Biology subjects

Tanti, A.

Publications and source records attributed to Tanti, A..

6 recordsLinked to original sources

bioRxiv2025

Disruption of emotional processing by GBR 12909 in male and female mice highlights novel behavioral paradigms relevant to bipolar disorders.

Bipolar disorders (BD) are defined by a chronic recurrence of manic and depressive phases. Along with mood, acute phases are associated with altered emotions. The biological underpinnings of these changes are unresolved, mostly because modeling the cycling nature of BD is still a major challenge in preclinical studies. One model is based on GBR 12909 administration, a dopamine transporter inhibitor aiming at mimicking some dimensions of mania. It has recently been shown that this model generates a mixed phenotype with negative hedonic biases and anxiety along with hyperlocomotion. These studies have been only performed in male animals, and other behavioral dimensions relevant for BD remain to be explored, in particular recognition of conspecifics emotions and reactivity to danger. The objective of this study is to further characterize the GBR model in both sexes by introducing two novel behavioral assays, the sweeping/looming disk and the negative emotion recognition tasks to evaluate response to threat and emotion discrimination. First, we replicated the previous results in the GBR model: higher anxiety, hyperlocomotion, anhedonia in males. These phenotypes were less pronounced in females. GBR also induced a hypersensibility to threat in both sexes in the sweeping/looming disk. GBR abolished preference for the emotional target only in males, suggesting altered emotion recognition. This work introduces new phenotypic dimensions relevant to study BD and highlights the necessity to study both sexes which are not strictly equivalent in their behavioral responses.

neuroscience↗

bioRxiv2023

Synaptic tagging and capture underlie neuronal co-allocation and temporal association memory in behaving mice

Episodic memory has the ability to link distinct memories formed at temporal proximity (minutes-hours) into a coherent episodic representation. The neuronal mechanisms supporting such time associations remain however to be understood. The synaptic tagging and capture hypothesis (STC) provides a theoretical framework in which plasticity-related proteins produced for consolidating a memory trace at a synapse can potentially benefit to the consolidation of another trace at another synapse of the same neuron, thereby promoting neuronal co-allocations and temporal associations of memory traces. STC has however never been demonstrated in behaving animals, leaving its existence and functional relevance for memory formation unknown. We therefore investigated STC-like mechanisms in freely-behaving mice by recording hippocampal CA1 neurons during encoding and retrieval of distinct events. We found that reactivation of engram neurons at retrieval and the stability of place cells were strongly impaired by protein synthesis inhibition during encoding, but strikingly, were rescued in neurons that were coactive at another encoding close in time, having potentially benefitted from proteins produced at temporal proximity, as predicted by STC hypothesis. All our results together provide the first evidence of STC-like mechanisms in behaving animals and reveal an instrumental role of STC for time association of memory traces.

neuroscience↗

bioRxiv2021

Fatty acid dysregulation in the anterior cingulate cortex of depressed suicides with a history of child abuse

Child abuse (CA) strongly increases the lifetime risk of suffering from major depression and predicts an unfavorable course for the illness. Severe CA has been associated with a specific dysregulation of oligodendrocyte function and thinner myelin sheaths in the human anterior cingulate cortex (ACC) white matter. Given that myelin is extremely lipid-rich, it is plausible that these findings may be accompanied by a disruption of the lipid profile that composes the myelin sheath. This is important to explore since the composition of fatty acids (FA) in myelin phospholipids can influence its stability, permeability, and compactness. Therefore, the objective of this study was to quantify and compare FA concentrations in postmortem ACC white matter in the choline glycerophospholipid pool (ChoGpl), a key myelin phospholipid pool, between adult depressed suicides with a history of CA (DS-CA) matched depressed suicides without CA (DS) and healthy non-psychiatric controls (CTRL). Total lipids were extracted according to the Folch method and separated into respective classes using thin-layer chromatography. FA methyl esters from the ChoGpl fraction were quantified using gas chromatography. Our analysis revealed a strong age-related decrease in most FAs, and specific effects of CA in FAs from the arachidonic acid synthesis pathway, which was further validated with RNA-sequencing data. Furthermore, the concentration of most FAs was found to decrease with age. By extending the previous molecular level findings linking CA with altered myelination in the ACC, these results provide further insights regarding white matter alterations associated with early-life adversity.

neuroscience↗

bioRxiv2020

Widespread decrease of cerebral vimentin-immunoreactive astrocytes in depressed suicides

1Postmortem investigations have implicated cerebral astrocytes immunoreactive (-IR) for glial fibrillary acidic protein (GFAP) in the etiopathology of depression and suicide. However, it remains unclear whether astrocytic subpopulations IR for other astrocytic markers are similarly affected. Astrocytes IR to vimentin (VIM) display different regional densities than GFAP-IR astrocytes in the healthy brain, and so may be differently altered in depression and suicide. To investigate this, we compared the densities of GFAP-IR astrocytes and VIM-IR astrocytes in postmortem brain samples from depressed suicides and matched non-psychiatric controls in three brain regions (dorsomedial prefrontal cortex, dorsal caudate nucleus and mediodorsal thalamus). A quantitative comparison of the fine morphology of VIM-IR astrocytes was also performed in the same regions and subjects. Finally, given the close association between astrocytes and blood vessels, we also assessed densities of CD31-IR blood vessels. Like for GFAP-IR astrocytes, VIM-IR astrocyte densities were found to be globally reduced in depressed suicide relative to controls. By contrast, CD31-IR blood vessel density and VIM-IR astrocyte morphometric features in these regions were similar between groups, except in prefrontal white matter, in which vascularization was increased and astrocytes displayed fewer primary processes. By revealing a widespread reduction of cerebral VIM-IR astrocytes in cases vs. controls, these findings further implicate astrocytic dysfunctions in depression and suicide.

neuroscience↗

bioRxiv2020

Child abuse associates with increased recruitment of perineuronal nets in the ventromedial prefrontal cortex: evidence for an implication of oligodendrocyte progenitor cells

Child abuse (CA) is a strong predictor of psychopathologies and suicide, altering normal trajectories of brain development in areas closely linked to emotional responses such as the prefrontal cortex (PFC). Yet, the cellular underpinnings of these enduring effects are unclear. Childhood and adolescence are marked by the protracted formation of perineuronal nets (PNNs), which orchestrate the closure of developmental windows of cortical plasticity by regulating the functional integration of parvalbumin interneurons (PV) into neuronal circuits. Using well-characterized post-mortem brain samples, we show that a history of CA is specifically associated with increased densities and morphological complexity of WFL-labeled PNNs in the ventromedial PFC (BA11/12), possibly suggesting increased recruitment and maturation of PNNs. Through single-nucleus sequencing and fluorescent in-situ hybridization, we found that the expression of canonical components of PNNs is enriched in oligodendrocyte progenitor cells (OPCs), and that they are upregulated in CA victims. These correlational findings suggest that early-life adversity may lead to persistent patterns of maladaptive behaviors by reducing the neuroplasticity of cortical circuits through the enhancement of developmental OPC-mediated PNN formation.

neuroscience↗

bioRxiv2019

Evidence of decreased gap junction coupling between astrocytes and oligodendrocytes in the anterior cingulate cortex of depressed suicides

Glial dysfunction is a major feature in the pathophysiology of mood disorders. While altered astrocyte (AS) and oligodendrocyte-lineage (OL) cell functions have been associated with depression, the crosstalk between these two major glial cell types has never been assessed in that context. AS are potent regulators of OL cells and myelination, in part through gap junction-mediated intercellular communication made possible by the heterotypic coupling of AS-specific (Cx30 and Cx43) and OL-specific (Cx32 and Cx47) connexins, allowing cytosolic transport and metabolic support to OL cells. Because changes in the expression of AS-specific connexins have been previously reported in the brain of depressed individuals, this study aimed at addressing the integrity of AS-OL coupling in the anterior cingulate cortex (ACC) of depressed suicides. Using immunofluorescence and confocal imaging, we characterized the distribution of the AS-specific Cx30 in the ACC, and mapped its expression onto oligodendrocyte somas and myelinated axons as well as brain vasculature in post-mortem brain samples from depressed suicides (N=48) and matched controls (N=23). The differential gene expression of key components of the gap junction nexus was also screened through RNA-sequencing dataset previously generated by our group, and validated by quantitative real-time PCR. Our results indicate that Cx30 expression mapping to OL cells is selectively decreased in depressed suicides, an effect that was associated with decreased expression of OL-specific connexins Cx32 and Cx47, as well as the downregulation of major connexin-interacting proteins essential for the scaffolding, trafficking and function of gap junction channels. These results provide a first evidence of impaired gap junction mediated communication between astrocytes and oligodendrocytes in the ACC of individuals with mood disorders. These changes in glial coupling are likely to have significant impact on brain function, and may contribute to the altered OL function previously reported in this brain region.

neuroscience↗