Brain activations show association with subsequent endocrine responses to oral glucose challenge in a satiation-level dependent manner.

Aims: The communication between brain and peripheral homeostatic systems is a central element of ingestive control. We set out to explore which parts of the brain have strong functional connections to peripheral signalling molecules in a physiological context. It was hypothesised that associations can be found between endocrine response to glucose ingestion and preceding brain activity in dependence of the nutritional status of the body. Materials and methods: Young, healthy male participants underwent both a 38 â€‹h fasting and a control condition with standardized meals. On the second day of the experiment, participants underwent fMRI scanning followed by ingestion of glucose solution in both conditions. Subsequent endocrine responses relevant to energy metabolism were assessed. Associations between preceding brain activation and endocrine responses were examined. Results: In both fasting and non-fasting conditions, brain activity was associated with subsequent endocrine responses after glucose administration, but relevant brain areas differed substantially between the conditions. In the fasting condition relations between the caudate nucleus and the orbitofrontal regions with insulin and C-peptide were prevailing, whereas in the non-fasting condition associations between various brain regions and adiponectin and cortisol were the predominant significant outcome. Conclusion: Connections between endocrine response following a glucose challenge and prior brain activity suggests that the brain is playing an active role in the networks regulating food intake and associated endocrine signals. Further studies are needed to demonstrate causation.

Endocrine profile dataset of fasting and normally eating young, healthy men and following activation of brain areas involved in ingestive behaviour.

Data includes endocrine data (adiponectin, ACTH, cortisol, C-peptide, insulin and glucose) of a 38 hour fasting intervention and a control condition with standardised meals in young healthy male subjects. The data was collected using a within-design approach. The data of ten common bilateral regions of interest (ROIs) involved in ingestive behaviour are included as fMRI percent signal change measurements of the amygdala, caudate nucleus, insula (classified into three regions), nucleus accumbens (NAcc), orbitofrontal cortex (OFC, classified into two different regions), pallidum, and lastly, the putamen. These measurements were performed whilst images of food were shown to participants during fMRI who would rate them on a scale from 1 to 8. Reaction times as well as each image's score are also included in the dataset. Endocrine data is especially useful as it is a well-controlled dataset of healthy young males in fasting and satiated conditions. Furthermore, this data can provide a physiological reference for experiments in patients with impaired glucose tolerance or metabolic syndrome. fMRI data may be useful as an extension of an existing dataset or for replication of the collected data.

Modulation of brain activity by hormonal factors in the context of ingestive behaviour.

INTRODUCTION: Metabolic and hormonal signals have been shown to be associated with brain activity in the context of ingestive behaviour. However, this has mostly been seen in studies using external administration of hormones or glucose. We therefore studied endocrine-brain interaction in a physiological setting with hormone levels determined by metabolic conditions such as normal food intake vs. prolonged fasting. METHODS: 24 healthy, normal weight men participated in two sessions, one involving a 38-hour fasting period and one a non-fasting control condition with standardized meals. Functional magnetic resonance imaging was performed at the end of the experiment with participants being required to rate pictures of food. Brain activation was compared between conditions in predefined regions of interest (ROIs). Multiple blood samples were taken to determine levels of insulin, C-peptide, cortisol, ACTH, glucose and adiponectin. These were used as a predictor variable in a regression analysis on brain activations in the different ROIs. RESULTS: Food pictures were rated as more desirable in the fasting condition. Univariate analysis of ROI activations revealed mainly effects of food rating and no significant effects of the metabolic state. Multiple regression analysis revealed associations between orbitofrontal cortex activation and blood glucose in the non-fasting condition. In the fasting condition adiponectin was associated with the signal from the caudate nucleus and insulin and C-peptide were associated with functional activity of orbitofrontal regions. DISCUSSION: Associations of endocrine signals and functional neural regions could be demonstrated in a realistic setting without external administration of hormones. As the current approach was correlational, further studies need to address the causal role of hormonal signals.

Endocrine responses and food intake in fasted individuals under the influence of glucose ingestion.

INTRODUCTION: Different metabolic conditions can affect what and how much we eat. Hormones of glucose metabolism and adipokines such as adiponectin take part in the control of these decisions and energy balance of the body. However, a comprehensive understanding of how these endocrine and metabolic factors influence food intake has not been reached. We hypothesised that the amount of food a person consumes differs substantially after a fasting period even after the energy deficit was partially removed by glucose ingestion and endocrine signals like insulin and C-peptide indicated a high glucose metabolic status. Furthermore, the macronutrient composition of the consumed food and a possible association with adiponectin under the influence of glucose ingestion was assessed. METHODS: In a within-subject design, 24 healthy males participated in both a fasting (42 h) and control (non-fasting) condition. A total of 20 blood samples from each subject were collected during each condition to assess serum levels of adiponectin, insulin, C-peptide, cortisol and ACTH. At the end of each condition food intake was measured with an ad libitum buffet after the acute energy deficit was compensated using a carbohydrate-rich drink. RESULTS: The total amount of caloric intake and single macronutrients was higher after the fasting intervention after replenishment with glucose. All recorded hormone levels, except for adiponectin, were significantly different for at least one of the study intervals. The relative proportions of the macronutrient composition of the consumed food were stable in both conditions under the influence of glucose ingestion. In the non-fasting condition, the relative amount of protein intake correlated with adiponectin levels during the experiment. DISCUSSION AND CONCLUSION: An anabolic glucose metabolism after glucose ingestion following a fasting intervention did not even out energy ingestion compared to a control group with regular food intake and glucose ingestion. Anorexigenic hormones like insulin in this context were not able despite higher levels than in the control condition to ameliorate the drive for food intake to normal or near normal levels. Relative macronutrient intake remains stable under these varying metabolic conditions and glucose influence. Serum adiponectin levels showed a positive association with the relative protein intake in the non-fasting condition under the influence of glucose although adiponectin levels overall did not differ in between the conditions.