Studies of multiple morphine and enkephalin receptors: evidence for mu1 receptors

Contributions of the International Narcotics Research Conference to Opioid Research Over the Past 50 years

The International Narcotics Research Conference (INRC), founded in 1969, has been a successful forum for research into the actions of opiates, with an annual conference since 1971. Every year, scientists from around the world have congregated to present the latest data on novel opiates, opiate receptors and endogenous ligands, mechanisms of analgesic activity and unwanted side effects, etc. All the important discoveries in the opiate field were discussed, often first, at the annual INRC meeting. With an apology to important events and participants not discussed, this review presents a short history of INRC with a discussion of groundbreaking discoveries in the opiate field and the researchers who presented from the first meeting up to the present.

Exosomes and cancer: from molecular mechanisms to clinical applications

Exosomes are extracellular nanovesicles secreted from almost all types of normal and cancer cells. Collective evidence suggests that exosomes participate in cell-cell communication via transmitting their cargo, including nucleic acids, proteins, and metabolites to recipient cells. Tumor-derived exosomes (TEXs) play prominent roles in the regulation of molecular pathways in malignancies. Internalization of exosomes by tumor cells affects cellular pathways and several cancer hallmarks, including reprogramming of stromal cells, modulating immune responses, reconstructing extracellular matrix architecture, or even endowing tumor cells with drug features resistance. The unique biogenesis pathways of exosomes, their composition, low immunogenicity, and nontoxicity, together with their ability to target tumor cells, bring them up as an attractive vesicles for cancer therapy. Thus, understanding the molecular mechanisms of exosomes' participation in tumorigenesis will be critical for the next generation of cancer therapeutics. This review aims to summarize the exosomes' roles in different mechanisms underlying cancer progression for the rational design of tailored strategies against this illness. The present study also highlights the new findings on using these smart vesicles as therapeutic targets and potential biomarkers. Recent advances in exosome biology will open up new, more effective, less invasive, and more individualized clinical applications for treating cancer patients.

Interactions between different antidepressants and morphine alter gastrointestinal transit in mice

To determine different serotoninergic antidepressants' effects on the gastrointestinal (GI) inhibiting effect induced by morphine, mice were pretreated with mianserin (a tetracyclic antidepressant with multiple 5-HT receptor subtypes interactions) and with fluoxetine (a selective 5-HT reuptake inhibitor). Mianserin alone, produced gastrointestinal inhibition in a dose-dependent manner. Naloxone did not reverse this inhibiting effect, indicating that different mechanism of action are involved in morphine- and mianserin-induced inhibition of the gastrointestinal transit. Fluoxetine injected alone produced an increased propulsive motility of the GI transit. This effect was not reversed by naloxone. Fluoxetine did not reduce significantly mianserin-induced inhibition of GI transit. Fluoxetine also mildly reversed morphine-induced gastrointestinal inhibition, suggesting some degree of involvement of the opiates through the serotoninergic system.

Expression cloning of cDNA encoding a seven-helix receptor from human placenta with affinity for opioid ligands

Here we report the expression cloning of cDNA encoding a putative opioid receptor from a human placenta cDNA library. Placental opioid receptors are of the kappa type. As the dynorphin opioid peptides are kappa-selective, a dynorphin ligand was used in an affinity-enrichment (panning) procedure to select transiently transfected COS-7 cells expressing kappa receptor binding sites. The cloned cDNA encodes a 440-residue protein of the seven-helix guanine nucleotide-binding protein (G-protein)-coupled receptor family. Ligand binding reveals a stereospecific site with typical opioid properties, which binds peptide and nonpeptide opioids with moderate affinity (Kd approximately 100 nM) and which lacks the expected kappa selectivity. The deduced transmembrane domain is 93% identical to the homologous region of the human neuromedin K (neurokinin B) receptor, but the N-terminal and C-terminal sequences have many dissimilarities. The expressed receptor binds opioid ligands but not tachykinins; and under the same conditions, a cloned rat neuromedin K receptor binds tachykinins but not opioids.