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Long‐term, calorie‐restricted intake of a high‐fat diet in rats reduces impulse control and ventral striatal D 2 receptor signalling – two markers of addiction vulnerability
Author(s) -
Adams Wendy K.,
Sussman Jacob L.,
Kaur Sukhbir,
D'souza Anna M.,
Kieffer Timothy J.,
Winstanley Catharine A.
Publication year - 2015
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/ejn.13117
Subject(s) - impulsivity , overeating , ventral striatum , striatum , endocrinology , psychology , medicine , addiction , dopamine , creb , neuroscience , endocannabinoid system , biology , developmental psychology , receptor , obesity , transcription factor , biochemistry , gene
High impulsivity, mediated through ventral striatal dopamine signalling, represents an established risk factor for substance abuse, and may likewise confer vulnerability to pathological overeating. Mechanistically, the assumption is that trait impulsivity facilitates the initiation of maladaptive eating styles or choices. However, whether consumption of appetitive macronutrients themselves causes deficits in impulse control and striatal signalling, thereby contributing to cognitive changes permissive of overeating behaviour, has yet to be considered. We examined the effects of chronic maintenance on restricted equicaloric, but high‐fat or high‐sugar, diets (48 kcal/day; 60 kcal% fat or sucrose) on rats’ performance in the five‐choice serial reaction time task, indexing impulsivity and attention. Markers of dopamine signalling in the dorsal and ventral striatum, and plasma insulin and leptin levels, were also assessed. Rats maintained on the high‐fat diet ( HFD ) were more impulsive, whereas the high‐sugar diet ( HSD ) did not alter task performance. Importantly, body weight and hormone levels were similar between groups when behavioural changes were observed. Maintenance on HFD , but not on HSD , reduced the levels of dopamine D 2 receptor (D 2 R), cAMP response element‐binding protein ( CREB ) and phosphophorylated CREB (Ser133) proteins in the ventral, but not dorsal, striatum. D 2 R expression in the ventral striatum also negatively correlated with impulsive responding, independently of diet. These data indicate that chronic exposure to even limited amounts of high‐fat foods may weaken impulse control and alter neural signalling in a manner associated with vulnerability to addictions – findings that have serious implications for the propagation of uncontrolled eating behaviour in obesity and binge‐eating disorder.