Excessive sugar intake alters binding to dopamine and mu-opioid receptors in the brain

Behavioural and physiological effects of binge eating: A systematic review and meta-analysis of animal models

Binge eating is defined as eating abnormally large amounts in a brief period of time. Many animal studies have examined the behavioural and physiological effects of binge eating of high-fat, high-sugar foods to model the consequences of human binge eating. The present systematic review of 199 rodent studies sought to identify the behavioural and physiological consequences of binge eating and determine whether changes were specific to binge eating or to general effects of exposure to a palatable diet. A meta-analysis of 18 rodent studies revealed that binge eating produces greater anxiety-like behaviour on the Elevated Plus-Maze with a small effect size and significant funnel plot asymmetry, suggesting that the true effect size is overestimated. A history of binge-like access generally increases progressive ratio breakpoint for the binged food, without altering 'liking' as measured by lick microstructure, suggesting that dissociable effects on 'wanting' but not 'liking' accompany binge eating behaviour and contribute to its persistence. Binge eating appears to enhance compulsive food-seeking behaviour and prevent stress-induced reductions in intake but does not appear to alter depression-like behaviour or locomotor activity. Notably, binge eating may produce comparable metabolic impairments to those observed after extended continuous exposure to a palatable diet despite no overall effects on body weight outcomes in most studies.

The Meal Type Rather than the Meal Sequence Affects the Meal Duration, Number of Chews, and Chewing Tempo

BACKGROUND/AIM

Obese individuals are often said to eat fast. Given that obese individuals are often reported to consume fast food more frequently, we hypothesized that fast food can be eaten more quickly. This study aimed to examine the effects of meal type on meal duration, considering meal sequence.

METHODS

Meal duration, number of chews and bites, and chewing tempo were measured among 41 participants (18 males, 23 females; average age, 41.1 years) using two meals: pizza (301 kcal) and hamburger steak bento (hamburger, rice and broccoli, 304 kcal; two eating sequences: vegetables first or last).

RESULTS

Compared with pizza, bento meals (vegetables first or last) were associated with longer meal durations (sec) (mean differences in pizza-bento (vegetable first): -182 [-245.6, -118.9], p < 0.0001; pizza-bento (vegetables last): -216.0 [-273.3, -158.7], p < 0.0001). In contrast, no differences in meal duration (sec) were observed regardless of the order of vegetable consumption (p = 0.14). These findings were consistent with the number of chews and chewing tempos across both sexes. The number of bites was similar among pizza, bento (vegetable fast), and bento (vegetable last). Meal duration was positively associated with the number of chews and bites and meal type and negatively associated with age and sex. BMI was not associated with meal duration.

CONCLUSIONS

Meal type affected meal duration, the number of chews, and the chewing tempo, independent of meal sequence. To eat more slowly, it is important to pay attention to the meal type.

Food Addiction

In this review, we aim to draw a connection between drug addiction and overconsumption of highly palatable food (OHPF) by discussing common behaviors and neurochemical pathways shared by these two states. OHPF can stimulate reward pathways in the brain that parallel those triggered by drug use, increasing the risk of dependency. Behavioral similarities between food and drug addiction can be addressed by tracking their stages: loss of control when eating (bingeing), withdrawal, craving, sensitization, and cross-sensitization. The brain adapts to addiction by way of the mesolimbic dopamine system, endogenous opioids and receptors, acetylcholine and dopamine balance, and adaptations of serotonin in neuroanatomy. Studies from the current literature are reviewed to determine how various neurological chemicals contribute to the reinforcement of drug addiction and OHPF. Finally, protocols for treating food addiction are discussed, including both clinical and pharmacological modalities. There is consistent evidence that OHPF changes brain chemistry and leads to addiction in similar ways to drugs. However, more long-term research is needed on food addiction, binge eating, and their neurobiological effects.

Excessive sucrose consumption reduces synaptic density and increases cannabinoid receptors in Göttingen minipigs

Diets high in sucrose and fat are becoming more prevalent the world over, accompanied by a raised prevalence of cardiovascular diseases, cancers, diabetes, obesity, and metabolic syndrome. Clinical studies link unhealthy diets with the development of mental health disorders, particularly depression. Here, we investigate the effects of 12 days of sucrose consumption administered as 2 L of 25% sucrose solution daily for 12 days in Göttingen minipigs on the function of brain receptors involved in reward and motivation, regulating feeding, and pre- and post-synaptic mechanisms. Through quantitative autoradiography of cryostat sections containing limbic brain regions, we investigated the effects of sucrose restricted to a 1-h period each morning, on the specific binding of [3H]raclopride on dopamine D2/3 receptors, [3H]UCB-J at synaptic vesicle glycoprotein 2A (SV2A), [3H]MPEPγ at metabotropic glutamate receptor subtype 5 (mGluR5) and [3H]SR141716A at the cannabinoid receptor 1 (CB1). Compared to control diet animals, the sucrose group showed significantly lower [3H]UCB-J and [3H]MPEPγ binding in the prefrontal cortex. The sucrose-consuming minipigs showed higher hippocampal CB1 binding, but unaltered dopamine D2/3 binding compared to the control group. We found that the sucrose diet reduced the synaptic density marker while increasing CB1 binding in limbic brain structures, which may subserve maladaptive changes in appetite regulation and feeding. Further studies of the effects of diets and lifestyle habits on brain neuroreceptor and synaptic density markers are warranted.

Metabolic bariatric surgery, alcohol misuse and liver cirrhosis: a narrative review

Bariatric surgery and liver cirrhosis have considerable overlap. Bariatric procedures intend to reduce metabolic dysfunction-associated steatotic liver disease (MASLD); however, these procedures are thought to increase the propensity for alcohol misuse. This may predispose the bariatric surgical patient to a new form of liver insult in the postoperative period. This review explores the complex relationship between obesity and alcohol misuse in the context of the bariatric surgical patient. There is evidence to support the safety of bariatric procedures in compensated cirrhotic patients, with an improvement of liver function and architecture. However, data suggest that after a two-year period, these patients exhibit an increased propensity for alcohol misuse postoperatively, particularly after sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB) procedures. A paucity of evidence exists with respect to alcohol-induced liver dysfunction, or MASLD and increased alcohol intake (MetALD) in the post-bariatric surgery patient. This review aims to provide an overview of the current evidence and offer recommendations for further robust studies.

Dietary fiber induces a fat preference associated with the gut microbiota

Eating behavior is essential to human health. However, whether future eating behavior is subjected to the conditioning of preceding dietary composition is unknown. This study aimed to investigate the effect of dietary fiber consumption on subsequent nutrient-specific food preferences between palatable high-fat and high-sugar diets and explore its correlation with the gut microbiota. C57BL/6NJcl male mice were subjected to a 2-week dietary intervention and fed either a control (n = 6) or inulin (n = 6) diet. Afterward, all mice were subjected to a 3-day eating behavioral test to self-select from the simultaneously presented high-fat and high-sugar diets. The test diet feed intakes were recorded, and the mice's fecal samples were analyzed to evaluate the gut microbiota composition. The inulin-conditioned mice exhibited a preference for the high-fat diet over the high-sugar diet, associated with distinct gut microbiota composition profiles between the inulin-conditioned and control mice. The gut microbiota Oscillospiraceae sp., Bacteroides acidifaciens, and Clostridiales sp. positively correlated with a preference for fat. Further studies with fecal microbiota transplantation and eating behavior-related neurotransmitter analyses are warranted to establish the causal role of gut microbiota on host food preferences. Food preferences induced by dietary intervention are a novel observation, and the gut microbiome may be associated with this preference.

Efficacy of Naltrexone/Bupropion in Treatment of Binge Eating: A Systematic Review and Meta-Analysis

Background: As the most widespread eating disorder in the world now, binge eating disorder (BED) is a mental condition characterized by recurrent periods of excessive food consumption and an inability to regulate one’s portion sizes. The utilization of a bupropion–naltrexone (NB) combination has been suggested as a potential therapeutic approach for BED. Assessing the effectiveness of NB in the treatment of BED and its accompanying obesity is the purpose of this research. Methods: A comprehensive search was conducted in order to obtain any pertinent articles. PubMed, Scopus, Web of Science, and Cochrane Clinical Trials were consulted against in the databases that were searched. In our final meta-analysis, we incorporated interventional or observational studies that documented the effects of NB therapy for binge eating in adults. We also examined the difference in the mean change between the NB and placebo groups, as well as the disparity in outcomes before and after treatment. Results: This study shows that the use of an NB combination is associated with a statistically significant reduction in the weight, BMI, and Binge Eating Scale (BES) of the patients compared to their weight before treatment with MD: −8.52 (95% CI: −10.01–−6.94, p < 0.00001), MD: −4.95 (95%CI: −9.72–−0.17, p = 0.04), and MD: −7.66 (95%CI: −14.36–0.96, p = 0.02), respectively. The absolute mean change was statistically significantly higher in the drug combination group compared to the placebo group. Conclusions: NB showed efficacy in the improvement of the weight and psychiatric symptoms associated with BED and this provides a promising treatment option.

The Effectiveness of Transcranial Direct Current Stimulation (tDCS) in Binge Eating Disorder (BED)-Review and Insight into the Mechanisms of Action

INTRODUCTION

Binge eating disorder (BED) is the most common eating disorder among those contributing to the development of obesity, and thus acts as a significant burden on the lives and health of patients. It is characterized by complex neurobiology, which includes changes in brain activity and neurotransmitter secretion. Existing treatments are moderately effective, and so the search for new therapies that are effective and safe is ongoing.

AIM AND METHODS

This review examines the use of transcranial direct current stimulation (tDCS) in the treatment of binge eating disorder. Searches were conducted on the PubMed/Medline, Research Gate, and Cochrane databases.

RESULTS

Six studies were found that matched the review topic. All of them used the anodal stimulation of the right dorsolateral prefrontal cortex (DLPFC) in BED patients. tDCS proved effective in reducing food cravings, the desire to binge eat, the number of binging episodes, and food intake. It also improved the outcomes of inhibitory control and the treatment of eating disorder psychopathology. The potential mechanisms of action of tDCS in BED are explained, limitations in current research are outlined, and recommendations for future research are provided.

CONCLUSIONS

Preliminary evidence suggests that the anodal application of tDCS to the right DLPFC reduces the symptoms of BED. However, caution should be exercised in the broader use of tDCS in this context due to the small number of studies performed and the small number of patients included. Future studies should incorporate neuroimaging and neurophysiological measurements to elucidate the potential mechanisms of action of tDCS in BED.

Sex-specific effects of sucrose withdrawal on anxiety-like behavior and neuroimmune response

Sugar bingeing induces maladaptive neuroadaptations to decrease dietary control and promote withdrawal symptoms. This study investigated sex differences in sucrose bingeing, sucrose withdrawal-induced negative mood effects and underlying neuroimmune response in the prefrontal cortex (PFC) and nucleus accumbens (NAc) of C57BL/6J male and female mice. Two-bottle sucrose choice paradigm was used to develop sucrose dependence in mice. Female mice consumed more sucrose than male mice when given free access to water and 10% sucrose for four weeks. A significant increase in the mRNA expression of neuroinflammatory markers (Il1β, Tnfα) was found in the PFC of males exposed to sucrose withdrawal. Sucrose bingeing and subsequent sucrose withdrawal showed elevated protein levels of pro-inflammatory cytokines/chemokines/growth factors in the PFC (IL-1β, IL-6, TNFα, IFN-γ, IL-10, CCL5, VEGF) and NAc (IL-1β, IL-6, IL-10, VEGF) of male mice as compared to their water controls. These effects were concurrent with reduced mRNA expression of neuronal activation marker (cFos) in the PFC of sucrose withdrawal males. One week of sucrose withdrawal after prolonged sucrose consumption showed anxiety-like behavior in male mice, not in females. In conclusion, this study demonstrates that repeated access to sucrose induces anxiety-like behavior when the sugar is no longer available in the diet and these effects are male-specific. Elevated neuroinflammation in reward neurocircuitry may underlie these sex-specific effects.

Opioidergic signaling contributes to food-mediated suppression of AgRP neurons

Opioids are generally known to promote hedonic food consumption. Although much of the existing evidence is primarily based on studies of the mesolimbic pathway, endogenous opioids and their receptors are widely expressed in hypothalamic appetite circuits as well; however, their role in homeostatic feeding remains unclear. Using a fluorescent opioid sensor, deltaLight, here we report that mediobasal hypothalamic opioid levels increase by feeding, which directly and indirectly inhibits agouti-related protein (AgRP)-expressing neurons through the μ-opioid receptor (MOR). AgRP-specific MOR expression increases by energy surfeit and contributes to opioid-induced suppression of appetite. Conversely, its antagonists diminish suppression of AgRP neuron activity by food and satiety hormones. Mice with AgRP neuron-specific ablation of MOR expression have increased fat preference without increased motivation. These results suggest that post-ingestion release of endogenous opioids contributes to AgRP neuron inhibition to shape food choice through MOR signaling.

Role of Endogenous Opioids in the Pathophysiology of Obesity and Eating Disorders

This second chapter in our trilogy reviews and critically appraises the scientific evidence for the role of endogenous opioid system (EOS) activity in the onset and progression of both obesity and eating disorders. Defining features of normative eating and maladaptive eating behaviors are discussed as a foundation. We review the scientific literature pertaining to the predisposing risk factors and pathophysiology for obesity and eating disorders. Research targeting the association between obesity, disordered eating, and psychiatric comorbidities is reviewed. We conclude by discussing the involvement of endogenous opioids in neurobiological and behavior traits, and the clinical evidence for the role of the EOS in obesity and eating disorders.

The influence of ultra-processed food consumption on reward processing and energy intake: Background, design, and methods of a controlled feeding trial in adolescents and young adults

BACKGROUND

The greatest age-related weight gain occurs in the early/mid-20s. Overall dietary quality among adolescents and emerging adults (age 18-25) is poor, with ultra-processed foods (UPF) representing more than two-thirds of adolescents' total energy intake (i.e., 68%). UPF consumption may impact cognitive and neurobiological factors that influence dietary decision-making and energy intake (EI). To date, no research has addressed this in this population.

METHODS

Participants aged 18-25 will undergo two 14-day controlled feeding periods (81% UPF, 0% UPF) using a randomly assigned crossover design, with a 4-week washout between conditions. Brain response to a UPF-rich milkshake, as well as behavioral measures of executive function, will be evaluated before and after each diet. Following each diet, measurements include ad libitum buffet meal EI, food selection, eating rate, and eating in the absence of hunger (EAH). Prior to initiating recruitment, controlled diet menus, buffet, and EAH snacks were developed and evaluated for palatability. Sensory and texture attributes of buffet and EAH snack foods were also evaluated.

RESULTS

Overall diet palatability was rated "like very much" (8)/"like moderately"(7) (UPF: 7.6 ± 1.0; Non-UPF: 6.8 ± 1.5). Subjective hardness rating (range = 1-9 [1 = soft, 9 = hard] was similar between UPF and Non-UPF buffet and snack items (UPF:4.22 ± 2.19, Non-UPF: 4.70 ± 2.03), as was the objective measure of hardness (UPF: 2874.33 ± 2497.06 g, Non-UPF: 2243.32 ± 1700.51 g).

CONCLUSIONS

Findings could contribute to an emerging neurobiological understanding of the effects of UPF consumption including energy overconsumption and weight gain among individuals at a critical developmental stage.

Reduced Striatal Dopamine Transporter Availability and Heightened Response to Natural and Pharmacological Stimulation in CCK-1R-Deficient Obese Rats

Alterations in dopamine neurotransmission are associated with obesity and food preferences. Otsuka Long-Evans Tokushima Fatty (OLETF) rats that lack functional cholecystokinin receptor type-1 (CCK-1R), due to a natural mutation, exhibit impaired satiation, are hyperphagic, and become obese. In addition, compared to lean control Long-Evans Tokushima (LETO) rats, OLETF rats have pronounced avidity for over-consuming palatable sweet solutions, have greater dopamine release to psychostimulants, reduced dopamine 2 receptor (D2R) binding, and exhibit increased sensitivity to sucrose reward. This supports altered dopamine function in this strain and its general preference for palatable solutions such as sucrose. In this study, we examined the relationship between OLETF's hyperphagic behavior and striatal dopamine signaling by investigating basal and amphetamine stimulated motor activity in prediabetic OLETF rats before and after access to sucrose solution (0.3 M) compared to non-mutant control LETO rats, as well as availability of dopamine transporter (DAT) using autoradiography. In the sucrose tests, one group of OLETF rats received ad libitum access to sucrose while the other group received an amount of sucrose equal to that consumed by the LETO. OLETFs with ad libitum access consumed significantly more sucrose than LETOs. Sucrose exerted a biphasic effect on basal activity in both strains, i.e., reduced activity for 1 week followed by increased activity in weeks 2 and 3. Basal locomotor activity was reduced (-17%) in OLETFs prior to sucrose, compared to LETOs. Withdrawal of sucrose resulted in increased locomotor activity in both strains. The magnitude of this effect was greater in OLETFs and the activity was increased in restricted compared to ad-libitum-access OLETFs. Sucrose access augmented AMPH-responses in both strains with a greater sensitization to AMPH during week 1, an effect that was a function of the amount of sucrose consumed. One week of sucrose withdrawal sensitized AMPH-induced ambulatory activity in both strains. In OLETF with restricted access to sucrose, withdrawal resulted in no further sensitization to AMPH. DAT availability in the nucleus accumbens shell was significantly reduced in OLETF compared with aged-matched LETO. Together, these findings show that OLETF rats have reduced basal DA transmission and a heightened response to natural and pharmacological stimulation.

The Role of the Endocannabinoid System in Binge Eating Disorder

Eating disorders are multifactorial disorders that involve maladaptive feeding behaviors. Binge eating disorder (BED), the most prevalent of these in both men and women, is characterized by recurrent episodes of eating large amounts of food in a short period of time, with a subjective loss of control over eating behavior. BED modulates the brain reward circuit in humans and animal models, which involves the dynamic regulation of the dopamine circuitry. The endocannabinoid system plays a major role in the regulation of food intake, both centrally and in the periphery. Pharmacological approaches together with research using genetically modified animals have strongly highlighted a predominant role of the endocannabinoid system in feeding behaviors, with the specific modulation of addictive-like eating behaviors. The purpose of the present review is to summarize our current knowledge on the neurobiology of BED in humans and animal models and to highlight the specific role of the endocannabinoid system in the development and maintenance of BED. A proposed model for a better understanding of the underlying mechanisms involving the endocannabinoid system is discussed. Future research will be necessary to develop more specific treatment strategies to reduce BED symptoms.

All the Pringle ladies: Neural and behavioral responses to high-calorie food rewards in young adult women

Reward processing is vital for learning and survival, and can be indexed using the Reward Positivity (RewP), an event-related potential (ERP) component that is larger for rewards than losses. Prior work suggests that heightened motivation to obtain reward, as well as greater reward value, is associated with an enhanced RewP. However, the extent to which internal and external factors modulate neural responses to rewards, and whether such neural responses motivate reward-seeking behavior, remains unclear. The present study investigated whether the degree to which a reward is salient to an individual's current motivational state modulates the RewP, and whether the RewP predicts motivated behaviors, in a sample of 133 women. To elicit the RewP, participants completed a forced-choice food reward guessing task. Data were also collected on food-related behaviors (i.e., type of food chosen, consumption of the food reward) and motivational salience factors (i.e., self-reported hunger, time since last meal, and subjective "liking" of food reward). Results showed that hungrier participants displayed an enhanced RewP compared to less hungry individuals. Further, self-reported snack liking interacted with RewP magnitude to predict behavior, such that when participants reported low levels of snack liking, those with a smaller RewP were more likely to consume their snacks than those with a larger RewP. Our data suggest that food-related motivational state may increase neural sensitivity to food reward in young women, and that neural markers of reward sensitivity might interact with subjective reward liking to predict real-world eating behavior.

Co-administration of bromocriptine and corticosterone produces short- and long-lasting reduction in intake of high-fat food in male rats

Dopaminergic and glucocorticoid activity has been associated with reduced food consumption; however, their possible synergic action has not yet been studied. With the aim of examining the effect of the co-administration of the dopamine receptor D2 agonist bromocriptine and corticosterone on palatable food intake, male Wistar rats were administered either bromocriptine (1 mg/kg), corticosterone (2 mg/kg), bromocriptine + corticosterone (1 mg + 2 mg/kg) or a vehicle, with a fifth group used as a control. In all cases, substances were administered 30 min before exposure to standard food or palatable food, the latter high in carbohydrates [high carbohydrate food (HCF), 75%] or high-fat food (HFF, 67%). Food consumption and body weight were recorded daily. Results showed higher consumption of standard food but lower consumption of HCF and HFF in the groups that received bromocriptine, alone or in combination. In general, lower total kcal intake was observed in the bromocriptine and bromocriptine + corticosterone groups during the period of pharmacological treatment and following re-exposure to palatable food. The low HFF intake in the bromocriptine + corticosterone group persisted 10 days after the pharmacological treatment was interrupted. This effect suggests plastic changes in either the mechanisms involved in the incentive value of palatable food - particularly foods with high-fat content - or those that regulate lipid metabolism. Our findings suggest that homeostatic and reward mechanisms could be influenced by the co-participation of the dopaminergic and hypothalamic-pituitary-adrenal systems, and the macronutrient content of food.

Sugary beverages and genetic risk in relation to brain structure and incident dementia: a prospective cohort study

BACKGROUND

The relation of intake of sugary beverages and genetic predisposition to the long-term risk of dementia and brain structure remains unclear.

OBJECTIVES

This study aimed to assess the associations of sugar-sweetened beverages (SSBs), artificially-sweetened beverages (ASBs), and natural juices (NJs) and the genetic predisposition with dementia risk and brain structure.

METHODS

We included 177,926 UK Biobank participants without dementia at baseline and followed them until March 2021. Intake of SSBs, ASBs, and NJs was assessed using repeated web-based 24-h dietary recalls from 2009 to 2012. We calculated a polygenic risk score (PRS) to indicate genetic predisposition of dementia for each individual. We estimated the HRs and 95% CIs using Cox proportional hazard models for dementia risk and β coefficients and 95% CIs using linear models for brain imaging markers.

RESULTS

During study follow-up (mean = 9.5 years), 1293 participants developed dementia (69.1 cases/100,000 person-years) excluding dementia cases within the first 2 years. Higher intake of SSBs and ASBs (>2 units/d compared with none) was each associated with a higher risk of dementia (HR: 1.34; 95% CI: 1.01, 1.77; P-trend = 0.040 for SSBs and 1.20; 95% CI: 0.84, 1.72; P-trend = 0.004 for ASBs). In contrast, moderate intake of NJs (>0-1 unit/d compared with none) was related to a lower dementia risk (HR: 0.77; 95% CI: 0.68, 0.87), a larger volume of brain gray matter (β = 0.05; 95% CI: 0.02, 0.08), and a lower volume of white matter hyperintensities (β = -0.07; 95% CI: -0.11, -0.03). The associations were not significantly modified by genetic risk (P-interactions = 0.839 for SSB × PRS, 0.732 for ASB × PRS, and 0.950 for NJ × PRS).

CONCLUSIONS

Higher SSB and ASB intake was associated with higher risk of dementia, and moderate NJ intake was associated with a lower risk of dementia. Am J Clin Nutr 20XX;xx:xx-xx.

Pregabalin and hyperbaric oxygen therapy on pain thresholds and anxio-depressive behaviors in a preclinical fibromyalgia pain model

Fibromyalgia (FM) is a chronic, widespread pain disorder generally of a non-inflammatory nature with many known affective and cognitive comorbidities. There is promise in the implementation of hyperbaric oxygen therapy (HBO₂) for alleviating FM pain and comorbidities, despite no work investigating the efficacy of this treatment in prominent preclinical FM models. This project aimed to investigate the affective components, specifically anhedonia and anxiety, associated with an acidic saline model of FM in rats. We investigated the acidic saline model's ability to produce the sensory component of FM through reduced mechanical thresholds, as well as anxiety-like and avoidance behaviors through measures of open field and place escape/avoidance. We further investigated the use of pregabalin, a known FM therapeutic agent, in reducing negative sensory and affective measures within the model. Results revealed insignificant between-group differences for measures of anxiety, despite animals in the FM condition showing significantly reduced mechanical thresholds. Results further revealed that the acidic saline model was effective in increasing place escape/avoidance behavior among animals in the FM condition, with pregabalin reducing avoidance behaviors. In addition, we investigated the role of HBO₂ [two 60-minute treatments at 2.0 ATA (atmospheres absolute)] in alleviating FM-like pain, anxiety, and anhedonia in the acidic saline model, utilizing mechanical paw withdrawal thresholds, open field, and sucrose preference measures. Results revealed that the acidic saline model produced reduced thresholds indicative of FM-like pain. Data did not provide support for the presence of anxio-depressive comorbidities associated with the FM model. HBO₂ treatment did not significantly increase mechanical thresholds as expected. Future studies should seek to investigate the experimental circumstances within which the acidic saline model produces negative affect alongside hyperalgesia in order to contribute to the development of a multidimensional FM treatment methodology.

Factors associated with a cariogenic diet among adolescents: a structural equation modeling approach

OBJECTIVE

To investigate the factors directly and indirectly associated with a cariogenic diet among southern Brazilian adolescents.

MATERIALS AND METHODS

This cross-sectional study included 15-19-year-old students attending high schools in Santa Maria, southern Brazil. The participants completed a questionnaire on sociodemographic and behavioral variables. The Oral Health Impact Profile-14 was applied to collect data on oral health-related quality of life (OHRQoL). Clinical examination was used to assess the dental caries status (decayed, missing, and filled teeth index). A cariogenic diet was considered a latent variable measured by the self-perception of a healthy diet and the frequency of consumption of sugary foods and drinks. Structural equation modeling was used to analyze the direct and indirect pathways to a cariogenic diet.

RESULTS

A total of 1197 adolescents were included. Low toothbrushing frequency (standardized coefficient (SC), 0.10; p < 0.05), cigarette smoking (SC, 0.15; p < 0.01), and alcoholic beverages (SC, 0.14; p < 0.01) were directly linked to a cariogenic diet, which, in turn, was directly linked to untreated dental caries (SC, 0.18; p < 0.01) and poor OHRQoL (SC, 0.16; p < 0.01). In addition, household income (via toothbrushing frequency) and age (via alcoholic beverages) were indirectly linked to a cariogenic diet.

CONCLUSION

A cariogenic diet was consistently associated with a range of unhealthy behaviors during adolescence as well as poor household income.

CLINICAL RELEVANCE

Health promotion strategies to restrict sugar consumption and encourage healthier lifestyles should be aware of the synergism observed among unhealthy behaviors during adolescence.

Utility of 'substance use disorder' as a heuristic for understanding overeating and obesity

Rates of obesity and obesity-associated diseases have increased dramatically in countries with developed economies. Substance use disorders (SUDs) are characterized by the persistent use of the substance despite negative consequences. It has been hypothesized that overconsumption of palatable energy dense food can elicit SUD-like maladaptive behaviors that contribute to persistent caloric intake beyond homeostatic need even in the face of negative consequences. Palatable food and drugs of abuse act on many of the same motivation-related circuits in the brain, and can induce, at least superficially, similar molecular, cellular, and physiological adaptations on these circuits. As such, applying knowledge about the neurobiological mechanisms of SUDs may serve as useful heuristic to better understand the persistent overconsumption of palatable food that contributes to obesity. However, many important differences exist between the actions of drugs of abuse and palatable food in the brain. This warrants caution when attributing weight gain and obesity to the manifestation of a putative SUD-related behavioral disorder. Here, we describe similarities and differences between compulsive drug use in SUDs and overconsumption in obesity and consider the merit of the concept of "food addiction".

A High-Sugar Diet Consumption, Metabolism and Health Impacts with a Focus on the Development of Substance Use Disorder: A Narrative Review

Carbohydrates are important macronutrients in human and rodent diet patterns that play a key role in crucial metabolic pathways and provide the necessary energy for proper body functioning. Sugar homeostasis and intake require complex hormonal and nervous control to proper body energy balance. Added sugar in processed food results in metabolic, cardiovascular, and nervous disorders. Epidemiological reports have shown enhanced consumption of sweet products in children and adults, especially in reproductive age and in pregnant women, which can lead to the susceptibility of offspring's health to diseases in early life or in adulthood and proneness to mental disorders. In this review, we discuss the impacts of high-sugar diet (HSD) or sugar intake during the perinatal and/or postnatal periods on neural and behavioural disturbances as well as on the development of substance use disorder (SUD). Since several emotional behavioural disturbances are recognized as predictors of SUD, we also present how HSD enhances impulsive behaviour, stress, anxiety and depression. Apart from the influence of HSD on these mood disturbances, added sugar can render food addiction. Both food and addictive substances change the sensitivity of the brain rewarding neurotransmission signalling. The results of the collected studies could be important in assessing sugar intake, especially via maternal dietary patterns, from the clinical perspective of SUD prevention or pre-existing emotional disorders. Methodology: This narrative review focuses on the roles of a high-sugar diet (HSD) and added sugar in foods and on the impacts of glucose and fructose on the development of substance use disorder (SUD) and on the behavioural predictors of drugs abuse. The literature was reviewed by two authors independently according to the topic of the review. We searched the PubMed and Scopus databases and Multidisciplinary Digital Publishing Institute open access scientific journals using the following keyword search strategy depending on the theme of the chapter: "high-sugar diet" OR "high-carbohydrate diet" OR "sugar" OR "glucose" OR "fructose" OR "added sugar" AND keywords. We excluded inaccessible or pay-walled articles, abstracts, conference papers, editorials, letters, commentary, and short notes. Reviews, experimental studies, and epidemiological data, published since 1990s, were searched and collected depending on the chapter structure. After the search, all duplicates are thrown out and full texts were read, and findings were rescreened. After the selection process, appropriate papers were included to present in this review.

The impulsive horse: comparing genetic, physiological and behavioral indicators to that of human addiction

Stress and genotype elicit changes in impulse control in a range of species that are attributable to adaptations in both the central and peripheral nervous system. We examined aspects of this mechanism in the horse by assessing the effect of a dopamine receptor genotype (DRD4) and central dopaminergic tone (measured via spontaneous blink rate [SBR] and behavioral initiation rate [BIR]), on measures of impulsivity, compulsivity (3-choice serial reaction time task) and sympathetic/ parasympathetic system balance (heart rate variability [HRV]). Genotype did not have a significant effect on any of the parameters measured. SBR but not BIR correlated significantly with levels of impulsivity. There was no clear association of HRV parameters with either measures of central dopaminergic activity or impulsivity/compulsivity. Overall, some elements of the data suggest that the horse may be a useful animal model for assessing the genetic and environmental factors that lead to the physiological and behavioral phenotype of human addiction, particularly when considering the relationship between central dopaminergic tone and impulsivity.

Intermittent sucrose solution intake and its schedule of access modulate energy intake and weight gain in response to chronic variable stress in mice

There is a strong relationship between stress and the intake of calorically-dense palatable food. Additionally, intake of sodas is an important contributory factor to obesity, and is often associated with palatable food consumption. We studied the effects of 2-h intermittent access to sucrose-sweetened water (SSW, 12.3%, soda-like) and its schedule of administration on the response to chronic variable stress in mice fed a high-fat, high-sugar diet. C57BL/6 mice (n = 64) had access to water or to both water and 2-h SSW during 5 weeks, in addition to their diet. After the first two weeks, half of the animals from each group were stressed daily using a chronic variable stress (CVS) paradigm, while the other half were kept undisturbed. During the CVS exposure period, 2-h SSW access was either scheduled randomly, right before the stressors or right after the stressors. The effects of SSW and its schedule of administration on dietary intake, stress hormones and adiposity were analyzed. Results showed a larger consumption of SSW and higher bodyweight gain in mice receiving SSW after the stressor. In addition, SSW consumption was shown to affect appetite regulation by reducing CCK sensitivity. The present study suggests that SSW leads to overconsumption and weight gain only if provided after exposure to stress. These findings may implicate a relation between exposure to stress, binge-drinking behaviors of sugar sweetened beverages that ensues, and weight gain in humans consuming a western diet.

Behavioral plasticity: Role of neuropeptides in shaping feeding responses

Behavioral plasticity refers to changes occurring due to external influences on an organism, including adaptation, learning, memory and enduring influences from early life experience. There are 2 types of behavioral plasticity: "developmental", which refers to gene/environment interactions affecting a phenotype, and "activational" which refers to innate physiology and can involve structural physiological changes of the body. In this review, we focus on feeding behavior, and studies involving neuropeptides that influence behavioral plasticity - primarily opioids, orexin, neuropeptide Y, and oxytocin. In each section of the review, we include examples of behavioral plasticity as it relates to actions of these neuropeptides. It can be concluded from this review that eating behavior is influenced by a number of external factors, including time of day, type of food available, energy balance state, and stressors. The reviewed work underscores that environmental factors play a critical role in feeding behavior and energy balance, but changes in eating behavior also result from a multitude of non-environmental factors, such that there can be no single mechanism or variable that can explain ingestive behavior.

Sucrose solution concentration and the intermittent access induced consumption increase

Animals fed ad libitum consume less of a preferred additional food with daily access than with access only once every few days. With 4% sucrose solution, rats can drink over twice as much in a day if they receive it every fourth day compared to daily access. These differences are maintained when all rats are put on the same schedule. We explored the intermittency effect with 1, 4, 8, and 16% sucrose solutions available for 23 h daily or every third day in adult male rats. The consumption difference was only evident with the 4% solution. In a second experiment with a 16% solution, only a small difference was seen in the first phase. When the sucrose concentration was lowered to 4% in a second phase with alternate day access, the rats with prior every third-day access showed an immediate, pronounced elevation in consumption compared to rats with initial daily access. These results suggest that intermittency induces a long-lasting elevation in the sucrose solution's value for rats, but it may only be evident under the appropriate testing conditions. The relevance of this increased consumption for understanding human obesity and binge eating is discussed.

Bacteroides uniformis CECT 7771 Modulates the Brain Reward Response to Reduce Binge Eating and Anxiety-Like Behavior in Rat

Food addiction (FA) is characterized by behavioral and neurochemical changes linked to loss of food intake control. Gut microbiota may influence appetite and food intake via endocrine and neural routes. The gut microbiota is known to impact homeostatic energy mechanisms, but its role in regulating the reward system is less certain. We show that the administration of Bacteroides uniformis CECT 7771 (B. uniformis) in a rat FA model impacts on the brain reward response, ameliorating binge eating and decreasing anxiety-like behavior. These effects are mediated, at least in part, by changes in the levels of dopamine, serotonin, and noradrenaline in the nucleus accumbens and in the expression of dopamine D1 and D2 receptors in the prefrontal cortex and intestine. B. uniformis reverses the fasting-induced microbiota changes and increases the abundance of species linked to healthy metabolotypes. Our data indicate that microbiota-based interventions might help to control compulsive overeating by modulating the reward response.

Binge eating and psychostimulant addiction

Many of the various factors, characteristics, and variables involved in the addictive process can determine an individual’s vulnerability to develop drug addiction. Hedonic eating, based on pleasure rather than energy needs, modulates the same reward circuits, as do drugs of abuse. According to the last report of the World Health Organization, the worldwide obesity rate has more than doubled since 1980, reaching especially critical levels in children and young people, who are overexposed to high-fat, high-sugar, energy-dense foods. Over the past few decades, there has been an increase in the number of studies focused on how eating disorders can lead to the development of drug addiction and on the comorbidity that exists between the two disorders. Herein, we review the most recent research on the subject, focusing especially on animal models of binge eating disorders and drug addiction. The complex profile of patients with substance use and binge eating disorders requires an integrated response to dually diagnosed patients. Nutritional patterns should be considered an important variable in the treatment of substance use disorders, and future studies need to focus on specific treatments and interventions in individuals who show a special vulnerability to shift from one addiction to the other.

Sucrose drinking mimics effects of nucleus accumbens µ-opioid receptor stimulation on fat intake and brain c-Fos-expression

Objectives: We have previously shown that the combined consumption of fat and a sucrose solution induces overeating, and there is evidence indicating that sucrose drinking directly stimulates fat intake. One neurochemical pathway by which sucrose may enhance fat intake is through the release of endogenous opioids in the nucleus accumbens (NAC).Methods: To test this hypothesis, we provided rats with a free-choice high-fat diet for two weeks. During the second week, rats had access to an additional bottle of water or a 30% sucrose solution for five minutes per day. After these two weeks, we infused vehicle or the μ-opioid receptor agonist [D-Ala2, N-MePhe4, Gly-ol]-enkephalin (DAMGO) into the NAC 30 min after their daily access to the additional bottle of water or the sucrose solution.Results: Sucrose drinking had two effects, (1) it stimulated fat intake in the absence of DAMGO infusion, (2) it diminished sensitivity to DAMGO, as it prevented the rapid increase in fat intake typically seen upon DAMGO infusion in the nucleus accumbens. In a second experiment, we confirmed that these results are not due to the ingested calories of the sucrose solution. Lastly, we investigated which brain areas are involved in the observed effects on fat intake by assessing c-Fos-expression in brain areas previously linked to DAMGO's effects on food intake. Both intra-NAC DAMGO infusion and sucrose consumption in the absence of DAMGO infusion had no effect on c-Fos-expression in orexin neurons and the central amygdala but increased c-Fos-expression in the NAC as well as the basolateral amygdala.Discussion: In conclusion, we confirm that sucrose drinking stimulates fat intake, likely through the release of endogenous opioids.

Fructose and Uric Acid as Drivers of a Hyperactive Foraging Response: A Clue to Behavioral Disorders Associated with Impulsivity or Mania?

Several behavioral disorders, including attention deficit hyperactivity disorder (ADHD), bipolar disorder, and aggressive behaviors are linked with sugar intake and obesity. The reason(s) for this association has been unclear. Here we present a hypothesis supporting a role for fructose, a component of sugar and high fructose corn syrup (HFCS), and uric acid (a fructose metabolite), in increasing the risk for these behavioral disorders. Recent studies have shown that the reason fructose intake is strongly associated with development of metabolic syndrome is that fructose intake activates an evolutionary-based survival pathway that stimulates foraging behavior and the storage of energy as fat. While modest intake may aid animals that would like to store fat as a protective response from food shortage or starvation, we propose that high intake of sugar and HFCS causes a hyperactive foraging response that stimulates craving, impulsivity, risk taking and aggression that increases the risk for ADHD, bipolar disease and aggressive behavior. High glycemic carbohydrates and salty foods may also contribute as they can be converted to fructose in the body. Some studies suggest uric acid produced during fructose metabolism may mediate some of these effects. Chronic stimulation of the pathway could lead to desensitization of hedonic responses and induce depression. In conclusion, a hyperactive foraging response driven by high glycemic carbohydrates and sugars may contribute to affective disorders.

Acute acetate administration increases endogenous opioid levels in the human brain: A [11C]carfentanil molecular imaging study

INTRODUCTION

A recent study has shown that acetate administration leads to a fourfold increase in the transcription of proopiomelanocortin (POMC) mRNA in the hypothalamus. POMC is cleaved to peptides, including β-endorphin, an endogenous opioid (EO) agonist that binds preferentially to the µ-opioid receptor (MOR). We hypothesised that an acetate challenge would increase the levels of EO in the human brain. We have previously demonstrated that increased EO release in the human brain can be detected using positron emission tomography (PET) with the selective MOR radioligand [¹¹C]carfentanil. We used this approach to evaluate the effects of an acute acetate challenge on EO levels in the brain of healthy human volunteers.

METHODS

Seven volunteers each completed a baseline [¹¹C]carfentanil PET scan followed by an administration of sodium acetate before a second [¹¹C]carfentanil PET scan. Dynamic PET data were acquired over 90 minutes, and corrected for attenuation, scatter and subject motion. Regional [¹¹C] carfentanil BP_ND values were then calculated using the simplified reference tissue model (with the occipital grey matter as the reference region). Change in regional EO concentration was evaluated as the change in [¹¹C]carfentanil BP_ND following acetate administration.

RESULTS

Following sodium acetate administration, 2.5-6.5% reductions in [¹¹C]carfentanil regional BP_ND were seen, with statistical significance reached in the cerebellum, temporal lobe, orbitofrontal cortex, striatum and thalamus.

CONCLUSIONS

We have demonstrated that an acute acetate challenge has the potential to increase EO release in the human brain, providing a plausible mechanism of the central effects of acetate on appetite in humans.

Binge sucrose-induced neuroadaptations: A focus on the endocannabinoid system

Binge eating, the defining feature of binge eating disorder (BED), is associated with a number of adverse health outcomes as well as a reduced quality of life. Animals, like humans, selectively binge on highly palatable food suggesting that the behaviour is driven by hedonic, rather than metabolic, signals. Given the links to both reward processing and food intake, this study examined the contribution of the endocannabinoid system (ECS) to binge-like eating in rats. Separate groups were given intermittent (12 h) or continuous (24 h) access to 10% sucrose and food over 28 days, with only the 12 h access group displaying excessive sucrose intake within a discrete period of time (i.e., binge eating). Importantly, this group also exhibited alterations in ECS transcripts and endocannabinoid levels in brain reward regions, including an increase in cannabinoid receptor 1 (CB1R) mRNA in the nucleus accumbens as well as changes in endocannabinoid levels in the prefrontal cortex and hippocampus. We then tested whether different doses (1 and 3 mg/kg) of a CB1R antagonist, Rimonabant, modify binge-like intake or the development of a conditioned place preference (CPP) to sucrose. CB1R blockade reduced binge-like intake of sucrose and blocked a sucrose CPP, but only in rats that had undergone 28 days of sucrose consumption. These findings indicate that sucrose bingeing alters the ECS in reward-related areas, modifications that exacerbate the effect of CB1R blockade on sucrose reward. Overall, our results broaden the understanding of neural alterations associated with bingeing eating and demonstrate an important role for CB1R mechanisms in reward processing. In addition, these findings have implications for understanding substance abuse, which is also characterized by excessive and maladaptive intake, pointing towards addictive-like properties of palatable food.

An open-label trial on the efficacy and tolerability of naltrexone/bupropion SR for treating altered eating behaviours and weight loss in binge eating disorder

PURPOSE

Binge eating disorder (BED) has a considerable clinical relevance by virtue of its high numerous psychiatric and medical comorbidities; among the latter, the most frequent is obesity. Available treatments for BED have shown frequent relapse of binges or weight regain in the long term. The new combination of naltrexone and bupropion sustained release (NB) has proved to be effective for weight loss among obese patients. As NB acts on hypothalamic and reward circuits, that seem involved in the pathogenesis and maintenance of BED symptoms, this study aims to evaluate the efficacy of NB in improving pathological eating behavior and losing weight in BED patients.

METHODS

In this preliminary study, 23 obese-BED patients and a control group of 20 obese non-BED patients (respectively, Groups 1 and 2) who had previously undergone at least 5 unsuccessful weight-loss programs were treated with NB in addition to modified life style. Evaluation at t0 and after 16 weeks of treatment (t1) included anthropometric measurement, eating behavior assessment and psychopathological questionnaires (EDE-Q, BES, YFAS, BDI and STAI).

RESULTS

A significant and similar weight loss (ΔBMI% ≈ 8%) was evident for both groups. Pathological eating behavior (i.e., binge, grazing, emotional eating, craving for carbohydrates, and post-dinner eating), BES score and YFAS severity significantly improved, especially among BED. NB was well tolerated and drop-out rate was low.

CONCLUSION

Treatment with NB, in addition to a reduced-calorie diet and increased physical activity, seems an effective and well-tolerated option for improving pathological eating behavior and losing weight in obese-BED patients.

LEVEL OF EVIDENCE

Level III case-control study.

Adaptive Changes in the Central Control of Energy Homeostasis Occur in Response to Variations in Energy Status

Energy homeostasis is regulated in coordinate fashion by the brain-gut axis, the homeostatic energy balance circuitry in the hypothalamus and the hedonic energy balance circuitry comprising the mesolimbcortical A10 dopamine pathway. Collectively, these systems convey and integrate information regarding nutrient status and the rewarding properties of ingested food, and formulate it into a behavioral response that attempts to balance fluctuations in consumption and food-seeking behavior. In this review we start with a functional overview of the homeostatic and hedonic energy balance circuitries; identifying the salient neural, hormonal and humoral components involved. We then delve into how the function of these circuits differs in males and females. Finally, we turn our attention to the ever-emerging roles of nociceptin/orphanin FQ (N/OFQ) and pituitary adenylate cyclase-activating polypeptide (PACAP)-two neuropeptides that have garnered increased recognition for their regulatory impact in energy homeostasis-to further probe how the imposed regulation of energy balance circuitry by these peptides is affected by sex and altered under positive (e.g., obesity) and negative (e.g., fasting) energy balance states. It is hoped that this work will impart a newfound appreciation for the intricate regulatory processes that govern energy homeostasis, as well as how recent insights into the N/OFQ and PACAP systems can be leveraged in the treatment of conditions ranging from obesity to anorexia.

A narrative review of highly processed food addiction across the lifespan

Evidence is growing that highly processed (HP) foods (i.e., foods high in refined carbohydrates and fat) are highly effective in activating reward systems and may even be capable of triggering addictive processes. Unlike traditional drugs of abuse, exposure to HP foods is common very early in development. HP food addiction has been associated with negative outcomes, including higher body mass index (BMI), more frequent binge eating, greater failure in weight loss treatment trials, and poorer mental and physical health. Although most research on HP food addiction has been conducted using adult samples, research on this topic now spans across the life span beginning in utero and extending through older adulthood. HP food addiction and related reward-based changes are associated with negative outcomes at every life stage, which has important implications for developmentally tailored prevention and treatment efforts. Using a developmentally informed approach, the current study comprehensively reviews the existing research on HP food addiction across the lifespan and highlights important areas of future research.

The FODRAT study (FOod addiction, DRugs, Alcohol and Tobacco): first data on food addiction prevalence among patients with addiction to drugs, tobacco and alcohol

OBJECTIVES

The main focus of this study was to evaluate the prevalence of food addiction (FA) in a population of 575 subjects, all affected by drugs, alcohol and/or tobacco addiction.

METHODS

Patients were enrolled in Addiction Service Centers and 25 items YFAS questionnaire was administered. Prevalence of FA was studied among patients who already have an addiction and then this prevalence was compared between groups of abusers (by type of substance), comparing mono abusers with polyabusers, as well as regressions by age, BMI, sex, through multiple regression analysis.

RESULTS

Prevalence of FA in the sample is 20.17%. Risk of FA increases with the number of substances used (polyabuse). Results show a positive correlation, in addicted people, between BMI values and FA, with significant values (OR 1.08; 95% CI 1.04-1.13; p = 0.006). Age is inversely correlated with FA (OR 0.97; 95% CI 0.95-0.99; p = 0.01). Female sex is positively associated (OR 2.60; 95% CI 1.59-4.27, p = 0.000). No significant association appears with any substance, even if the highest prevalence is recorded among cannabis users (31.03%), and heroin (21.07%), followed by cocaine (18.53%), alcohol (14.49%) and tobacco (11.61%). A comparison between the FA prevalence in our study and that from another study in the Italian general population (11%) shows a significant difference (p < 0.001).

CONCLUSIONS

Prevalence of FA among addicted people is greater than in the general population. Risk of FA increases with the increase in number of used substances (polyabuse). Age is inversely correlated with FA. There is a positive and significant correlation between BMI and FA among substance/tobacco abusers.

LEVEL OF EVIDENCE

Level V, observational cross-sectional descriptive study.

Breaking It Down: Investigation of Binge Eating Components in Animal Models to Enhance Translation

Binge eating (BE) is a core eating disorder behavior that is present across nearly all eating disorder diagnoses (e. g., bulimia nervosa, binge eating disorder, anorexia nervosa binge/purge subtype), and is also widely present in the general population. Despite the prevalence of BE, limited treatment options exist and there are often high rates of relapse after treatment. There is evidence showing that genetic factors contribute to the heritability of BE and support for biological contributions to BE. However, more work is needed to fully understand neurobiological mechanisms underlying BE. One approach to target this problem is to separate BE into its distinct clinical components that can be more easily modeled using pre-clinical approaches. To date, a variety of animal models for BE have been used in pre-clinical studies; but there have been challenges translating this work to human BE. Here, we review these pre-clinical approaches by breaking them down into three clinically-significant component parts (1) consumption of a large amount of food; (2) food consumption within a short period of time; and (3) loss of control over eating. We propose that this rubric identifies the most frequently used and effective ways to model components of BE behavior using pre-clinical approaches with the strongest clinical relevance. Finally, we discuss how current pre-clinical models have been integrated with techniques using targeted neurobiological approaches and propose ways to improve translation of pre-clinical work to human investigations of BE that could enhance our understanding of BE behavior.

Personality traits in substance use disorders and obesity when compared to healthy controls

BACKGROUND AND AIMS

Although personality traits are implicated in substance use disorders (SUDs) and obesity, differences and similarities between them have not been assessed. Our main aim was to compare personality traits between people with different SUDs, obese people and healthy controls.

DESIGN

This was a secondary analysis of personality scores obtained from participants in neuroimaging studies from Brookhaven National Laboratory and the Laboratory of Neuroimaging, National Institutes of Health.

SETTING

United States.

PARTICIPANTS/CASES

Individuals with obesity (OB) n = 41, alcohol use disorder (AUD) n = 39, marijuana use disorder (MUD) n = 24, cocaine use disorder (CUD) n = 100, and healthy controls (HC) n = 117 (237 males and 84 females).

MEASUREMENTS

The Multidimensional Personality Questionnaire, which characterizes positive emotionality (PEM), negative emotionality (NEM) and constraint (CON) traits. Adjusted covariates included cigarette smoking status, age, gender and body mass index (BMI).

FINDINGS

Multivariate analysis of covariance showed a main group effect (i.e. OB, AUD, MUD, CUD and HC) only on NEM (P < 0.0001, η²  = 0.17) and CON (P = 0.005, η²  = 0.12). Specifically, NEM was higher in AUD (P < 0.0001, d = 10.4), CUD (P < 0.0001, d = 8.2) and MUD (P = 0.001, d = 9.2), but not in OB (P > 0.05, d = 2.8) relative to HC. CUD showed lower CON (P = 0.015, d = 5.4) and PEM (P = 0.018, d = 4.8) than HC; however, these differences were not significant in the other groups. NEM and CON were negatively correlated for groups combined (r = -0.26, P < 0.0001), and separately for OB (r = -0.49, P = 0.001) and CUD (r = -0.22, P = 0.03). Cigarette smoking status did not influence group differences in NEM, PEM or CON.

CONCLUSIONS

Compared with healthy controls, people with substance use disorders appear to show higher negative emotionality, and people with cocaine use disorders appear to show lower positive emotionality and constraint traits. Similar findings were not found among people with obesity.

Effect of short-term intake of high- and low-concentrations of sucrose solution on the neurochemistry of male and female mice

The effect of short-term intake of high- and low-concentrations of sucrose solution on the neurochemistry of male and female mice was studied. The body weight, feed intake, sucrose solution consumption and brain monoamine neurotransmitters were determined after 34 days' intake of 1% and 8% sucrose solutions. The gene expression and protein levels related to dopamine and opioids were also determined. The results showed that the intake of 1% and 8% sucrose solution for 34 days did not cause significant changes in the weight development of both male and female mice. The preference for sucrose varies with sex. Both males and females had greater preference for the high concentration sucrose solution than the low concentration sucrose solution. The continuous intake of sucrose stimulated the release of monoamine neurotransmitters (DA, 5-HT, NE) in the brains of mice, and the reward effect of 8% sucrose solution is significantly higher than that of 1% sucrose solution. The sex of mice did not affect the release of neurotransmitters. The gene expressions of D1 and D2 were up-regulated in the 1% sucrose group of male mice, while the OPRM1 gene expression was down-regulated. The expression of these three genes in the 8% sucrose group of male mice was all down-regulated, while the gene expressions of D1 and D2 in the 1% and 8% sucrose group (p < 0.05) of female mice were both up-regulated.

Taste association capabilities differ in high- and low-yawning rats versus outbred Sprague-Dawley rats after prolonged sugar consumption

Yawning is a stereotypical behavior pattern commonly associated with other behaviors such as grooming, sleepiness, and arousal. Several differences in behavioral and neurochemical characteristics have been described in high-yawning (HY) and low-yawning (LY) sublines from Sprague-Dawley (SD) rats that support they had changes in the neural mechanism between sublines. Differences in behavior and neurochemistry observed in yawning sublines could also overlap in processes needed during taste learning, particularly during conditioned taste aversion (CTA) and its latent inhibition. Therefore, the aim of this study was to analyze taste memory differences, after familiarization to novel or highly sweet stimuli, between yawning sublines and compare them with outbred SD rats. First, we evaluated changes in appetitive response during long-term sugar consumption for 14 days. Then, we evaluated the latent inhibition of CTA strength induced by this long pre-exposure, and we also measured aversive memory extinction rate. The results showed that SD rats and the two sublines developed similar CTA for novel sugar and significantly stronger appetitive memory after long-term sugar exposure. However, after 14 days of sugar exposure, HY and LY sublines were unable to develop latent inhibition of CTA after two acquisition trials and had a slower aversive memory extinction rate than outbreed rats. Thus, the inability of the HY and LY sublines to develop latent inhibition of CTA after long-term sugar exposure could be related to the time/context processes involved in long-term appetitive re-learning, and in the strong inbreeding that characterizes the behavioral traits of these sublines, suggesting that inbreeding affects associative learning, particularly after long-term exposure to sweet stimuli which reflects high familiarization.

Neuroendocrine and Metabolic Effects of Low-Calorie and Non-Calorie Sweeteners

Since excessive sugar consumption has been related to the development of chronic metabolic diseases prevalent in the western world, the use of sweeteners has gradually increased worldwide over the last few years. Although low- and non-calorie sweeteners may represent a valuable tool to reduce calorie intake and prevent weight gain, studies investigating the safety and efficacy of these compounds in the short- and long-term period are scarce and controversial. Therefore, future studies will need to elucidate the potential beneficial and/or detrimental effects of different types of sweeteners on metabolic health (energy balance, appetite, body weight, cardiometabolic risk factors) in healthy subjects and patients with diabetes, obesity and metabolic syndrome. In this regard, the impact of different sweeteners on central nervous system, gut hormones and gut microbiota is important, given the strong implications that changes in such systems may have for human health. The aim of this narrative review is to summarize the current evidence for the neuroendocrine and metabolic effects of sweeteners, as well as their impact on gut microbiota. Finally, we briefly discuss the advantages of the use of sweeteners in the context of very-low calorie ketogenic diets.

Maternal Diet Influences the Reinstatement of Cocaine-Seeking Behavior and the Expression of Melanocortin-4 Receptors in Female Offspring of Rats

Recent studies have emphasized the role of the maternal diet in the development of mental disorders in offspring. Substance use disorder is a major global health and economic burden. Therefore, the search for predisposing factors for the development of this disease can contribute to reducing the health and social damage associated with addiction. In this study, we focused on the impact of the maternal diet on changes in melanocortin-4 (MC-4) receptors as well as on behavioral changes related to cocaine addiction. Rat dams consumed a high-fat diet (HFD), high-sugar diet (HSD, rich in sucrose), or mixed diet (MD) during pregnancy and lactation. Using an intravenous cocaine self-administration model, the susceptibility of female offspring to cocaine reward and cocaine-seeking propensities was evaluated. In addition, the level of MC-4 receptors in the rat brain structures related to cocaine reward and relapse was assessed. Modified maternal diets did not affect cocaine self-administration in offspring. However, the maternal HSD enhanced cocaine-seeking behavior in female offspring. In addition, we observed that the maternal HSD and MD led to increased expression of MC-4 receptors in the nucleus accumbens, while increased MC-4 receptor levels in the dorsal striatum were observed after exposure to the maternal HSD and HFD. Taken together, it can be concluded that a maternal HSD is an important factor that triggers cocaine-seeking behavior in female offspring and the expression of MC-4 receptors.

Maternal high-sugar diet changes offspring vulnerability to reinstatement of cocaine-seeking behavior: Role of melanocortin-4 receptors

Maternal diet significantly influences the proper development of offspring in utero. Modifications of diet composition may lead to metabolic and mental disorders that may predispose offspring to a substance use disorder. We assessed the impact of a maternal high-sugar diet (HSD, rich in sucrose) consumed during pregnancy and lactation on the offspring phenotype in the context of the rewarding and motivational effects of cocaine and changes within the central melanocortin (MC) system. Using an intravenous cocaine self-administration model, we showed that maternal HSD leads to increased relapse of cocaine-seeking behavior in male offspring. In addition, we demonstrated that cocaine induces changes in the level of MC-4 receptors in the offspring brain, and these changes depend on maternal diet. These studies also reveal that an MC-4 receptor antagonist reduces the reinstatement of cocaine-seeking behavior, and offspring exposed to maternal HSD are more sensitive to its effects than offspring exposed to the maternal control diet. Taken together, the results suggest that a maternal HSD and MC-4 receptors play an important role in cocaine relapse.

Maternal exercise during gestation and lactation decreases high-fat diet preference by altering central reward system gene expression in adult female offspring from high-fat fed dams

Exposure to maternal high-fat (HF) diet during gestation and lactation alters adult offspring's feeding behavior and diet preference. However, the impact of maternal exercise on offspring's diet preference and reward system development is less studied. In this study, we investigate the effect of perinatal maternal exercise on the development of diet preference, dopamine- and opioid-related gene expression in the central reward system in female offspring from HF-fed Sprague-Dawley rat dams. We found maternal HF diet did not alter adult offspring HF preference, but influenced offspring's dopamine and opioid system both at weaning and in adulthood, and these offspring retained higher body weight in adulthood. However, offspring from dams exposed to both HF diet and exercise during gestation and lactation had normalized body weight, decreased fat mass and lower HF-diet preference but increased energy intake in adulthood. The dopamine- and opioid-related gene expression in central reward system and POMC expression in hypothalamus was elevated in these adult offspring. We conclude that maternal exercise during gestation and lactation can potentially overcome the negative effects of perinatal exposure to HF diet in female offspring by altering their diet preference, central reward system signaling and hypothalamus neuropeptide expression.

The association between banana consumption and the depressive symptoms in Chinese general adult population: A cross-sectional study

BACKGROUND

Banana contains many kinds of substances that are beneficial to depressive symptoms. However, there are no epidemiological researches directly to explore the association between banana consumption and depressive symptoms. This study aimed to investigate whether the banana consumption is related to depressive symptoms in a general adult population.

METHODS

A cross-sectional study was performed in 24,673 adults in Tianjin. Banana consumption was evaluated via a validated food frequency questionnaire. Depressive symptoms were assessed by using Self-Rating Depression Scale (SDS). The association between banana consumption and depressive symptoms was analyzed by multiple logistic regression analysis.

RESULTS

The prevalence of depressive symptoms was 16.1% in males and 18.4% in females (SDS ≥ 45), respectively. In males, comparing to the reference group (almost never), the multivariable adjusted odds ratios (ORs) (95% confidence intervals) of depressive symptoms across banana consumption were 0.86 (0.74, 0.99) for <1 time/week, 0.76 (0.66, 0.88) for 1-3 times/week and 0.97 (0.82, 1.16) for ≥4 times/week. By contrast, the multivariable adjusted ORs (95% confidence intervals) were 1.11 (0.94, 1.32) for <1 time/week, 0.99 (0.85, 1.16) for 1-3 times/week and 1.22 (1.02, 1.46) for ≥4 times/week in females. Similar association was observed when other cut-offs (SDS ≥ 48 and 50) were used to define depressive symptoms.

LIMITATION

This is a cross-sectional study, causality remains unknown.

CONCLUSION

Findings from this study suggested a negative association between moderate banana consumption and depressive symptoms in males. In females, high banana consumption is positively related to depressive symptoms.