[Show abstract][Hide abstract] ABSTRACT: Anxiety is a key consequence of ethanol withdrawal and important risk factor for relapse. The neuropeptide nociceptin/orphanin FQ (N/OFQ) or agonists at this peptide's receptor (NOP) exert anxiolytic-like and antistress actions. N/OFQ dysfunction has been linked to both a high-anxiety behavioral phenotype and excessive ethanol intake. Recent studies suggest a possible link between genetic polymorphisms of the NOP transcript and alcoholism. Thus, in the present study, the effects of intracerebroventricularly administered N/OFQ were tested for modification of anxiety-like behaviors, using the shock-probe defensive burying and elevated plus-maze tests, in ethanol-dependent versus non-dependent rats, 1 and 3 weeks following termination of ethanol exposure. Additionally, prepro-N/OFQ (ppN/OFQ) and NOP receptor gene expression was measured in the central nucleus of the amygdala, in the bed nucleus of the stria terminalis and in the lateral hypothalamus at the same timepoints in separate subjects. One week post-ethanol, N/OFQ dose-dependently attenuated elevated anxiety-like behavior in ethanol-dependent rats and produced anxiolytic-like effects in non-dependent controls in both behavioral tests. However, 3 weeks post-ethanol, N/OFQ altered behavior consistent with anxiogenic-like actions in ethanol-dependent rats but continued to exert anxiolytic-like actions in non-dependent controls. These findings were paralleled by ethanol history-dependent changes of ppN/OFQ and NOP gene expression that showed a distinctive time course in the examined brain structures. The results demonstrate that ethanol dependence and withdrawal are associated with neuroadaptive changes in the N/OFQ-NOP system, suggesting a role of this neuropeptidergic pathway as a therapeutic target for the treatment of alcohol abuse.
[Show abstract][Hide abstract] ABSTRACT: The etiology of bipolar disorder (BD) is still poorly understood, involving genetic and epigenetic mechanisms as well as environmental contributions. This study aimed to investigate the degree of DNA methylation at the promoter region of the brain-derived neurotrophic factor (BDNF) gene, as one of the candidate genes associated with major psychoses, in peripheral blood mononuclear cells isolated from 94 patients with BD (BD I=49, BD II=45) and 52 healthy controls. A significant BDNF gene expression downregulation was observed in BD II 0.53±0.11%; P<0.05), but not in BD I (1.13±0.19%) patients compared with controls (CONT: 1±0.2%). Consistently, an hypermethylation of the BDNF promoter region was specifically found in BD II patients (CONT: 24.0±2.1%; BDI: 20.4±1.7%; BDII: 33.3±3.5%, P<0.05). Of note, higher levels of DNA methylation were observed in BD subjects on pharmacological treatment with mood stabilizers plus antidepressants (34.6±4.2%, predominantly BD II) compared with those exclusively on mood-stabilizing agents (21.7±1.8%; P<0.01, predominantly BD I). Moreover, among the different pharmacological therapies, lithium (20.1±3.8%, P<0.05) and valproate (23.6±2.9%, P<0.05) were associated with a significant reduction of DNA methylation compared with other drugs (35.6±4.6%). Present findings suggest selective changes in DNA methylation of BDNF promoter in subjects with BD type II and highlight the importance of epigenetic factors in mediating the onset and/or susceptibility to BD, providing new insight into the mechanisms of gene expression. Moreover, they shed light on possible mechanisms of action of mood-stabilizing compounds vs antidepressants in the treatment of BD, pointing out that BDNF regulation might be a key target for their effects.
Neuropsychopharmacology: official publication of the American College of Neuropsychopharmacology 02/2012; 37(7):1647-55. · 8.68 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Neurofibrillary tangles and senile plaques are hallmarks of Alzheimer's disease (AD) although the molecular basis of their coexistence remains elusive. The peptidyl-prolyl cis/trans isomerase Pin1 acts on both tau and amyloid precursor protein to regulate their functions by influencing tau phosphorylation and amyloid precursor protein processing.
In order to identify potential biomarkers for AD in easily accessible cells and to gain insight into the relationship between the brain and peripheral compartments in AD pathology, we investigated Pin1 expression and activity in the peripheral blood mononuclear cells of subjects with late-onset AD (LOAD) and age-matched controls (CT).
Gene and protein expression, promoter methylation, Ser(16) phosphorylation and activity of Pin1 were evaluated in 32 samples from subjects with LOAD and in 28 samples from CT.
In LOAD subjects, there was a statistically significant reduction in Ser(16) phosphorylation (-30%; p = 0.041) and promoter methylation (-8%; p = 0.001), whereas Pin1 expression was significantly increased (+74%; p = 0.018).
The modifications of Pin1 found in LOAD subjects support its involvement in the pathogenesis of the disease with an important role being played by epigenetic mechanisms.
[Show abstract][Hide abstract] ABSTRACT: It has been shown that chronic cocaine increases prodynorphin mRNA in the caudate putamen and decreases it in the hypothalamus. In addition, treatment with a kappa-opioid receptor agonist produced the opposite effect on prodynorphin gene expression in these brain regions and also evoked a decrease in the hippocampus. It is already known that kappa-opioid receptor agonists decrease the development of sensitization to some of the behavioral effects of cocaine. The serotonin system has also been shown to regulate dynorphin gene expression and a continuous infusion of fluoxetine induced prodynorphin gene expression in the same pattern as the kappa-opioid agonist (+)(5a,7a,8b)-N-methyl-N-[7-(1-pyrrolidinyl)-1 oxaspiro[4.5]dec-8-yl]-benzeneacetamide (U-69593) in the brain regions investigated. It is interesting to note that treatment with a continuous infusion of cocaine produced different effects on this parameter. To determine whether serotonin plays a role in the regulation of prodynorphin mRNA by kappa-opioid agonists or cocaine, rats were treated with the serotonin depleter parachloroamphetamine (PCA). Beginning 24 h later, rats were treated with the selective kappa-opioid agonist U-69593 for 5 days or continuously with cocaine for 7 days and prodynorphin mRNA was measured. Prodynorphin mRNA was decreased significantly in the hypothalamus, caudate putamen, and hippocampus of rats treated with a single injection of PCA. Subsequent to PCA administration the effects of U-69593 or cocaine on prodynorphin mRNA were differentially affected across brain regions. Prodynorphin gene expression was still increased by U-69593 treatment in the hypothalamus and decreased in the caudate putamen. Cocaine treatment still produced a decrease in this parameter in the hypothalamus and an increase in the caudate putamen. In contrast, in the hippocampus, the decrease in prodynorphin mRNA produced by U-69593 was no longer evident after PCA and cocaine, which previously had no effect, now increased it in the serotonin-depleted group. These findings suggest that serotonin is necessary to maintain normal levels of dynorphin mRNA in all of the investigated brain areas and that the regulation of prodynorphin mRNA expression by chronic treatment with a kappa-opioid receptor agonist or cocaine requires serotonin in the hippocampus, but not in the hypothalamus or caudate putamen.
[Show abstract][Hide abstract] ABSTRACT: Previous studies showed that opioid drugs-oxycodone-6-oxime and 14-methoxy-5-methyl-dihydromorphinone (14-methoxymetopon)-produced less respiratory depressive effect and slower rate of tolerance and dependence, respectively. It was also reported that morphine decreased the prodynorphin gene expression in the rat hippocampus, striatum and hypothalamus. In this study, we determined the prodynorphin gene expression and dynorphin levels in selected brain regions of opioid tolerant rats. We found that in the striatum morphine decreased, while oxycodone-6-oxime increased and 14-methoxymetopon did not alter the prodynorphin gene expression. In the nucleus accumbens, morphine and oxycodone-6-oxime did not change, while 14-methoxymetopon increased the prodynorphin gene expression. In the hippocampus both oxycodone-6-oxime and 14-methoxymetopon enhanced, whereas morphine did not alter the prodynorphin gene expression. In the rat striatum only oxycodone-6-oxime increased dynorphin levels significantly in accordance with the prodynorphin mRNA changes. In the hippocampus both opioid agonists increased the dynorphin levels significantly similarly to the augmented prodynorphin gene expression. In ventral tegmental area only 14-methoxymetopon increased dynorphin levels significantly. In nucleus accumbens and the temporal-parietal cortex the changes in the prodynorphin gene expression and the dynorphin levels did not correlate. Since the endogenous prodynorphin system may play a modulatory role in the development of opioid tolerance, the elevated supraspinal dynorphin levels appear to be partly responsible for the reduced degree of tolerance induced by the investigated opioids.
Brain Research Bulletin 08/2006; 70(3):233-9. · 2.94 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The prodynorphin system is implicated in the neurochemical mechanism of psychostimulants. Exposure to different drugs of abuse can induce neuroadaptations in the brain and affect opioid gene expression. The present study aims to examine the possibility of a common neurobiological substrate in drug addiction processes. We studied the effects of single and repeated 3,4-methylenedioxy-N-methylamphetamine ('Ecstasy') on the gene expression of the opioid precursor prodynorphin, and on the levels of peptide dynorphin A in the rat brain. Acute (8 mg/kg, intraperitoneally) 3,4-methylenedioxy-N-methylamphetamine markedly raised, two hours later, prodynorphin mRNA levels in the prefrontal cortex, and in the caudate putamen, whereas it decreased gene expression in the ventral tegmental area. Chronic (8 mg/kg, intraperitoneally, twice a day for 7 days) 3,4-methylenedioxy-N-methylamphetamine increased prodynorphin mRNA in the nucleus accumbens, hypothalamus and caudate putamen and decreased it in the ventral tegmental area. Dynorphin A levels increased after chronic treatment in the ventral tegmental area and decreased after acute treatment in the nucleus accumbens, prefrontal cortex and hypothalamus. These findings confirm the role of the dynorphinergic system in mediating the effects of drugs of abuse, such as 3,4-methylenedioxy-N-methylamphetamine, in various regions of the rat brain, which may be important sites for the opioidergic mechanisms activated by addictive drugs.
[Show abstract][Hide abstract] ABSTRACT: To investigate the role of orphanin FQ/nociceptin (OFQ/N) in epilepsy, we analyzed (a) proOFQ/N (the OFQ/N precursor) and ORL-1 (the OFQ/N receptor) messenger RNA (mRNA) levels in the kainate and in the kindling models of epilepsy in the rat; and (b) seizure expression in proOFQ/N knockout mice.
Epilepsy models: kainate and kindling. Northern blot analysis, radioactive in situ hybridization.
Increased proOFQ/N mRNA levels were found in the thalamus (reticular nucleus) after kainate administration. In contrast, ORL-1 gene expression decreased dramatically in the amygdala, hippocampus, thalamus, and cortex after kainate administration. OFQ/N knockout mice displayed reduced susceptibility to kainate-induced seizures, in that (a) lethality was reduced, (b) latency to generalized seizure onset was significantly prolonged, and (c) behavioral seizure scores were significantly reduced. Furthermore, kindling progression was delayed in OFQ/N-/- mice.
These data indicate that limbic seizures are associated with increased OFQ/N release in multiple brain areas, causing downregulation of ORL-1 receptors and activation of OFQ/N biosynthesis in selected areas, and support the notion that the OFQ/N-ORL-1 system may play a facilitatory role in ictogenesis and in epileptogenesis.
[Show abstract][Hide abstract] ABSTRACT: Male Wistar rats were administered with naloxone (1 mg/kg i.p.) or MR 2266 (5 mg/kg i.p) 15 min before paracetamol (400 mg/kg i.p.) treatment and the pain threshold was evaluated. Rats were subjected to the hot-plate and formalin tests and immunoreactive dynorphin A (ir-dynorphin A) levels were measured in the hypothalamus, hippocampus, striatum, brainstem, frontal and parietal-temporal cortex by radioimmunoassay. Pretreatment with naloxone abolished paracetamol antinociceptive activity both in hot-plate and in the first phase, but not in the second phase of the formalin test, while MR 2266 pretreatment was able to antagonise paracetamol effect either in the hot-plate test or in both phases of the formalin test. Among different brain areas investigated paracetamol significantly decreased ir-dynorphin A levels only in the frontal cortex. MR 2266 but not naloxone reversed the decrease in ir-dynorphin A levels elicited by paracetamol. Paracetamol seems to exert its antinociceptive effect also through the opioidergic system modulating dynorphin release in the central nervous system (CNS) of the rat, as suggested by the decrease in the peptide levels.
[Show abstract][Hide abstract] ABSTRACT: Two 1,2,3,4-tetrahydoquinoline-based compounds were synthesized and evaluated for antinociceptive properties. Both compounds displayed no significant analgesic activity and at the higher dose showed no characterized CNS depressant activity.
[Show abstract][Hide abstract] ABSTRACT: A new derivative of the neuropeptide nociceptin (NC) has recently been developed. This molecule, the pseudopeptide [Phe1psi(CH2-NH)Gly2]-nociceptin(1-13)-NH2 was found to antagonize NC inhibitory effects in peripheral smooth muscle preparations in vitro. However, contrasting results have appeared as regards its pharmacodynamic profile in the CNS. Here, we investigated the pseudopeptide effects, in vivo, on nociceptive responses in the rat. [Phe1psi(CH2-NH)Gly2]-nociceptin(1-13)-NH2 was administered intracerebroventricularly (i.c.v.) or intrathecally (i.t.) (alone or in combination with NC), and tail-flick latencies (TFL) to radiant heat were assessed. I.c.v. [Phe1psi(CH2-NH)Gly2]-nociceptin(1-13)-NH2 (1-10 nmol/rat) caused a short-lasting decrease (5 min) of TFL and did not antagonize the threshold lowering effect of i.c.v. NC (1 nmol/rat). At the spinal level, the i.t. administration (0.2-10 nmol/rat) of [Phe1psi(CH2-NH)Gly2]-nociceptin(1-13)-NH2 produced a dose-dependent and long-lasting antinociceptive effect that was not modified by the administration of a high dose (30 nmol/rat i.t.) of the opioid antagonist naloxone. The i.t. co-administration of the pseudopeptide (10 nmol/rat) did not block the antinociceptive effect of i.t. NC (10 nmol/rat). These data indicate that the pseudopeptide behaves as an NC agonist at supraspinal and spinal levels in the rat tail-flick test of nociception. These different profiles in the periphery and the CNS could suggest differences between central and peripheral NC receptor/s and provide a basis for further development of antagonist molecules suitable for their characterization.
Life Sciences 02/2000; 66(3):257-64. · 2.56 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We studied pronociceptin gene expression following limbic seizures. Northern blot analysis revealed increased pronociceptin mRNA levels in the thalamus (but not in the hippocampus) 3-24 h after kainate administration, with maximal effect (2-fold increase over basal levels) reached at 6 h. No variation in pronociceptin mRNA levels was observed 1-6 h after a stimulus-evoked kindled seizure. Carrageenan failed to affect pronociceptin gene expression in the thalamus, indicating that pain and/or acute stress do not account for kainate effects. In situ hybridization revealed that kainate evokes a dramatic (4-fold) increase in pronociceptin mRNA levels over the thalamic reticular nucleus. Kindled seizures evoked only a small, non-significant increase in pronociceptin gene expression over the dentate gyrus of the hippocampus.
[Show abstract][Hide abstract] ABSTRACT: The opioid peptide dynorphin is thought to be implicated in specific types of seizures. In particular, complex partial seizures have been shown to cause release of dynorphin, activation of prodynorphin gene expression, and new peptide synthesis in the hippocampus. In this study, the kinetics of the seizure-induced changes in prodynorphin mRNA and ir-dynorphin A levels in the hippocampus have been compared with those induced in the temporal and frontal cortex, i.e., in other regions involved in the pathophysiology of complex partial seizures. Experiments have been run using kindling, one of the most valuable models of partial epilepsy. In the hippocampus (1) prodynorphin mRNA levels transiently increase (threefold) 1 h after kindled seizures, and return to baseline by 2 h, and (2) dynorphin A levels are slightly decreased at 1 h, but increase (twofold) at 2 h and return to baseline by 6 h. In the temporal and in the frontal cortex, a late (beginning at 2 h) and prolonged (up to 24 h) decrease in both prodynorphin mRNA and ir-dynorphin A levels have been observed. These data suggest that differential changes in dynorphin metabolism occur in different brain areas after seizures. The mechanisms and functional implications of this observation remain to be investigated.
Journal of Molecular Neuroscience 01/1999; 13(1-2):69-75. · 2.89 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Levels of mRNA for c-fos and prodynorphin were studied by in situ hybridization in adjacent coronal sections taken from kindled rats 30-60 min after the last seizure. Within this time frame, expression of both genes was induced in multiple brain areas. Anatomical colocalization of the induced gene expressions was found in the hippocampus. Induction of c-fos in the dentate gyrus was bilateral and symmetrical in a subgroup of rats, ipsilateral in another subgroup and absent in a third subgroup. However, no relative increase was observed in the ipsilateral compared with the contralateral prodynorphin expression in the dentate gyrus when c-fos expression was induced ipsilaterally only. These observations suggest that, at variance with other experimental situations, Fos is not involved in the mechanisms of kindled seizure-induced activation of prodynorphin transcription in the rat forebrain.
European Journal of Neuroscience 11/1996; 8(10):2064-7. · 3.75 Impact Factor