Dopaminergic Regulation of Circadian Food Anticipatory Activity Rhythms in the Rat

Abstract

Circadian activity rhythms are jointly controlled by a master pacemaker in the hypothalamic suprachiasmatic nuclei (SCN) and by food-entrainable circadian oscillators (FEOs) located elsewhere. The SCN mediates synchrony to daily light-dark cycles, whereas FEOs generate activity rhythms synchronized with regular daily mealtimes. The location of FEOs generating food anticipation rhythms, and the pathways that entrain these FEOs, remain to be clarified. To gain insight into entrainment pathways, we developed a protocol for measuring phase shifts of anticipatory activity rhythms in response to pharmacological probes. We used this protocol to examine a role for dopamine signaling in the timing of circadian food anticipation. To generate a stable food anticipation rhythm, rats were fed 3h/day beginning 6-h after lights-on or in constant light for at least 3 weeks. Rats then received the D2 agonist quinpirole (1 mg/kg IP) alone or after pretreatment with the dopamine synthesis inhibitor α-methylparatyrosine (AMPT). By comparison with vehicle injections, quinpirole administered 1-h before lights-off (19h before mealtime) induced a phase delay of activity onset prior to the next meal. Delay shifts were larger in rats pretreated with AMPT, and smaller following quinpirole administered 4-h after lights-on. A significant shift was not observed in response to the D1 agonist SKF81297. These results provide evidence that signaling at D2 receptors is involved in phase control of FEOs responsible for circadian food anticipatory rhythms in rats.

Circadian Insights into Motivated Behavior

“…Perturbation of dopaminergic transmission alters the timing or amplitude of anticipatory activity (Liu et al 2012;Smit et al 2013). Loss of the D1 receptor attenuates anticipation of daily scheduled meals, even when the meal is palatable and high in fat (Gallardo et al 2014).…”

Mice that are resistant to diet-induced weight loss have greater food anticipatory activity and altered melanocortin-3 receptor (MC3R) and dopamine receptor 2 (D2) gene expression

“…An important role for the dopaminergic system in regulating goal-directed behaviour, i.e., food anticipatory activity (FAA), and timing of these behaviours has also been suggested based on evidence that the total amount of activity prior to mealtime is reduced following acute treatment with D1 and D2 specific antagonists (Liu et al, 2012, Mistlberger andMumby, 1992). In (Sutton et al, 2008) and the dopaminergic system (Smit et al, 2013) on FAA is part of the same regulatory system.…”

Association between oropharyngeal microbiome and weight gain in piglets during pre and post weaning life

“…Hedonic feeding refers to the non-homeostatic feeding that is not driven by energy requirements but simply driven by pleasure or desire to consume palatable feed [58]. Some catecholamines have been shown to induce feeding behavior such as food-anticipatory activity, search for food and motivation to feed [59]. Breakdown of these catecholamines, interferes with systemic regulation of their production [60].…”