The μ opioid receptor (MOR) is a prominent member of the G protein-coupled receptor family and the molecular target of morphine and other opioid drugs. Despite the long tradition of MOR-targeting drugs, still little is known about the ligand-receptor interactions and structure-function relationships underlying the distinct biological effects upon receptor activation or inhibition. With the resolved crystal structure of the β-funaltrexamine-MOR complex, we aimed at the discovery of novel agonists and antagonists using virtual screening tools, i.e. docking, pharmacophore- and shape-based modeling. We suggest important molecular interactions, which active molecules share and distinguish agonists and antagonists. These results allowed for the generation of theoretically validated in silico workflows that were employed for prospective virtual screening. Out of 18 virtual hits evaluated in in vitro pharmacological assays, three displayed antagonist activity and the most active compound significantly inhibited morphine-induced antinociception. The new identified chemotypes hold promise for further development into neurochemical tools for studying the MOR or as potential therapeutic lead candidates.

Background and purposeThe κ receptor has a central role in modulating neurotransmission in central and peripheral neuronal circuits that subserve pain and other behavioural responses. Although κ receptor agonists do not produce euphoria or lead to respiratory suppression, they induce dysphoria and sedation. We hypothesized that brain‐penetrant κ receptor ligands possessing biased agonism towards G protein signalling over β‐arrestin2 recruitment would produce robust antinociception with fewer associated liabilities.Experimental approachTwo new diphenethylamines with high κ receptor selectivity, HS665 and HS666, were assessed following i.c.v. administration in mouse assays of antinociception with the 55°C warm‐water tail withdrawal test, locomotor activity in the rotorod and conditioned place preference. The [35S]‐GTPγS binding and β‐arrestin2 recruitment in vitro assays were used to characterize biased agonism.Key resultsHS665 (κ receptor agonist) and HS666 (κ receptor partial agonist) demonstrated dose‐dependent antinociception after i.c.v. administration mediated by the κ receptor. These highly selective κ receptor ligands displayed varying biased signalling towards G protein coupling in vitro, consistent with a reduced liability profile, reflected by reduced sedation and absence of conditioned place aversion for HS666.Conclusions and implicationsHS665 and HS666 activate central κ receptors to produce potent antinociception, with HS666 displaying pharmacological characteristics of a κ receptor analgesic with reduced liability for aversive effects correlating with its low efficacy in the β‐arrestin2 signalling pathway. Our data provide further understanding of the contribution of central κ receptors in pain suppression, and the prospect of dissociating the antinociceptive effects of HS665 and HS666 from κ receptor‐mediated adverse effects.

Glioblastoma is the most common and malignant brain cancer in adults. Current therapy consisting of surgery followed by radiation and temozolomide has a moderate success rate and the tumor reappears. Among the features that a cancer cell must have to survive the therapeutic treatment and reconstitute the tumor is the ability of self-renewal. Therefore, it is vital to identify the molecular mechanisms that regulate this activity. Sex-determining region Y (SRY)-box 2 (SOX2) is a transcription factor whose activity has been associated with the maintenance of the undifferentiated state of cancer stem cells in several tissues, including the brain. Several groups have detected increased SOX2 levels in biopsies of glioblastoma patients, with the highest levels associated with poor outcome. Therefore, SOX2 silencing might be a novel therapeutic approach to combat cancer and particularly brain tumors. In this review, we will summarize the current knowledge about SOX2 in glioblastoma and recapitulate several strategies that have recently been described targeting SOX2 in this malignancy.

Transforming growth factors-␤ (TGF-␤s

of the long-term actions of gabapentin and pregabalin in dorsal root ganglia and substantia gelatinosa. J Neurophysiol 112: 2398 -2412, 2014. First published August 13, 2014; doi:10.1152/jn.00168.2014.-The ␣2␦-ligands pregabalin (PGB) and gabapentin (GBP) are used to treat neuropathic pain. We used whole cell recording to study their long-term effects on substantia gelatinosa and dorsal root ganglion (DRG) neurons. Spinal cord slices were prepared from embryonic day 13 rat embryos and maintained in organotypic culture for Ͼ5 wk (neuronal age equivalent to young adult rats). Exposure of similarly aged DRG neurons (dissociated and cultured from postnatal day 19 rats) to GBP or PGB for 5-6 days attenuated high-voltage-activated calcium channel currents (HVA I Ca ). Strong effects were seen in medium-sized and in small isolectin B 4 -negative (IB 4 Ϫ) DRG neurons, whereas large neurons and small neurons that bound isolectin B 4 (IB 4 ϩ) were hardly affected. GBP (100 M) or PGB (10 M) were less effective than 20 M Mn 2ϩ in suppression of HVA I Ca in small DRG neurons. By contrast, 5-6 days of exposure to these ␣2␦-ligands was more effective than 20 M Mn 2ϩ in reducing spontaneous excitatory postsynaptic currents at synapses in substantia gelatinosa. Spinal actions of gabapentinoids cannot therefore be ascribed to decreased expression of HVA Ca 2ϩ channels in primary afferent nerve terminals. In substantia gelatinosa, 5-6 days of exposure to PGB was more effective in inhibiting excitatory synaptic drive to putative excitatory neurons than to putative inhibitory neurons. Although spontaneous inhibitory postsynaptic currents were also attenuated, the overall long-term effect of ␣2␦-ligands was to decrease network excitability as monitored by confocal Ca 2ϩ imaging. We suggest that selective actions of ␣2␦-ligands on populations of DRG neurons may predict their selective attenuation of excitatory transmission onto excitatory vs. inhibitory neurons in substantia gelatinosa.