Manganese-Enhanced Magnetic Resonance Imaging for Mapping of Whole Brain Activity Patterns Associated with the Intake of Snack Food in Ad Libitum Fed Rats

Abstract

Non-homeostatic hyperphagia, which is a major contributor to obesity-related hyperalimentation, is associated with the diet’s molecular composition influencing, for example, the energy content. Thus, specific food items such as snack food may induce food intake independent from the state of satiety. To elucidate mechanisms how snack food may induce non-homeostatic food intake, it was tested if manganese-enhanced magnetic resonance imaging (MEMRI) was suitable for mapping the whole brain activity related to standard and snack food intake under normal behavioral situation. Application of the MnCl2 solution by osmotic pumps ensured that food intake was not significantly affected by the treatment. After z-score normalization and a non-affine three-dimensional registration to a rat brain atlas, significantly different grey values of 80 predefined brain structures were recorded in ad libitum fed rats after the intake of potato chips compared to standard chow at the group level. Ten of these areas had previously been connected to food intake, in particular to hyperphagia (e.g. dorsomedial hypothalamus or the anterior paraventricular thalamic nucleus) or to the satiety system (e.g. arcuate hypothalamic nucleus or solitary tract); 27 areas were related to reward/addiction including the core and shell of the nucleus accumbens, the ventral pallidum and the ventral striatum (caudate and putamen). Eleven areas associated to sleep displayed significantly reduced Mn2+-accumulation and six areas related to locomotor activity showed significantly increased Mn2+-accumulation after the intake of potato chips. The latter changes were associated with an observed significantly higher locomotor activity. Osmotic pump-assisted MEMRI proved to be a promising technique for functional mapping of whole brain activity patterns associated to nutritional intake under normal behavior.

Snack food intake in ad libitum fed rats is triggered by the combination of fat and carbohydrates

“…Although the feeding experiments were performed during the light cycle of the day, i.e., the resting phase of the rats (Hoch et al, 2013), considerable additional food intake was observed, which was dependent on the composition of the test food. A lack of side- or place-preference was observed when powdered STD was provided in both of the food dispensers resulting in a similar food and energy intake from both dispensers without significant difference ( p = 0.3311, Figures 3A,B; Tables 1A,B ).…”

Food quality and motivation: A refined low-fat diet induces obesity and impairs performance on a progressive ratio schedule of instrumental lever pressing in rats

“…Finally, the REF diet was highly refined; that is, its ingredients had been broken down into simple components and reconstituted into compact pellets. There is evidence that the exact same nutrients dysregulate appetite and impair satiety mechanisms to promote obesity when ingested as refined flours instead of as whole foods [4,22,25,37]. It is likely that the aspects of the REF diet that are obesogenic and disrupt normal cognitive function will prove multifactorial in nature.…”

Brain activation induced by voluntary alcohol and saccharin drinking in rats assessed with manganese-enhanced magnetic resonance imaging

“…MEMRI combined with delivery of Mn 2+ with osmotic minipumps has been used recently for mapping brain activity in various behavioral tasks in rats (Eschenko et al 2010;Bangasser et al 2013;Hoch et al 2013). Here, we hypothesized that recruitment of neuronal circuits by voluntary alcohol drinking results in an alteration of functional activity that could be detected with MEMRI.…”