Fluorescence two-dimensional difference gel electrophoresis for biomaterial applications

Fluorescence two-dimensional difference gel electrophoresis (DiGE) is rapidly becoming established as a powerful technique for the characterization of differences in protein expression levels between two or more conditions. In this review, we consider the application of DiGE—both minimal and saturation labelling—to biomaterials research, considering the challenges and rewards of this approach

Role of kinin B2 receptors in opioid-induced-hyperalgesia in inflammatory pain in mice

Postoperative pain management is a clinical challenge that can be complicated by opioid-induced hyperalgesia (OIH). Kinin receptors could mediate both the acute and chronic phases of inflammation and pain. A few recent studies suggest that dynorphin A could maintain neuropathic pain by activating the bradykinin (BK) receptor. Thus, the effect of a single administration of sufentanil (a mu-opioid receptor agonist) was investigated in a model of carrageenan-induced inflammatory pain using three strains of mice, i.e., knockout mice for one kinin receptor, B1R or B2R (B1KO, B2KO), and wild-type C57/BL6J mice (WT) treated with either a B1R (R954) or a B2R antagonist (HOE140) or a KKS inhibitor (aprotinin). Pain was assessed and compared between the different groups using two behavioral tests exploring mechanical (von Frey filaments) and thermal (Hargreaves test) sensitivity. Pretreatment with sufentanil induced a sustained increase in pain sensitivity with a delayed return to baseline values characterizing an OIH in carrageenan-injected mice only. Sufentanil-induced OIH was not observed in B2KO but persisted in B1KO and was blunted by aprotinin and the B2R antagonist only. Collectively, our data indicate that the B2R receptor and BK synthesis or availability are essential peripheral steps in the mechanism leading to OIH in a pain context

Ventral tegmental area dopamine projections to the hippocampus trigger long-term potentiation and contextual learning

Abstract In most models of neuronal plasticity and memory, dopamine is thought to promote the long-term maintenance of Long-Term Potentiation (LTP) underlying memory processes, but not the initiation of plasticity or new information storage. Here, we used optogenetic manipulation of midbrain dopamine neurons in male DAT::Cre mice, and discovered that stimulating the Schaffer collaterals – the glutamatergic axons connecting CA3 and CA1 regions - of the dorsal hippocampus concomitantly with midbrain dopamine terminals within a 200 millisecond time-window triggers LTP at glutamatergic synapses. Moreover, we showed that the stimulation of this dopaminergic pathway facilitates contextual learning in awake behaving mice, while its inhibition hinders it. Thus, activation of midbrain dopamine can operate as a teaching signal that triggers NeoHebbian LTP and promotes supervised learning

The NOP antagonist BTRX-246040 increases stress resilience in mice without affecting adult neurogenesis in the hippocampus

Nociceptin/orphanin FQ (N/OFQ) is the endogenous ligand of an inhibitory G protein coupled receptor named N/OFQ peptide receptor (NOP). Clinical and preclinical findings suggest that the blockade of the NOP signaling induces antidepressant-like effects. Additionally, the blockade of the NOP receptor during inescapable stress exposure prevented the acquisition of the helplessness phenotype, suggesting that NOP antagonists are able to increase stress resilience. BTRX-246040 (aka LY2940094) is a NOP receptor antagonist with high affinity, potency and selectivity for the NOP over classical opioid receptors. BTRX-246040 is under development for the treatment of depression, eating disorders and alcohol abuse and it already entered clinical trials. In the present study, the antidepressant effects of BTRX-246040 were evaluated in mice subjected to the forced swimming test and to the learned helplessness model of depression. Additionally, the ability of BTRX-246040 to prevent the development of the helpless behavior and to modulate adult hippocampal neurogenesis has been investigated. BTRX-246040 (30 mg/kg, i.p.) produced antidepressant-like effects in the forced swimming test and in the learned helplessness model. More interestingly, when given before the stress induction sessions it was able to prevent the development of the helplessness behavior. Under these experimental conditions, BTRX-246040 did not modulate adult hippocampal neurogenesis, neither in naive nor in stressed mice. This study, performed with a clinically viable ligand, further corroborates growing evidence indicating that the blockade of the NOP signaling may provide an innovative strategy for the treatment of stress related psychopathologies

Br J Pharmacol

BACKGROUND AND PURPOSE Opiates remain the most effective compounds for alleviating severe pain across a wide range of conditions. However, their use is associated with significant side effects. Neuropeptide FF (NPFF) receptors have been implicated in several opiate-induced neuroadaptive changes including the development of tolerance. In this study, we investigated the consequences of NPFF receptor blockade on acute and chronic stimulation of opioid receptors in mice by using RF9, a potent and selective antagonist of NPFF receptors that can be administered systemically. EXPERIMENTAL APPROACH The effects of RF9 were investigated on opioid pharmacological responses including locomotor activity, antinociception, opioid-induced hyperalgesia, rewarding properties and physical dependence. KEY RESULTS RF9 had no effect on morphine-induced horizontal hyperlocomotion and slightly attenuated the decrease induced in vertical activity. Furthermore, RF9 dose-dependently blocked the long-lasting hyperalgesia produced by either acute fentanyl or chronic morphine administration. RF9 also potentiated opiate early analgesic effects and prevented the development of morphine tolerance. Finally, RF9 increased morphine-induced conditioned place preference without producing any rewarding effect by itself and decreased naltrexone-precipitated withdrawal syndrome following chronic morphine treatment. CONCLUSION AND IMPLICATIONS The NPFF system is involved in the development of two major undesirable effects: tolerance and dependence, which are clinically associated with prolonged exposure to opiates. Our findings suggest that NPFF receptors are interesting therapeutic targets to improve the analgesic efficacy of opiates by limiting the development of tolerance, and for the treatment of opioid dependence

Involvement of Protein Degradation by the Ubiquitin Proteasome System in Opiate Addictive Behaviors

Plastic changes in the nucleus accumbens (NAcc), a structure occupying a key position in the neural circuitry related to motivation, are among the critical cellular processes responsible for drug addiction. During the last decade, it has been shown that memory formation and related neuronal plasticity may rely not only on protein synthesis but also on protein degradation by the ubiquitin proteasome system (UPS). In this study, we assess the role of protein degradation in the NAcc in opiate-related behaviors. For this purpose, we coupled behavioral experiments to intra-accumbens injections of lactacystin, an inhibitor of the UPS. We show that protein degradation in the NAcc is mandatory for a full range of animal models of opiate addiction including morphine locomotor sensitization, morphine conditioned place preference, intra-ventral tegmental area morphine self-administration and intra-venous heroin self-administration but not for discrimination learning rewarded by highly palatable food. This study provides the first evidence of a specific role of protein degradation by the UPS in addiction