Biology subjects

Ambrosio, E.

Publications and source records attributed to Ambrosio, E..

12 recordsLinked to original sources

bioRxiv2026

Exploratory spatial peptidomic profiling during incubation of drug seeking following cocaine plus alcohol self-administration in young adult rats

BackgroundConcurrent cocaine and alcohol use is one of the most prevalent forms of polysubstance consumption and is associated with poorer clinical outcomes than cocaine use alone. However, the regional molecular adaptations induced by combined exposure remain poorly understood. Here, we used matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS) to characterize peptide/protein alterations in addiction-related brain regions following cocaine and cocaine-alcohol self-administration. MethodsYoung adult male and female Wistar rats underwent intravenous self-administration of saline, cocaine (1 mg/kg/infusion) or cocaine plus ethanol (1 mg/kg cocaine and 133 mg/kg ethanol per infusion), followed by extinction of drug-seeking behaviour. Coronal brain sections containing the anterior cingulate cortex (ACC) and ventral hippocampus (vHPC) were analysed by MALDI-IMS. Differential molecular features were identified using an exploratory statistical approach (FDR q < 0.20) and subsequently subjected to MS/MS analysis. ResultsThe ACC exhibited a substantially greater number of treatment-associated molecular alterations than the vHPC, suggesting a higher regional susceptibility to cocaine-induced molecular remodelling. Several molecular features were shared between the cocaine and cocaine-alcohol groups, indicating persistent cocaine-driven neuroadaptations. In contrast, additional signals were selectively associated with combined cocaine-alcohol exposure, while others present after cocaine alone were absent following alcohol co-exposure, supporting a modulatory effect of alcohol on specific cocaine-induced molecular responses. Overall, combined exposure generated a distinct regional molecular profile rather than simply reproducing the effects of cocaine alone. ConclusionsThis exploratory study demonstrates that MALDI-IMS enables the identification of region-specific peptide/protein alterations associated with cocaine and cocaine-alcohol exposure while preserving their spatial distribution within the brain. These findings highlight the ACC as a particularly responsive region and provide a framework for future studies aimed at validating molecular pathways involved in cocaine-alcohol polysubstance use.

neuroscience↗

bioRxiv2026

Maternal immune activation and peripubertal stress differentially disrupt glutamatergic, endocannabinoid, and neuromodulatory signalling in the adult rat dorsal hippocampus: implications for excitatory-inhibitory balance

Disruptions in excitatory-inhibitory (E/I) balance during neurodevelopment have been implicated in a range of psychiatric conditions, yet the neurochemical alterations associated to early-life insults and their potential contribution to E/I imbalance remain poorly understood. Using a "two-hit" rat model combining maternal immune activation (MIA; lipopolysaccharide -LPS- on gestational days 15-16) and peripubertal unpredictable stress (PUS; postnatal days 28-38), we examined the long-term effects of these insults, alone and in combination, on the adult dorsal hippocampus. Assessments included gene and/or protein expression of glutamatergic and GABAergic markers, endocannabinoid system enzymes, neuromodulatory amino acid level and prepulse inhibition (PPI) of the acoustic startle response. MIA increased GluN1 protein expression, while PUS reduced the Grin2a/Grin2b mRNA ratio, indicating incomplete NMDA receptor subunit maturation. GABA levels and GABA-A{gamma}2 expression were unchanged, suggesting deficient inhibitory compensation in the face of heightened excitatory tone. PUS increased Mgll gene expression, whereas a trend towards reduced Dagla expression was observed exclusively in non-stressed LPS-exposed animals, suggesting that MIA may suppress 2-AG synthesis only in the absence of subsequent stress. MIA and PUS displayed interactive effects on taurine levels, with elevation observed only in the double-hit condition; glycine was elevated by MIA independently of PUS. These findings support a model in which MIA and PUS converge on hippocampal E/I balance through complementary adaptations -- excitatory upregulation, incomplete synaptic maturation, and reduced endocannabinoid tone -- inadequately counterbalanced by inhibitory systems. Taurine and glycine emerge as potential markers of homeostatic compensation in response to early neurochemical dysregulation.

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bioRxiv2025

Specific and converging modulation of the CRH and noradrenergic systems across drug classes and natural rewards in an incubation of seeking paradigm

Stress is known to play a critical role in relapse to drug use as well as in food craving. Craving itself is a key determinant of relapse, and cue-induced drug craving has been shown to increase, or incubate, over time for certain drugs such as cocaine and nicotine, though this effect is less consistent for others such as opiates. However, the modulations of stress-related biochemical systems after early or protracted withdrawal that could contribute to this incubation phenomenon have not yet been systematically examined in animal models, nor has the specificity of these mechanisms been tested across different drug classes or reinforcers. To address this gap, we analysed brains from male Lewis rats that self-administered cocaine (0.75 mg/kg, i.v.), heroin (0.075 mg/kg, i.v.), or saline, and subsequently assessed changes in plasma corticosterone, ornithine and other stress-related amines, alongside central gene and protein expression CRH, CRH2 receptor, and - and {beta}-adrenergic receptor subunits -Adra1, Adra2a and Adrb1) in cortico-striato-amygdalar nodes (after 1 or 30 days of withdrawal). A parallel experiment was conducted using sucrose as a reinforcer. Our findings indicate that although most effects were reinforcer-specific, convergent adaptations were also observed, particularly within noradrenergic systems and the basolateral amygdala, expanding our knowledge about the neurochemical rearrangements occurring during withdrawal.

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bioRxiv2024

A hidden mark of a troubled past: neuroimaging and transcriptomic analyses reveal interactive effects of maternal immune activation and adolescent THC exposure in the absence of overt behavioural disruptions

Maternal exposure to infections during gestation has been shown to predispose individuals to the development of schizophrenia. Additionally, clinical data suggest that cannabis use could trigger the onset of schizophrenia in vulnerable individuals. However, the direction of causality remains unclear. To elucidate this issue, we utilised a rat model of maternal immune activation, combined with exposure to increasing doses of THC during adolescence, in both male and female rats. We investigated several behaviours in adulthood that resemble specific symptoms of schizophrenia, including impairments in working memory, deficits in sensorimotor gating, alterations in social behaviour, anhedonia, and potential changes in implicit learning (conditioned taste aversion). Furthermore, we conducted a longitudinal positron emission tomography (PET) study to identify affected brain regions and subsequently collected brain samples from one of these regions (the orbitofrontal cortex) for RNA sequencing analyses. These analyses were also performed on peripheral blood mononuclear cells to identify peripheral biomarkers. Notably, while no overt behavioural disruptions were observed, our PET scans revealed several brain alterations dependent on the combination of both exposures. Additionally, the transcriptomic studies demonstrated that maternal immune activation affected glutamatergic and serotoninergic genes, with the combination of both exposures shifting the expression from down-regulation to up-regulation. In peripheral cells, interactive effects were observed on inflammatory pathways, and some genes were proposed as biomarkers of the disease. These results suggest that the combination of these two vulnerability factors leaves a lasting mark on the body, potentially predisposing individuals to the disease even before behavioural alterations manifest.

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bioRxiv2023

LACK OF INTERACTIONS BETWEEN PRENATAL IMMUNE ACTIVATION AND delta9-TETRAHYDROCANNABINOL EXPOSURE DURING ADOLESCENCE IN BEHAVIOURS RELEVANT TO SYMPTOM DIMENSIONS OF SCHIZOPHRENIA IN RATS

The causality in the association between cannabis use and the risk of developing schizophrenia has been the subject of intense debate in the last years. The development of animal models recapitulating several aspects of the disease is crucial for shedding light on this issue. Maternal infections are a known risk for schizophrenia. Here, we used the maternal immune activation (MIA) model combined with THC exposure during adolescence to examine several behaviours in rats (working memory in the Y maze, sociability in the three-chamber test, sucrose preference as a measure, prepulse inhibition and formation of incidental associations) that are similar to the different symptom clusters of the disease. To this end, we administered LPS to pregnant dams and when the offspring reached adolescence, we exposed them to a mild dose of THC to examine their behaviour in adulthood. We also studied several parameters in the dams, including locomotor activity in the open field, elevated plus maze performance and their response to LPS, that could predict symptom severity of the offspring, but found no evidence of any predictive value of these variables. In the adult offspring, MIA was associated with impaired working memory and sensorimotor gating, but surprisingly, it increased sociability, social novelty and sucrose preference. THC, on its own, impaired sociability and social memory, but there were no interactions between MIA and THC exposure. These results suggest that, in this model, THC during adolescence does not trigger or aggravate symptoms related to schizophrenia in rats.

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bioRxiv2021

Additive, synergic and antagonistic interactions between maternal immune activation and peripubertal stress in cocaine addiction-like behaviour, morphofunctional brain parameters and striatal transcriptome.

Substance use disorders are more prevalent in schizophrenia, worsening its course and prognosis. Here, we used a double-hit rat model, combining maternal immune activation (MIA) and peripubertal stress (PUS), to study cocaine addiction and the underlying neurobehavioural alterations. We injected lipopolysaccharide or saline on gestational days 15 and 16 to pregnant rats. Their male offspring were then subjected to 5 episodes of unpredictable stress every other day during adolescence (from postnatal day 28 to 38). When rats reached adulthood, we studied cocaine addiction-like behaviour, impulsivity, conditioning processes and several aspects of brain structure and function by MRI, PET and RNAseq. MIA facilitated the acquisition of cocaine self-administration while PUS reduced cocaine intake, an effect that was reversed by MIA. MIA increased motivation for cocaine and reversed the effects of PUS during extended access. Incubation of seeking was unaffected. Neither hit alone nor their combination impacted Pavlovian or instrumental conditioning or impulsiveness. At the brain level, PUS reduced hippocampal volume and hyperactivated the dorsal subiculum. MIA+PUS altered the structure and function of the dorsal striatum increasing its volume and interfering with glutamatergic dynamics. MIA did not affect the gene expression of the nucleus accumbens but, when combined with PUS, modulated specific genes that could account for the restored cocaine intake. PUS had a profound effect on the dorsal striatal transcriptome however, this was obliterated when PUS occurred in animals with MIA. These results describe a complex interplay between MIA and stress on neurodevelopment and in the susceptibility to develop cocaine addiction.

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bioRxiv2020

Testing The Role Of Δ9-Tetrahydrocannabinol During Adolescence As A Gateway Drug: Behavioural, Brain Imaging And Transcriptomic Studies

Cannabis is widely consumed by adolescents, and is also a potential prior step leading to the use of other drugs later in life (Gateway Hypothesis); however, the evidence for this hypothesis is controversial. This work aimed to increase our understanding of the long-term consequences of adolescent exposure to {Delta}9-tetrahydrocannabinol (THC) and to test the Gateway Hypothesis, experimentally. We exposed rats of both sexes to THC and studied its effects on reward-related processes, brain morphology (MRI), metabolism (1H-MRS), function (PET) and the transcriptomic profiles of the nucleus accumbens (RNASeq). Lastly, we studied cocaine-induced cellular activation (c-Fos) and cocaine addiction-like behaviours. THC exposure increased Pavlovian to instrumental transfer in males, goal-tracking (regardless of the sex) and impulsivity, but did not affect habit formation. Adolescent THC reduced striatal volume (in females), commissural integrity and ventricular volume. Also, there were lower levels of choline compounds in the cortex of THC-exposed rats and cerebellar hypoactivation in THC-females. THC also modified some of the gene expression programs of the nucleus accumbens, which could contribute to the behavioural features observed. Lastly, THC exposure increased cocaine-induced c-Fos levels in cortical and hypothalamic areas and increased the motivation for cocaine, followed by a higher rebound of use in THC-females after reestablishing low-effort conditions. Critically, acquisition of cocaine self-administration, compulsive seeking, intake under extended access or the incubation of seeking were unaltered. These results suggest that adolescent THC exposure alters psychological and brain development and that the Gateway Hypothesis does not entirely pass the test of preclinical enquiry.

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bioRxiv2020

3D SYNAPTIC ORGANIZATION OF THE RAT CA1 AND ALTERATIONS INDUCED BY COCAINE SELF-ADMINISTRATION

The hippocampus plays a key role in contextual conditioning and has been proposed as an important component of the cocaine addiction brain circuit. To gain knowledge about cocaine-induced alterations in this circuit, we used Focused Ion Beam milling/Scanning Electron Microscopy (FIB/SEM) to reveal and quantify the 3D synaptic organization of the stratum radiatum of rat CA1, under normal circumstances and after cocaine-self administration (SA). Most synapses are asymmetric (excitatory), macular-shaped, and in contact with spine heads. After cocaine-SA, the size and complexity of both asymmetric and symmetric (inhibitory) synapses increased but no changes were observed in the synaptic density. This work constitutes the first detailed report on the 3D synaptic organization in the stratum radiatum of the CA1 field of cocaine-SA rats. Our data contribute to the elucidation of the normal and altered synaptic organization of the hippocampus, which is crucial for better understanding the neurobiological mechanisms underlying cocaine addiction.

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bioRxiv2020

Comparative analysis of the modulation of perineuronal nets in the prefrontal cortex of rats during protracted withdrawal from cocaine, heroin and sucrose self-administration

Relapse into drug use is a significant problem for people recovering from addiction. The ability that conditioned cues have to reinstate and reinvigorate drug-seeking is potentiated over time (incubation of seeking), posing an additional difficulty for maintaining abstinence. While the prefrontal cortex has been involved in the incubation phenomenon and the extracellular matrix, perineuronal nets (PNN) in particular, may play a vital role in brain plasticity associated to drug relapse, there are no comparative analyses between different drug classes and natural reinforcers. Here, we compare the effects of early (1 day) and protracted (30 days) withdrawal from to cocaine, heroin and sucrose self-administration on the PNN content of different territories of the prefrontal cortex of male Lewis rats. Our results show that cocaine self-administration and protracted withdrawal decreased PNN content in the prelimbic cortex. Also, heroin self-administration increased PNN content in the infralimbic cortex, but this effect was lost after 30 days of withdrawal. Heroin self-administration also decreased PNNs in the insula, an effect that remained even after protracted withdrawal from the drug. Finally, the self-administration of sucrose-sweetened water decreased PNN content in the dorsomedial prefrontal cortex and increased PNNs in the insular cortex, which was still evident after protracted withdrawal. Our results show that three different rewards with specific pharmacological and physiological actions differentially modulate PNNs in specific areas of the rodent prefrontal cortex with potential implications for the incubation of seeking phenomenon.

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bioRxiv2019

Maternal immune activation in rats is associated with a lower number of dopamine receptor 3-expressing granulocytes in the male offspring with no alterations in cocaine reward, resistance to extinction or cue-induced reinstatement

There is evidence for increased rates of drug use among schizophrenic patients. However, the causality in this relationship remains unclear. In addition, biomarkers of schizophrenia are vital, given the heterogeneous nature of the disorder that can lead to difficulties in the early diagnosis. In the present work, we use a maternal immune activation model to experimentally test whether animals at high risk of developing a schizophrenia-like condition are more prone to acquire cocaine self-administration, show enhanced sensitivity to the reinforcing actions of cocaine or if they are resistant to extinction or vulnerable to relapse. Pregnant rats were injected with lipopolysaccharide (LPS) (2 mg/kg s.c.) or saline every other day during pregnancy, and the offspring was tested for sensorimotor gating (prepulse inhibition -PPI-). After this test, one group of rats was submitted to cocaine self-administration (0.5 mg/kg) under fixed and progressive ratio schedules, dose-response testing, extinction and cue-induced drug-seeking. Another group was sacrificed to study potential biomarkers in the immune blood cells by flow cytometry. While rats born to LPS-treated mothers showed impaired PPI, there were no differences in cocaine self-administration acquisition, responsiveness to dose shifts, extinction or cue-induced reinstatement. Finally, there were fewer DRD3+ granulocytes in the LPS-offspring and an exciting trend for CNR2+ lymphocytes to be more abundant in LPS-exposed rats. Our results indicate that the higher prevalence of cocaine abuse among people with schizophrenia is not due to a pre-existing pathology and suggest that DRD3+ granulocytes and possibly CNR2+ lymphocytes could be potential biomarkers of schizophrenia.

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bioRxiv2019

Ex vivo 1H-MRS brain metabolic profiling in a two-hit model of schizophrenia-related alterations: effects of prenatal immune activation and peripubertal stress.

Prenatal infections are environmental risk factors for neurodevelopmental disorders. In addition, traumatic experiences during adolescence in individuals exposed to infections during gestation could increase the risk of schizophrenia. Given the tremendous burden that these diseases pose on societies when they fully manifest, it is of the most crucial importance to discover potential markers of the disease in its early stages or even before its onset, so that therapeutic strategies may be implemented. In the present study, we combined a well-characterized two-hit model of schizophrenia-related symptoms with proton magnetic resonance spectroscopy to discover potential biomarkers. To this end, we i.p. injected 100 g/kg/ml of lipopolysaccharide (LPS) or saline on gestational days 15 and 16 to pregnant rats. Their male offspring were then subjected to five episodes of stress or handling on alternate days during postnatal days (PND) 28 to 38. Once the animals reached adulthood (PND70), we evaluated prepulse inhibition (PPI). At PND90, we performed an ex vivo proton magnetic resonance spectroscopy study in the cortex and striatum. While we did not detect alterations in PPI at the age tested, we found neurochemical disturbances induced by LPS, stress or (more interestingly) their interaction. LPS decreased glucose levels in the cortex and striatum and altered glutamate, glutamine and N-acetylaspartate levels. Glutamate and glutamine levels in the left (but not right) striatum were differentially affected by prenatal LPS exposure in a manner that depended on stress experiences. These results suggest that alterations in the glutamate cycle in the striatum may predate the full emergence of disorders of the schizophrenic spectrum and could be used as early markers of the disease.

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bioRxiv2018

Modulation of the mTOR pathway in male Lewis rats after morphine self-administration and subsequent extinction training

Addiction is a chronic disorder with an elevated risk of relapse, even after long periods of abstinence. Some of the neural mechanisms mediating addictions require protein synthesis, which could be relevant for the development of more effective treatments. The mTOR signaling pathway regulates protein synthesis processes that have recently been linked to the development of drug addiction. Thus, we have assessed the effects of morphine self-administration and its subsequent extinction on the expression of several genes that act in this pathway, and on the levels of some phosphoproteins in three brain areas related to reward learning and extinction: the amygdala, the nucleus accumbens, and the prefrontal cortex. We found an increase in Raptor and Eif4ebp2 gene expression in the amygdala of rats that self-administered morphine, and this persisted beyond the extinction period. The expression of Insr in the amygdala of control animals decreased over time while the opposite effect was seen in the rats that self-administered morphine. We also found a strong correlation between some of the biochemical variables measured and behavioral traits, suggesting a significant role for the genes and phosphoproteins identified, mostly in the amygdala, in the behavioral effects of morphine.

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