Biology subjects

Desfor, S.

Publications and source records attributed to Desfor, S..

3 recordsLinked to original sources

bioRxiv2026

Reln haploinsufficiency alters fentanyl-induced striatal activity and adaptive responding without affecting opioid reinforcement

The Reln gene encodes the extracellular glycoprotein Reelin that regulates synaptic plasticity and activity-dependent gene expression with implications in several neuropsychiatric disorders, including substance use disorder. While reduced Reln expression alters responses to psychostimulants and cannabinoid, its role in opioid-related behaviors remains unknown. Here, we examined whether Reln haploinsufficiency modifies behavioral and molecular responses to the synthetic opioid fentanyl. Heterozygous Reeler (Reln+/-) mice and wild-type littermates were assessed using using complementary contingent and non-contingent models of fentanyl exposure, including multi-phase fentanyl intravenous self-administration paradigm, conditioned place preference paradigm, locomotor assay, and dorsal striatal immediate early gene expression. Reln haploinsufficiency did not alter acquisition, extinction, or cue-induced reinstatement during self-administration, indicating stable opioid reinforcement and relapse-like behavior. Progressive ratio testing revealed a sex-dependent effect in which male Reln+/- mice showed reduced motivation for fentanyl compared to male wild-type mice. In contrast, following passive fentanyl exposure, Reln+/- mice exhibited enhanced fentanyl-induced locomotion and increased Fos immunoreactivity in the dorsal striatum, while CPP remained unchanged. Together, these findings demonstrate that Reln haploinsufficiency does not substantially modify opioid reinforcement or cue-driven drug seeking but enhances acute pharmacological sensitivity to fentanyl. These results identify Reln as a modulatory factor in opioid-responsive neural circuits that preferentially influences acute drug-evoked neuronal activation rather than the associative learning processes underlying opioid reinforcement.

neuroscience↗

bioRxiv2025

The development of FEDUPP: Feeding Experimentation Device Users Processing Package to Assess Learning and Cognitive Flexibility

Cognitive flexibility, the ability to adapt behavior in response to changing contingencies, is a key component of adaptive decision-making and is impaired in multiple neuropsychiatric disorders. Traditional rodent assays of cognitive flexibility are conducted in experimenter-controlled sessions in restrictive environments, limiting ecological validity and temporal resolution. Here, we developed a fully automated, home-cage paradigm using the Feeding Experimentation Device 3 (FED3) and a companion open-source analysis pipeline, the Feeding Experimentation Device Users Processing Package (FEDUPP), to assess learning and cognitive flexibility with minimal experimenter intervention. The paradigm combines a single-day fixed-ratio 1 (FR1) task with a multi-day, reversal learning task in which active port assignment switches every 25 pellets collected. FEDUPP implements multi-scale learning metrics, including overall accuracy, an 80% accuracy milestone, and a machine learning-based classification of meal accuracy to capture motivated, goal-directed feeding. In wild-type mice, the paradigm detected rapid FR1 acquisition and progressive within-block adaptation during reversal. Application to mice with dorsal hippocampal knockdown of the scaffolding protein CASK revealed faster FR1 acquisition and higher accuracy than controls but a delayed onset of the first accurate meal after reversal, suggesting a selective deficit in updating goal-directed feeding behavior. These findings demonstrate that FEDUPP enables high-resolution, continuous assessment of learning and cognitive flexibility in ethologically relevant settings, and that meal-based accuracy provides a sensitive metric for detecting subtle flexibility impairments not captured by traditional measures.

animal behavior and cognition↗

bioRxiv2025

Long-Term Effects of Adolescent 5F-MDMB-PICA Intravenous self-administration: Neurobehavioral Consequences and medial Prefrontal Cortex Dysfunction in Adult Mice

BackgroundSynthetic Cannabinoids Receptor Agonists (SCRAs) are the largest group of new psychoactive substances monitored worldwide. 5F-MDMB-PICA is a recent SCRA classified as a potent full agonist at CB1/CB2 receptors able to activate the mesolimbic dopamine (DA) transmission in adolescent but not in adult mice. Here, we have studied its reinforcing effects in adolescent mice and characterized the neurochemical and behavioral effects induced in the same animals in adulthood. MethodsWe utilized an intravenous self-administration (IVSA) protocol in adolescent (PND 40-56) CD-1 male mice. In adulthood (PND 66-78), we conducted several behavioral and neurobiological assessments including: Sucrose Preference Test (SPT); Resident Intruder Test (RIT); Olfactory Reactivity Test (ORT); brain microdialysis to quantify DA levels in the medial Prefrontal Cortex (mPFC); and fiber photometry analysis using the GCaMP calcium sensor to monitor excitatory neural dynamics in the mPFC after exposure to an aversive odorant. ResultsWe found that 5F-MDMB-PICA, administered through IVSA in adolescent mice, produced an inverted U-shaped dose-response curve. The dose of 2.5 g/kg/25ul elicited behavior consistent with drug seeking. Adult mice exposed to 5F-MDMB-PICA during adolescence exhibited significant behavioral and neurochemical changes in adulthood compared to control mice. These behaviors included increased aggression, reduced social interaction, an anhedonic state, and an abolishment of mPFC DA response to an aversive odorant, as measured by in vivo brain microdialysis. Moreover, fiber photometry analysis of excitatory neuronal activity in the mPFC showed diminished calcium activity in response to the same aversive odorant in 5F-MDMB-PICA-exposed mice compared to controls. ConclusionsNotably, this study is the first to demonstrate that adolescent mice can acquire and sustain IVSA of 5F-MDMB-PICA. Furthermore, it highlights the long-term behavioral and neurochemical changes associated with adolescent exposure to 5F-MDMB-PICA, underscoring the potential detrimental effects of its use during this critical developmental period.

neuroscience↗