u-0126 and Substance-Withdrawal-Syndrome

Recent evidence suggests that histone deacetylase (HDAC) inhibitors facilitate extinction of rewarding memory of drug taking. However, little is known about the role of chromatin modification in the extinction of aversive memory of drug withdrawal. In this study, we used conditioned place aversion (CPA), a highly sensitive model for measuring aversive memory of drug withdrawal, to investigate the role of epigenetic regulation of brain-derived neurotrophic factor (BDNF) gene expression in extinction of aversive memory. We found that CPA extinction training induced an increase in recruiting cAMP response element-binding protein (CREB) to and acetylation of histone H3 at the promoters of BDNF exon I transcript and increased BDNF mRNA and protein expression in the ventromedial prefrontal cortex (vmPFC) of acute morphine-dependent rats and that such epigenetic regulation of BDNF gene transcription could be facilitated or diminished by intra-vmPFC infusion of HDAC inhibitor trichostatin A or extracellular signal-regulated kinase (ERK) inhibitor U0126 (1,4-diamino-2,3-dicyano-1,4-bis(methylthio)butadiene) before extinction training. Correspondingly, disruption of the epigenetic regulation of BDNF gene transcription with U0126 or suppression of BDNF signaling with Trk receptor antagonist K252a or BDNF scavenger tyrosine kinase receptor B (TrkB)-Fc blocked extinction of CPA behavior. We also found that extinction training-induced activation of ERK and CREB and extinction of CPA behavior could be potentiated or suppressed by intra-vmPFC infusion of d-cycloserine, a NMDA receptor partial agonist or aminophosphonopentanoic acid, a NMDA receptor antagonist. We conclude that extinction of aversive memory of morphine withdrawal requires epigenetic regulation of BDNF gene transcription in the vmPFC through activation of the ERK-CREB signaling pathway perhaps in a NMDA receptor-dependent manner.

Topics: Acetylation; Animals; Association Learning; Avoidance Learning; Brain-Derived Neurotrophic Factor; Butadienes; Chromatin Assembly and Disassembly; Conditioning, Classical; Cyclic AMP Response Element-Binding Protein; Epigenetic Repression; Extinction, Psychological; Histone Deacetylase Inhibitors; Histones; Male; MAP Kinase Signaling System; Morphine; Morphine Dependence; Nitriles; Prefrontal Cortex; Protein Kinase Inhibitors; Protein Processing, Post-Translational; Rats; Rats, Sprague-Dawley; Receptor, trkB; Receptors, N-Methyl-D-Aspartate; Reward; Substance Withdrawal Syndrome; Transcription, Genetic

To explore the effects of intrathecal injection of mitogen-activated protein kinases inhibitors U0126 on the behavioral changes of morphine-induced dependent and withdrawal rats and the expression of nitric oxide synthase (NOS) in spinal cord.. All the rats were divided into 4 groups: control group, dependent group, withdrawal group, U0126 group (5 microg). Global withdrawal score, Touch evoked agitation scores (TEA score), immunohistochemical and Western blot technique were undertaken to evaluate behavioral changes and expression of FOS, nNOS and iNOS in spinal cord respectively.. The results showed that intrathecal administration of U0126 significantly alleviated withdrawal symptom, withdrawal scores of U0126 group (22.5 +/- 4.09) were significantly lower than than those of withdrawal group (28.6 +/- 4.89) (P < 0.05). TEA scores of withdrawal group were 13.5 +/- 2.55, which were significantly higher than those of U0126 group (10.0 +/- 2.76, P < 0.05). Fos-like positive neurons in dorsal horn of withdrawal group were 380 +/- 71, which were higher than those of U0126 group(287 +/- 54, P < 0.05). Also nNOS and iNOS positive neurons in dorsal horn of U0126 group were 180 +/- 32, 10.8 +/- 2.8 respectively, which were significantly lower than that of withdrawal group (239 +/- 45, 16.8 +/- 5.1, P < 0.05). Compared with withdrawal group, levels of nNOS and iNOS protein in spinal cord of U0126 group were significantly lower.. MEK inhibitors could alleviate withdrawal symptom of morphine-induced dependent rats and could suppress expression of NOS in spinal cord, and extracellular signal-regulate kinase (ERK) might involve the expression of NOS in spinal cord.

Topics: Animals; Behavior, Animal; Butadienes; Enzyme Inhibitors; Extracellular Signal-Regulated MAP Kinases; Male; Mitogen-Activated Protein Kinases; Morphine; Morphine Dependence; Nitric Oxide Synthase; Nitriles; Rats; Rats, Sprague-Dawley; Spinal Cord; Substance Withdrawal Syndrome

To explore effects of intrathecal injection of U0126 on morphine withdrawal response and the spinal Phospho-CREB expression in morphine-induced withdrawal rats.. All the rats were divided into 5 groups: control group, dependence group, withdrawal group, U0126 group (5 microg, it) and DMSO group. Morphine withdrawal score, touch evoked agitation scores(TEA score), immunohistochemical and Western-blotting technique were used to evaluate morphine withdrawal response and the expression of Phospho-CREB in the spinal cord.. Intrathecal injection of MEK inhibitor U0126 significantly alleviated morphine withdrawal symptoms. Morphine withdrawal scores in U0126 group (22.5 +/- 4.09) were significantly lower than that of withdrawal group (28.6 +/- 4.89, P < 0.05). TEA score of withdrawal group was 13.5 +/- 2.55, which was significantly higher than that of U0126 group (10.0 +/- 2.76, P < 0.05). Phospho-CREB positive neurons in the spinal dorsal horn of withdrawal group were 380 +/- 71, which is higher than that of U0126 group (293 +/- 47, P < 0.05). Compared with withdrawal group, level of Phospho-CREB protein detected by Western blot in spinal cord of U0126 group was significantly lower.. MEK inhibitors U0126 could suppress expression of Phospho-CREB in the spinal cord.

Topics: Animals; Butadienes; Cyclic AMP Response Element-Binding Protein; Injections, Spinal; Male; Morphine Dependence; Nitriles; Protein Kinase Inhibitors; Rats; Rats, Sprague-Dawley; Spinal Cord; Substance Withdrawal Syndrome

Using a rat model of craving and relapse, we have previously found time-dependent increases in cue-induced cocaine seeking over the first months of withdrawal from cocaine, suggesting that drug craving incubates over time. Here, we explored the role of the amygdala extracellular signal-regulated kinase (ERK) signaling pathway in this incubation. Cocaine seeking induced by exposure to cocaine cues was substantially higher after 30 withdrawal days than after 1 withdrawal day. Exposure to these cues increased ERK phosphorylation in the central, but not the basolateral, amygdala after 30 d, but not 1 d, of withdrawal. After 30 d of withdrawal from cocaine, inhibition of central, but not basolateral, amygdala ERK phosphorylation decreased cocaine seeking. After 1 d of withdrawal, stimulation of central amygdala ERK phosphorylation increased cocaine seeking. Results suggest that the incubation of cocaine craving is mediated by time-dependent increases in the responsiveness of the central amygdala ERK pathway to cocaine cues.

Topics: Amygdala; Anesthetics, Local; Animals; Behavior, Addictive; Behavior, Animal; Blotting, Western; Butadienes; Cocaine; Cocaine-Related Disorders; Conditioning, Operant; Cues; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Interactions; Enzyme Inhibitors; Excitatory Amino Acid Agonists; Extinction, Psychological; Extracellular Signal-Regulated MAP Kinases; Food; Injections, Intravenous; Male; N-Methylaspartate; Nitriles; Phosphorylation; Rats; Rats, Long-Evans; Reinforcement, Psychology; Self Administration; Signal Transduction; Substance Withdrawal Syndrome; Time Factors

Extracellular signal-regulated kinase (ERK), a mitogen-activated protein kinases (MAPK), transduces a broad range of extracellular stimuli into diverse intracellular responses. Recent studies have showed that ERK activation in the supraspinal level involved in the development of drug dependence, especially in psychological dependence. In this study, we reported that the spinal ERK signaling pathway was activated by chronic morphine injection. There was a further increase in ERK activation after naloxone-precipitated withdrawal. Furthermore, attenuation of the spinal ERK phosphorylation by intrathecal a MAPK kinase (MEK) inhibitor U0126 or knockdown of the spinal ERK by antisense oligonucleotides not only decreased the scores of morphine withdrawal, but also attenuated withdrawal-induced allodynia, which were accompanied by decreased ERK phosphorylation in the spinal cord. The spinal ERK inhibition or knockdown also reduced morphine withdrawal-induced phosphorylation of cAMP response element binding protein (CREB), which is one of the important downstream substrates of ERK pathway, and Fos expression. The involvement of the spinal ERK in morphine withdrawal was supported by our finding that intrathecal N-methyl-D-aspartate receptor antagonist MK-801 or protein kinase C inhibitor chelerythrine chloride suppressed withdrawal-induced ERK activation in the spinal cord and attenuated morphine withdrawal symptoms. These findings suggest activation of the spinal ERK signaling pathway contributes naloxone-precipitated withdrawal in morphine-dependent rats.

Topics: Animals; Butadienes; Extracellular Signal-Regulated MAP Kinases; Male; MAP Kinase Signaling System; Morphine Dependence; Naloxone; Nitriles; Rats; Rats, Sprague-Dawley; Spinal Cord; Substance Withdrawal Syndrome