Physiology & Behavior

Poor maternal diet and psychosocial stress represent two environmental factors that can significantly impact maternal health during pregnancy. While various mouse models have been developed to study the relationship between maternal health and offspring development, few incorporate multiple sources of stress that mirror the complexity of human experiences. Maternal high-fat diet (HF) models in rodents are well-established, whereas maternal psychosocial stress models are still emerging. The social instability stress (SIS) paradigm, serves as a chronic and unpredictable form of social stress. To evaluate the combined effects of a poor maternal diet and social stress on maternal health and behaviour, we developed a novel maternal stress model in adult female C57Bl/6 mice. We observed that all HF+ mice demonstrated rapid weight gain, elevated fasting blood glucose levels and impaired glucose tolerance independent of the presence (+) or absence (-) of SIS. Behavioural testing revealed anxiety-like behaviors remained across all groups prior to pregnancy. However, we did observe a trend of poorer nest quality among all HF+ mice compared to HF-mice following nest building testing. Unlike the other HF+ and HF-stress groups, which exhibited significantly reduced plasma ACTH and corticosterone levels following SIS exposure, we did not observe this reduction in HF+/SIS+ females. In addition, HF+/SIS+ females demonstrated significant postpartum maternal neglect, resulting in fewer numbers of live offspring. These findings suggest that prolonged maternal HF diet consumption, coupled with SIS, places a significant burden on the maternal stress response system, resulting in reduced parental investment and negative postpartum behaviour towards offspring.

Changes in motivation have been observed following induction of diet-induced obesity. However, to date, results have been contradictory, some authors reporting an increase in motivation to obtain palatable food, but others observing a decrease. Observed differences might be associated with the length of both the evaluation period and exposure to the diet. Therefore, the aim of this study was to evaluate changes in motivation during 20 weeks of exposure to a hypercaloric diet. Performance of the subjects in a progressive ratio schedule was evaluated before and during the exposure to a high-fat, high-sugar choice diet (HFHSc). A decrease in motivation was observed after 2 weeks of diet exposure, low levels of motivation remained throughout 20 weeks. A comparable decrease in motivation took longer (3 weeks) to develop using chow diet in the control group. Overall, our results suggest that, when changes in motivation are being evaluated, long periods of diet exposure made no further contribution, once motivation decreased, it remained low up to 18 weeks. Exposure to a HFHSc diet is a useful animal model of obesity, since it replicates some pathophysiological and psychological features of human obesity such as an increase in fasting glucose levels, body weight and the weight of adipose tissue.

Humans show aversion toward inequality of social reward, and this aversion plays important roles for the establishment of social cooperation. However, it has remained unknown whether commonly used experimental animals show negative responses to social reward inequality. In this study, we found that rats showed bonding-like behavior to an affiliative human who repeatedly stroked the rats. In addition, these rats emitted distress calls, an index of negative emotion, when an affiliative human stroked another rat in front of them. These distress calls had acoustic characteristics different from those emitted in response to physical stress stimuli such as air-puff. Rats emitted calls with higher frequency (28 kHz) and shorter durations (0.05 sec) in an inequality condition than the frequency and durations of calls emitted when receiving air-puff. Our results suggested that rats exhibited negative emotion with unique distress calls in response to a social inequality condition.

Sugar-preference behavior is considered to be universally innate among humans and animals. Current research on the detection and mechanisms of sugar-preference behavior largely adopts the "two-bottle choice assay", and most experiments use male mice as the model, which has serious methodological flaws, leading to questionable conclusions. As expected, through adopting our improved experimental method, we discovered distinct sugar preferences between male and female mice: females possess an innate preference, while males do not. However, the innate sugar preference in female mice can be lost due to their long-term normal diet. Even after "training" with high-sugar food for a long time, the results still show differences between males and females. Female mice retain a significant preference for sugar, while male mice are not influenced by the training of high-sugar food and still do not evolve a sugar preference. From this, we conclude that gender determines the emergence and development of sugar preference in mice. Our results can provide researchers with a new understanding of sugar preference, which will help them fill in or even correct the gaps in the original experimental design methods to obtain more reliable conclusions.

It is generally believed that humans are the only species that values life. However, it is not well understood whether animals have a nature that values life. In this study, we attempted to determine whether male Wistar rats have this nature. Normally-reared rats did not show lifesaving-like actions towards anesthesia-induced comatose rats, although they seemed to distinguish life from death. Considering the possibility that different rearing conditions may foster a life-valuing nature, male Wistar rat pups were reared in several ways: normal rearing, loving rearing (LR; rats reared as if they were cute pets), rearing in an enriched environment, reared with gentle stroking of the back, and normal rearing of offspring of rats raised under LR conditions. When placed in an anxiety-producing environment, only LR rats escaped into the hands of the person who reared them, indicating attachment. Only the LR rats displayed lifesaving-like actions towards unknown comatose rats or drowning pups. LR rats also stopped attacks by biting ICR mice that were attacking C57BL/6 mice. Thus, rearing in an affectionate environment may foster a life-valuing nature, even in rats, suggesting that the valuing of life may be neither innate nor human-specific.

Vagus nerve signals from the gut to brain carry information about nutrients and drive food reward. Such signals are disrupted by consuming large amounts of high-calorie foods, necessitating greater food intake to elicit a similar neural response. Non-invasive vagus nerve stimulation (nVNS) via a branch innervating the ear is a candidate treatment for obesity in humans. There is disagreement on the optimal location of nVNS in the ear for experimental and clinical studies. There are also no studies comparing nVNS in hungry and full states. We aimed to compare ear position(s) for nVNS and explore the effects of nVNS during hungry and full states on proxies for autonomic outflow (heart-rate variability) and efferent metabolism (gastric frequency and resting energy expenditure). In a within-subject design, 14 participants (10 women, on average 29.4 +/- 6.7 years old) received nVNS in four different locations (cymba conchae, tragus, earlobe, or tragus AND cymba conchae) on separate days. In each session, participants were asked to consume a palatable chocolate flavored milk. With electrography on the abdomen and indirect calorimetry in a canopy, we measured electro-cardiogram, electro-gastrogram and resting energy expenditure for 15 minutes before and at least 35 minutes after consumption of the palatable drink. We also collected ratings of the palatable drink and internal and other states. Pre-drink consumption (in a hungry state) we observed no differences in the effect of location of acute nVNS on resting energy expenditure and gastric frequency. However, nVNS in cymba conchae decreases heart-rate variability and ratings of how much participants want to consume the drink. After drink consumption and with continued nVNS, gastric frequency is unchanged, and resting energy expenditure increases regardless of stimulation location. Heart-rate variability decreases in all locations, except cymba conchae. We also observe a trend for an increase in gastric frequency in late post-drink consumption time-points in cymba conchae. These results suggest that nVNS in the cymba conchae in a hungry state has a similar acute effect on vagal tone as food consumption: to decrease heart rate variability. This effect then negates the usual postprandial effects of a decrease in heart rate variability as seen in the other nVNS locations. This suggests that nVNS in cymba conchae may act primarily on vagal afferent autonomic (and only modestly on metabolic output) in a similar way as food consumption does. HighlightsO_LIWe measured autonomic outflow and efferent metabolism before and after consumption C_LIO_LIWe manipulated the location of nVNS stimulation in the outer ear C_LIO_LIThe different locations were earlobe, cymba conchae, tragus, cymba conchae+tragus C_LIO_LInVNS in cymba conchae decreases pre-consumption heart-rate variability and wanting C_LIO_LInVNS in other locations decreases post-consumption heart-rate variabilty C_LI

The physiological, psychological and behavioural traits of tail biting/bitten pigs have been widely studied, with most research focusing on identifying traits to predict tail biting phenotypes (biters, victims, or uninvolved neutrals). However, it is not clear if these traits persist once pigs are no longer involved in performing or receiving tail bites. This study investigated whether there was a difference in behavioural responses to a novel object test (NOT) between pigs which were tail biting performers (BITER), recipients (VICTIM), or not involved in the biting events (NEUTRAL). We then investigated whether these differences in responses were still evident six weeks later, when tail biting was less prevalent. We hypothesised that biters would exhibit more behaviours indicative of boldness, but also stress, than victims or neutrals, and that these differences would still be present later. A total of 120 undocked pigs (BITER, n = 48; VICTIM, N = 48; NEUTRAL, n = 24; 60 male, 60 female) were selected for testing. At the time of the first test (one week after pigs were moved into the finisher house at 12 weeks of age; T1), the prevalence of tail biting peaked. The same test was repeated six weeks later (T2) when biting had eased. Each pig was tested separately in a novel arena. After a minute of habituation, a brush head was introduced by dropping it down from above, at which point the 5 min test began. A saliva sample was taken immediately before the habituation (baseline) and after each test to evaluate cortisol concentration. Direct continuous behaviour observation was conducted. Overall, salivary cortisol concentrations were higher after than before the NOT (P < 0.001), although VICTIM pigs had a reduced elevation in cortisol after the test (P = 0.02) compared to BITER and NEUTRAL pigs in T2. Between phenotypes, baseline saliva cortisol concentrations were similar. BITER pigs approached the object quicker than VICTIM pigs (P = 0.01), but also had more high-pitched vocalisations (P < 0.01), but these differences observed in T1 were no longer present in T2. The results suggested that the NOT was sensitive to detect different levels of behavioural response; however, differences in BITER pigs behavioural responses were transient and did not persist once biting behaviour ceased. The long-term consequence of chronic stress caused by being tail bitten was manifested in VICTIM pigs blunted cortisol elevation six weeks later, after severe tail biting events.

RationaleGlucagon-like peptide-1 (GLP-1) receptor agonists, such as semaglutide, are increasingly utilized in clinical practice due to their efficacy in promoting sustained weight loss following chronic administration. While acute treatment with GLP-1 receptor agonists has been shown to suppress food intake and reward-seeking behaviors in rodent models, the impact of prolonged exposure on preclinical measures of motivated behavior remains insufficiently characterized. ObjectivesThis study aimed to systematically evaluate the effects of chronic administration of semaglutide on both the acquisition and expression phases of Pavlovian conditioned approach (PavCA)--a behavioral paradigm used to assess the attribution of incentive salience to a food-paired cue. The influence of chronic semaglutide on the conditioned reinforcing properties of the food-associated cue, performance on a progressive ratio (PR) schedule for food reward, and ad libitum consumption of the food reward were also assessed. ResultsChronic semaglutide administration did not significantly alter either the acquisition or the expression of PavCA behavior. However, relative to vehicle-treated controls, semaglutide markedly enhanced responding for the food-associated cue during a conditioned reinforcement test and increased PR responding for the food reward. In contrast, semaglutide reduced both free consumption of the food reward and homecage chow intake. ConclusionsThese findings demonstrate that chronic semaglutide administration potentiates the incentive value of food-paired cues and increases motivation for food reward under restricted access conditions, yet attenuates overall food consumption when food is freely available. This dissociation highlights the nuanced effects of semaglutide on motivated behavior and suggests an amplification of the reinforcing properties of discrete, limited food rewards and associated cues.

Food is generally hidden in a natural environment and require free-living animals to search for it. Although such food-seeking behaviors involve motivation and exploration, previous studies examined food-seeking simply by measuring the time spent in the food zone or the frequency of pursuing food-cued context. Moreover, after discovering food, animals need to taste and smell it in order to evaluate their nutritional value or possible toxicity. However, researchers could not easily distinguish food-seeking from food-evaluating behaviors because food was visible or accessible throughout each test. Herein, we describe a behavioral protocol that triggers animals to show the behavioral dynamics of food-seeking (e.g., navigation, nose-digging, and paw-digging) and that exclusively elicits food-seeking without provoking any other food-evaluating behaviors. First, we prepared an open-field box with the floor covered with bedding. After we hid foods under the bedding of each corner, the test mice were habituated in this arena for four days (pre-test phase). On the next day (test phase), they were placed under the same conditions, but the foods previously hidden were removed. This process enabled the mice to perceive their surroundings as a food-hidden environment, which induced the animal to exhibit sustained food-seeking. In conclusion, the protocol presented here is a powerful method for provoking multiple forms of food-seeking and quantifies food-seeking independently from other food-related behavioral stages.

Dietary choice plays a critical role in metabolic and neurological health, yet the biological factors that shape macronutrient preference remain poorly understood. Evidence from both humans and rodents suggests potential sex differences in the attractiveness of specific nutrients, though findings have been inconsistent and often rely on self-report or diets with mixed macronutrient composition. The present study examined sex differences in macronutrient preference and food-directed behavior in mice using a controlled three-food choice paradigm. Adult male (n = 12) and female (n = 11) C57BL/6J mice were given simultaneous access to foods consisting of fat, sucrose, or a fat-carbohydrate combination across 14 days. Intake, latency to approach, and time spent near each food source were quantified, and estrous cycle stage was monitored in females. Female mice consumed significantly more food than males overall, driven by a selective increase in fat intake. Behavioral measures paralleled these results, with females spending more time in proximity to fat-associated food zones. In contrast, males preferentially consumed the fat-carbohydrate combination and showed weaker nutrient-specific engagement. Estrous cycle stage modestly influenced feeding behavior, with estrus associated with increased overall intake and greater consumption of combination diets, reflecting elevated carbohydrate intake. These findings demonstrate robust sex differences in macronutrient preference and suggest that hormonal state may selectively modulate nutrient-specific feeding behavior.

The sex of the experimenter may cause stress in animal models and be a major confounding factor in preclinical research. We studied the effects of the sex of the experimenter on female and male rat anxiety behaviours using thigmotaxis in the open field test, anxiety-induced changes in brain and back temperature using infra-red thermography, and alterations in plasma concentrations of stress hormones, corticosterone and oxytocin. Female rats displayed consistently exacerbated anxiety-related behaviours along with increased infrared cutaneous temperature during repeated exposure to male experimenters. Experimental stress further intensified thermal responses to a male experimenter, especially in female rats. These behavioural responses to a male experimenter in females were associated with higher circulating corticosterone and lower oxytocin levels. Similar responses were induced by a T-shirt worn by a human male. These findings suggest that emotional and physiological responses of female rats to a male experimenter are influenced by visual and olfactory cues. These results emphasize the need to standardize and report experimenter sex throughout a study to avoid ambiguity in interpretation of the results.

Emotional contagion, the process leading to emotional state matching between individuals is considered a cornerstone for the proper functioning of social groups, via its contribution to group coordination and cohesion, the ability to learn from others and engage in prosocial behaviors. However, to date, most studies of emotional contagion investigate the transfer of negative emotional states thereby bypassing the neurobiology of positive affect sharing. In this study, we aimed to leverage on the innately rewarding and salient nature of play behaviour, to investigate the potential contagiousness of positive affective states in juvenile rats. Observers that had been moderately socially deprived for varying durations first witnessed highly-playful (Play) or non-playful (Control) demonstrator rats prior to being reunited and given the opportunity to freely interact. Surprisingly, we observed the emission of negatively-valenced 22 kHz calls in a subset of sessions which was also associated with heightened play behavior of the demonstrators. We found that the reunited observers showed an increase in play behavior following observation in the Play condition compared to the Control condition, but only after short social isolation and in sessions without 22 kHz calls. In addition, an overall higher number of positively-valenced 50 kHz calls were emitted in the Play condition, again in sessions without 22 kHz emissions. Despite the limitations of the experimental procedure, our results highlight the complex nature of positive emotional sharing and provide encouraging first indications of using social play observation to study positive emotional contagion. Highlights- Social deprivation positively modulates play behavior and USV emission in reunited juvenile rats - Heightened play is associated with 22 kHz USVs following social deprivation - Heightened play was observed following play observation in the absence of 22 kHz USVs - Play observation was associated with an overall increased number of 50 kHz calls emissions - Play observation as an encouraging approach to study positive emotional contagion in rat

In behavior analysis, the modulation of the effect of time-based schedules by the spatial characteristics of the environment has been scarcely studied. Furthermore, the spatial organization of behavior, despite its ubiquity and ecological relevance, has not been widely addressed. The purpose of the present work was to analyze the effect of water delivery location (peripheral vs. central) on the spatial organization of water-feeding behavior under time-based schedules. One group of rats was exposed to a Fixed Time 30 s-water-delivery schedule and a second group to a Variable Time 30 s schedule. For both groups, in the first phase, the water dispenser was located in the perimetral zone. In the second condition, the water dispenser was located in the central zone. Each location was presented for 20 sessions. Rats trajectories, distance to the dispenser, accumulated time in regions, and entropy measures were analyzed. A differential effect of the location of water delivery in interaction with the time-based schedule was observed on all the analyzed spatial qualities of behavior. The findings are discussed in relation to the ecological proposal of Timberlakes behavioral systems.

BackgroundGestational protein intake restriction induces long-lasting harmful outcomes in the offsprings organs and systems. AimsThis study sought to evaluate the effects of protein restriction during pregnancy and breastfeeding in 42-day-old male offspring on the structure of the hippocampus, behavior tests related to memory and emotions, and the influence of an enriched environment on these parameters. Results and DiscussionThe current study demonstrated that maternal protein restriction during neural development causes crucial morphological changes in the hippocampus, making the LP offspring vulnerable to specific neural disorders in adulthood. In addition, it supports the selfish brain theory, a paradigm that postulates the brain maintains its mass selfishly by reallocating resources from other body parts when faced with nutritional stress. However, the hippocampus cellularity pattern was profoundly altered, significantly reducing the number of neurons after the breastfeeding period. This may expand the understanding of nutritional stress affecting the brain areas constitution and its supposed effects on posterior behavioral disorders. Here, reciprocal data was observed between brain masses, changes in the hippocampus cell pattern, and decreased body mass in the LP progeny. In conclusion it was demonstrated that neuronal composition and structure profoundly modified by dietary restriction are surprisingly restored from primordial cells by exposure to the enriched environment. In addition, we must emphasize that although we have observed a significant reduction in the number of neurons after gestational and breastfeeding periods, we demonstrated for the first time a substantial reduction in the fear-reflecting behavior, which an enriched environment exposure may revert. The enriched environment also significantly modified the discrimination ratio, increasing the ability of both progenies to discriminate between novel and familiar objects in a short time associated with reverse abnormal hippocampus cell patterns. These findings underscore the potential for environmental interventions to mitigate the effects of early=life nutritional stress on brain development and behavior.

Introduction and ObjectivesThere is increasing evidence suggesting the impact of human gut microbiota on digestion and metabolism. It is hypothesized that the microbiome in obese subjects is more efficient than that in lean subjects in absorbing energy from food, thus predisposing to weight gain. A transformation in gut microbiota has been demonstrated in patients who have undergone bariatric surgery which has been positively associated with post-surgical weight loss. However, there is lack of studies investigating the impact of probiotics on weight loss in post-bariatric surgery patients. The objectives of our study were to investigate the impact of a probiotic, Lactobacillus GG (LGG), on weight loss and quality of life in patients who have undergone bariatric surgery. MethodsThe study was registered with ClinicalTrials.gov NCT01870544. Subjects were randomized to receive either LGG or placebo capsules. Percent total weight loss at their post-operative visits was calculated and differences between the two groups were tested using a t-test with unequal variances. The effect of LGG on Gastrointestinal Quality of Life Index (GIQLI) scores was estimated using a mixed model repeated measures model. ResultsThe mean rate of change in percent total weight loss at the 30-day post-operative visit for the placebo and treatment groups was 0.098 and 0.079 (p = 0.41), respectively, whereas that at the 90-day post-operative visit was 0.148 and 0.126 (p = 0.18), respectively. The difference in GIQLI scores on 30-day and 90-day visits were 0.5 (-7.1, 8.0), p=0.91 and 3.7 (-4.9, 12.3), p=0.42, respectively. LGG was recovered from the stools of 3 out of 5 subjects in the treatment group. ConclusionWe did not appreciate a significant difference in the mean rate of weight loss or GIQLI scores between the groups who received LGG versus placebo. This study demonstrated survival of lactobacillus during transit through the gastrointestinal tract.

Olfactory acuity, which includes detection thresholds, identification and appreciation/intensity, seems to decline with aging, obesity, and various neurological disorders. Knowing that the sense of smell influences energy intake, the interest in protecting this sense is constantly increasing. Physical activity might be a key intervention to counteract the loss of olfactory function. This systematic review aims to explore the literature on the effect of physical activity on olfactory acuity. The search strategy consisted of using index terms and keywords in MEDLINE, EMBASE, EBM Reviews - Cochrane Central Register of Controlled Trials, CINAHL, SPORTDiscus, and Web of Science search engine. Data from 17 studies that include 10 861 participants revealed that physical activity has improved olfactory thresholds, identification, and intensity. More precisely, chronic physical activity seemed to have better effects on olfactory components than acute practice. Even though this review clarified evidence about the effect of physical activity on the sense of smell, better methodological consistency is needed across studies such as standardized experimental conditions, the time of the day data are collected, and similar relative energy intake between participants to produce more robust results.

Food cues that appear in the visual field capture our attention easily and can influence eating behavior. The current study investigated the influence of food-related stimuli on visual attention, considering the macronutrient composition of food items. Images representing sweet and savory foods were employed, the latter consisting primarily of high-protein foods. The participants were primed with these images prior to performing the attentional task. We found that both sets of food images elicited an emotional attentional blink (EAB), but a stronger EAB was observed for the high-protein foods, and this observation was further supported by a negative correlation between the attentional bias (ABias) and the proportion of protein consumed by the participants before the experiment, with participants who consumed less protein exhibiting a stronger ABias toward high-protein foods. These findings suggest that an ABias might also arise to facilitate the consumption of high-protein foods when prior consumption of this macronutrient is low.

Exposure to food rich in fat and sugar (High Fat and Sugar Diet, HFSD) is believed to induce behavioral and neurobiological changes that would produce addiction-like behavior and increase the risks of obesity and overweight. Studies in rodents have led to conflicting results suggesting that several factors such as sex and age of exposure contribute to the development of maladaptive behavior towards food. In addition, it is not clear whether the effects of exposure to HFSD persist after its discontinuation which would indicate long-term risk to develop addiction-like behavior. In this study, we investigated the persistent effects of an intermittent 8-week exposure to HFSD in male and female rats as a function of age of exposure (adult and adolescent). We found that intermittent exposure to HFSD did not alter body weight, but it affected consumption of standard food during the time of exposure in all groups. In addition, in adults, HFSD produced a decrease in the initial baseline responding in FR1 schedules that persisted for 4 weeks in males but not in female rats. However, we found that exposure to HFSD did not affect resistance to punishment measured by progressive shock strength (PSS) break points or motivation for food measured by progressive-ratio break points regardless of sex or age of exposure. Altogether, these results do not provide support to the hypothesis that intermittent exposure to HFSD produce persistent increases in the vulnerability to develop addiction-like behaviors towards palatable food.

Current feeding behaviors contribute to the epidemic levels of obesity and diabetes observed in Europe and worldwide. Together with other sensory modalities, olfaction is involved in the control of food intake. Olfactory cues can influence eating behaviors, yet the nutritional status and diet can also alter olfactory abilities. Patients with metabolic disorders present impaired olfactory sensitivity which could in turn worsen their eating behaviors. Here we examined the short-term impact of a Western diet enriched in fat and sugar (High-Fat High-Sugar, HFHS) on the anatomy and physiology of the olfactory epithelium of mice. After 8 weeks of diet, HFHS fed animals presented higher adiposity without overweight, were glucose intolerant without any change in basal blood glucose or plasma insulin. A buried food test indicated impaired olfactory capacities in the HFHS group. Whereas food related odours increased food intake in control chow fed animals, HFHS mice showed an altered response to olfactory appetitive food cues. HFHS fed mice presented olfactory sensory neurons (OSN) with shorter cilia. Finally, electro-olfactogram (EOG) recorded in response to different odorant molecules showed lower amplitudes in HFHS fed mice. HFHS diet withdrawal during one month at the end of the HFHS diet exposure improved metabolic parameters and restored both the OSN cilia length and EOGs. Our results show that diet enriched in fat and sugar can rapidly alter the physiology of the olfactory epithelium before the development of significant metabolic disorders. Anatomical changes of individual olfactory sensory neurons may participate to the reduced olfactory sensitivity.

ObjectiveA growing literature suggests manipulating dietary protein status decreases sweet consumption in rodents and in humans. Underlying neurocircuit mechanisms have not yet been determined, but previous work points towards hedonic rather than homeostatic pathways. Here we hypothesized that a history of protein restriction reduces sucrose seeking by altering mesolimbic dopamine signaling. MethodsWe tested this hypothesis using established behavioral tests of palatability and motivation, including the palatability contrast and conditioned place preference (CPP) tests. We used modern optical sensors for measuring real-time nucleus accumbens (NAc) dopamine dynamics during sucrose consumption, via fiber photometry, in male C57/Bl6J mice maintained on low-protein high-carbohydrate (LPHC) or control (CON) diet for [~]5 weeks. ResultsA history of protein restriction decreased the consumption of a sucrose dessert in sated mice by [~]50% compared to controls [T-test, p< 0.05]. The dopamine release in NAc during sucrose consumption was reduced, also by [~]50%, in LPHC-fed mice compared to CON [T-test, p< 0.01]. Furthermore, LPHC-feeding blocked the sucrose-conditioned place preference we observed in CON-fed mice [paired T-test, p< 0.05], indicating reduced motivation. This was accompanied by a 33% decrease in neuronal activation of the NAc core, as measured by c-Fos immunolabeling from brains collected directly after the CPP test. ConclusionsDespite ongoing efforts to promote healthier dietary habits, adherence to recommendations aimed at reducing the intake of added sugars and processed sweets remains challenging. This study highlights chronic dietary protein restriction as a nutritional intervention that suppresses the motivation for sucrose intake, via blunted sucrose-evoke dopamine release in NAc.