Bariatric surgery and the central nervous system

Effects of Probiotic Supplementation Added to a Weight Loss Program on Anthropometric Measures, Body Composition, Eating Behavior, and Related Hormone Levels in Patients with Food Addiction and Weight Regain After Bariatric Surgery: A Randomized Clinical Trial

PURPOSE

Weight regain after metabolic bariatric surgery is a common problem. Food addiction is an eating disorder that can be one of the reasons for weight regain in these patients. This study aimed to evaluate the effects of probiotic supplementation with a weight loss program and cognitive behavioral therapy (CBT) on anthropometric measures, eating behavior, food addiction, and related hormone levels, in patients with food addiction and weight regain after metabolic bariatric surgery.

MATERIALS AND METHODS

This randomized, triple-blind, placebo-controlled clinical trial was conducted on patients with food addiction and weight regain after metabolic bariatric surgery. Participants (n = 50) received a weight loss program and CBT plus probiotic, or placebo for 12 weeks. Then, anthropometric measurements, biochemical markers, eating behavior, and food addiction were assessed.

RESULTS

Weight and body mass index (BMI) decreased significantly in the probiotic group compared to placebo (p = 0.008, p = 0.001, respectively). Fat mass was significantly decreased in the probiotic group (p < 0.001). Moreover, a significant improvement was observed in the probiotic group's eating behavior and food addiction compared to the placebo group (p < 0.001). Serum levels of leptin decreased significantly (p = 0.02), and oxytocin serum levels increased significantly (p = 0.008) in the probiotic group compared to the placebo group.

CONCLUSION

Adding probiotic supplements to the weight loss program and CBT is superior to the weight loss program and CBT alone in improving weight loss, eating behavior, and food addiction in patients with food addiction and weight regain after metabolic bariatric surgery.

Effects of probiotic supplementation with weight reducing intervention on anthropometric measures, body composition, eating behavior, and related hormone levels in patients with food addiction and weight regain after bariatric surgery: a study protocol for a randomized clinical trial

BACKGROUND

One of the unfortunate events after bariatric surgery is the weight regain, which occurs in some patients. Food addiction is an eating disorder related to the brain-intestinal axis and can be effective in weight regain after bariatric surgery. In addition, the gut microbiome plays a vital role in eating behaviors, including food addiction. So, this study will aim to evaluate the effects of probiotic supplementation with a weight-reducing diet and cognitive behavioral therapy on anthropometric measures, body composition, eating behavior, and related hormone levels, leptin, oxytocin, and serotonin, in patients with food addiction and weight regain after bariatric surgery.

METHODS

We will carry out a triple-blinded randomized clinical trial for 12 weeks to evaluate the effect of probiotic supplementation with a weight-reducing diet and cognitive behavioral therapy on anthropometric measures, body composition, eating behavior, and related hormone levels including leptin, oxytocin, and serotonin, in patients with food addiction and weight regain after bariatric surgery.

DISCUSSION

Based on the available evidence, probiotic supplementation by modifying the intestinal microbiome can improve food addiction and subsequent weight loss.

TRIAL REGISTRATION

Iranian Registry of Clinical Trials IRCT20220406054437N1 Registered on 2022-06-01.

Habenular connectivity predict weight loss and negative emotional-related eating behavior after laparoscopic sleeve gastrectomy

Habenular (Hb) processes negative emotions that may drive compulsive food-intake. Its functional changes were reported following laparoscopic-sleeve-gastrectomy (LSG). However, structural connectivity (SC) of Hb-homeostatic/hedonic circuits after LSG remains unclear. We selected regions implicated in homeostatic/hedonic regulation that have anatomical connections with Hb as regions-of-interest (ROIs), and used diffusion-tensor-imaging with probabilistic tractography to calculate SC between Hb and these ROIs in 30 obese participants before LSG (PreLSG) and at 12-month post-LSG (PostLSG12) and 30 normal-weight controls. Three-factor-eating-questionnaire (TFEQ) and Dutch-eating-behavior-questionnaire (DEBQ) were used to assess eating behaviors. LSG significantly decreased weight, negative emotion, and improved self-reported eating behavior. LSG increased SC between the Hb and homeostatic/hedonic regions including hypothalamus (Hy), bilateral superior frontal gyri (SFG), left amygdala (AMY), and orbitofrontal cortex (OFC). TFEQ-hunger negatively correlated with SC of Hb-Hy at PostLSG12; and increased SC of Hb-Hy correlated with reduced depression and DEBQ-external eating. TFEQ-disinhibition negatively correlated with SC of Hb-bilateral SFG at PreLSG. Increased SC of Hb-left AMY correlated with reduced DEBQ-emotional eating. Higher percentage of total weight-loss negatively correlated with SC of Hb-left OFC at PreLSG. Enhanced SC of Hb-homeostatic/hedonic regulatory regions post-LSG may contribute to its beneficial effects in improving eating behaviors including negative emotional eating, and long-term weight-loss.

Cerebral effects of glucagon-like peptide-1 receptor blockade before and after Roux-en-Y gastric bypass surgery in obese women: A proof-of-concept resting-state functional MRI study

AIM

To assess the effects of Roux-en-Y gastric bypass surgery (RYGB)-related changes in glucagon-like peptide-1 (GLP-1) on cerebral resting-state functioning in obese women.

MATERIALS AND METHODS

In nine obese females aged 40-54 years in the fasted state, we studied the effects of RYGB and GLP-1 on five a priori selected networks implicated in food- and reward-related processes as well as environment monitoring (default mode, right frontoparietal, basal ganglia, insula/anterior cingulate and anterior cingulate/orbitofrontal networks).

RESULTS

Before surgery, GLP-1 receptor blockade (using exendin9-39) was associated with increased right caudate nucleus (basal ganglia network) and decreased right middle frontal (right frontoparietal network) connectivity compared with placebo. RYGB resulted in decreased right orbitofrontal (insula/anterior cingulate network) connectivity. In the default mode network, after surgery, GLP-1 receptor blockade had a larger effect on connectivity in this region than GLP-1 receptor blockade before RYGB (all P_FWE  < .05). Results remained similar after correction for changes in body weight. Default mode and right frontoparietal network connectivity changes were related to changes in body mass index and food scores after RYGB.

CONCLUSIONS

These findings suggest GLP-1 involvement in resting-state networks related to food and reward processes and monitoring of the internal and external environment, pointing to a potential role for GLP-1-induced changes in resting-state connectivity in RYGB-mediated weight loss and appetite control.

Bariatric Surgery for Treatment of Hypothalamic Obesity After Craniopharyngioma Therapy: a Matched Case-Control Study

Craniopharyngioma and its treatment lead to weight gain and pituitary hormone deficiencies. This study aimed to investigate the effectiveness of bariatric surgery for treatment of hypothalamic obesity after craniopharyngioma therapy. Five patients with hypothalamic obesity after craniopharyngioma treatment were included. Patients were treated with sleeve gastrectomy or Roux-en-Y gastric bypass and individually matched to 2 control patients treated for common obesity. At 2 years of follow-up, total and excess weight loss in cases were 14.7% (p = 0.002) and 38.0% (p = 0.001), respectively; differences between both groups were 13.6% (p = 0.02) and 31.6% (p = 0.03). Minor postoperative alterations in hormone substitution in all 5 cases were observed. Thus, bariatric surgery induced significant weight loss in patients with craniopharyngioma-related hypothalamic obesity, even though a superior weight loss in controls was observed.

Mechanisms of Weight Loss After Sleeve Gastrectomy and Adjustable Gastric Banding: Far More Than Just Restriction

Obesity has reached global epidemic proportions in recent decades. Bariatric surgery is currently accepted as most effective in alleviating morbid obesity and related disorders. Sleeve gastrectomy (SG) and adjustable gastric banding (AGB) have gained popularity since the beginning of this century because of their efficacy, safety, and simplicity. SG, in particular, has emerged as the most popular bariatric procedure because of its simpler concept and shorter operative time compared with gastric bypass. Caloric restriction, however, cannot account for the sustained weight loss and improved glucose metabolism seen following SG and AGB. Other mechanisms, including changes in gastrointestinal hormone secretion, rearrangement of hypothalamic and vagal control, alteration in energy expenditure, and re-regulation of bile acid metabolism and the intestinal flora environment, are thought to contribute to the postoperative benefits. This review focuses on clinical and experimental literature addressing the potential mechanisms for SG and AGB procedures in human and animal models. Understanding such mechanisms can provide important insight into how current gastric restrictive procedures work and how future treatments of obesity, both surgical and nonsurgical, can be developed.

Taste Changes after Bariatric Surgery: a Systematic Review

BACKGROUND

Alterations in taste perception and preferences may contribute to dietary changes and subsequent weight loss following bariatric surgery.

METHODS

A systematic search was performed to identify all articles investigating gustation, olfaction, and sensory perception in both animal and human studies following bariatric procedures.

RESULTS

Two hundred fifty-five articles were identified after database searches, bibliography inclusions and deduplication. Sixty-one articles were included. These articles provide evidence supporting changes in taste perception and hedonic taste following bariatric procedures. Taste sensitivity to sweet and fatty stimuli appears to increase post-operatively. Additionally, patients also have a reduced hedonic response to these stimuli.

CONCLUSIONS

Available evidence suggests that there is a change in taste perception following bariatric procedures, which may contribute to long-term maintenance of weight loss following surgery.

Interventions for the Treatment of Craniopharyngioma-Related Hypothalamic Obesity: A Systematic Review

OBJECTIVE

Craniopharyngiomas (CPs) and their treatment are associated with hypothalamic damage that causes hypothalamic obesity (HO) in 30%-70% of cases. Thus, there is ongoing research regarding tangible solutions for HO, because these patients have unrelenting resistance to basic weight-loss interventions. This review aims to summarize the interventions that are used to treat CP-related HO (CP-HO), including pharmacotherapy and bariatric surgery.

METHODS

The Cochrane Library, EMBASE, and PubMed databases were searched up to June 2017 for relevant reports. Two reviewers conducted independent evaluations of the studies identified.

RESULTS

Eighteen articles were included in the systematic review, with 3 reports describing pharmacotherapy in randomized controlled trials and 15 reports describing bariatric surgery. Although several studies described effective interventions for treating CP-HO, the evidence base was limited by its low quality and our inability to perform a meta-analysis, which was related to a lack of adequate or integrated data.

CONCLUSIONS

Octreotide appears to be a preferred treatment for patients with CP-HO, based on limited data. Gastric bypass surgery may also be suitable for select patients with CP-HO, based on a review of various procedures in this setting. Microsurgical preservation of the hypothalamic structures is mandatory to decrease CP-HO-related morbidity and mortality. Further studies with adequate analytical power and sufficient follow-up are needed to identify effective strategies for CP-HO treatment.

Elevated Postoperative Endogenous GLP-1 Levels Mediate Effects of Roux-en-Y Gastric Bypass on Neural Responsivity to Food Cues

OBJECTIVE

It has been suggested that weight reduction and improvements in satiety after Roux-en-Y gastric bypass (RYGB) are partly mediated via postoperative neuroendocrine changes. Glucagon-like peptide-1 (GLP-1) is a gut hormone secreted after food ingestion and is associated with appetite and weight reduction, mediated via effects on the central nervous system (CNS). Secretion of GLP-1 is greatly enhanced after RYGB. We hypothesized that postoperative elevated GLP-1 levels contribute to the improved satiety regulation after RYGB via effects on the CNS.

RESEARCH DESIGN AND METHODS

Effects of the GLP-1 receptor antagonist exendin 9-39 (Ex9-39) and placebo were assessed in 10 women before and after RYGB. We used functional MRI to investigate CNS activation in response to visual food cues (pictures) and gustatory food cues (consumption of chocolate milk), comparing results with Ex9-39 versus placebo before and after RYGB.

RESULTS

After RYGB, CNS activation was reduced in the rolandic operculum and caudate nucleus in response to viewing food pictures (P = 0.03) and in the insula in response to consumption of palatable food (P = 0.003). GLP-1 levels were significantly elevated postoperatively (P < 0.001). After RYGB, GLP-1 receptor blockade resulted in a larger increase in activation in the caudate nucleus in response to food pictures (P = 0.02) and in the insula in response to palatable food consumption (P = 0.002).

CONCLUSIONS

We conclude that the effects of RYGB on CNS activation in response to visual and gustatory food cues may be mediated by central effects of GLP-1. Our findings provide further insights into the mechanisms underlying the weight-lowering effects of RYGB.

Olfactory and Gustatory Function After Bariatric Surgery

BACKGROUND

Neither hormone levels nor malabsorption alone fully explains the distinct weight loss after bariatric surgery in morbidly obese patients. Postoperatively, patients regularly report a change in the sense of taste and the development of food aversions. Hedonic and sensory components like olfactory and gustatory stimuli significantly affect appetite and flavour.

METHODS

We prospectively analysed the orthonasal olfactory and gustatory function with psychophysical testing in 44 patients undergoing laparoscopic Roux-en-Y gastric bypass (RYGB), sleeve gastrectomy (SG) or adjustable gastric banding (AGB) and in 23 healthy controls.

RESULTS

About 22.7 % of morbidly obese patients were hyposmic, showing significantly lower threshold-discrimination-identification (TDI) scores (p = 0.009) with decreased discrimination and identification ability. In addition, 22.7 % of patients were tested to be limited in gustatory function, with significantly lower taste strip test (TST) scores (p = 0.003). Six months after surgery, olfactory and gustatory function was not different when compared to healthy controls.

CONCLUSIONS

Due to obesity, patients frequently show impaired olfactory and gustatory function. Six months after laparoscopic bariatric surgery, both chemosensory functions improve. The TDI test is an appropriate tool to measure olfactory function in obese patients.

Bariatric surgery: beta cells in type 2 diabetes remission

Bariatric surgery is a new emerging treatment that demonstrates a favourable effect on type 2 diabetes, although its underlying mechanisms still remain unknown. After receiving bariatric surgery, beta cells undergo the process of rebirth, which involves apoptosis evasion, regeneration and improved beta-cell function. Therefore, further studies are necessary to elucidate how bariatric surgery can resolve type 2 diabetes. Here, our review focuses mainly on beta cells, the insulin-generating cells, whose biological features change dramatically after bariatric surgery. Copyright © 2015 John Wiley & Sons, Ltd.

Obesity surgery and Ramadan: a prospective analysis of nutritional intake, hunger and satiety and adaptive behaviours during fasting

BACKGROUND

Fasting for religious or lifestyle reasons poses a challenge to people who have undergone bariatric surgery. A total fast (abstaining from all forms of nourishment including liquids) during long summer days puts these patients at risk of dehydration and poor calorie and nutrient intake.

METHODS

We undertook telephone surveys of 24-h food recall, hunger and satiety scores, medication use, adverse symptoms and depression scores on a fasting day in Ramadan and a non-fasting day subsequently.

RESULTS

We studied 207 participants (166 women) who had undergone sleeve gastrectomy. The mean (standard error) age was 35.2 (0.7) years. Men and women consumed 20.4 % (P = 0.018) and 16.9 % (P < 0.001) fewer calories and 44.8 % (P < 0.001) and 32.4 % (P < 0.001) less protein during fasting, respectively. There was no significant difference in the intake of fluids or incidence of adverse gastrointestinal, hypoglycaemic and sympathoadrenal symptoms. Of participants on pharmacotherapy, 89.5 % took their prescribed medications; 86.3 % made no changes to the doses, but 80.4 % changed the timing of the medications. Both women and men reported feeling less hungry and a preference for savoury foods during Ramadan. There was no difference in depression and work impairment scores.

CONCLUSIONS

Fasting was well tolerated in persons who had undergone sleeve gastrectomy. It may be advisable to raise awareness about dietary protein intake and managing medications appropriately during fasting.

Obesity: pathophysiology and intervention

Obesity presents a major health hazard of the 21st century. It promotes co-morbid diseases such as heart disease, type 2 diabetes, obstructive sleep apnea, certain types of cancer, and osteoarthritis. Excessive energy intake, physical inactivity, and genetic susceptibility are main causal factors for obesity, while gene mutations, endocrine disorders, medication, or psychiatric illnesses may be underlying causes in some cases. The development and maintenance of obesity may involve central pathophysiological mechanisms such as impaired brain circuit regulation and neuroendocrine hormone dysfunction. Dieting and physical exercise offer the mainstays of obesity treatment, and anti-obesity drugs may be taken in conjunction to reduce appetite or fat absorption. Bariatric surgeries may be performed in overtly obese patients to lessen stomach volume and nutrient absorption, and induce faster satiety. This review provides a summary of literature on the pathophysiological studies of obesity and discusses relevant therapeutic strategies for managing obesity.

Striatal dopamine homeostasis is altered in mice following Roux-en-Y gastric bypass surgery

Roux-en-Y gastric bypass (RYGB) is an effective treatment for obesity. Importantly, weight loss following RYGB is thought to result in part from changes in brain-mediated regulation of appetite and food intake. Dopamine (DA) within the dorsal striatum plays an important role in feeding behavior; we therefore hypothesized that RYGB alters DA homeostasis in this subcortical region. In the current study, obese RYGB-operated mice consumed significantly less of a high-fat diet, weighed less by the end of the study, and exhibited lower adiposity than obese sham-operated mice. Interestingly, both RYGB and caloric restriction (pair feeding) resulted in elevated DA and reduced norepinephrine (NE) tissue levels compared with ad libitum fed sham animals. Consequently, the ratio of NE to DA, a measure of DA turnover, was significantly reduced in both of these groups. The RYGB mice additionally exhibited a significant increase in phosphorylation of tyrosine hydroxylase at position Ser31, a key regulatory site of DA synthesis. This increase was associated with augmented expression of extracellular-signal-regulated kinases ERK1/2, the kinase targeting Ser31. Additionally, RYGB has been shown in animal models and humans to improve insulin sensitivity and glycemic control. Curiously, we noted a significant increase in the expression of insulin receptor-β in RYGB animals in striatum (a glucosensing brain region) compared to sham ad libitum fed mice. These data demonstrate that RYGB surgery is associated with altered monoamine homeostasis at the level of the dorsal striatum, thus providing a critical foundation for future studies exploring central mechanisms of weight loss in RYGB.

The neuropathology of obesity: insights from human disease

Obesity, a pathologic state defined by excess adipose tissue, is a significant public health problem as it affects a large proportion of individuals and is linked with increased risk for numerous chronic diseases. Obesity is the result of fundamental changes associated with modern society including overnutrition and sedentary lifestyles. Proper energy homeostasis is dependent on normal brain function as the master metabolic regulator, which integrates peripheral signals, modulates autonomic outflow and controls feeding behavior. Therefore, many human brain diseases are associated with obesity. This review explores the neuropathology of obesity by examining brain diseases which either cause or are influenced by obesity. First, several genetic and acquired brain diseases are discussed as a means to understand the central regulation of peripheral metabolism. These diseases range from monogenetic causes of obesity (leptin deficiency, MC4R deficiency, Bardet-Biedl syndrome and others) to complex neurodevelopmental disorders (Prader-Willi syndrome and Sim1 deficiency) and neurodegenerative conditions (frontotemporal dementia and Gourmand's syndrome) and serve to highlight the central regulatory mechanisms which have evolved to maintain energy homeostasis. Next, to examine the effect of obesity on the brain, chronic neuropathologic conditions (epilepsy, multiple sclerosis and Alzheimer's disease) are discussed as examples of obesity leading to maladaptive processes which exacerbate chronic disease. Thus, obesity is associated with multiple pathways including abnormal metabolism, altered hormonal signaling and increased inflammation which act in concert to promote downstream neuropathology. Finally, the effect of anti-obesity interventions is discussed in terms of brain structure and function. Together, understanding human diseases and anti-obesity interventions leads to insights into the bidirectional interaction between peripheral metabolism and central brain function, highlighting the need for continued clinicopathologic and mechanistic studies of the neuropathology of obesity.

Potential mechanisms by which bariatric surgery improves systemic metabolism

Over the past several decades, excessive body weight has become a major health concern. As the obesity epidemic continues to expand, metabolic disorders associated with excess body weight, including type 2 diabetes, dyslipidemia, hypertension, and cardiovascular disease, have exponentially increased. Dysregulation of satiety hormones and factors that regulate long-term energy storage can disrupt normal metabolic functions and lead to excess body fat. While diet and exercise seem to provide a logical means for weight loss, an unhealthy lifestyle coupled to responses initiated by perceived energy deficit impede sustained long term weight loss. Furthermore, because of the additional lack of effective pharmaceutical interventions to treat excess body weight, patients with severe obesity resort to bariatric surgery as an effective alternative for treatment of obesity and resolution of its associated comorbidities. Interestingly, the precise method by which bariatric surgery promotes rapid improvement in systemic metabolism and long-term weight loss remains incompletely understood and may vary between procedures. Multiple mechanisms likely contribute to the improved glucose metabolism seen after bariatric surgery, including caloric restriction, changes in the enteroinsular axis, alterations in the adipoinsular axis, release of nutrient-stimulated hormones from endocrine organs, stimulation from the nervous system, and psychosocial aspects including a dramatic improvement in quality of life. The current review will highlight the potential contribution of these responses to the improvement in systemic energy metabolism elicited by bariatric surgery.