Enhancing adult hippocampal neurogenesis with lysophosphatidic acid: a proposal for erasing cocaine contextual memory

Stimulating adult hippocampal neurogenesis (AHN) has been uncovered as a promising approach in the manipulation of retrograde memories. This work aims to study whether increasing AHN with lysophosphatidic acid (LPA, an endogenous lysophospholipid with proneurogenic actions) promotes the forgetting of previously established cocaine-contextual associations. C57BL/6J mice previously trained in a cocaine-induced conditioned place preference (CPP) paradigm were submitted to 23 days of withdrawal, during which they received repeated intracerebroventricular infusions of LPA, ki16425 (a selective LPA1/3 receptors antagonist), or vehicle solution. Then, CPP maintenance was assessed, and the causal role of AHN in this process was evaluated using a mediation analysis. In a complementary experiment, wild-type and LPA1-null mice were acutely infused with LPA or ki16425 to determine the involvement of the LPA1 receptor in the in vivo proneurogenic actions of LPA. The chronic LPA treatment significantly weakened the long-term retention of a previously acquired cocaine-CPP memory, an effect clearly mediated by a LPA-induced increase in the number of adult-born dentate granule cells. In contrast, the ki16425-treated mice displayed aberrant responses of initially decreased CPP retention that progressively increased CPP across the extinction sessions, in absence of effects on AHN. The histological studies suggested that the proneurogenic actions of LPA were related to the enhancement of cell proliferation and critically depended on the LPA1 receptor function. Our results suggest that the LPA/LPA1-pathway acts as a potent in vivo modulator of AHN, and highlight the usefulness of a post-learning increase of adult-born hippocampal neurons as a strategy to promote the forgetting of cocaine-context associations.Plan Propio de Investigación y Transferencia. Campus de Excelencia Internacional Andalucía Tech. Spanish Ministry of Economy and Competitiveness (Agencia Estatal de Investigación), co‐funded by the European Research Development Fund (AEI/FEDER, UE) (PSI2013‐44901‐P and PSI2017‐82604‐R to L.J.S. and PSI2015‐73156‐JIN to E.C.O.); by the National System of Health‐Instituto de Salud Carlos III, which is co‐funded by AEI/FEDER, UE (Red de Trastornos Adictivos; RD16/0017/0001 to F.R.d.F.); and by the Andalusian R&D&I Programme, Regional Ministry of Economy and Knowledge (PAIDI CTS643 to G.E.T.). D.L.G.M. hold a FPU grant from the Spanish Ministry of Education, Culture and Sports (FPU13/04819 ). F.R.d.F. and G.E.T. are supported by Nicolas Monardes Programme, from the Andalusian Regional Ministry of Health. E.C.O. holds a ‘Jóvenes Investigadores’ grant (code: PSI2015‐73156‐JIN) from the Spanish Ministry of Economy and Competitiveness (Agencia Estatal de Investigación), which is co‐funded by the AEI/FEDER, UE

Role of the LPA1 receptor in mood and emotional regulation

Depression is a debilitating psychiatric condition characterized by anhedonia and behavioural despair among others symptoms. Despite the high prevalence and devastating impact of depression, underlying neurobiological mechanisms of mood disorders are still not well known. Regardless its complexity, central features of this disease can be modelled in rodents in order to better understand the potential mechanisms underlying. On the other hand, the lack of LPA1 receptor compromises the morphological and functional integrity of the limbic circuit and the neurogenesis in hippocampus, induces cognitive alterations on hippocampal-dependent tasks and dysfunctional coping of chronic stress, provokes exaggerated endocrine responses to emotional stimuli and impairs adaptation of the hypothalamic-pituitary-adrenal axis after chronic stress. Factors, which all have been related with depression. Here, we sought to establish the involvement of the LPA1 receptor in regulation of mood and emotion. To this end, in wild-type and maLPA1-null mice active coping responses to stress were examined using the forced swimming test (FST). To assess hedonic behaviour saccharine preference test and female urine sniffing test were used. Our data indicated that the absence of the LPA1 receptor significantly affected to coping strategies. Thus, while null mice displayed less immobility than wt in FST, exhibited more climbing and less swimming behaviour, responses that could be interpreted as an emotional over-reaction (i.e., a panic-like response) to stress situations. Concerning hedonic behaviour, the lack of the LPA1 receptor diminished saccharin preference and female urine sniffing time. Overall, these data supports the role of LPA1 receptor in mood and emotional regulation. Specially, the lack of this receptor induced emotional dysregulation and anhedonic behaviour, a core symptom of depression.Universidad de Málaga, Campus de Excelencia Andalucía Tech. Andalusian Regional Ministries of Economy, Innovation, Science and Employment (SEJ-1863; CTS643) and of Health (PI-0234-2013; Nicolas Monardes Programme), MINECO (PSI2013-44901-P) and National Institute of Health Carlos III (Sara Borrel)

Vitamin B12 effects on chlorinated methanes-degrading microcosms: Dual isotope and metabolically active microbial populations assessment

Field-derived anoxic microcosms were used to characterize chloroform (CF) and carbon tetrachloride (CT) natural attenuation to compare it with biostimulation scenarios in which vitamin B12 was added (B12/pollutant ratio of 0.01 and 0.1) by means of by-products, carbon and chlorine compound-specific stable-isotope analysis, and the active microbial community through 16S rRNA MiSeq high-throughput sequencing. Autoclaved slurry controls discarded abiotic degradation processes. B12 catalyzed CF and CT biodegradation without the accumulation of dichloromethane, carbon disulphide, or CF. The carbon isotopic fractionation value of CF (ƐCCF) with B12 was − 14 ± 4 , and the value for chlorine (ƐClCF) was − 2.4 ± 0.4 . The carbon isotopic fractionation values of CT (ƐCCT) were − 16 ± 6 with B12, and − 13 ± 2 without B12; and the chlorine isotopic fractionation values of CT (ƐClCT) were − 6 ± 3 and − 4 ± 2 , respectively. Acidovorax, Ancylobacter, and Pseudomonas were the most metabolically active genera, whereas Dehalobacter and Desulfitobacterium were below 0.1% of relative abundance. The dual C-Cl element isotope slope (Λ = Δδ13C/Δδ37Cl) for CF biodegradation (only detected with B12, 7 ± 1) was similar to that reported for CF reduction by Fe(0) (8 ± 2). Several reductive pathways might be competing in the tested CT scenarios, as evidenced by the lack of CF accumulation when B12 was added, which might be linked to a major activity of Pseudomonas stutzeri; by different chlorine apparent kinetic isotope effect values and Λ which was statistically different with and without B12 (5 ± 1 vs 6.1 ± 0.5), respectively. Thus, positive B12 effects such as CT and CF degradation catalyst were quantified for the first time in isotopic terms, and confirmed with the major activity of species potentially capable of their degradation. Moreover, the indirect benefits of B12 on the degradation of chlorinated ethenes were proved, creating a basis for remediation strategies in multi-contaminant polluted sites

Unravelling long-term source removal effects and chlorinated methanes natural attenuation processes by C and Cl stable isotopic patterns at a complex field site

The effects of contaminant sources removal in 2005 (i.e. barrels, tank, pit and wastewater pipe sources) on carbon tetrachloride (CT) and chloroform (CF) concentration in groundwater were assessed at several areas of a fractured multi-contaminant aquifer (Òdena, Spain) over a long-term period (2010-2014). Changes in redox conditions, in these chlorinated methanes (CMs) concentration and in their carbon isotopic compositions (δ13C) were monitored in multilevel wells. δ13C values from these wells were compared to those obtained from sources (barrels, tank and pit before their removal, 2002-2005) and to commercial solvents values in literature. Additionally, CMs natural attenuation processes were identified by C-Cl isotope slopes (Λ). Analyses revealed the downstream migration of the pollutant focus and an efficient removal of DNAPLs in the pit source's influence area. However, the removal of the contaminated soil from former tank and wastewater pipe was incomplete as leaching from unsaturated zone was proved, evidencing these areas are still active sources. Nevertheless, significant CMs degradation was detected close to all sources and Λ values pointed to different reactions. For CT in the tank area, Λ value fitted with hydrogenolysis pathway although other possible reduction processes were also uncovered. Near the wastewater pipe area, CT thiolytic reduction combined with hydrogenolysis was derived. The highest CT degradation extent accounted for these areas was 72 ± 11% and 84 ± 6%, respectively. For CF, the Λ value in the pit source's area was consistent with oxidation and/or with transport of CF affected by alkaline hydrolysis from upstream interception trenches. In contrast, isotope data evidenced CF reduction in the tank and wastewater pipe influence areas, although the observed Λ slightly deviates from the reference values, likely due to the continuous leaching of CF degraded in the non-saturated zone by a mechanism different from reduction

Dual element (C-Cl) isotope approach to distinguish abiotic reactions of chlorinated methanes by Fe(0) and by Fe(II) on iron minerals at neutral and alkaline pH

A dual element CCl isotopic study was performed for assessing chlorinated methanes (CMs) abiotic transformation reactions mediated by iron minerals and Fe(0) to further distinguish them in natural attenuation monitoring or when applying remediation strategies in polluted sites. Isotope fractionation was investigated during carbon tetrachloride (CT) and chloroform (CF) degradation in anoxic batch experiments with Fe(0), with FeCl2(aq), and with Fe-bearing minerals (magnetite, Mag and pyrite, Py) amended with FeCl2(aq), at two different pH values (7 and 12) representative of field and remediation conditions. At pH 7, only CT batches with Fe(0) and Py underwent degradation and CF accumulation evidenced hydrogenolysis. With Py, thiolytic reduction was revealed by CS2 yield and is a likely reason for different Λ value (Δδ13C/Δδ37Cl) comparing with Fe(0) experiments at pH 7 (2.9 ± 0.5 and 6.1 ± 0.5, respectively). At pH 12, all CT experiments showed degradation to CF, again with significant differences in Λ values between Fe(0) (5.8 ± 0.4) and Fe-bearing minerals (Mag, 2 ± 1, and Py, 3.7 ± 0.9), probably evidencing other parallel pathways (hydrolytic and thiolytic reduction). Variation of pH did not significantly affect the Λ values of CT degradation by Fe(0) nor Py. CF degradation by Fe(0) at pH 12 showed a Λ (8 ± 1) similar to that reported at pH 7 (8 ± 2), suggesting CF hydrogenolysis as the main reaction and that CF alkaline hydrolysis (13.0 ± 0.8) was negligible. Our data establish a base for discerning the predominant or combined pathways of CMs natural attenuation or for assessing the effectiveness of remediation strategies using recycled minerals or Fe(0)

Carbon and chlorine isotope fractionation patterns associated with different engineered chloroform transformation reactions

To use compound-specific isotope analysis for confidently assessing organic contaminant attenuation in the environment, isotope fractionation patterns associated with different transformation mechanisms must first be explored in laboratory experiments. To deliver this information for the common groundwater contaminant chloroform (CF), this study investigated for the first time both carbon and chlorine isotope fractionation for three different engineered reactions: oxidative C-H bond cleavage using heat-activated persulfate, transformation under alkaline conditions (pH ∼ 12) and reductive C-Cl bond cleavage by cast zerovalent iron, Fe(0). Carbon and chlorine isotope fractionation values were −8 ± 1 and −0.44 ± 0.06 for oxidation, −57 ± 5 and −4.4 ± 0.4 for alkaline hydrolysis (pH 11.84 ± 0.03), and −33 ± 11 and −3 ± 1 for dechlorination, respectively. Carbon and chlorine apparent kinetic isotope effects (AKIEs) were in general agreement with expected mechanisms (C-H bond cleavage in oxidation by persulfate, C-Cl bond cleavage in Fe(0)-mediated reductive dechlorination and E1CB elimination mechanism during alkaline hydrolysis) where a secondary AKIECl (1.00045 ± 0.00004) was observed for oxidation. The different dual carbon-chlorine (Δδ13C vs Δδ37Cl) isotope patterns for oxidation by thermally activated persulfate and alkaline hydrolysis (17 ± 2 and 13.0 ± 0.8, respectively) vs reductive dechlorination by Fe(0) (8 ± 2) establish a base to identify and quantify these CF degradation mechanisms in the field

More adult-born dentate gyrus neurons to weaken cocaine-related retrograde memories: an in vivo strategy employing exogenous lysophosphatidic acid

The post-training enhancement of adult hippocampal neurogenesis (AHN) has been receiving growing interest as a potential method to manipulate retrograde memories. Recent hypothesis suggest that the addition of adult-born dentate granule cells might promotes remodeling of pre-existing hippocampal circuits, which might both clear cocaine-related memories and facilitate the learning of new adaptive information. Here, we study the effect of stimulating AHN in vivo with exogenous lysophosphatidic acid (LPA) on the maintenance of retrograde cocaine-contextual associative memories. Male C57BL/6J mice trained in a cocaine-induced Conditioned Place Preference (CPP) model were later submitted to repeated intracerebroventricular (i.c.v.) injections of LPA, Ki16425 or vehicle solution during withdrawal. Afterwards, the long-term persistence of the cocaine-CPP was assessed and the mediational role of AHN in this process was evaluated. In addition, wild-type and mice lacking the LPA1 receptor received a single i.c.v. injection of LPA, Ki16425 or vehicle to assess the role of the LPA1 receptor in the LPA-induced increase of AHN. Our results revealed that the chronic administration of LPA decreased the retention of a previously acquired cocaine-induced CPP. This effect was mediated by an LPA-induced increase of AHN. In contrast, mice treated with Ki16425 showed reduced cocaine-CPP retention, but they increased their preference for the cocaine-paired compartment throughout CPP extinction. Besides, no effects of Ki16425 on AHN were found. Immunohistochemical studies suggested that LPA stimulated cell proliferation and promoted neuronal maturation with a key role of the LPA1 receptor. These findings emphasize the relevance of LPA and its LPA1 receptor as an in vivo modulator of AHN and the utility of the post-training increase of adult-born hippocampal neurons to weaken cocaine-context associations.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Lysophosphatidic acid-induced increase in adult hippocampal neurogenesis facilitates the forgetting of cocaine-contextual memory

Author manuscriptErasing memories of cocaine-stimuli associations might have important clinical implications for addiction therapy. Stimulating hippocampal plasticity by enhancing adult hippocampal neurogenesis (AHN) is a promising strategy because the addition of new neurons may not only facilitate new learning but also modify previous connections and weaken retrograde memories. To investigate whether increasing AHN prompted the forgetting of previous contextual cocaine associations, mice trained in a cocaine-induced conditioned place preference (CPP) paradigm were administered chronic intracerebroventricular infusions of lysophosphatidic acid (LPA, an endogenous lysophospholipid with pro-neurogenic actions), ki16425 (a LPA1/3 receptor antagonist), or a vehicle solution, and they were tested 23 days later for CPP retention and extinction. The results of immunohistochemical experiments showed that the LPA-treated mice exhibited reduced long-term CPP retention and an ~two-fold increase in the number of adult-born hippocampal cells that differentiated into mature neurons. Importantly, mediation analyses confirmed a causal role of AHN in reducing CPP maintenance. In contrast, the ki16425-treated mice displayed aberrant responses, with initially decreased CPP retention that progressively increased across the extinction sessions, leading to no effect on AHN. The pharmacological treatments did not affect locomotion or general exploratory or anxiety-like responses. In a second experiment, normal and LPA1 receptor-deficient mice were acutely infused with LPA, which revealed that LPA1-mediated signaling was required for LPA-induced proliferative actions. These results suggest that the LPA/LPA1-pathway acts as a potent in vivo modulator of AHN and highlight the potential usefulness of pro-AHN strategies to treat aberrant cognition in those addicted to cocaine.This study was funded by grants from the Spanish Ministry of Economy and Competitiveness (Agencia Estatal de Investigación), which is cofunded by the European Research Development Fund AEI/FEDER, UE- (PSI2013-44901-P and PSI2017-82604-R to LJS and PSI2015-73156-JIN to ECO); by the National System of Health-Instituto de Salud Carlos III, which is co-funded by AEI/FEDER, UE (Red de Trastornos Adictivos; RD16/0017/0001 to FRdF); and by the Andalusian R&D&I Programme, Regional Ministry of Economy and Knowledge (PAIDI CTS643 to GET). DLGM and RDMF hold FPU grants from the Spanish Ministry of Education, Culture and Sports (FPU13/04819 and FPU14-01610, respectively). CRV received a ‘Plan Propio’ grant from the University of Malaga. FJP and AS hold ‘Miguel Servet’ grants (CP14/00212 and CP14/00173, respectively) from the National System of Health-Instituto de Salud Carlos III, which is co-funded by AEI/FEDER, UE. FRdF and GET are supported by Nicolas Monardes Programme, from the Andalusian Regional Ministry of Health. ECO holds a ‘Jóvenes Investigadores’ grant (code: PSI2015- 73156-JIN) from the Spanish Ministry of Economy and Competitiveness (Agencia Estatal de Investigación) which is co-funded by the European Research Development Fund (AEI/FEDER, UE)

The absence of LPA1 receptor results in lipidome dysregulation and Neuropeptide-Y underexpression

LPA1 receptor is one of the six characterized G protein-coupled receptors (LPA1-6) through which lysophosphatidic acid acts as an intercellular signaling molecule. It has been shown that the LPA1 receptor is involved in emotional regulation and, when depleted, has a key role in vulnerability to stress. In this sense, maLPA1-null mice, a knockout model for LPA1 receptor has been recently proposed as a model of anxious depression. Here, we sought to elucidate the effect of the genetic depletion of this receptor of LPA1 receptor in both lipidome and Neuropeptide-Y (NPY) signaling, two factors associated with adaptive stress regulation. For that purpose, we measured the lipidomic profile of wild-type mice and maLPA1-null mice in both hippocampus and serum. In addition, through immunohistochemical procedures we quantified NPY+ cells in hippocampus, basolateral amygdala (BLA) and central amygdala (CeA). Interestingly, the comparative lipidomics analysis revealed differences in certain subspecies which are related to LPA1 receptor functionality. Regarding NPY, we found a reduction in BLA, but not in hippocampus. Overall, both lipid abnormalities and amygdalar dysfunction of NPY can be related to lower resources in stress coping and, in turn, higher vulnerability to the noxious effect of stress that might lead to anxiety and depressive-like states.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Absence of LPA1 receptor results in altered pattern of limbic activation after tail suspension test

Stress serves as an adaptive mechanism and helps organisms to cope with life-threatening situations. However, individual vulnerability to stress and dysregulation of this system may precipitate stress-related disorders such as depression. The neurobiological circuitry in charge of dealing with stressors has been widely studied in animal models. Recently our group has demonstrated a role for lysophosphatidic acid (LPA) through the LPA1 receptor in vulnerability to stress, in particular the lack of this receptor relates to robust decrease of adult hippocampal neurogenesis and induction of anxious and depressive states. Nevertheless, the specific abnormalities in the limbic circuit in reaction to stress remains unclear. The aim of this study is to examine the differences in the brain activation pattern in the presence or absence of LPA1 receptor after acute stress. For this purpose, we have studied the response of maLPA1-null male mice and normal wild type mice to an intense stressor: Tail Suspension Test. Activation induced by behaviour of brain regions involved in mood regulation was analysed by stereological quantification of c-Fos immunoreactive positive cells. We also conducted multidimensional scaling analysis in order to unravel coativation between structures. Our results revealed hyperactivity of stress-related structures such as amygdala and paraventricular nucleus of the hypothalamus in the knockout model and different patterns of coactivation in both genotypes using a multidimensional map. This data provides further evidence to the engagement of the LPA1 receptors in stress regulation and sheds light on different neural pathways under normal and vulnerability conditions that can lead to mood disorders.Universidad de Malaga, Campus de Excelencia internacional Andalucía Tech. Andalusian Ministry of Economy, Innovation, Science and Employment (SEJ1863); Postdoctoral Fellowship ‘Sara Borrell’ of the National Institute of Health Carlos III E. C.; Grant of the Andalusian Ministry of Economy, Innovation , Science and Employment C. R. (FPDI 2010). Grant of the Spanish Ministry of Education, Culture and Sport s (FPU14/01610)