Nicholas T. Bello - US grants

[unreadable] DESCRIPTION (provided by applicant): The postingestive effects of a meal can have a substantial influence on that meal's preference value. This influence is most likely mediated by the interaction between peripheral metabolic signals and the neural mechanisms controlling feeding behavior. The current project aims to investigate the effects of peripheral insulin on the central motivational system. The proposed hypothesis is that elevated plasma insulin facilitates the release of dopamine in the nucleus accumbens of the rat. This hypothesis will be tested by using in vivo microdialysis to assess dopamine release in combination with a hyperinsulinemic-euglycemic clamping technique to accurately determine insulin's effects by controlling for insulin-induced hypoglycemia. Thus, this approach will not only allow for an examination of the concentration effects of peripheral insulin on dopamine release (Specific Aim I), but will provide a means for investigating whether insulin's modulation of food-related dopamine release affects food preference (Specific Aim II). Furthermore, the specificity of insulin's effects on dopamine release will be verified by using in vitro voltammetry in an accumbens slice preparation (Specific Aim III). Insulin's modulation of food-related dopamine release may serve to increase the positive effects of palatable foods to contribute to pathological overeating and diet-induced obesity. [unreadable] [unreadable]

[unreadable] DESCRIPTION (provided by applicant): Binge eating is a prominent characteristic of most eating disorders. A history of caloric restriction and the over-consumption of highly palatable foods are two main variables that participate in the state-dependent perpetuation of bingeing behavior. The objective of the current project is to investigate alterations that occur in the mu-opioid control of the caudal brainstem function in female rats exposed to a repeated cycle of calorie restriction and access to palatable foods. The proposed hypothesis is that a history of binge-like eating results in alterations in gastrointestinal sensory feedback, which are mediated, in part, through central opioid mechanisms. The hypothesis will be tested by using in situ hybridization labeling of the mu-opioid receptor mRNA, immunohistochemical staining of the protein product of the early immediate gene, c-Fos, and neuro-electrophysiological techniques. These approaches will allow us to determine how binge-like eating alters caudal brai nstem mu-opioid receptors (Specific Aim 1). In addition, we will determine how central mu-opioid activity alters feeding, neuronal activation (Specific Aim 2), and single unit activity of GI responsive neurons in the nucleus of the solitary tract to gastric loads (Specific Aim 3). The long-term objective of this line of research is to understand how repeated cycles of calorie restriction and access to palatable foods leads to alterations in the neural mechanisms involved in the homeostatic processes of food intake. This project is unique in that it will assess the caudal brainstem sensory adaptations to the maintenance of binge-like eating. The findings from this project, therefore, will be especially relevant for the identification of sustaining factors and potential treatments for binge-related eating disorders, bulimia nervosa (BN) and binge eating disorder (BED).

Obesity is a risk factor for several preventable diseases. In recent years, there has been a dramatic rise in the consumer use of dietary supplements for weight management. Raspberry ketone [4-(p-hydroxyphenyl)-2-butanone] is derived from the fruit of the red raspberry (Rubus idaeus) and has purported antiobesity properties. Despite the supplement's consumer popularity, raspberry ketone has not been systematically tested to determine effectiveness for weight loss. The overall objective of this project is to determine the mechanisms by which raspberry ketone decreases feeding and prevents the metabolic consequences of diet-induced obesity. The central hypothesis of this project that raspberry ketone has a dual action to suppress feeding by activation of transient receptor potential cation channel subfamily V member 1 (TRPV1) channels and to increase fat oxidation mediated by peroxisome proliferator- activated receptor (PPAR) alpha pathways. This proposal will use diet-induced obese (DIO) mice to investigate the acute and long-term effects of raspberry ketone on body weight homeostasis and metabolic signatures. Aim 1 will determine the mechanism(s) by which raspberry ketone suppresses feeding. This will include caloric intake and meal patterns, gene expression of gastrointestinal and hypothalamic feeding-related signals, circulating hormones, and potential for hepatic and intestinal pathology. Aim 2 will determine the mechanism(s) by which raspberry ketone influences metabolic outcomes. This will include measuring energy expenditure, thermoregulatory activity, hemodynamic parameters, and glucose homeostasis. Aim 3 will determine the bioacessibility of raspberry ketone using a functional model of the human digestive system (TNO intestinal model) and in vivo animal model to determine the metabolism and bioavailability of raspberry ketone. The findings from these studies will identify the in vivo mechanisms of preventative actions of raspberry ketone on weight gain and other obesity-related outcomes. The proposed project is relevant to the overall NIH goal of enhancing translational research by providing critical mechanistic data on a commonly used dietary supplement.

PROJECT SUMMARY Raspberry ketone [4-(p-hydroxyphenyl)-2-butanone] (RK) is the principal naturally occurring aroma compound from the fruit of red raspberries (Rubus idaeus L.). Currently, RK is marketed and sold in the US as a popular dietary supplement for the management of body weight. One of the primary aims of the parent grant is to examine the bioavailability and metabolic fates of RK in mouse models. The objective of this supplement is to optimize and fully validate our comprehensive analytical methods integrating liquid-liquid phenolic extraction, microelution solid-phase extraction (µSPE), lipid removal and sample clean-up, and targeted metabolomics using UHPLC-QqQ- MS/MS, for efficient and reliable analysis of RK and its metabolites in plasma, brain, liver and WAT specimens to support the RK pharmacokinetic and bioavailability studies. For the proposed supplement project, first we will further optimize the method developed for bioanalysis of plasma and expand the application to the lipid-rich tissues e.g. brain, liver and white adipose tissue (WAT) (Aim 1); we will then conduct full validation for the methods developed including the reliability characteristics of Limit of detection (LOD), Limit of quantification (LOQ), Calibration linearity, Compound stability, Accuracy, Repeatability/Precision, Recovery, and Matrix effects following the FDA's Bioanalytical Method Validation Guidance for Industry (Aim 2). Outcomes from this Administrative Supplement studies will ensure sensitive, accurate and reproducible quantitative analysis of RK and derived metabolites following oral administration of RK in obesity prevention and provide innovative and reliable approaches for others to examine RK and RK structurally-related phenolics in RK-enriched botanical preparations in vivo. The proposed project is also relevant to the overall NIH goal of supporting the performance and publication of formal single-laboratory validation studies of quantitative analytical methods.