Biology subjects

Backes, H.

Publications and source records attributed to Backes, H..

4 recordsLinked to original sources

bioRxiv2026

Midbrain Tet1 dosage defines inter-individual binge-eating susceptibility

Binge-eating disorder (BED) is the most common eating disorder worldwide and carries life-altering comorbidities. While genetic and environmental risk factors have been identified, the mechanisms that determine inter-individual susceptibility to BED remain largely unknown. Here, we demonstrate that developmental dosage of the DNA hydroxymethylase Tet1 defines stable inter-individual differences in binge-eating susceptibility. In mice, midbrain dopaminergic neurons of the ventral tegmental area (VTADA) are essential for the induction of addictive binge-eating behavior, express high levels of Tet1, and undergo rapid and widespread DNA hydroxymethylation remodeling upon experimental binge eating. Strikingly, Tet1 haploinsufficiency creates pronounced inter-individual variation in binge-eating susceptibility even among genetically identical mice, which we trace to reduced connectivity between the prelimbic medial prefrontal cortex (mPFCPL) and the VTA. Chemogenetic inhibition of mPFCPL[->]VTA projections reduces binge-eating susceptibility, whereas EGR1-guided re-activation of TET1 in VTA dopaminergic neurons restores susceptibility, supporting a causal role for this axis. Importantly, TET1 promoter methylation in patients associates with binge-eating behavior and reward-circuit function, suggesting conservation of this regulatory network in humans. Collectively, these findings identify Tet1 dosage as a novel regulator of binge-eating susceptibility and provide a mechanistic basis for how inter-individual differences in behavior are established.

neuroscience↗

bioRxiv2025

A lateralized pathway for associating nutrients with flavors

Animals learn about the external world, in part, via interoceptive signals1,2. For example, the nutrient content of food is first estimated in the mouth, in the form of flavor, and then measured again via slower signals from the gut. How these signals from the mouth and gut are integrated to drive learning is unknown. Here we identify a lateralized dopamine pathway that is specialized for learning about the nutrient content of food. We show that dopamine neurons in the ventral tegmental area (VTADA) are necessary for associating nutrients with flavors, and that post-ingestive nutrients trigger DA release selectively in a small region of the anterior basolateral amygdala (BLA) but not canonical DA targets in striatum. Remarkably, this nutrient-triggered DA release occurs preferentially on the left side of the brain in both mice and humans, revealing that the DA system is functionally lateralized. We identify the gut sensors that are responsible for nutrient-triggered DA release; show that they activate BLA-projecting DA neurons defined by expression of cholecystokinin (CCK); and demonstrate that stimulation of DA axon terminals in the anterior BLA drives flavor-nutrient learning but not other aspects of feeding behavior. Two-photon imaging of neurons in the left anterior BLA reveals that they integrate gustatory and post-ingestive cues, and silencing these neurons prevents flavor-nutrient learning. These findings establish a neural basis for how animals learn about the nutrient content of their food. They also reveal unexpectedly that post-ingestive nutrients are differentially represented on the right and left sides of the brain.

neuroscience↗

bioRxiv2024

A combination of the geroprotectors trametinib and rapamycin is more effective than either drug alone

Genetic suppression of activity of the insulin/IGF/mTORC1/Ras network can ameliorate the effects of ageing in animals. The network provides multiple drug targets because of its role in metabolic disease and cancer, and these are candidates for repurposing for geroprotection. For instance, inhibition of the activity of the mTORC1 complex by rapamycin can extend lifespan in multiple organisms including mice, with early indications of efficacy in humans. Trametinib inhibits MEKs in the Ras pathway and can extend lifespan in Drosophila. However, it is not yet known if trametinib alone or in combination with rapamycin can extend mouse lifespan or improve health at older ages. We assessed survival and health indices of female and male mice treated with trametinib or rapamycin alone, or with the two in combination at the same doses. Trametinib treatment extended lifespan in both sexes, while its combination with rapamycin caused further, additive prolongation. Combination treatment reduced liver tumours in both sexes and spleen tumours in males, and ameliorated the age-related increase in brain glucose uptake. There was a striking reduction in inflammation in the brain, kidney, spleen and muscle with combination treatment, accompanied by reduced circulating levels of pro-inflammatory cytokines. Trametinib alone is therefore geroprotective in mice, but combined trametinib and rapamycin treatment is more geroprotective than treatment with either drug alone, suggesting immediate translational potential for humans.

physiology↗

bioRxiv2023

Deficiency of Orexin Receptor Type 1 in Dopaminergic Neurons Increases Novelty-Induced Locomotion and Exploration

Orexin signaling in the ventral tegmental area and substantia nigra promotes locomotion and reward processing, but it is not clear whether dopaminergic neurons directly mediate these effects. We show that dopaminergic neurons in these areas mainly express orexin receptor subtype 1 (Ox1R). In contrast, only a minor population in the medial ventral tegmental area express orexin receptor subtype 2 (Ox2R). To analyze the functional role of Ox1R signaling in dopaminergic neurons, we deleted Ox1R specifically in dopamine transporter-expressing neurons of mice and investigated the functional consequences. Deletion of Ox1R increased locomotor activity and exploration during exposure to novel environments or when intracerebroventricularely injected with orexin A. Spontaneous activity in home cages, anxiety, reward processing, and energy metabolism did not change. Positron emission tomography imaging revealed that Ox1R signaling in dopaminergic neurons affected distinct neural circuits depending on the stimulation mode. In line with an increase of neural activity in the lateral paragigantocellular nucleus (LPGi) of Ox1R{Delta}DAT mice, we found that dopaminergic projections innervate the LPGi in regions where the inhibitory dopamine receptor subtype D2 but not the excitatory D1 subtype resides. These data suggest a crucial regulatory role of Ox1R signaling in dopaminergic neurons in novelty-induced locomotion and exploration.

neuroscience↗