Rapid Development Of Tolerance Research Articles

A Novel Leu-Enkephalin Prodrug Produces Pain-Relieving and Antidepressant Effects.

Persistent pain is a significant healthcare problem with limited treatment options. The high incidence of comorbid chronic pain and depression significantly reduces life quality and complicates the treatment of both conditions. Antidepressants are less effective for pain and depression than for depression alone and they induce severe side effects. Opioids are highly efficacious analgesics, but rapid development of tolerance, dependence, and debilitating side effects limit their efficacy and safe use. Leucine-enkephalin (Leu-ENK), the endogenous delta opioid receptor agonist, controls pain and mood and produces potent analgesia with reduced adverse effects compared to conventional opioids. High proteolytic instability, however, makes Leu-ENK ineffective after systemic administration and limits its clinical usefulness. KK-103, a Leu-ENK prodrug, was developed to overcome these limitations of Leu-ENK via markedly increased plasma stability in mice. We showed rapid and substantially increased systemic adsorption and blood plasma exposure of KK-103 compared to Leu-ENK. We also observed brain uptake of radiolabeled KK-103 after systemic administration, indicating a central effect of KK-103. We then established KK-103's prolonged antinociceptive efficacy in the ramped hot plate and formalin test. In both models, KK-103 produced a comparable dose to the maximum antinociceptive-effect relationship. The pain-alleviating effect of KK-103 primarily resulted from activating the delta opioid receptor after the likely conversion of KK-103 to Leu-ENK in vivo. Finally, KK-103 produced an antidepressant-like activity comparable to the antidepressant desipramine, but with minimal gastrointestinal inhibition and no incidence of sedation.

Molecular and Medical Aspects of Psychedelics.

Psychedelics belong to the oldest psychoactive drugs. They arouse recent interest due to their therapeutic applications in the treatment of major depressive disorder, substance use disorder, end-of-life anxiety,= and anxiety symptoms, and obsessive-compulsive disorder. In this review, the current state of preclinical research on the mechanism of action, neurotoxicity, and behavioral impact of psychedelics is summarized. The effect of selective 5-HT2A receptor agonists, 25I- and 25B-NBOMe, after acute and repeated administration is characterized and compared with the effects of a less selective drug, psilocybin. The data show a significant effect of NBOMes on glutamatergic, dopaminergic, serotonergic, and cholinergic neurotransmission in the frontal cortex, striatum, and nucleus accumbens. The increases in extracellular levels of neurotransmitters were not dose-dependent, which most likely resulted from the stimulation of the 5-HT2A receptor and subsequent activation of the 5-HT2C receptors. This effect was also observed in the wet dog shake test and locomotor activity. Chronic administration of NBOMes elicited rapid development of tolerance, genotoxicity, and activation of microglia. Acute treatment with psilocybin affected monoaminergic and aminoacidic neurotransmitters in the frontal cortex, nucleus accumbens, and hippocampus but not in the amygdala. Psilocybin exhibited anxiolytic properties resulting from intensification of GABAergic neurotransmission. The data indicate that NBOMes as selective 5-HT2A agonists exert a significant effect on neurotransmission and behavior of rats while also inducing oxidative DNA damage. In contrast to NBOMes, the effects induced by psilocybin suggest a broader therapeutic index of this drug.

Hallucinogenic activity, neurotransmitters release, anxiolytic and neurotoxic effects in Rat's brain following repeated administration of novel psychoactive compound 25B-NBOMe

2-(4-Bromo-2,5-dimethoxyphenyl)-N-(2-methoxybenzyl)etanoamine (25B-NBOMe) is a highly selective 5-HT2A receptor agonist, exhibiting a potent hallucinogenic activity. In the present study, we investigated the effect of a 7-day treatment with 25B-NBOMe in a dose of 0.3 mg/kg on the following: the neurotransmitter release in vivo using microdialysis in freely moving animals, hallucinogenic activity measured in the Wet Dog Shake (WDS) test, anxiety level as measured in the light/dark box (LDB) and locomotor activity in the open field (OF) test, DNA damage with the comet assay, and on a number of neuronal and glial cells with immunohistochemistry. Repeated administration of 25B-NBOMe decreased the response to a challenge dose (0.3 mg/kg) on DA, 5-HT and glutamatergic neurons in the rats’ frontal cortex, striatum, and nucleus accumbens. The WDS response dropped drastically after the second day of treatment, suggesting a rapid development of tolerance. LDB and OF tests showed that the effect of 25B-NBOMe on anxiety depends on the treatment and environmental settings. Results obtained with the comet assay indicate a genotoxic properties in the frontal cortex and hippocampus. An increase in immunopositive glial but not neuronal cells was observed in the cortical regions but not in the hippocampus. In conclusion, our study showed that a chronic administration of 25B-NBOMe produces the development of tolerance observed in the neurotransmitters release and hallucinogenic activity. The oxidative damage of cortical and hippocampal DNA implies the generation of free radicals by the drug, resulting in genotoxicity but rather not in neurotoxic tissue damage. Behavioral tests show that 25B-NBOMe exerts anxiogenic effect after single and repeated treatment.

Rapid and Chronic Ethanol Tolerance Are Composed of Distinct Memory-Like States in Drosophila.

Ethanol tolerance is the first type of behavioral plasticity and neural plasticity that is induced by ethanol intake, and yet its molecular and circuit bases remain largely unexplored. Here, we characterize the following three distinct forms of ethanol tolerance in male Drosophila: rapid, chronic, and repeated. Rapid tolerance is composed of two short-lived memory-like states, one that is labile and one that is consolidated. Chronic tolerance, induced by continuous exposure, lasts for 2 d, induces ethanol preference, and hinders the development of rapid tolerance through the activity of histone deacetylases (HDACs). Unlike rapid tolerance, chronic tolerance is independent of the immediate early gene Hr38/Nr4a Chronic tolerance is suppressed by the sirtuin HDAC Sirt1, whereas rapid tolerance is enhanced by Sirt1 Moreover, rapid and chronic tolerance map to anatomically distinct regions of the mushroom body learning and memory centers. Chronic tolerance, like long-term memory, is dependent on new protein synthesis and it induces the kayak/c-fos immediate early gene, but it depends on CREB signaling outside the mushroom bodies, and it does not require the Radish GTPase. Thus, chronic ethanol exposure creates an ethanol-specific memory-like state that is molecularly and anatomically different from other forms of ethanol tolerance.SIGNIFICANCE STATEMENT The pattern and concentration of initial ethanol exposure causes operationally distinct types of ethanol tolerance to form. We identify separate molecular and neural circuit mechanisms for two forms of ethanol tolerance, rapid and chronic. We also discover that chronic tolerance forms an ethanol-specific long-term memory-like state that localizes to learning and memory circuits, but it is different from appetitive and aversive long-term memories. By contrast, rapid tolerance is composed of labile and consolidated short-term memory-like states. The multiple forms of ethanol memory-like states are genetically tractable for understanding how initial forms of ethanol-induced neural plasticity form a substrate for the longer-term brain changes associated with alcohol use disorder.

Novel Designer Benzodiazepines: Comprehensive Review of Evolving Clinical and Adverse Effects.

As tranquilizers, benzodiazepines have a wide range of clinical uses. Recently, there has been a significant rise in the number of novel psychoactive substances, including designer benzodiazepines. Flubromazolam(8-bromo-6-(2-fluorophenyl)-1-methyl-4H-[1,2,4]triazolo[4,3-a][1,4]benzodiazeZpine) is a triazolo-analogue of flubromazepam. The most common effects noted by recreational users include heavy hypnosis and sedation, long-lasting amnesia, and rapid development of tolerance. Other effects included anxiolysis, muscle-relaxing effects, euphoria, loss of control, and severe withdrawals. Clonazolam, or 6-(2-chlorophenyl)-1-methyl-8-nitro-4H-[1,2,4]triazolo[4,3-α]-[1,4]-benzodiazepine, is a triazolo-analog of clonazepam. It is reported to be over twice as potent as alprazolam. Deschloroetizolam (2-Ethyl-9-methyl-4-phenyl-6H-thieno[3,2-f][1,2,4]triazolo[4,3-a][1,4]diazepine) is part of the thienodiazepine drug class, which, like benzodiazepines, stimulates GABA-A receptors. Meclonazepam ((3S)-5-(2-chlorophenyl)-3-methyl-7-nitro-1,3-dihydro-1,4-benzodiazepin-2-one) is a designer benzodiazepine with additional anti-parasitic effects. Although it has proven to be an efficacious therapy for schistosomiasis, its sedative side effects have prevented it from being marketed as a therapeutic agent. The use of DBZs has been a subject of multiple recent clinical studies, likely related to increasing presence and availability on the internet drug market and lack of regulation. Many studies have aimed to identify the prevalence of DBZs and their effects on those using them. This review discussed these designer benzodiazepines and the dangers and adverse effects that the clinician should know.

Changes in the development of opioid tolerance on re-exposure among people who use heroin: A qualitative study.

This qualitative study aimed to explore how the development of tolerance to both the psychoactive and respiratory depressant effects of heroin on re-exposure are experienced by people who use heroin. Semi-structured one-to-one interviews were conducted with 20 adults who currently or previously used heroin (for at least 6 months), with any type of administration (injected, smoked) and experience of abstinence (at least 2 weeks) and relapse. Topic guides explored the participants understanding of tolerance, their experience of developing tolerance to heroin and of tolerance following relapse. Interviews were audio-recorded and transcribed. Thematic analysis was used to generate salient themes. The analysis produced three broad themes: lay understanding of tolerance; tolerating tolerance; and rapid tolerance development following relapse. Tolerance was defined as the body adapting to regular drug use, so that the drug no longer produced the same level of effect. Tolerance was experienced as interacting and co-developing with physical dependence and the symptoms of withdrawal. Indeed, several participants did not differentiate between tolerance and dependence. Most participants did not notice tolerance to respiratory depression. Tolerance levels fluctuated-increasing over periods of regular use and reducing when abstinent. Using more drug was the most common response to increasing tolerance to the desired effects. On re-use following abstinence, tolerance was experienced as developing more quickly in the most recent relapse compared to the first. Tolerance was also perceived to return more quickly with each abstinence-relapse cycle. Qualitative accounts of tolerance report that tolerance returns more quickly with each relapse episode. By elucidating the mechanism(s) involved and potentially discovering how they could be switched on prior to relapse occurring we might be able to develop a beneficial harm reduction treatment for people in abstinence that would protect against overdose occurring on subsequent relapse.

Comparative Investigation of Five Cobras’ Venoms Analgesic Capacity

Every day, a lot of people suffer from different types and intensity pain. Pain is probably the most common symptomatic reason to seek medical consultation. Unfortunately, despite improved knowledge of underlying mechanisms and better treatments, many people who have any type of pain receive inadequate care and non-effective drugs. Although the pain transmission channels are intensively studied, and the drug market is constantly replenished with new analgesics, it is well known that existing medications for the treatment of pain are often associated with serious side effects and rapid development of tolerance (moderate efficiency, physical dependence, respiratory arrest, suffocation, cardiac arrest, etc.). Thus, there is a need for new, more effective remedies. For this reason, despite the presence of a large number of anti-pain drugs, research and development of more effective and safe means for anaesthesia continue. Natural resources, particularly venoms, are a perspective supplier of antinociceptive and anti-inflammatory medicines. Venoms are complex mixtures of bioactive substances with high selectivity for physiological processes, including modulation of different ion channels, receptors function, and metabolic pathways. Thus, venoms represent an extensive source of molecules for the development of therapeutic agents. The goal of this study was the comparison of antinociceptive effects of five different cobras' venom antinociceptive action of cobras’ venoms was carried out under the same experimental conditions, at the same doses, during acute and inflammatory pain in mice in “formalin test”. To avoid toxic effects, the sublethal dose of each cobra venom (approximately 1/10 LD 50 ) was selected. The behavioural study showed that all tested venoms had a slight sensitizing effect in the acute phase during the first 5 min. In the second, inflammatory phase (16*25min), all tested cobra’s venoms (3μg/0.1ml, intraperitoneal) showed significant antinociceptive action, particularly the Naja naja oxiana venom decreased pain sensitivity by 48.4%, the Naja naja pallida venom by 75.4%, the Naja naja nigricincta venom by 38.5%, the Naja naja kaouthia venom by 33.2%, and the Ophiophagus Hannah venom by 78.3%, (p<0.05). The analgesic capacity of Analgin and Diclofenac under the same conditions were 77.9% and 88.7%, respectively. Thus, the Naja n. pallida and Ophiophagus Hannah venoms have shown the most expressed antinociceptive action, and they have competitive effectiveness compared to classic analgesics. They may be chosen as the most effective from tested venoms for further development of pain relief remedies.

CB1 Cannabinoid Receptor Signaling and Biased Signaling.

The CB1 cannabinoid receptor is a G-protein coupled receptor highly expressed throughout the central nervous system that is a promising target for the treatment of various disorders, including anxiety, pain, and neurodegeneration. Despite the wide therapeutic potential of CB1, the development of drug candidates is hindered by adverse effects, rapid tolerance development, and abuse potential. Ligands that produce biased signaling—the preferential activation of a signaling transducer in detriment of another—have been proposed as a strategy to dissociate therapeutic and adverse effects for a variety of G-protein coupled receptors. However, biased signaling at the CB1 receptor is poorly understood due to a lack of strongly biased agonists. Here, we review studies that have investigated the biased signaling profile of classical cannabinoid agonists and allosteric ligands, searching for a potential therapeutic advantage of CB1 biased signaling in different pathological states. Agonist and antagonist bound structures of CB1 and proposed mechanisms of action of biased allosteric modulators are used to discuss a putative molecular mechanism for CB1 receptor activation and biased signaling. Current studies suggest that allosteric binding sites on CB1 can be explored to yield biased ligands that favor or hinder conformational changes important for biased signaling.

Fish allergy tolerance 16 months after diagnosis.

Fish allergy is generally thought to be persistent, and approximately 80% of patients with fish allergies do not develop tolerance even 10 years after diagnosis. There have been no reports of rapid tolerance development in patients with severe fish allergies. We report the development of tolerance 16 months after the diagnosis of fish allergies. A 13-month-old boy was diagnosed with rosefish allergy (Sebastes matsubarae) and Japanese jack mackerel allergy (Trachurus japonicus). To find out which species of fish he could consume safely, he underwent several oral food challenge (OFC) tests. It was determined that he could consume tuna, salmon, cod, sardine, chub mackerel (Scomber japonicus), and Japanese amberjack (Seriola quinqueradiata) without eliciting signs of allergy. He continued to eat the fish that did not produce allergic reactions three to four times a week. The titer of serum allergen-specific immunoglobulin E (IgE) to fish had decreased in a subsequent ImmunoCAP®-specific IgE blood test performed 16 months after the diagnosis of the rosefish allergy. Following this test result, he underwent OFCs with rosefish and Japanese jack mackerel, both of which turned out to be negative, and it was determined that he had developed tolerance to fish. In this case, the repeated OFCs were useful in identifying fish species that were safe for consumption. In addition, the decrease in allergen-specific IgE was useful in predicting the development of tolerance. We hypothesize that proactive consumption of available fish species may lead to this rapid induction of tolerance to fish allergens.

Contribution of Lymphotoxin-Beta Receptor Signaling in Oral Cancer Pain

Oral cancer pain is difficult to treat with limited efficacy or rapid development of tolerance and severe side effects of available medications. The immune system has been shown to play a critical role in controlling chronic pain, however, very few studies have explored its role in oral cancer pain. We have identified novel targets that have shown to play a significant role in mediating persistent inflammation in autoimmune and chronic inflammatory disease. The Lymphotoxin-beta receptor and its ligand LIGHT (TNFSF14), belong to the family of tumor-necrosis factor and have shown to be expressed in a variety of cells that make up the microenvironment. The current study explores the contribution of LIGHT and LTβR in mediating oral cancer pain. An orthotopic tongue cancer pain model using human oral squamous cell carcinoma (OSCC) cells were employed for all experiments. We determined effect of local injection of LIGHT and LTβR antagonistic antibody (LTβRIg) on tumor-induced pain behaviors including feeding behaviors and Von Frey thresholds in the face. Body weights and tumor volumes were also measured. Further, we determined expression of LTβR and LIGHT in several cell types within tumor-bearing tongues using immunohistochemistry. Our data showed that local injection of LIGHT reversed tongue-tumor induced reduction in feeding behavior and increased body weights compared to vehicle group. Conversely, injection of local LTβRIg worsened tumor-induced feeding behavior and decreased body weights compared to the control group. LIGHT and LTβRIg had no effect on tumor volumes. Anatomical analyses showed LTβR expression in cancer cells and stromal cells within the tumor and LIGHT expression in immune cells. Taken together, our data demonstrate that LIGHT/LTβR signaling may inhibit oral cancer-induced pain via modulating downstream signaling in OSCC cells and the associated stromal cells which in turn may control peripheral lingual sensory nerve activities. Title: LIGHT and Lymphotoxin targeting for the treatment of chronic orofacial pain conditions. R01 DE029187 from NIH/NIDCR. Oral cancer pain is difficult to treat with limited efficacy or rapid development of tolerance and severe side effects of available medications. The immune system has been shown to play a critical role in controlling chronic pain, however, very few studies have explored its role in oral cancer pain. We have identified novel targets that have shown to play a significant role in mediating persistent inflammation in autoimmune and chronic inflammatory disease. The Lymphotoxin-beta receptor and its ligand LIGHT (TNFSF14), belong to the family of tumor-necrosis factor and have shown to be expressed in a variety of cells that make up the microenvironment. The current study explores the contribution of LIGHT and LTβR in mediating oral cancer pain. An orthotopic tongue cancer pain model using human oral squamous cell carcinoma (OSCC) cells were employed for all experiments. We determined effect of local injection of LIGHT and LTβR antagonistic antibody (LTβRIg) on tumor-induced pain behaviors including feeding behaviors and Von Frey thresholds in the face. Body weights and tumor volumes were also measured. Further, we determined expression of LTβR and LIGHT in several cell types within tumor-bearing tongues using immunohistochemistry. Our data showed that local injection of LIGHT reversed tongue-tumor induced reduction in feeding behavior and increased body weights compared to vehicle group. Conversely, injection of local LTβRIg worsened tumor-induced feeding behavior and decreased body weights compared to the control group. LIGHT and LTβRIg had no effect on tumor volumes. Anatomical analyses showed LTβR expression in cancer cells and stromal cells within the tumor and LIGHT expression in immune cells. Taken together, our data demonstrate that LIGHT/LTβR signaling may inhibit oral cancer-induced pain via modulating downstream signaling in OSCC cells and the associated stromal cells which in turn may control peripheral lingual sensory nerve activities. Title: LIGHT and Lymphotoxin targeting for the treatment of chronic orofacial pain conditions. R01 DE029187 from NIH/NIDCR.

Sustained-release buprenorphine induces acute opioid tolerance in the mouse

Sustained-release buprenorphine is widely used in mice with the intention of providing long-lasting analgesia. Statements about duration of therapeutic efficacy are based on persistence of serum buprenorphine levels over a minimum threshold, but behavioral data demonstrating sustained efficacy is not established. Additionally, chronic opioid exposure can induce tolerance and/or hyperalgesia; mice receiving sustained-release buprenorphine have not been evaluated for these effects. This study assessed clinical efficacy and duration of sustained-release buprenorphine in inflammatory, post-operative, and cancer pain; and screened for centrally-mediated opioid-induced hyperalgesia as well as opioid tolerance. At 1–2 mg/kg sustained-release buprenorphine, statistically significant analgesic efficacy occurred only at time points up to 2 h. These animals showed no changes in von Frey thresholds on the contralateral side, i.e. no centrally-mediated opioid hyperalgesia. To establish whether acute onset opioid tolerance resulted from a single sustained-release buprenorphine administration, we used the tail flick assay, exposing mice to sustained-release buprenorphine or saline on Day 1 and buprenorphine on Day 2. We measured duration and efficacy of 1 mg/kg buprenorphine after 1 mg/kg sustained-release buprenorphine, and also quantified a dose-response curve of buprenorphine (0.1–3 mg/kg) after 2 mg/kg sustained-release buprenorphine. Compared to control animals, mice previously exposed to sustained-release buprenorphine showed diminished analgesic response to buprenorphine; the resultant dose-response curve showed decreased efficacy. Pretreatment with naloxone, an opioid receptor antagonist, blocked sustained-release buprenorphine analgesic action. The short duration of antinociception following administration of sustained-release buprenorphine in mice is caused by the rapid development of tolerance.

Tools for Community-Based Pharmacist Patient Care Services to Support Optimal Opioid Use

Tools for Community-Based Pharmacist Patient Care Services to Support Optimal Opioid Use

Organic nitrates and tolerance in cardiovascular diseases: effects of isosorbide-2-mononitrate compared to traditional nitrates

Nitrates are a cornerstone in the treatment of coronary heart disease and heart fail- ure. Although they are widely used in clinical practice, their therapeutic value is partially com- promised by the rapid development of tolerance. The effect of different nitrates, nitroglycerin (NTG), isosorbide dinitrate (ISDN), 5-mononitrate (5MN) and 2-mononitrate (2MN) and the mech- anism responsible for nitrate tolerance were investigated on isolated rabbit hearts and aortic strips. Preparation was stimulated by different spasmogenic agents: KCl, angiotensin II (A) and noradrenaline (NA); nitrates were administered on the plateau contraction, at the concentration of maximum inhibitory effect. Nitrates produced the following maximum inhibitions on NA-in- duced contraction: NTG 90% (10 -6 M), ISDN 60% (10 -4 M), 5MN 55% (10 -4 M) and 2MN 80% (10 -4 M). In another series of experiments, preparations were pre-incubated with the maximum inhibitory concentration of each nitrate to evaluate the induction of tolerance. After incubation a loss of vasodilator effect of nearly 50-60% was observed for all the nitrates considered except 2MN, in which the loss of effect was significantly lower (36%). The cyclic GMP (cGMP) levels measured in the preparations were lower in the presence of 2MN than in the other compounds. These data suggest that 2MN is able to induce a lesser cGMP increase and a lesser tolerance in- duction; since these observations seem to be correlated the vasodilator effect of 2MN probably in- volves mechanisms other than guanylyl cyclase stimulation. (Heart International 2007; 3: 112-21)

The slippery slope of flubromazolam: Experiences of a novel psychoactive benzodiazepine as discussed on a Swedish online forum.

Aim:The purpose of this qualitative study was to investigate the effects experienced by users of a novel psychoactive substance, the benzodiazepine flubromazolam, by analysing users’ own accounts on the Swedish forum Flashback.org.Method:A thematic analysis of anonymous self-reports published on the forum was performed and generated five general themes describing effects and experiences by flubromazolam users.Results:The themes which emerged were: Onset and duration, Desired effects, Adverse effects and addiction, Loss of control, General estimations and evaluations. The main reported characteristics of flubromazolam were heavy hypnotic and sedative effects, long-lasting amnesiac effects and the rapid development of tolerance. Flubromazolam was also anxiolytic and acted as a muscle relaxant for many users. Some users experienced euphoria or intense wellbeing. Other prominent characteristics were loss of control (leading to poor choices and actions, with unpleasant consequences) and long-lasting, often severe withdrawals. There were also serious incidents where users had been admitted to hospital, acute psychiatric treatment or taken into custody by the police.Conclusion:Flubromazolam appears to be a highly addictive and precarious benzodiazepine with many, possibly severe, side effects. The substance is generally described as very potent and with long-lasting effects. Memory loss and loss of control are common adverse effects, and withdrawals appear to be severe for many users.

Usefulness for the combination of G-protein- and β-arrestin-biased ligands of μ-opioid receptors: Prevention of antinociceptive tolerance.

Backgroundµ-Opioid receptor internalization is considered to be critically linked to antinociceptive tolerance. Although µ-opioid receptor agonists have been administered simultaneously with other drugs to control pain, little information is available regarding opioid–opioid interactions. Therefore, the present study was designed to further investigate the utility of a new G protein-biased ligand for µ-opioid receptors, TRV130, which has an antinociceptive effect without β-arrestin-dependent µ-opioid receptor internalization, and its combination with fentanyl using µ-opioid receptor-expressing cells and mice.ResultsIn the present study, we confirmed that fentanyl produced a profound increase in β-arrestin-2 recruitment accompanied by µ-opioid receptor internalization, whereas TRV130 did not induce either the recruitment of β-arrestin-2 or µ-opioid receptor internalization in µ-opioid receptor-expressing cells. Under these conditions, β-arrestin-2 recruitment accompanied by µ-opioid receptor internalization induced by fentanyl was abolished by TRV130, whereas TRV130 did not alter the reduction of cyclic adenosine monophosphate formation by fentanyl in µ-opioid receptor-expressing cells. In a behavioral assay, TRV130 exerted an antinociceptive effect in a hot-plate test in mice. In a combination test, the antinociceptive effect of TRV130 was synergistically increased by fentanyl. Fentanyl induced antihyperalgesia and development of its tolerance under a neuropathic pain-like state following sciatic nerve ligation. However, treatment of mice with an antinociceptive dose of TRV130 did not induce the rapid development of tolerance to its antihyperalgesic effect under a neuropathic pain-like state. Furthermore, the rapid development of tolerance to the antihyperalgesic effect induced by fentanyl plus TRV130 in mice with sciatic nerve ligation was not observed, unlike in the case of fentanyl alone.ConclusionsThese findings provide evidence that activation of the G protein-biased pathway through µ-opioid receptors can alter signaling in the β-arrestin-2 pathway linked to the stimulation of µ-opioid receptors. Furthermore, the combination of G protein-biased and β-arrestin-biased ligands of µ-opioid receptors exerts an ideal antinociceptive effect without the rapid development of antinociceptive tolerance.

СУЧАСНИЙ СТАН СТВОРЕННЯ, ВИРОБНИЦТВА ТА ДОСЛІДЖЕННЯ ТАБЛЕТОВАНИХ ЛІКАРСЬКИХ ПРЕПАРАТІВ. Повідомлення 24. Осмотичні системи вивільнення та доставки лікарських речовин: розробка, характеристика та їх класифікація

Проведено огляд літературних джерел щодо розробки та дослідження осмотичних систем вивільнення та доставки лікарських речовин

Morphine Regulated Synaptic Networks Revealed by Integrated Proteomics and Network Analysis

Despite its efficacy, the use of morphine for the treatment of chronic pain remains limited because of the rapid development of tolerance, dependence and ultimately addiction. These undesired effects are thought to be because of alterations in synaptic transmission and neuroplasticity within the reward circuitry including the striatum. In this study we used subcellular fractionation and quantitative proteomics combined with computational approaches to investigate the morphine-induced protein profile changes at the striatal postsynaptic density. Over 2,600 proteins were identified by mass spectrometry analysis of subcellular fractions enriched in postsynaptic density associated proteins from saline or morphine-treated striata. Among these, the levels of 34 proteins were differentially altered in response to morphine. These include proteins involved in G-protein coupled receptor signaling, regulation of transcription and translation, chaperones, and protein degradation pathways. The altered expression levels of several of these proteins was validated by Western blotting analysis. Using Genes2Fans software suite we connected the differentially expressed proteins with proteins identified within the known background protein-protein interaction network. This led to the generation of a network consisting of 116 proteins with 40 significant intermediates. To validate this, we confirmed the presence of three proteins predicted to be significant intermediates: caspase-3, receptor-interacting serine/threonine protein kinase 3 and NEDD4 (an E3-ubiquitin ligase identified as a neural precursor cell expressed developmentally down-regulated protein 4). Because this morphine-regulated network predicted alterations in proteasomal degradation, we examined the global ubiquitination state of postsynaptic density proteins and found it to be substantially altered. Together, these findings suggest a role for protein degradation and for the ubiquitin/proteasomal system in the etiology of opiate dependence and addiction.

Organic Nitrate Therapy, Nitrate Tolerance, and Nitrate-Induced Endothelial Dysfunction: Emphasis on Redox Biology and Oxidative Stress

Organic nitrates, such as nitroglycerin (GTN), isosorbide-5-mononitrate and isosorbide dinitrate, and pentaerithrityl tetranitrate (PETN), when given acutely, have potent vasodilator effects improving symptoms in patients with acute and chronic congestive heart failure, stable coronary artery disease, acute coronary syndromes, or arterial hypertension. The mechanisms underlying vasodilation include the release of •NO or a related compound in response to intracellular bioactivation (for GTN, the mitochondrial aldehyde dehydrogenase [ALDH-2]) and activation of the enzyme, soluble guanylyl cyclase. Increasing cyclic guanosine-3′,-5′-monophosphate (cGMP) levels lead to an activation of the cGMP-dependent kinase I, thereby causing the relaxation of the vascular smooth muscle by decreasing intracellular calcium concentrations. The hemodynamic and anti-ischemic effects of organic nitrates are rapidly lost upon long-term (low-dose) administration due to the rapid development of tolerance and endothelial dysfunction, which is in most cases linked to increased intracellular oxidative stress. Enzymatic sources of reactive oxygen species under nitrate therapy include mitochondria, NADPH oxidases, and an uncoupled •NO synthase. Acute high-dose challenges with organic nitrates cause a similar loss of potency (tachyphylaxis), but with distinct pathomechanism. The differences among organic nitrates are highlighted regarding their potency to induce oxidative stress and subsequent tolerance and endothelial dysfunction. We also address pleiotropic effects of organic nitrates, for example, their capacity to stimulate antioxidant pathways like those demonstrated for PETN, all of which may prevent adverse effects in response to long-term therapy. Based on these considerations, we will discuss and present some preclinical data on how the nitrate of the future should be designed. Antioxid. Redox Signal. 23, 899–942.

Endothelin ETA receptor antagonist reverses naloxone-precipitated opioid withdrawal in mice.

Long-term use of opioids for pain management results in rapid development of tolerance and dependence leading to severe withdrawal symptoms. We have previously demonstrated that endothelin-A (ETA) receptor antagonists potentiate opioid analgesia and eliminate analgesic tolerance. This study was designed to investigate the involvement of central ET mechanisms in opioid withdrawal. The effect of intracerebroventricular administration of ETA receptor antagonist BQ123 on morphine and oxycodone withdrawal was determined in male Swiss Webster mice. Opioid tolerance was induced and withdrawal was precipitated by the opioid antagonist naloxone. Expression of ETA and ETB receptors, nerve growth factor (NGF), and vascular endothelial growth factor was determined in the brain using Western blotting. BQ123 pretreatment reversed hypothermia and weight loss during withdrawal. BQ123 also reduced wet shakes, rearing behavior, and jumping behavior. No changes in expression of vascular endothelial growth factor, ETA receptors, and ETB receptors were observed during withdrawal. NGF expression was unaffected in morphine withdrawal but significantly decreased during oxycodone withdrawal. A decrease in NGF expression in oxycodone- but not in morphine-treated mice could be due to mechanistic differences in oxycodone and morphine. It is concluded that ETA receptor antagonists attenuate opioid-induced withdrawal symptoms.

Analgesic tolerance to morphine is regulated by PPARγ.

Opioid drugs are potent analgesics. However, their chronic use leads to the rapid development of tolerance to their analgesic effects and subsequent increase of significant side effects, including drug dependence and addiction. Here, we investigated the role of PPARγ in the development of analgesic tolerance to morphine in mice. We monitored analgesia on alternate days using the tail immersion test. Daily administration of morphine (30 mg·kg(-1) , bid) resulted in the rapid development of tolerance to thermal analgesia. Co-administration of pioglitazone (10 and 30 mg·kg(-1) , bid) significantly attenuated the development and expression of tolerance. However, pretreatment with GW-9662 (5 mg·kg(-1) , bid), a selective PPARγ antagonist, completely abolished this effect. Injection of GW-9662 and a lower dose of morphine (15 mg·kg(-1) , bid) accelerated the development of tolerance to its antinociceptive effect. Subsequently, we found that conditional neuronal PPARγ knockout (KO) mice develop a more rapid and pronounced tolerance to morphine antinociception compared with wild-type (WT) controls. Moreover, in PPARγ KO mice, pioglitazone was no longer able to prevent the development of morphine tolerance. Overall, our results demonstrate that PPARγ plays a tonic role in the modulation of morphine tolerance, and its pharmacological activation may help to reduce its development. These findings provide new information about the role of neuronal PPARγ and suggest that combining PPARγ agonists with opioid analgesics may reduce the development of tolerance and possibly attenuate the potential for opioid abuse.