Biology subjects

Apergis-Schoute, J.

Publications and source records attributed to Apergis-Schoute, J..

6 recordsLinked to original sources

bioRxiv2025

Dietary protein restriction in rats leads to a rapid within-session preference for protein

Evolution has provided species with adaptive behavioural mechanisms that guarantee tight dietary protein regulation. However, an unsolved question is whether the well-established preference for protein-containing food manifested during states of protein restriction is innate or learned. Here, we tackled this problem by maintaining male rats on either a low-protein diet (5% protein, protein-restricted) or a control diet (22% protein, non-restricted) for 9-12 days, and then offered them two novel foods, a protein-containing solution (4% casein) and a carbohydrate-containing solution (4% maltodextrin) during a daily 60-minute free-choice test, repeated for 5 consecutive days. We assessed both the total and cumulative intake of each solution throughout each test, as well as the microstructure of licking behaviour as an index of the solutions palatability. In a second experiment, we exposed a different cohort of rats, before any behavioural test, to the same protein source (i.e., casein) that they would encounter during the free-choice tests, to assess whether familiarity with casein would drive subsequent casein intake even in non-restricted rats. We found that dietary protein restriction leads to a rapid preference (within 16 minutes of first exposure) for a casein-rich solution, and this preference is persistent over subsequent exposures. Increased palatability of protein during initial exposure correlated with protein preference in the restricted rats. Moreover, familiarity with casein did not lead to protein preference in non-restricted rats. This study demonstrates that, when in need of protein, protein preference is a rapid adaptation that requires minimal experience of protein. HighlightsO_LIProtein-restricted rats show a rapid preference for protein over carbohydrate C_LIO_LIThe preference emerges within 5 minutes of exposure to solutions C_LIO_LIIncreased palatability of casein is partially related to preference C_LIO_LIExposure to casein without protein restriction does not lead to preference C_LI

animal behavior and cognition↗

bioRxiv2022

Incertohypothalamic A13 dopaminergic neurons are involved in fine forelimb movements but not reward

Tyrosine hydroxylase (TH)-containing neurons of the dopamine (DA) cell group A13 are well-positioned to impact known dopamine-related functions since their descending projections innervate target regions that regulate vigilance, sensorimotor integration and execution. Despite this known connectivity little is known regarding the functionality of A13-DA circuits. Using TH-specific loss-of-function methodology and techniques to monitor population activity in transgenic rats in vivo we investigated the contribution of A13-DA neurons in reward and movement-related actions. Our work demonstrates a role for A13-DA neurons in grasping and handling of objects that is independent from reward. A13-DA neurons respond strongly when animals grab and manipulate food items while their inactivation or degeneration prevents animals from successfully doing so - a deficit partially attributed to a reduction in grip strength. In contrast, there was no relation between A13-DA activity and food-seeking behavior when animals were tested on a reward-based task that did not include a reaching/grasping response. Moreover, motivation for food was unaffected as goal-directed behavior for food items was in general intact following A13 neuronal inactivation/degeneration. These results demonstrate a functional role for A13-DA neurons in prehensile actions that are uncoupled from reward and as such position A13-DA neurons into the functional framework regarding centrally-located DA populations and their ability to coordinate movement.

neuroscience↗

bioRxiv2022

Restriction of dietary protein in rats increases progressive-ratio motivation for protein

Low-protein diets can impact food intake and appetite, but it is not known if motivation for food is changed. In the present study, we used an operant behavioral task - the progressive ratio test - to assess whether motivation for different foods was affected when rats were maintained on a protein-restricted diet (REST, 5% protein diet) compared to non-restricted control rats (CON, 18% protein). Rats were tested either with nutritionally-balanced pellets (18.7% protein, Experiment 1) or protein-rich pellets (35% protein, Experiment 2) as reinforcers. Protein restriction increased breakpoint for protein-rich pellets, relative to CON rats, whereas no difference in breakpoint for nutritionally-balanced pellets was observed between groups. When given free access to either nutritionally-balanced pellets or protein-rich pellets, REST and CON rats did not differ in their intake. We also tested whether a previous history of protein restriction might affect present motivation for different types of food, by assessing breakpoint of previously REST animals that were subsequently put on standard maintenance chow (protein-repleted rats, REPL, Experiment 2). REPL rats did not show increased breakpoint, relative to their initial encounter with protein-rich pellets while they were protein-restricted. This study demonstrates that restriction of dietary protein induces a selective increased motivation for protein-rich food, a behavior that disappears once rats are not in need of protein.

neuroscience↗

bioRxiv2021

Predictive and motivational factors influencing anticipatory contrast: A comparison of contextual and gustatory predictors in food restricted and free-fed rats

In anticipation of palatable food, rats can learn to restrict consumption of a less rewarding food type resulting in a binge on the preferred food when it is made available. This construct is known as anticipatory negative contrast (ANC) and can help elucidate the processes that underlie binge-like behavior as well as self-control in rodent motivation models. In the current investigation we aimed to shed light on the ability of distinct predictors of a preferred food choice to generate contrast effects and the motivational processes that underlie this behavior. Using a novel set of rewarding solutions, we directly compared contextual and gustatory ANC predictors in both food restricted and free-fed Sprague-Dawley rats. Our results indicate that, despite being food restricted, rats are selective in their eating behavior and show strong contextually-driven ANC and do so after fewer training sessions than free-fed animals. These differences mirrored changes in palatability for the less preferred solution across the different sessions as measured by lick microstructure analysis. Moreover, in contrast to previous research, gustatory cues in both food restricted and free-fed rats were sufficient for ANC to develop although this flavor-driven ANC did not relate to a corresponding change in lick patterning. These differences in the lick microstructure between context- and flavor-driven ANC indicate that the motivational processes underlying ANC generated by the two predictor types are distinct.

animal behavior and cognition↗

bioRxiv2018

Basal forebrain and brainstem cholinergic neurons differentially impact amygdala circuits and learning-related behavior

The central cholinergic system and the amygdala are important for motivation and mnemonic processes. Different cholinergic populations innervate the amygdala but it is unclear how these projections impact amygdala processes. Using optogenetic circuit-mapping strategies in ChAT-cre mice we demonstrate that amygdala-projecting basal forebrain and brainstem ChAT-containing neurons can differentially affect amygdala circuits and behavior. Photo-activating ChAT terminals in vitro revealed the underlying synaptic impact of brainstem inputs to the central lateral division to be excitatory, mediated via the synergistic glutamatergic activation of AMPA and NMDA receptors. In contrast, stimulating basal forebrain inputs to the basal nucleus resulted in endogenous ACh release resulting in biphasic inhibition-excitation responses onto principal neurons. Such response profiles are physiological hallmarks of neural oscillations and could thus form the basis of acetylcholine-mediated rhythmicity in amygdala networks. Consistent with this, in vivo NBm activation strengthened amygdala basal nucleus theta and gamma frequency rhythmicity, both of which continued for seconds after stimulation and were dependent on local muscarinic or nicotinic receptor activation, respectively. Activation of brainstem ChAT-containing neurons however resulted in a transient increase in central lateral amygdala activity that was independent of cholinergic receptors. In addition, driving these respective inputs in behaving animals induced opposing appetitive and defensive learning-related behavioral changes. Since learning and memory is supported by both cellular and network-level processes in central cholinergic and amygdala networks, these results provide a route by which distinct cholinergic inputs can convey salient information to the amygdala and promote associative biophysical changes that underlie emotional memories.

neuroscience↗

bioRxiv2018

Electrophysiological characterization and MCH/orexin neuronal distribution in the lateral hypothalamus of naked mole-rats (Heterocephalus glaber)

The lateral hypothalamus (LH) controls various homeostatic processes, including sleep-wake cycles, energy balance and thermoregulation in many mammalian species. In the LH, melanin-concentrating hormone (MCH) and hypocretin/orexin (HO) containing neurons differentially regulate these processes. Naked mole-rats (NMR) (Heterocephalus glaber) are eusocial mammals with remarkable physiological peculiarities including extreme longevity without significant weight gain and absence of thermoregulation. Altered hypothalamic function could potentially underlie the unusual NMR phenotypes, but to date electrophysiological characterization of LH NMR neurons and expression of MCH and HO is missing. Here, we performed whole-cell recordings from LH neurons in acute NMR and mouse brain slices and found that NMR and mouse neuronal basic properties and activities were comparable. Additionally, we showed that both MCH-positive and HO-positive neuronal populations exist in the NMR hypothalamus and although the majority of MCH- and HO-positive neurons are located in the LH, as previously described in rodents, significant differences exist in MCH/HO distribution in other NMR hypothalamic areas. These results indicate that NMR LH neurons are comparable to mouse neurons with respect to their electrophysiological properties, but differences in the neuronal MCH and HO populations in hypothalamic regions exist and may contribute to the adaptive changes seen in NMR homeostatic processes.

neuroscience↗