, plateau time, slope, and fold increase in r1) during 70 min myocardial ischemia in isolated perfused rat heart.

RESULTS(1) Pretreatment with U50,488H concentration dependently increased formazan content and reduced LDH release induced by 30 min of ischemia and 120 min of reperfusion. (2) The onset of electrical uncoupling and plateau time during prolonged ischemia was delayed by kappa-opioid receptor activation with U50,488H. (3) Linear regression analysis shown that the increase in formazan content and decrease in LDH release produced by kappa-opioid receptor activation was associated with delayed electrical uncoupling during prolonged ischemia. (4) The effects of U50,488H on formazan content, LDH release and on electrical coupling were abolished by nor-BNI, or 5-HD.

CONCLUSIONThis results demonstrate that the onset of electrical uncoupling during prolonged ischemia is delayed by kappa-opioid receptor activation with a selective kappa-opioid receptor agonist U50,488H, and that delayed electrical uncoupling is associated with the cardioprotection induced by kappa-opioid receptor activation with U50,488H. These effects of kappa-opioid receptor activation with U50,488H are mediated by mitochondrial K(ATP) channels.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer ; pharmacology ; Animals ; Antihypertensive Agents ; Heart ; drug effects ; physiopathology ; In Vitro Techniques ; Male ; Myocardial Ischemia ; physiopathology ; Myocardium ; metabolism ; Naltrexone ; analogs & derivatives ; pharmacology ; Potassium Channels ; metabolism ; Rats ; Rats, Sprague-Dawley ; Receptors, Opioid, kappa ; agonists

OBJECTIVETo investigate the dual effects by the delta opioid receptor agonists DPDPE on the delayed rectified potassium channels in NG108-15 cells.

METHODSA series of outward currents were evoked in NG108-15 cells by depolarizing voltage from -50 mV to +80 mV at holding potential of -90 mV. These currents were delayed rectified potassium currents. Relatively selected delta opioid receptor agonists DPDPE of higher and lower concentrations were used to modulate the delayed rectified K+ current in NG108-15 cells. Opioid receptor antagonist Naloxone (NAL) and relatively selected delta opioid receptor antagonist Naltrindole (NTI) were used in the present experiments for the characterization of the actions of opioid receptors.

RESULTSThe relatively higher concentrations of delta opioid receptor agonist DPDPE (> or = 10(-6) mol/L) significantly increased the amplitude of the delayed rectified K+ current. On the contrary, the relatively lower concentrations of DPDPE (< or = 10(-12) mol/L) decreased the amplitude of the delayed rectified K+ current (P < 0.05). Furthermore both the increase and decrease were time-dependent.

CONCLUSIONSdelta opioid receptor agonist has dual regulatory effects on the delayed rectified potassium channels in NG108-15 cells.

Animals ; Cell Membrane ; metabolism ; Enkephalin, D-Penicillamine (2,5)- ; pharmacology ; Glioma ; metabolism ; pathology ; Hybrid Cells ; metabolism ; Mice ; Naloxone ; pharmacology ; Naltrexone ; analogs & derivatives ; pharmacology ; Neuroblastoma ; metabolism ; pathology ; Patch-Clamp Techniques ; Potassium Channels, Inwardly Rectifying ; drug effects ; metabolism ; Rats ; Receptors, Opioid, delta ; agonists ; Tumor Cells, Cultured