Reduced phasic dopamine release and slowed dopamine uptake occur in the nucleus accumbens after a diet high in saturated but not unsaturated fat.

High-fat diets are linked with obesity and changes in dopamine neurotransmission. Mounting evidence shows that saturated fat impacts dopamine neurons and their terminal fields, but little is known about the effect a diet high in unsaturated fat has on the dopamine system. This study sought to determine whether fat type, saturated vs. unsaturated, differentially affected body weight, blood glucose regulation, locomotor behavior, and control of dopamine release and uptake at dopamine neuron terminals in the nucleus accumbens (NAc). C57BL/6 mice were fed a control diet or a nutrient-matched diet high in saturated fat (SF), unsaturated flaxseed oil (Flax) or a blend of the two fats. After 6-weeks, mice from each high-fat diet group gained significantly more weight than Controls, but the group fed Flax gained less weight than the SF group and had fasting blood glucose levels similar to Controls. Ex-vivo fast scan cyclic voltammetry revealed the SF group also had significantly slower synaptic dopamine clearance and a reduced capacity for phasic dopamine release in the nucleus accumbens (NAc), but the Flax and Blend groups resembled Controls. These data show that different types of dietary fat have substantially different effects on metabolic phenotype and influence how dopamine terminals in the NAc regulate dopamine neurotransmission. Our data also suggests that a diet high in unsaturated fat may preserve normal metabolic and behavioral parameters as well as dopamine signaling in the NAc.

The Nourish Protocol: A digital health randomized controlled trial to promote the DASH eating pattern among adults with hypertension.

INTRODUCTION: Over 100 million adults in the United States have hypertension. The DASH (Dietary Approaches to Stop Hypertension) eating pattern is an evidence-based first-line treatment option for hypertension; however, adherence to the DASH eating pattern at a population level remains low. To address this gap, we will implement Nourish, a randomized controlled efficacy trial that will leverage a commercially-available smartphone application and evidence-based behavior change principles to improve adherence to the DASH eating pattern among adults with hypertension. METHODS: The Nourish trial is a two-arm, 12-month randomized control trial that will enroll adults (N = 300) with hypertension, defined as a systolic blood pressure of 120-159 mmHg; a diastolic blood pressure of 80-99 mmHg; and/or adults on blood pressure-lowering medication. Nourish will test the efficacy of a digital health intervention, as compared to the attention control arm, on DASH eating pattern adherence and blood pressure. Intervention components will include skills training, self-monitoring, personalized feedback, and responsive coaching. The primary outcome of the trial is 6-month changes in adherence to the DASH eating pattern, as measured by 24-h dietary recalls. DISCUSSION: Millions of Americans remain in need of effective behavioral interventions to manage and improve their hypertension and its adverse consequences. The ubiquity of smartphones offers a promising approach to disseminate the DASH eating pattern. By leveraging these widely used smartphone applications, combined with evidence-based behavior change principles and the DASH eating plan, Nourish will demonstrate the effectiveness of a digital health intervention to improve DASH adherence, and ultimately, to reduce blood pressure. Trial Number: NCT03875.