Influence of the gut microbiome on appetite-regulating neuropeptides in the hypothalamus: Insight from conventional, antibiotic-treated, and germ-free mouse models of anorexia nervosa.

Recent research highlights the profound impact of the gut microbiome on neuropsychiatric disorders, shedding light on its potential role in shaping human behavior. In this study, we investigate the role of the gut microbiome in appetite regulation using activity-based anorexia (ABA) mouse model of anorexia nervosa (AN) - a severe eating disorder with significant health consequences. ABA was induced in conventional, antibiotic-treated, and germ-free mice. Our results show the clear influence of the gut microbiome on the expression of four orexigenic (neuropeptide Y, agouti-related peptide, melanin-concentrating hormone, and orexin) and four anorexigenic peptides (cocaine- and amphetamine-regulated transcript, corticotropin-releasing hormone, thyrotropin-releasing hormone, and pro-opiomelanocortin) in the hypothalamus. Additionally, we assessed alterations in gut barrier permeability. While variations were noted in germ-free mice based on feeding and activity, they were not directly attributable to the gut microbiome. This research emphasizes that the gut microbiome is a pivotal factor in AN's appetite regulation beyond just dietary habits or physical activity.

Anorexia nervosa: Gut microbiota-immune-brain interactions.

Anorexia nervosa is a psychiatric disorder defined by an extremely low body weight, a devastating fear of weight gain, and body image disturbance, however the etiopathogenesis remains unclear. The objective of the article is to provide a comprehensive review on the potential role of gut microbiota in pathogenesis of anorexia nervosa. Recent advances in sequencing techniques used for microbial detection revealed that this disease is associated with disruption of the composition of normal gut microbiota (dysbiosis), manifested by low microbial diversity and taxonomic differences as compared to healthy individuals. Microorganisms present in the gut represent a part of the so called "microbiota-gut-brain" axis that affect the central nervous system and thus human behavior via the production of various neuroactive compounds. In addition, cells of the immune system are equipped with receptors for these neuroactive substances. Microbiota of the intestinal system also represent a very important antigenic source. These antigens can mimic some host neuropeptides and neurohormones and thus trigger the production of autoantibodies which cross-react with these compounds. The levels and affinities of these antibodies are thought to be associated with neuropsychiatric conditions including anxiety, depression, and eating and sleep disorders. The study of microbiota function in diseases could bring new insights to the pathogenetic mechanisms.

[Changes of plasma obestatin and ghrelin levels after soluble fiber with glucose and after fiber alone in healthy women and in patients with bulimia nervosa]. / Zmeny plazmatických hladin obestatinu a ghrelinu po podání rozpustné vlákniny s glukózou a samotné vlákniny zdravým zenám a pacientkám s bulimia nervosa.

BACKGROUND: The recent identification of obestatin, a novel peptide hormone derived from the same gene as ghrelin, has added further complexity to ghrelin physiology. Despite the rapid progress, many questions remain unanswered, including the regulation of orexigen ghrelin and putative anorexigen obestatin secretion by food composition in humans. The present study was undertaken to investigate the influence of caloric and noncaloric food on plasma ghrelin and obestatin concentrations in healthy women (n = 6; age 23.83 +/- 1.1 years; BMI 20.85 +/- 0.87 kg/m2) and in bulimia nervosa patients (n = 6; age 26.6 +/- 5.2 years; BMI 19.2 +/- 1.44 kg/m2), characterized by abnormal eating behaviour and imbalance in energy homeostasis. METHODS AND RESULTS: After overnight fasting, plasma ghrelin and obestatin were measured by commercial radioimmunoassay kits before and after consumption of soluble fiber alone or with glucose. In both groups plasma ghrelin and obestatin levels did not change after fiber alone, but decreased after fiber with glucose. During 30-90 min after ingestion we observed significant decrease (p < 0.05) of plasma ghrelin and obestatin levels after soluble fiber with glucose in healthy women and also in patients with bulimia nervosa, after then the levels of both hormones started to increase to preprandial levels. CONCLUSIONS: We conclude that postprandial ghrelin and obestatin plasma levels decrease in relation to caloric content of the meal in healthy women and in patients with bulimia nervosa.

Normalizing effect of bright light therapy on temperature circadian rhythm in patients with eating disorders.

OBJECTIVES: Light and food are important synchronizers of circadian rhythmicity. In eating disorders, the circadian rhythms of food intake and temperature are abnormal. METHODS: We analyzed the effect of the morning light application on the circadian rhythm of tympanic temperature and its association with hunger and mood changes in the sample of 25 female patients hospitalized with DSM-IV diagnosis of eating disorders (14 bulimia nervosa and 11 anorexia nervosa) and in 6 healthy women. RESULTS: Light therapy reduced interindividual variability of the temperature acrophase, synchronized the temperature and hunger rhythms and showed an antidepressant effect on patients with eating disorders. Bright light therapy normalized the circadian rhythm of body temperature in both anorexic and bulimic patients: phase advanced rhythm was delayed and phase delayed rhythm was advanced. In contrast with anorexic patients, the majority of bulimic patients had normal temperature rhythm before the therapy and this rhythm was not changed by the therapy. CONCLUSION: The light therapy normalized temperature circadian rhythm in patient with eating disorders. We hypothesize that the light therapy can also contribute to improvement of pathological eating pattern because of the functional connections between light and food entrained oscillators. The light may help to restore the irregular circadian rhythmicity induced by chaotic food intake.