Modulation of histone deacetylase attenuates naloxone-precipitated opioid withdrawal syndrome

Biotechnological Innovations from Ocean: Transpiring Role of Marine Drugs in Management of Chronic Disorders

Marine drugs are abundant in number, comprise of a diverse range of structures with corresponding mechanisms of action, and hold promise for the discovery of new and better treatment approaches for the management of several chronic diseases. There are huge reserves of natural marine biological compounds, as 70 percent of the Earth is covered with oceans, indicating a diversity of chemical entities on the planet. The marine ecosystems are a rich source of bioactive products and have been explored for lead drug molecules that have proven to be novel therapeutic targets. Over the last 70 years, many structurally diverse drug products and their secondary metabolites have been isolated from marine sources. The drugs obtained from marine sources have displayed an exceptional potential in the management of a wide array of diseases, ranging from acute to chronic conditions. A beneficial role of marine drugs in human health has been recently proposed. The current review highlights various marine drugs and their compounds and role in the management of chronic diseases such as cancer, diabetes, neurodegenerative diseases, and cardiovascular disorders, which has led to the development of new drug treatment approaches.

Pathways from epigenomics and glycobiology towards novel biomarkers of addiction and its radical cure

The recent demonstration that addiction-relevant neuronal ensembles defined by known master transcription factors and their connectome is networked throughout mesocorticolimbic reward circuits and resonates harmonically at known frequencies implies that single-cell pan-omics techniques can improve our understanding of Substance Use Disorders (SUD's). Application of machine learning algorithms to such data could find diagnostic utility as biomarkers both to define the presence of the disorder and to quantitate its severity and find myriad applications in a developmental pipeline towards therapeutics and cure. Recent epigenomic studies have uncovered a wealth of clinically important data relating to synapse-nucleus signalling, memory storage, lineage-fate determination and cellular control and are contributing greatly to our understanding of all SUD's. Epigenetics interacts extensively with glycobiology. Glycans decorate DNA, RNA and many circulating critical proteins particularly immunoglobulins. Glycosylation is emerging as a major information-laden post-translational protein modification with documented application for biomarker development. The integration of these two emerging cutting-edge technologies provides a powerful and fertile algorithmic-bioinformatic space for the development both of SUD biomarkers and novel cutting edge therapeutics.

HYPOTHESES

These lines of evidence provide fertile ground for hypotheses relating to both diagnosis and treatment. They suggest that biomarkers derived from epigenomics complemented by glycobiology may potentially provide a bedside diagnostic tool which could be developed into a clinically useful biomarker to gauge both the presence and the severity of SUD's. Moreover they suggest that modern information-based therapeutics acting on the epigenome, via RNA interference or by DNA antisense oligonucleotides may provide a novel 21st century therapeutic development pipeline towards the radical cure of addictive disorders. Such techniques could be focussed and potentiated by neurotrophic vectors or the application of interfering electric or magnetic fields deep in the medial temporal lobes of the brain.

Epigenetic Activation of μ-Opioid Receptor Gene via Increased Expression and Function of Mitogen- and Stress-Activated Protein Kinase 1

Since the discovery of μ-opioid receptor (MOR) gene two decades ago, various regulatory factors have been shown to interact with the MOR promoter and modulate transcript levels. However, the majority of early transcriptional studies on MOR gene have not addressed how intracellular signaling pathways mediate extracellular modulators. In this study, we demonstrate that MOR epigenetic regulation requires multiple coordinated signals converging at the MOR promoter, involving mitogen-activated protein kinase (MAPK) activation and mitogen- and stress-activated protein kinase 1 (MSK1)-ranges of intracellular signaling pathways similar to those activated by opioid agonists. Inhibiting p38 MAPK or extracellular signal-regulated kinase (ERK) 1/2 MAPK (upstream activators of MSK1) reduced MOR expression levels; accordingly, the functional role of MSK1, but not MSK2, was demonstrated using genetic approaches. However, for maximal MSK1 effect, an open chromatin configuration was required, because in vitro CpG methylation of the MOR promoter abolished MSK1 activity. Finally, endogenous MSK1 levels concomitantly increased to regulate MOR gene expression during neuronal differentiation of P19 cells, suggesting a conserved role of this kinase in the epigenic activation of MOR in neurons. Taken together, our findings indicate that the expression of MOR gene requires the activity of intracellular signaling pathways that have been implicated in the behavioral outcomes of opioid drugs, which suggests that an autoregulatory mechanism may function in opioid systems.

Redox-based epigenetic status in drug addiction: a potential contributor to gene priming and a mechanistic rationale for metabolic intervention

Alcohol and other drugs of abuse, including psychostimulants and opioids, can induce epigenetic changes: a contributing factor for drug addiction, tolerance, and associated withdrawal symptoms. DNA methylation is a major epigenetic mechanism and it is one of more than 200 methylation reactions supported by methyl donor S-adenosylmethionine (SAM). Levels of SAM are controlled by cellular redox status via the folate and vitamin B12-dependent enzyme methionine synthase (MS). For example, under oxidative conditions MS is inhibited, diverting its substrate homocysteine (HCY) to the trans sulfuration pathway. Alcohol, dopamine, and morphine, can alter intracellular levels of glutathione (GSH)-based cellular redox status, subsequently affecting SAM levels and DNA methylation status. Here, existing evidence is presented in a coherent manner to propose a novel hypothesis implicating the involvement of redox-based epigenetic changes in drug addiction. Further, we discuss how a “gene priming” phenomenon can contribute to the maintenance of redox and methylation status homeostasis under various stimuli including drugs of abuse. Additionally, a new mechanistic rationale for the use of metabolic interventions/redox-replenishers as symptomatic treatment of alcohol and other drug addiction and associated withdrawal symptoms is also provided. Hence, the current review article strengthens the hypothesis that neuronal metabolism has a critical bidirectional coupling with epigenetic changes in drug addiction exemplified by the link between redox-based metabolic changes and resultant epigenetic consequences under the effect of drugs of abuse.

In vivo and in vitro attenuation of naloxone-precipitated experimental opioid withdrawal syndrome by insulin and selective KATP channel modulator

RATIONALE

Opiate exposure for longer duration develops state of dependence in humans and animals, which is revealed by signs and symptoms of withdrawal precipitated by opioid receptor antagonists. The sudden withdrawal of opioids produces a withdrawal syndrome in opioid-dependent subjects. Insulin and ATP-sensitive potassium (KATP) channel-mediated glucose homeostasis have been shown to modulate morphine withdrawal.

OBJECTIVE

Present study has been structured to investigate the role of insulin and pharmacological modulator of KATP channel (gliclazide) in experimental morphine withdrawal syndrome, both invivo and invitro.

METHODS

In this study, naloxone-precipitated morphine withdrawal syndrome in mice (invivo) as well as in rat ileum (invitro) were utilized to assess opioid withdrawal phenomenon. Morphine withdrawal syndromes like jumping and rearing frequency, forepaw licking, circling, fore paw tremor, wet dog shake, sneezing, overall morphine withdrawal severity (OMWS), serum glucose, brain malondialdehyde (MDA), glutathione (GSH), nitrite/nitrate, and calcium (Ca(+2)) were assessed.

RESULTS

Naloxone has significantly increased morphine withdrawal syndrome, both invivo and invitro. Insulin and gliclazide have significantly attenuated, naloxone induced behavioral changes like jumping and rearing frequency, forepaw licking, wet dog shake, sneezing, straightening, circling, OMWS, and various biochemical impairments such as serum glucose, brain MDA, GSH, nitrite/nitrate, and Ca(+2) in morphine-dependent animals (invivo). In vitro, insulin and gliclazide have significantly reduced naloxone-induced contraction in morphine-withdrawn rat ileum preparation.

CONCLUSIONS

Insulin and gliclazide (KATP channel blocker) have attenuated naloxone-precipitated morphine withdrawal syndrome, both invivo and invitro. Thus, insulin and KATP channel modulation may provide new avenues for research in morphine withdrawal.

Endogenous opiates and behavior: 2012

This paper is the thirty-fifth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2012 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17).

Morphine epigenomically regulates behavior through alterations in histone H3 lysine 9 dimethylation in the nucleus accumbens

Dysregulation of histone modifying enzymes has been associated with numerous psychiatric disorders. Alterations in G9a (Ehmt2), a histone methyltransferase that catalyzes the euchromatic dimethylation of histone H3 at lysine 9 (H3K9me2), has been implicated recently in mediating neural and behavioral plasticity in response to chronic cocaine administration. Here, we show that chronic morphine, like cocaine, decreases G9a expression, and global levels of H3K9me2, in mouse nucleus accumbens (NAc), a key brain reward region. In contrast, levels of other histone methyltransferases or demethylases, or of other methylated histone marks, were not affected in NAc by chronic morphine. Through viral-mediated gene transfer and conditional mutagenesis, we found that overexpression of G9a in NAc opposes morphine reward and locomotor sensitization and concomitantly promotes analgesic tolerance and naloxone-precipitated withdrawal, whereas downregulation of G9a in NAc enhances locomotor sensitization and delays the development of analgesic tolerance. We identified downstream targets of G9a by providing a comprehensive chromatin immunoprecipitation followed by massively parallel sequencing analysis of H3K9me2 distribution in NAc in the absence and presence of chronic morphine. These data provide novel insight into the epigenomic regulation of H3K9me2 by chronic morphine and suggest novel chromatin-based mechanisms through which morphine-induced addictive-like behaviors arise.

Pharmacological modulation of geranylgeranyltransferase and farnesyltransferase attenuates opioid withdrawal in vivo and in vitro

Geranylgeranyltransferase and farnesyltransferase I, are noted to mediate a number of signal transduction cascades which are known to be involved in the causation of opioid withdrawal syndrome. GGTI-2133 and FTI-276 are selective modulators of geranylgeranyltransferase and farnesyltransferase subtype 1 respectively. Therefore, the present study investigated the effect of GGTI-2133 and FTI-276 on propagation of morphine dependence and resultant withdrawal signs in vivo, in sub-chronic morphine mouse model, and in vitro, in isolated rat ileum. Morphine was administered twice daily for 5 days following which a single day 6 injection of naloxone (8 mg/kg, i.p.) precipitated opioid withdrawal syndrome in mice. Withdrawal syndrome was quantitatively assessed in terms of withdrawal severity score and the frequency of jumping, rearing, fore paw licking & circling. Naloxone induced contraction in morphine withdrawn isolated rat ileum was employed as an in vitro model of opioid withdrawal syndrome. An isobolographic study design was employed to assess a potential synergistic activity between GGTI-2133 and FTI-276. GGTI-2133 and FTI-276 dose dependently attenuated naloxone induced morphine withdrawal syndrome both in vivo and in vitro. GGTI-2133 was also observed to exert a synergistic interaction with FTI-276. It is concluded that GGTI-2133 and FTI-276 attenuate the propagation of morphine dependence and reduce withdrawal signs possibly by a geranylgeranyl transferase; farnesyltransferase activation pathway linked mechanisms potentially in an interdependent manner.