[Altered expression of transporter and analgesic of morphine in neuropathic pain mice].

It is known that morphine is less effective for patients with neuropathic pain, accounting for approximately 70% of cancer patients with severe pain. One of the causes of the decline is reported as a decreased function of the µ-opioid receptor, which binds to the active metabolites of morphine in the mesencephalic ventral tegmental area. However, the details of this mechanism are not understood. We hypothesized that a decrease in the concentration of morphine in the brain reduces its analgesic effect on neuropathic pain, and found that the analgesic effect of morphine was correlated with its concentration in the brain. We examined the reason for the decreased concentration of morphine in the brain in case of neuropathic pain. We discovered increased P-glycoprotein (P-gp) expression in the small intestine, increased expression and activity of UGT2B in the liver, and increased P-gp expression in the brain under conditions of neuropathic pain. In this symposium, we argue that low brain morphine concentration is considered one of the causes of lower sensitivity to morphine in neuropathic pain patients.

Impact of P-glycoprotein at the blood-brain barrier on the uptake of heroin and its main metabolites: behavioral effects and consequences on the transcriptional responses and reinforcing properties.

RATIONALE: Transport across the BBB is a determinant of the rate and extent of drug distribution in the brain. Heroin exerts its effects through its principal metabolites 6-monoacetyl-morphine (6-MAM) and morphine. Morphine is a known substrate of P-glycoprotein (P-gp) at the blood-brain-barrier (BBB) however, little is known about the interaction of heroin and 6-MAM with P-gp. OBJECTIVE: The objective of this paper is to study the role of the P-gp-mediated efflux at the BBB in the behavioral and molecular effects of heroin and morphine. METHODS: The transport rates of heroin and its main metabolites, at the BBB, were measured in mice by in situ brain perfusion. We then examined the effect of inhibition of P-gp on the acute nociception, locomotor activity, and gene expression modulations induced by heroin and morphine. The effect of P-gp inhibition during the acquisition of morphine-induced place preference was also studied. RESULTS: Inhibition of P-gp significantly increased the uptake of morphine but not that of heroin nor 6-MAM. Inhibition of P-gp significantly increased morphine-induced acute analgesia and locomotor activity but did not affect the behavioral effects of heroin; in addition, acute transcriptional responses to morphine were selectively modulated in the nucleus accumbens. Increasing morphine uptake by the brain significantly increased its reinforcing properties in the place preference paradigm. CONCLUSIONS: The present study demonstrated that acute inhibition of P-gp not only modulates morphine-induced behavioral effects but also its transcriptional effects and reinforcing properties. This suggests that, in the case of morphine, transport across the BBB is critical for the development of dependence.

Heroin activates Bim via c-Jun N-terminal kinase/c-Jun pathway to mediate neuronal apoptosis.

Heroin is reported to cause spongiform leukoencephalopathy (SLE) in heroin addicts and the exact mechanism has not yet been identified. In the present study, we found that heroin could induce apoptosis of primary cultured cerebellar granule cells (CGCs) and Bim was upregulated both transcriptionally and post transcriptionally during CGCs apoptosis. Upregulated Bim translocated to mitochondria and Bax was activated under heroin treatment. Genetic knockdown of Bim using lentiviruses significantly prevented neuronal apoptosis induced by heroin. Meanwhile, c-Jun N-terminal kinase (JNK)/c-Jun pathway was activated in heroin-induced apoptosis. Bim was demonstrated as a downstream target of JNK/c-Jun pathway in this process because pharmacological inhibition of JNK reduced the levels of Bim mRNA and protein. These results indicate that Bim plays a critical role in the neurotoxic process by heroin and JNK/c-Jun pathway acts upstream of Bim in regulating heroin-induced neuronal death. This represents a detailed mechanism of heroin-induced neuronal apoptosis and may provide a new and effective strategy to treat heroin-induced addiction and SLE.

Role of sigma-1 receptors in paclitaxel-induced neuropathic pain in mice.

UNLABELLED: Sigma-1 (σ(1)) receptors play a role in different types of pain and in central sensitization mechanisms; however, it is unknown whether they are involved in chemotherapy-induced neuropathic pain. We compared the ability of paclitaxel to induce cold (acetone test) and mechanical (electronic Von Frey test) allodynia in wild-type (WT) and σ(1) receptor knockout (σ(1)-KO) mice. We also tested the effect on paclitaxel-induced painful neuropathy of BD-1063 (16-64 mg/kg, subcutaneously) and S1RA (32-128 mg/kg, subcutaneously), 2 selective σ(1) receptor antagonists that bind to the σ(1) receptor with high affinity and competitively. The responses to cold and mechanical stimuli were similar in WT and σ(1)-KO mice not treated with paclitaxel; however, treatment with paclitaxel (2 mg/kg, intraperitoneally, once per day during 5 consecutive days) produced cold and mechanical allodynia and an increase in spinal cord diphosphorylated extracellular signal-regulated kinase (pERK) in WT but not in σ(1)-KO mice. The administration of BD-1063 or S1RA 30 minutes before each paclitaxel dose prevented the development of cold and mechanical allodynia in WT mice. Moreover, the acute administration of both σ(1) receptor antagonists dose dependently reversed both types of paclitaxel-induced allodynia after they had fully developed. These results suggest that σ(1) receptors play a key role in paclitaxel-induced painful neuropathy. PERSPECTIVE: Antagonists of the σ(1) receptor may have therapeutic value for the treatment and/or prevention of paclitaxel-induced neuropathic pain. This possibility is especially interesting in the context of chemotherapy-induced neuropathy, where the onset of nerve damage is predictable and preventive treatment could be administered.

High-throughput simultaneous analysis of buprenorphine, methadone, cocaine, opiates, nicotine, and metabolites in oral fluid by liquid chromatography tandem mass spectrometry.

A method for simultaneous determination of buprenorphine (BUP), norbuprenorphine (NBUP), methadone, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP), cocaine, benzoylecgonine (BE), ecgonine methyl ester (EME), anhydroecgonine methyl ester (AEME), morphine, codeine, 6-acetylmorphine (6AM), heroin, 6-acetylcodeine (6AC), nicotine, cotinine, and trans-3'-hydroxycotinine (OH-cotinine) by liquid chromatography tandem mass spectrometry in oral fluid (OF) was developed and extensively validated. Acetonitrile (800 µL) and OF (250 µL) were added to a 96-well Isolute-PPT+protein precipitation plate. Reverse-phase separation was achieved in 16 min and quantification was performed by multiple reaction monitoring. The assay was linear from 0.5 or 1 to 500 µg/L. Intraday, interday, and total imprecision were less than 13% (n = 20), analytical recovery was 92-114% (n = 20), extraction efficiencies were more than 77% (n = 5), and process efficiencies were more than 45% (n = 5). Although ion suppression was detected for EME, cocaine, morphine, 6AC, and heroin (less than 56%) and enhancement was detected for BE and nicotine (less than 316%), deuterated internal standards compensated for these effects. The method was sensitive (limit of detection 0.2-0.8 µg/L) and specific (no interferences) except that 3-hydroxy-4-methoxyamphetamine interfered with AEME. No carryover was detected, and all analytes were stable for 24 h at 22 °C, for 72 h at 4 °C, and after three freeze-thaw cycles, except cocaine, 6AC, and heroin (22-97% loss). The method was applied to 41 OF specimens collected throughout pregnancy with a Salivette® OF collection device from an opioid-dependent BUP-maintained pregnant woman. BUP ranged from 0 to 7,400 µg/L, NBUP from 0 to 71 µg/L, methadone from 0 to 3 µg/L, nicotine from 32 to 5,020 µg/L, cotinine from 125 to 508 µg/L, OH-cotinine from 11 to 51 µg/L, cocaine from 0 to 419 µg/L, BE from 0 to 351 µg/L, EME from 0 to 286 µg/L, AEME from 0 to 7 µg/L, morphine from 0 to 22 µg/L, codeine from 0 to 1 µg/L, 6AM from 0 to 4 µg/L, and heroin from 0 to 2 µg/L. All specimens tested negative for EDDP and 6AC. This method permits a fast and simultaneous quantification of 16 drugs and metabolites in OF, with good selectivity and sensitivity.

Investigación de cocaína y marihuana en meconio de neonatos atendidos en un hospital público: primera experiencia realizada en la ciudad de Córdoba, Argentina / Screening of cocaine and marijuana in meconium of newborns from a public hospital of city of Córdoba, Argentina

Se investigaron cocaína y marihuana en meconio de neonatos nacidos en la Maternidad Provincial de la Ciudad de Córdoba y se relacionaron los resultados con las semanas de gestación y los pesos al nacer. Las determinaciones se realizaron utilizando inmunoensayo y cromatografía gaseosa-espectrometría de masas. Se analizaron 48 muestras de meconio recolectadas durante un año (2007-2008). De los 48 meconios analizados, 17 correspondieron a neonatos masculinos y 31 a neonatos femeninos. Se procesaron en paralelo 15 muestras de meconio como controles normales (niños no expuestos a drogas) seleccionados por historia clínica y controles prenatales. De las 48 muestras de meconio 13 fueron positivas para cocaína y/o marihuana. El peso y las semanas degestación de los neonatos cuyas muestras fueron positivas se compararon frente a un grupo control normal, hallándose mayores diferencias estadísticamente significativas (α=0,05 – p<0,0001) en relación a los pesos al nacer. Estos resultados, a pesar del reducido número de casos analizados, resaltan la importancia de la investigación de drogas de abuso en meconio, lo que permite confirmar el uso de drogas por parte de la madre durante el período gestacional temprano, y de ese modo interpretar las alteraciones (déficit de peso) observadas en el neonato al nacer, atribuibles al consumo de drogas durante la gestación.

We investigated cocaine and marijuana in meconium of newborns attended at the Hospital Materno Provincial of Córdoba City and the results were correlated with birthweight and weeks of pregnancy. The samples were analyzed using immunoassay (FPIA) and gas chromatography-mass spectrometry (GC-MS) for confirmation. Forty eight samples of meconium were collected during one year period (2007-2008). Of the 48 samples screened, 17 correspond to masculine sex and 31 to feminine. Fifteen samples of meconium from normal newborns (newborns not exposed to drugs) selected by maternal self report, pregnancy controls were processed as control group. The results obtained in 48 samples of meconium showed 13 cases tested positive for cocaine and/or marijuana. Birth weight and weeks of gestation of newborn with positive sample results were compared with a control group. A statistically significant difference (α= 0.05 - p<0.0001) was found in relation to birth weight. Although these results arise from a small number of samples, these data have relevance in public health and show the importance of the screening of drugs of abuse in meconium to confirm use in mothers during pregnancy and to interpret the alterations observed in the newborn after delivery as consequence of drug use in prenatal period.

Technical basis for polar and nonpolar narcotic chemicals and polycyclic aromatic hydrocarbon criteria. III. A polyparameter model for target lipid partitioning.

A method is presented for extending the target lipid model (TLM) of narcotic toxicity to polar narcotic chemicals. The proposed polyparameter TLM extends the applicability of the TLM by including polar compounds and removing explicit chemical class corrections. The validity of the model is tested using a data set of 1,687 acute toxicity tests for 42 aquatic species, including fish, amphibians, arthropods, mollusks, polychaetes, coelenterates, protozoans, and algae, and 398 chemicals. The target lipid-water partition coefficient is computed using the Abraham polyparameter model. This replaces use of the octanol-water partition coefficient so that the partitioning of polar narcotic chemicals can be described correctly. The model predicts the log median lethal concentration with a root mean square error of 0.460 for nonpolar and polar chemicals and 0.501 for only polar chemicals.

Gas chromatography-mass spectrometry designation and prediction of metabolic dealkylation and hydroxylation reactions in xenobiotics exemplified by tramadol.

Metabolic dealkylation and hydroxylation reactions in xenobiotics are common and may take place at different sites in the molecules. Sometimes confusion may arise as to the nature and site of the resulting metabolic change when there is more than one potential site. The use of GC-MS in resolving the problem has been demonstrated by using tramadol as example. Human urine samples containing tramadol and its metabolites were extracted under basic pH conditions and analyzed by GC-MS, in the electron impact and chemical ionization modes, before and after trimethylsilyl (TMS) derivatization. By recognizing the mass-to-charge ratios of molecular and base-peak ions in the mass spectra, it was possible to predict and designate sites of demethylation and hydroxylation in tramadol metabolites. In addition to the designation of the known tramadol metabolites, the practice has led to the tentative characterization of hydroxytramadol and norhydroxytramadol as new metabolites of tramadol in humans. Possible extension of the modus operandi to other xenobiotics was discussed.

[Individual differences in analgesic effects of narcotics].

Narcotic analgesics have been widely used for management of severe pain, especially for cancer pain. Most of these drugs are opioids, and they show their analgesic effects by acting through opioid receptors. Significant individual differences in opioid sensitivity can hamper effective pain treatments and increase side effects, which is associated with decreased quality of life. It is thought that genetic factors may affect individual differences in opioid sensitivity. Recent studies using various inbred and knockout mice have revealed that the mu-opioid receptor (MOP) plays a mandatory role in the analgesic properties of opioids. There is also increasing evidence that differences in the sequence of the MOP gene might significantly affect the amount of MOP gene mRNA expression and sensitivity to opioids. Furthermore, it can be thought that individual differences in opioid sensitivity are caused by genetic differences in not only MOP but other biomolecules, such as endogenous opioid peptides, molecules related with metabolic process and second messenger systems. Rapid advances in this research field are leading to a better understanding of relationships between gene polymorphisms and opioid sensitivities, which, in turn, will allow us to more accurately predict opioid sensitivity and opioid requirements in individual patients.

Validation of a procedure for the gas chromatography-mass spectrometry analysis of cocaine and metabolites in pericardial fluid.

A method is described for the simultaneous quantification of cocaine, benzoylecgonine, and cocaethylene in pericardial fluid. Pericardial fluid samples from autopsy casework involving cocaine-related deaths and deaths unrelated to drug abuse were collected. The extraction of cocaine and its metabolites was performed using Bond-Elut Certify columns. Pericardial fluid samples were adjusted to pH 7 and applied to the pre-conditioned cartridges. After the washing steps, compounds were eluted with a mixture of chloroform/isopropanol (80:20) with 2% ammonium hydroxide. The dry extracts were derivatized with pentafluoropropionic anhydride and hexafluoroisopropanol and analyzed by gas chromatography-mass spectrometry using electron impact ionization and selective ion monitoring acquisition. Deuterated internal standards were used. The analytical method developed was linear, sensitive, selective, accurate, and sufficiently precise to be applied routinely in forensic toxicology. In this study, the procedure has been successfully applied to a number of forensic cases involving cocaine intoxication.

In vitro and direct in vivo testing of mixture-based combinatorial libraries for the identification of highly active and specific opiate ligands.

The use of combinatorial libraries for the identification of novel opiate and related ligands in opioid receptor assays is reviewed. Case studies involving opioid assays used to demonstrate the viability of combinatorial libraries are described. The identification of new opioid peptides composed of L-amino acids, D-amino acids, or L-, D-, and unnatural amino acids is reviewed. New opioid compounds have also been identified from peptidomimetic libraries, such as peptoids and alkylated dipeptides, and those identified from acyclic (eg, polyamine, urea) and heterocyclic (eg, bicyclic guanidine) libraries are reviewed.

Increased vulnerability of ApoE4 neurons to HIV proteins and opiates: protection by diosgenin and L-deprenyl.

Human immunodeficiency virus (HIV) infection continues to rise in drug-abusing populations and causes a dementing illness in a subset of individuals. Factors contributing to the development of dementia in this population remain unknown. We found that HIV-infected individuals with the E4 allele of Apolipoprotein E (ApoE) or history of intravenous drug abuse had increased oxidative stress in the CNS. In vitro studies showed that HIV proteins, gp120 and Tat, Tat + morphine but not tumor necrosis factor-alpha (TNF-alpha), caused increased neurotoxicity in human neuronal cultures with ApoE4 allele. Microarray analysis showed a differential alteration of transcripts involved in energy metabolism in cultures of ApoE3 and 4 neurons upon treatment with Tat + morphine. This was confirmed using assays of mitochondrial function and exposure of the neurons to Tat + morphine. Using this in vitro model, we screened a number of novel antioxidants and found that only L-deprenyl and diosgenin protected against the neurotoxicity of Tat + morphine. Furthermore, Tat-induced oxidative stress impaired morphine metabolism which could also be prevented by diosgenin. In conclusion, opiate abusers with HIV infection and the ApoE4 allele may be at increased risk of developing dementia. L-deprenyl and a plant estrogen, diosgenin, may have therapeutic potential in this population.

Reinforcing properties of ethanol in neonatal rats: involvement of the opioid system.

Toward understanding why infant rats ingest high levels of ethanol without initiation procedures, the authors tested effects of mu and kappa receptor antagonists on ethanol reinforcement in neonatal rats. After an intracisternal injection of CTOP (micro antagonist), nor-Binaltorphimine (kappa antagonist), or saline, newborn (3-hr-old) rats were given conditioning pairings of an odor with intraorally infused ethanol or a surrogate nipple with ethanol administered intraperitoneally (to minimize ethanol's gustatory attributes). In each case, these opioid antagonists reduced or eliminated ethanol's reinforcement effect. The same effects occurred with saccharin as the reinforcer in olfactory conditioning. The results imply that activation of mu and kappa receptors, apparently acting jointly, is necessary for reinforcement or that antagonists of this activity impair basic conditioning.

Pronociceptive and antinociceptive effects of estradiol through endogenous opioid neurotransmission in women.

Prominent interindividual and sex-dependent differences have been described in responses to sustained pain and other stressful stimuli. Variations in mu-opioid receptor-mediated endogenous opioid neurotransmission may underlie some of these processes. We examined both baseline mu-opioid receptor levels and the activation of this neurotransmitter system during sustained pain using positron emission tomography in a sample of young healthy men and women. Women were studied twice, during low and high estrogen states. The high-estrogen state was associated with regional increases in baseline mu-opioid receptor availability in vivo and a greater activation of endogenous opioid neurotransmission during the pain stressor. The latter did not differ from that obtained in males. During the low estrogen condition, however, significant reductions in endogenous opioid tone were observed at the level of thalamus, nucleus accumbens, and amygdala, which were associated with hyperalgesic responses. Estrogen-associated variations in the activity of mu-opioid neurotransmission correlated with individual ratings of the sensory and affective perceptions of the pain and the subsequent recall of that experience. These data demonstrate a significant role of estrogen in modulating endogenous opioid neurotransmission and associated psychophysical responses to a pain stressor in humans.

Ligand triggers of classical preconditioning and postconditioning.

The cardioprotection afforded by ischemic preconditioning (IPC) and ischemic postconditioning (PC) are receptor mediated. In this review, we will focus on the major ligand classes and receptors that contribute to IPC and PC-induced cardioprotection. Ligand classes discussed include adenosine, bradykinin, opioids, erythropoietin, adrenergics and muscarinics. The cardioprotective therapeutic window of each ligand class will also be summarized, with particular focus as to whether ligands are protective when administered at or close to the time of reperfusion. Information will primarily be directed at studies in which infarct size reduction is the gold standard to assess the efficacy of IPC and PC. Myocardial stunning is a less robust endpoint for assessing cardioprotection and the use of this endpoint is only limited to studies with human tissue where infarct size assessment is not possible. Receptor cross-talk between ligands and the common signaling pathways involved for these ligands will also be briefly discussed.

G protein-coupled receptors in haematopoietic disruption.

Haematopoiesis is the process by which blood and immune cells are replenished from a finite number of resident bone marrow (BM) haematopoietic stem cells (HSCs). Regulatory molecules within the BM microenvironment contribute developmental signals to an interactive network capable of ensuring ordered biological processes. Many bioactive molecules contribute to the network through G protein-coupled receptors (GPCRs). GPCRs are seven-transmembrane receptors that, following ligand binding, signal by activating coupled heterotrimeric G proteins. This review focuses on those bioactive molecules that regulate haematopoietic development through GPCRs. Chemokines (SDF-1alpha, MIP-1), opioids and tachykinins (SP, NK-A) are important G protein-coupled haematopoietic regulators. Their biology in normal and diseased haematopoiesis is discussed below, as well as their potential as therapeutic targets.

Increased polysialic acid neural cell adhesion molecule expression in human hippocampus of heroin addicts.

Chronic exposure to heroin is known to cause cognitive deficits. However, little is known about the underlying molecular mechanisms. It has been suggested that opiate-induced neurotoxicity as well as impaired plasticity and regeneration may be relevant. One of the target regions where regeneration still can be observed in the adult brain is the hippocampus. Since polysialic acid neural cell adhesion molecule is regarded as one of the key players involved in plasticity and regeneration of neural tissue, we analyzed polysialic acid neural cell adhesion molecule expression in the fascia dentate hilus of the human hippocampus of 29 lethally intoxicated heroin addicts and matched controls. Immunohistochemistry with an antibody directed against polysialic acid neural cell adhesion molecule revealed its expression in differently sized cells which could be identified as neurons and glial cells. We observed an increase in the percentage of polysialic acid neural cell adhesion molecule positive neurons in hippocampal hilus of heroin addicts compared with controls (P = 0.001).Interestingly, we also observed polysialic acid neural cell adhesion molecule expression in glial cells as evidenced by double immunofluorescence with glial fibrillary acidic protein and polysialic acid neural cell adhesion molecule using confocal laser scanning microscopy. The fraction of polysialic acid neural cell adhesion molecule positive glial cells was also higher in heroin addicts compared with controls (P = 0.009). In addition, within the group of addicts morphine blood concentrations showed a positive correlation with the percentage of polysialic acid neural cell adhesion molecule positive neurons (P = 0.04; r = 0.547). In conclusion, we observed an increase in polysialic acid neural cell adhesion molecule positive neurons and glial cells in hippocampi of heroin addicts. This might reflect an attempt to repair cell damage due to heroin exposure.

Chronic pain induces anxiety with concomitant changes in opioidergic function in the amygdala.

Clinically, it has been reported that chronic pain induces depression, anxiety, and reduced quality of life. The endogenous opioid system has been implicated in nociception, anxiety, and stress. The present study was undertaken to investigate whether chronic pain could induce anxiogenic effects and changes in the opioidergic function in the amygdala in mice. We found that either injection of complete Freund's adjuvant (CFA) or neuropathic pain induced by sciatic nerve ligation produced a significant anxiogenic effect at 4 weeks after the injection or surgery. Under these conditions, the selective mu-opioid receptor agonist [D-Ala2,N-MePhe4,Gly5-ol]-enkephalin (DAMGO)- and the selective delta-opioid receptor agonist (+)-4-[(alphaR)-alpha-((2S,5R)-4-allyl-2,5-dimethyl-1-piperazinyl)-3-methoxybenzyl]-N,N-diethylbenzamide (SNC80)-stimulated [35S]GTPgammaS binding in membranes of the amygdala was significantly suppressed by CFA injection or nerve ligation. CFA injection was associated with a significant increase in the kappa-opioid receptor agonist 2-(3,4-dichlorophenyl)-N-methyl-N-[(1S)-1-phenyl-2-(1-pyrrolidinyl)ethyl]acetamide hydrochloride (ICI199,441)-stimulated [35S]GTPgammaS binding in membranes of the amygdala. The intracerebroventricular administration and microinjection of a selective mu-opioid receptor antagonist, a selective delta-opioid receptor antagonist, and the endogenous kappa-opioid receptor ligand dynorphin A caused a significant anxiogenic effect in mice. We also found that thermal hyperalgesia induced by sciatic nerve ligation was reversed at 8 weeks after surgery. In the light-dark test, the time spent in the lit compartment was not changed at 8 weeks after surgery. Collectively, the present data constitute the first evidence that chronic pain has an anxiogenic effect in mice. This phenomenon may be associated with changes in opioidergic function in the amygdala.