Biology subjects

Ducrocq, F.

Publications and source records attributed to Ducrocq, F..

6 recordsLinked to original sources

bioRxiv2025

A role for prefrontal dopamine signaling in control of goal-directed actions

Impairments in behavioral flexibility commonly found across psychiatric disorders have often been attributed to a dysfunction of the medial prefrontal cortex (mPFC), notably in relation with altered dopamine transmission. However, how dopamine transmission shapes neuronal activity in the mPFC to allow adapting to a changing situation remains largely elusive. Here, we show that dopamine dynamics in the mPFC encode the value of instrumental actions, in particular during reversal learning. Such signal shapes the activity of mPFC dopaminoceptive neurons during reversal learning through the recruitment of heteromers formed by dopamine D1 and D2 receptors with NMDA receptors. In accordance, blockade of either D1/NMDA or D2/NMDA heteromers in the mPFC selectively impairs reversal of outcome identities but not learning and expression of initial action-outcome associations. Our findings provide mechanistic evidence for a central role of dopamine in the mPFC to allow updating goal-directed actions.

neuroscience↗

bioRxiv2025

Developmental vitamin A deficiency induces sex-specific reward processing alterations through a dysregulation of the mesolimbic dopamine transmission in mice

Neurodevelopmental psychiatric diseases such as schizophrenia or affective disorders share common symptomatic dimensions, in particular reward processing dysfunctions, associated with dysregulation of dopamine (DA) transmission. Retinoic acid (RA) homeostasis is altered across psychiatric disorders but whether impaired developmental RA signaling impacts the functionality of DA-related reward processing at adulthood remains poorly explored. Herein, we explored in male and female mice how developmental vitamin A deficiency (VAD), as a model of blunted RA signaling, could impact motivational processes through a modulation of mesolimbic DA transmission. Behavioral performances were evaluated using operant conditioning tasks, parallel with investigations of the integrity of DA transmission through biochemical analyses of markers of DA transmission and measures of DA dynamics using DA biosensor coupled with fiber photometry. Finally, chemogenetic manipulation of the mesolimbic DA pathway was used to normalize DA transmission and assess the effect on motivational performance in VAD offspring. Developmental VAD induced sex-specific alterations of reward-related processes at adulthood. Indeed, while female behavioral performances were spared, VAD males exhibited elevated instrumental performance and impulsivity. These behavioral alterations were coherent with reduced DA transporter (DAT) expression and increased DA dynamic in the mesolimbic pathway. Strikingly, chemogenetic inhibition of the mesolimbic DA pathway normalized motivational performance in VAD males. Our results show that developmental RA hyposignaling induces sex-specific reward processing alterations in adulthood through hyperactivity of the mesolimbic DA pathway. Our data support that developmental impairment in RA signaling might be at the core of reward-related symptoms across psychiatric disorders.

neuroscience↗

bioRxiv2024

Fingerprinting and chemotyping approaches reveal a wide genetic and metabolic diversity among wild hops (Humulus lupulus L.)

Hop (Humulus lupulus L.) is an emblematic industrial crop in the French North East region that developed at the same time as the brewing activity. Presently, this sector, especially microbreweries, are interested in endemic wild hops, which give beer production a local signature. In this study, we investigated the genetic and metabolic diversity of thirty-six wild hops sampled in various ecological environments. These wild accessions were propagated aeroponically and cultivated under uniform conditions (the same soil and the same environmental factors). Our phytochemical approach based on UHPLC-ESI-MS/MS analysis led to the identification of three metabolic clusters based on leaf content and characterized by variations in the contents of twelve specialized metabolites that were identified (including xanthohumol, bitter acids, and their oxidized derivatives). Furthermore, molecular characterization was carried out using sixteen EST-SSR microsatellites, allowing a genetic affiliation of our wild hops with hop varieties cultivated worldwide and wild hops genotyped to date using this method. Genetic proximity was observed for both European wild and hop varieties, especially for Strisselspalt, the historical variety of our region. Finally, our findings collectively assessed the impact of the hop genotype on the chemical phenotype through multivariate regression tree (MRT) analysis. Our results highlighted the WRKY 224 allele as a key discriminator between high- and low-metabolite producers. Moreover, the model based on genetic information explained 40% of the variance in the metabolic data. However, despite this strong association, the model lacked predictive power, suggesting that its applicability may be confined to the datasets analyzed.

plant biology↗

bioRxiv2024

Reduced GABA transmission onto ventral tegmental area dopamine neurons underlies vulnerability for hyperactivity in a mouse model of Anorexia Nervosa

Anorexia nervosa (AN) has the highest mortality among psychiatric diseases. Hyperactivity is a persistent symptom, which is difficult to control for patients and a major barrier to recovery as it interferes with weight gain. Alteration of mesolimbic dopamine transmission has been hypothesized as a critical factor for the development and maintenance of the disease and for hyperactivity. At what level the changes in dopamine occur in anorexic states and whether local mesolimbic neurocircuit plasticity is causally involved remains unclear. Especially the role of local GABA control over dopamine neurons, a powerful regulator of the dopamine system, in an AN context is unknown. We hypothesize that combining caloric restriction with exercise, such as in the activity-based anorexia (ABA) model, alters dopamine transmission via GABA disinhibition that, in turn, facilitates the expression of maladaptive behaviors such as hyperactivity. Therefore, we characterized the impact of the ABA model on plasticity of the dopamine reward system. In ex-vivo brain slices of mice exposed to this model, ventral tegmental area dopamine (VTADA) neurons displayed a higher firing frequency compared to control mice supporting that the midbrain dopamine system undergoes plasticity. This coincided with reduced GABAergic transmission on VTADA neurons. This reduction was at least in part attributable to local VTA GABA (VTAGABA) neurons. Indeed, VTAGABA neurons were less excitable, displayed a lower firing frequency and a lower probability of release onto VTADA neurons. Restoring the excitability of VTAGABA neurons via chemogenetic activation rescued mice from starvation, by decreasing running wheel activity. In summary, we found that the anorexic state leads to dysregulation of VTAGABA transmission on VTADA neurons that reinforces maladaptive behaviors such as excessive exercise. We uncovered a new mechanism linked to the disturbed dopamine system in ABA-exposed animals, identifying a hitherto unknown role of decreased local GABAergic control over VTA dopamine neuron output.

neuroscience↗

bioRxiv2022

The ventral striatum contributes to energy balance

Accumulating evidence points to dysregulations of common brain systems in eating disorders (ED), the Nucleus Accumbens (NAc) in particular. However, to which extent alterations in NAc activity contribute to ED-like dimensions remains unclear. Using chemogenetic manipulations of dopamine D1 receptor-expressing and D2-expressing neuronal subpopulations of the NAc in male mice, we assessed their respective roles in incentive processes, food intake and the balance between feeding and exercise-mediated energy expenditure. We found that D1-neurons facilitate effort for a food reward but decreased food intake, while D2-neurons have opposite effects. The anorexigenic influence of D1-neurons was accompanied by increased voluntary exercise while the orexigenic effect of D2-neurons was concomitant with decreased running, congruent with D2-neurons being more active than D1-neurons during feeding while it is the opposite during running. Chronic manipulations of each subpopulations had limited effects on energy balance. However, repeated activation of D1-neurons combined with inhibition of D2-neurons biased behavior toward activity-related energy expenditure leading to weight/fat loss, whilst the opposite manipulations favored energy intake and hence weight/fat gain. Strikingly, concomitant activation of D1-neurons and inhibition of D2-neurons precipitated weight loss in anorexia models. These results suggest that dysregulations of NAc dopaminoceptive neurons might be at the core of EDs.

neuroscience↗

bioRxiv2022

Impact of membrane lipid polyunsaturation on dopamine D2 receptor ligand binding and signaling

The heterogenous and dynamic constitution of the membrane fine-tunes signal transduction. In particular, the polyunsaturated fatty acid (PUFA) tails of phospholipids influence the biophysical properties of the membrane, production of second messengers, or membrane partitioning. Few evidence mostly originating from studies of rhodopsin suggest that PUFAs directly modulate the conformational dynamic of transmembrane proteins. However, whether such properties translate to other G protein-coupled receptors remains unclear. We focused on the dopamine D2 receptor (D2R), a main target of antipsychotics. Membrane enrichment in n-3, but not n-6, PUFAs potentiates ligand binding. Molecular dynamics simulations show that the D2R preferentially interacts with n-3 over n-6 PUFAs. Furthermore, even though this mildly affects signalling in heterologous systems, in vivo n-3 PUFA deficiency blunts the effects of D2R ligands. These results suggest that n-3 PUFAs act as allosteric modulators of the D2R and provide a putative mechanism for their potentiating effect on antipsychotic efficacy.

cell biology↗