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Type-2 Diabetes (T2D) is characterized by insulin resistance and accompanied by psychiatric comorbidities including major depressive disorders (MDD). Patients with T2D are twice more likely to suffer from MDD and clinical studies have shown that insulin resistance is positively correlated with the severity of depressive symptoms. However, the potential contribution of central insulin signaling in MDD in patients with T2D remains elusive. Here we hypothesized that insulin modulates the serotonergic (5-HT) system to control emotional behavior and that insulin resistance in 5-HT neurons contributes to the development of mood disorders in T2D. Our results show that insulin directly modulates the activity of dorsal raphe (DR) 5-HT neurons to dampen 5-HT neurotransmission through a 5-HT1Areceptor-mediated inhibitory feedback. In addition, insulin-induced 5-HT neuromodulation is necessary to promote anxiolytic-like effect in response to intranasal insulin delivery. Interestingly, such an anxiolytic effect of intranasal insulin as well as the response of DR 5-HT neurons to insulin are both blunted in high-fat diet-fed T2D animals. Altogether, these findings point to a novel mechanism by which insulin directly modulates the activity of DR 5-HT neurons to dampen 5-HT neurotransmission and control emotional behaviors, and emphasize the idea that impaired insulin-sensitivity in these neurons is critical for the development of T2D-associated mood disorders.

AbstractDifferent modalities such as lectures, dissections, 3D models, and online learning are used for teaching anatomy. To date, online learning has been considered a useful additional didactic tool. This study aimed to compare veterinary students’ performance in radiographic anatomy (radio-anatomy) after online or classroom-based teaching to assess the extent to which the two methods were interchangeable. Three strategies were compared in a cohort of 83 learners. Students were committed to online learning only, online learning with the use of specimen equine bones, or learning on conventional radiographs with specimen equine bones. At baseline (pre-test), scores from a mental rotation test and radio-anatomy knowledge test were similar between groups. After training (post-test), scores in mental rotation and radio-anatomy significantly increased by 6.7/40 units (95% CI: 5.2–8.2; p< .001) and 5.1/20 units (95% CI: 4.3–5.9; p< .001), respectively. There was no difference in scores for mental rotation and radio-anatomy knowledge between groups at post-test. Gender influenced the mental rotation, with men scoring significantly higher than women at pre-test (M= 23.0, SD= 8.8 vs. M= 16.5, SD= 6.9; p= .001) and post-test (M= 32.1, SD= 5.5 vs. M= 22.7, SD= 8.6; p< .001). However, radio-anatomy knowledge was not influenced by gender. These results suggest radio-anatomy teaching can be safely achieved with either conventional radiographs or online resources. This is of interest since, due to the COVID-19 outbreak, rapidly changing from on-site to online methods for teaching veterinary medical education proved necessary.

RésuméL’enseignement de l’anatomie repose sur diverses techniques: les cours, les dissections, les modèles 3D ou encore les supports en ligne. Ces derniers sont généralement considérés comme des moyens d’apprentissage complémentaires. Cette étude vise à comparer les performances des étudiants vétérinaires (N=83) en anatomie radiographique (radioanatomie) après un apprentissage en ligne ou conventionnel, et de voir dans quelle mesure ces méthodes sont interchangeables. Trois stratégies sont comparées : apprentissage en ligne exclusif, apprentissage en ligne avec des os de chevaux, apprentissage sur radiographies conventionnelles avec des os de chevaux. Les performances au test de rotation mentale et au test de connaissance en radioanatomie sont similaires entre les 3 groupes à la base, lors du test préliminaire. Après l’apprentissage (test final), les scores de rotation mentale et de radioanatomie augment significativement de 6.7/40 points (CI : 5.2–8.2; p < .001) et de 5.1/20 points (CI: 4.3–5.9; p< .001). Il n’y a pas de différence entre les groupes pour les scores de rotation mentale et de radioanatomie après l’apprentissage. Le score de rotation mentale est influencé par le genre, et significativement plus élevé chez les hommes que chez les femmes au test préliminaire (M= 23.0, SD = 8.8 vs. M= 16.5, SD= 6.9; p= .001) et au test final (M= 32.1, SD= 5.5 vs. M= 22.7, SD= 8.6; p< .001). Les performances en radioanatomie ne sont pas influencées par le genre. Ces résultats suggèrent que l’enseignement de la radioanatomie peut être réalisé en présentiel avec des radiographies conventionnelles ou en ligne. Cette interchangeabilité entre apprentissage en présentiel et en distanciel est intéressante au regard des impératifs liés aux crises sanitaires, et des besoins d’adaptation rapide en distanciel.This translation was provided by the authors. To view the original article visit: https://doi.org/10.3138/jvme-2021-0153

Hypothalamic pro-opiomelanocortin (POMC) neurons are known to trigger satiety. However, these neuronal cells encompass heterogeneous subpopulations that release γ-aminobutyric acid (GABA), glutamate, or both neurotransmitters, whose functions are poorly defined. Using conditional mutagenesis and chemogenetics, we show that blockade of the energy sensor mechanistic target of rapamycin complex 1 (mTORC1) in POMC neurons causes hyperphagia by mimicking a cellular negative energy state. This is associated with decreased POMC-derived anorexigenic α-melanocyte-stimulating hormone and recruitment of POMC/GABAergic neurotransmission, which is restrained by cannabinoid type 1 receptor signaling. Electrophysiology and optogenetic studies further reveal that pharmacological blockade of mTORC1 simultaneously activates POMC/GABAergic neurons and inhibits POMC/glutamatergic ones, implying that the functional specificity of these subpopulations relies on mTORC1 activity. Finally, POMC neurons with different neurotransmitter profiles possess specific molecular signatures and spatial distribution. Altogether, these findings suggest that mTORC1 orchestrates the activity of distinct POMC neurons subpopulations to regulate feeding behavior.