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Chromatin modification is a crucial mechanism in several important phenomena in the brain, including drug addiction. Persistence of drug craving and risk of relapse could be attributed to drug-induced epigenetic mechanisms that seem to be candidates explaining long-lasting drug-induced behaviour and molecular alterations. Histone acetylation has been proposed to regulate drug-seeking behaviours and the extinction of rewarding memory of drug taking. In this work, we studied the epigenetic regulation during conditioned place aversion and after extinction of aversive memory of opiate withdrawal. Through immunofluorescence assays, we assessed some epigenetic marks (H4K5ac and p-Brd4) in crucial areas related to memory retrieval -basolateral amygdala (BLA) and hippocampus-. Additionally, to test the degree of transcriptional activation, we evaluated the immediate early genes (IEGs) response (Arc, Bdnf, Creb, Egr-1, Fos and Nfkb) and Smarcc1 (chromatin remodeler) through RT-qPCR in these nuclei. Our results showed increased p-Brd4 and H4K5ac levels during aversive memory retrieval, suggesting a more open chromatin state. However, transcriptional activation of these IEGs was not found, therefore suggesting that other secondary response may already be happening. Additionally, Smarcc1 levels were reduced due to morphine chronic administration in BLA and dentate gyrus. The activation markers returned to control levels after the retrieval of aversive memories, revealing a more repressed chromatin state. Taken together, our results show a major role of the tandem H4K5ac/p-Brd4 during the retrieval of aversive memories. These results might be useful to elucidate new molecular targets to improve and develop pharmacological treatments to address addiction and to avoid drug relapse., Competing Interests: Declaration of Competing Interest The authors declare no competing financial interests., (Copyright © 2023 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

Despite their indisputable efficacy for pain management, opiate prescriptions remain highly controversial partially due to their elevated addictive potential. Relapse in drug use is one of the principal problems for addiction treatment, with drug-associated memories being among its main triggers. Consequently, the extinction of these memories has been proposed as a useful therapeutic tool. Hence, by using the conditioned place aversion (CPA) paradigm in rats, we investigated some of the molecular mechanisms that occurr during the retrieval and extinction of morphine withdrawal memories in the basolateral amygdala (BLA) and the hippocampal dentate gyrus (DG), which control emotional and episodic memories, respectively. The retrieval of aversive memories associated with the abstinence syndrome paralleled with decreased mTOR activity and increased Arc and GluN1 expressions in the DG. Additionally, Arc mRNA levels in this nucleus very strongly correlated with the CPA score exhibited by the opiate-treated rats. On the other hand, despite the unaltered mTOR phosphorylation, Arc levels augmented in the BLA. After the extinction test, Arc and GluN1 expressions were raised in both the DG and BLA of the control and morphine-treated animals. Remarkably, Homer1 expression in both areas correlated almost perfectly with the extinction showed by morphine-dependent animals. Moreover, Arc expression in the DG correlated strongly with the extinction of the CPA manifested by the group treated with the opiate. Finally, our results support the coordinated activity of some of these neuroplastic proteins for the extinction of morphine withdrawal memories in a regional-dependent manner. Present data provide evidence of differential expression and activity of synaptic molecules during the retrieval and extinction of aversive memories of opiate withdrawal in the amygdalar and hippocampal regions that will likely permit the development of therapeutic strategies able to minimize relapses induced by morphine withdrawal-associated aversive memories.

Relapse in the seeking and intake of cocaine is one of the main challenges when treating its addiction. Among the triggering factors for the recurrence of cocaine use are the re-exposure to the drug and stressful events. Cocaine relapse engages the activity of memory-related nuclei, such as the basolateral amygdala (BLA) and the hippocampal dentate gyrus (DG), which are responsible for emotional and episodic memories. Moreover, D3 receptor (D3R) antagonists have recently arisen as a potential treatment for preventing drug relapse. Thus, we have assessed the impact of D3R blockade in the expression of some dopaminergic markers and the activity of the mTOR pathway, which is modulated by D3R, in the BLA and DG during the reinstatement of cocaine-induced conditioned place preference (CPP) evoked by drug priming and social stress. Reinstatement of cocaine CPP paralleled an increasing trend in D3R and dopamine transporter (DAT) levels in the BLA. Social stress, but not drug-induced reactivation of cocaine memories, was prevented by systemic administration of SB-277011-A (a selective D3R antagonist), which was able, however, to impede D3R and DAT up-regulation in the BLA during CPP reinstatement evoked by both stress and cocaine. Concomitant with cocaine CPP reactivation, a diminution in mTOR phosphorylation (activation) in the BLA and DG occurred, which was inhibited by D3R blockade in both nuclei before the social stress episode and only in the BLA when CPP reinstatement was provoked by a cocaine prime. Our data, while supporting a main role for D3R signalling in the BLA in the reactivation of cocaine memories evoked by social stress, indicate that different neural circuits and signalling mechanisms might mediate in the reinstatement of cocaine-seeking behaviours depending upon the triggering stimuli.

Alcohol interferes with foetal development and prenatal alcohol exposure can lead to adverse effects known as foetal alcohol spectrum disorders. We aimed to assess the underlying neurobiological mechanisms involved in alcohol intake and withdrawal in adolescent mice exposed to alcohol during early life stages, in discrete brain areas. Pregnant C57BL/6 female mice were exposed to binge alcohol drinking from gestation to weaning. Subsequently, alcohol seeking and taking behaviour were evaluated in male adolescent offspring, as assessed in the two-bottle choice and oral self-administration paradigms. Brain area samples were analysed to quantify AMPAR subunits GluR1/2 and pCREB/CREB expression following alcohol self-administration. We measured the expression of mu and kappa opioid receptors both during acute alcohol withdrawal (assessing anxiety alterations by the EPM test) and following reinstatement in the two-bottle choice paradigm. In addition, alcohol metabolism was analysed by measuring blood alcohol concentrations under an acute dose of 3 g/kg alcohol. Our findings demonstrate that developmental alcohol exposure enhances alcohol intake during adolescence, which is associated with a decrease in the pCREB/CREB ratio in the hippocampus, prefrontal cortex and striatum, while the GluR1/GluR2 ratio showed a decrease in the hippocampus. Moreover, PLAE mice showed behavioural alterations, such as increased anxiety-like responses during acute alcohol withdrawal, and higher BAC levels. No significant changes were identified for mu and kappa opioid receptors mRNA expression. The current study highlights that early alcohol exposed mice increased alcohol consumption during late adolescence. Furthermore, a diminished CREB signalling and glutamatergic neuroplasticity are proposed as underpinning neurobiological mechanisms involved in the sensitivity to alcohol reinforcing properties., Competing Interests: Declaration of Competing Interest The authors declare no conflicts of interest., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Purpose: The main objective was to quantify any potential differences in pharmacokinetic (PK) parameters (AUC and C max ) between RTXM83, a proposed rituximab biosimilar, and its reference product, using a population PK model approach., Methods: Rituximab PK and PD data were obtained from a randomized, double-blind, phase III clinical study (RTXM83-AC-01-11) in patients with diffuse large B-cell lymphoma (DLBCL) that received 375 mg/m 2 intravenous RTXM83 or its reference product with CHOP regimen, every 3 weeks, for six cycles. Rituximab levels were quantified by Meso Scale Discovery assay. PK analysis was performed using NONMEM 7.3.0. The effect of disease and patient covariates on RXTM83 PK was investigated. Model was evaluated using visual predictive check and non-parametric bootstrap., Results: In total, 251 DLBCL patients (127 and 124 in RXTM83-CHOP and rituximab-CHOP arms, respectively) and 5341 serum concentrations (2703 for RXTM83 and 2638 for rituximab, respectively) were available for the population PK analysis. The volume of distribution of the central compartment (V 1 ) and clearance of RXTM83 were estimated at 3.19 L and 12.5 mL/h, respectively. Body surface area allowed to explain the interindividual variability for V 1 . A statistical analysis showed that systemic exposure (AUC and C max ) of RTXM83 was similar to rituximab. The 90% confidence intervals for all pairwise comparisons were within the predefined bioequivalence interval of 0.80-1.25. PD similarity of B-cell depletion and recovery was also observed., Conclusions: The time course of RTXM83 was well characterized by the model developed. The systemic exposure of RTXM83 and its associated variability were similar to those for rituximab reference in DLBCL patients, demonstrating PK similarity. The PD similarity of RTXM83 and rituximab reference product was also demonstrated.

The microtubule-associated protein Tau tends to form aggregates in neurodegenerative disorders referred to as tauopathies. The tauopathy model transgenic (Tg) THY-Tau22 (Tau22) mouse shows disturbed septo-hippocampal transmission, memory deficits and no signs of motor dysfunction. The reports showing a hippocampal downregulation of choline acetyltransferase (ChAT) in SAMP8 mice, a model of aging, and an upregulation of acetylcholinesterase (AChE) in Tg-VLW mice, a model of FTDP17 tauopathy, may lead to think that the supply of ACh to the hippocampus can be threatened as aging or Tau pathology progress. The above was tested by comparing the mRNA levels for ACh-related enzymes in hippocampi of wild-type (wt) and Tau22 mice at ages when the neuropathological signs are debuting (3-4 months), moderate (6-7 months) and extensive (>9 months). Age-matched Tau22 and wt mice hippocampi displayed similar ChAT, AChE-T, butyrylcholinesterase (BChE) and a proline-rich membrane anchor (PRiMA) mRNA levels, any change most likely arising from ACh homeostasis. The unchanged hippocampal levels of AChE-T mRNA and enzyme activity observed in Tau22 mice, expressing G272V-P301S hTau, differed from the increase in AChE-T mRNA and activity observed in Tg-VLW mice, expressing G272V-P301L-R406W hTau. The difference supports the idea that AChE upregulation may proceed or not depending on the particular Tau mutation, which would dictate Tau folding, the accessibility/affinity to kinases and phosphatases, and P-Tau aggregation with itself and protein partners, transcription factors included.

Sleep is indispensable for maintaining regular daily life activities and is of fundamental physiological importance for cognitive performance. Sleep deprivation (SD) may affect learning capacity and the ability to form new memories, particularly with regard to hippocampus-dependent tasks. Transcranial magnetic stimulation (TMS) is a non-invasive procedure of electromagnetic induction that generates electric currents, activating nearby nerve cells in the stimulated cortical area. Several studies have looked into the potential therapeutic use of TMS. The present study was designed to evaluate how TMS could improve learning and memory functions following SD in Octodon degus. Thirty juvenile (18 months old) females were divided into three groups (control, acute, and chronic TMS treatment-with and without SD). TMS-treated groups were placed in plastic cylindrical cages designed to keep them immobile, while receiving head magnetic stimulation. SD was achieved by gently handling the animals to keep them awake during the night. Behavioral tests included radial arm maze (RAM), Barnes maze (BM), and novel object recognition. When TMS treatment was applied over several days, there was significant improvement of cognitive performance after SD, with no side effects. A single TMS session reduced the number of errors for the RAM test and improved latency and reduced errors for the BM test, which both evaluate spatial memory. Moreover, chronic TMS treatment brings about a significant improvement in both spatial and working memories.

The benefits of neuromodulatory procedures as a possible therapeutic application for cognitive rehabilitation have increased with the progress made in non-invasive modes of brain stimulation in aged-related disorders. Transcranial magnetic stimulation (TMS) is a non-invasive method used to examine multiple facets of the human brain and to ameliorate the impairment in cognition caused by Alzheimer's disease (AD). The present study was designed to evaluate how a chronic TMS treatment could improve learning and memory functions after sleep deprivation (SD) in old Octodon degus. SD was executed by gently handling to keep the animals awake throughout the night. Thirty young and twenty-four old O. degus females were divided in six groups (control, acute and chronic TMS treatment). Behavioral tests included; Radial Arm Maze (RAM), Barnes Maze (BM) and Novel Object Recognition (NOR). Although learning and memory functions improved in young animals with only one session of TMS treatment, a significant improvement in cognitive performance was seen in old animals after 4 and 7days of TMS, depending on the task that was performed. No side effects were observed following, which showed therapeutic potential for improving age-related cognitive performance., (Copyright © 2015 Elsevier Inc. All rights reserved.)

For some neurological disorders, disease is primarily RNA mediated due to expression of non-coding microsatellite expansion RNAs (RNA(exp)). Toxicity is thought to result from enhanced binding of proteins to these expansions and depletion from their normal cellular targets. However, experimental evidence for this sequestration model is lacking. Here, we use HITS-CLIP and pre-mRNA processing analysis of human control versus myotonic dystrophy (DM) brains to provide compelling evidence for this RNA toxicity model. MBNL2 binds directly to DM repeat expansions in the brain, resulting in depletion from its normal RNA targets with downstream effects on alternative splicing and polyadenylation. Similar RNA processing defects were detected in Mbnl compound-knockout mice, highlighted by dysregulation of Mapt splicing and fetal tau isoform expression in adults. These results demonstrate that MBNL proteins are directly sequestered by RNA(exp) in the DM brain and introduce a powerful experimental tool to evaluate RNA-mediated toxicity in other expansion diseases., (Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.)

We studied potential changes in the subventricular zone (SVZ) stem cell niche of the senescence-accelerated mouse prone-8 (SAM-P8) aging model. Bromodeoxyuridine (BrdU) assays with longtime survival revealed a lower number of label-retaining stem cells in the SAM-P8 SVZ compared with the SAM-Resistant 1 (SAM-R1) control strain. We also found that in SAM-P8 niche signaling is attenuated and the stem cell pool is less responsive to the self-renewal niche factor pigmented epithelium-derived factor (PEDF). Protein analysis demonstrated stable amounts of the PEDF ligand in the SAM-P8 SVZ niche; however, SAM-P8 stem cells present a significant expression decrease of patatin-like phospholipase domain containing 2, a receptor for PEDF (PNPLA2-PEDF) receptor, but not of laminin receptor (LR), a receptor for PEDF (LR-PEDF) receptor. We observed changes in self-renewal related genes (hairy and enhancer of split 1 (Hes1), hairy and enhancer of split 1 (Hes5), Sox2] and report that although these genes are down-regulated in SAM-P8, differentiation genes (Pax6) are up-regulated and neurogenesis is increased. Finally, sheltering mammalian telomere complexes might be also involved given a down-regulation of telomeric repeat binding factor 1 (Terf1) expression was observed in SAM-P8 at young age periods. Differences between these 2 models, SAM-P8 and SAM-R1 controls, have been previously detected at more advanced ages. We now describe alterations in the PEDF signaling pathway and stem cell self-renewal at a very young age, which could be involved in the premature senescence observed in the SAM-P8 model., (© FASEB.)

The early-onset, irreversible, severe deficits of learning and memory in the senescence-accelerated mouse (SAM)-prone/8 (SAMP8) support its use as an animal model for human dementias of early onset. Possible implication of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) in cognitive dysfunction of SAMP8 mice was studied by comparing cholinesterase (ChE) expression in brains of SAMP8 mice and of their normal control, SAM-resistant/1 (SAMR1) mice. The level of ChE mRNAs was the same in SAMP8 and SAMR1 brains, which agreed with their equal AChE activity (3.09 +/- 1.45 vs. 3.07 +/- 1.44 mumol.hr(-1).mg protein(-1), U/mg), but not with a doubled BuChE activity in SAMP8 brain (0.14 +/- 0.05 vs. 0.07 +/- 0.02 U/mg; P < 0.01). This great increase in neural BuChE activity may contribute to cognitive deficit of SAMP8 mice. Hydrophilic (G(4) (H), 8%) and amphiphilic (G(4) (A), 74%) AChE tetramers, besides dimers and monomers (G(2) (A) + G(1) (A), 18%), were identified in SAMR1 brains. They also contained G(4) (H) BuChE forms (18%) as well as G(4) (A) (53%) and G(2) (A) + G(1) (A) (29%) species. Although SAMP8 brain displayed proportions of AChE and BuChE forms that were similar to those of SAMR1 brain, phenyl-agarose chromatography with detergent-free extracts showed a rise in the proportion of secretory G(4) (H) BuChE from 35% in SAMR1 to 44% in SAMP8 brain. The strong immunolabelling of glial fibrillary acidic protein (GFAP), a marker of reactive gliosis, in SAMP8 brain and the consideration of BuChE as a marker of glial cells suggest a relationship between phenotypic changes in neuroglial cells and the excess of BuChE activity in SAMP8 brain.

In previous reports, we have shown in SH-SY5 cells that olomoucine and roscovitine, two inhibitory drugs of cyclin-dependent kinases, caused apoptosis independent of the extrinsic pathway. In this experimental paradigm, apoptosis was refractory to the protective effects of either Bcl-2 or Bcl-XL overexpression. We are now reporting that the failure of Bcl-XL to prevent dell death was consistent with no effect on the kinetics of caspase activation and cytochrome c release. To further characterize this issue, we have discarded a direct effect of either olomoucine or roscovitine on mitochondrial permeability transition. Moreover, we have evidence that an intrinsic pathway took place in SH-SY5Y cells by showing the mitochondrial translocation of a GFP-Bax construct on transfection and treatment with cyclin-dependent kinase inhibitory drugs. Finally, we tested the effect of olomoucine and roscovitine on wild-type, bax-/-, bak-/-, and double bax-/-bak-/- mouse embryonic fibroblasts (MEF). In wild-type MEFs, both drugs induced cell death by apoptosis in a dose-dependent manner. In bax-/-, bak-/-, and, particularly, double bax-/-bak-/- MEFs, we observed the inhibition of apoptosis. In conclusion, olomoucine and roscovitine caused apoptosis through an intrinsic pathway, with Bax and Bak proteins being involved.

Looking at cholinesterases (ChEs) changes in age-related mental impairment, the expression of ChEs in brain of senescence accelerated-resistant (SAMR1) and senescence accelerated-prone (SAMP8) mice was studied. Acetylcholinesterase (AChE) activity was unmodified and BuChE activity increased twofold in SAMP8 brain. SAMR1 brain contained many AChE-T mRNAs, less BuChE and PRiMA mRNAs and scant AChE-R and AChE-H mRNAs. Their content unchanged in SAMP8 brain. Amphiphilic (G(4)(A)) and hydrophilic (G(4)(H)) AChE and BuChE tetramers, besides amphiphilic dimers (G(2)(A)) and monomers (G(1)(A)) were identified in SAMR1 brain and their distribution was little modified in SAMP8 brain. Blood plasma does not seem to provide the excess of BuChE activity in SAMP8 brain; it probably arises from glial cell changes owing to astrocytosis.

Introduction: Stroke leads the list of causes of disability in adults and represents the second leading cause of death worldwide. Knowledge about the pathophysiology of ischemic stroke has improved substantially over the past 25 years, and, as a result of this, new therapeutic strategies have been developed with two main aims: restoration of cerebral flow and the minimization of the deleterious effects of ischemia on neurons. Although so far there are no drugs approved for the neuroprotection therapy in stroke, there are some compounds with promising results., Development: This paper makes a critical review of several studies on the preclinical stroke neuroprotection with drugs aimed to protect the brain tissue adjacent to the damaged central area or ischemic penumbra zone until either the physiological mechanisms or the treatment stop the ischemic insult. We expose the potential neuroprotective properties of these treatments mainly based on inhibiting excitotoxicity processes mediated by gamma-aminobutyric acid receptors, glutamate release and interacting with ion channels such as calcium and sodium. We focus on drugs which have shown to be capable of modulating intracellular degenerative pathways in mitochondria mediated apoptosis or the expression of apoptotic proteins in experimental models., Conclusion: It is very likely that the neuroprotective effects require a poly-drug therapy that combines different mechanisms of action.

Introduction: During the last decade, the neuroprotective effects of minocycline have been a matter of an intense debate. A broad amount of contradictory studies can be found in the scientific literature, going from neuroprotection to the exacerbation of toxicity in diverse experimental models. Such differences could be the result of minocycline acting on multiple pharmacological targets., Development: In the present review we will go over these pharmacological targets and the effects derived from their modulation by minocycline. Among others, its antioxidant activity derived from its chemical structure or its modulator effect on several enzymes such as nitric oxide synthase will be reviewed. Furthermore, the effects of minocycline on the intracellular pathways implicated in neurodegenerative processes including apoptosis stages, activation decision and execution will be addressed., Conclusions: All the mechanisms described herein have not escaped to a scientific community needed of new therapeutic drugs for the treatment of neurodegenerative conditions. However, the sparse clinical trials carried out so far are mainly aimed at assessing its tolerability and safety or are still in progress. We believe that more studies, both clinical and pre-clinical, should be carried out in order to ascertain the therapeutic window and the neurodegenerative disorders in which minocycline could be useful.

Introduction: In this review we will study the role of protein p53 in neurodegenerative processes and conduct a detailed analysis of the mechanisms responsible for regulating its levels and biological activity. We analyse the neuropathologies in which this protein is involved, such as Alzheimer's and Parkinson's diseases and amyotrophic lateral sclerosis, and we will also examine its regulation by second messengers such as the reactive species of oxygen and calcium, showing the signalling paths involved in the apoptotic processes., Development: The year 2004 sees the 25th anniversary of the discovery of protein p53. At first p53 was wrongly attributed with an oncogenic function due to its capacity to bind to the T antigen of the virus SV40 in transformed cells. Nevertheless, it was not until 1989 that it was attributed with its true physiological function as a tumour-suppressing protein. This milestone constitutes a turning point in the short life of this protein. Protein p53 plays a fundamental role in the mechanisms the cell uses to respond to damage or mutation in the genome. There is, therefore, a correlation between deletions or mutations in the p53 gene and the development of some kinds of cancer; additionally, increases in the protein levels of its native form have been reported in pathologies where apoptotic processes are high., Conclusions: Protein p53 plays an essential role in the mechanisms by which the cell responds to damage or mutation in the genome. It can activate two signalling mechanisms that lead either to stopping the cell cycle or to the death of the cell due to apoptosis if the cell cannot repair the damage to the genome. There is a correlation between its deletions and mutations and the development of cancer, and increases in its native form have been described in pathologies where apoptotic processes are high, as is the case of some neurodegenerative diseases.