Lateral hypothalamic self-stimulation with threshold current intensity induces emotional overeating in self-deprivation paradigm in well-fed rats: Role of orexin and dopaminergic systems of the brain

BACKGROUND: Emotional overeating in forms of соmpulsive overeating, or bulimia nervosa, and binge eating disorder (ВED) is underlying the basis of eating disorders. In particular, binge eating disorder is included in ICD-10 as a form of nonchemical dependence.

AIM: The participation of the orexin and dopamine systems of the brain was studied in conditions of food self-deprivation caused by self-stimulation of the lateral hypothalamus.

METHODS: To reproduce the self-stimulation of the lateral hypothalamus, male Wistar rats were trained to press the pedal in Skinner box. After training, rats received a food deprivation, a feeder was placed in the Skinner box, and a conditioned reflex on food reinforcement was developed in rats for 5 days. The food self-deprivation reaction was observed in these rats with a stimulating current intensity of 10% and above the threshold for self-stimulation.

RESULTS: “Hungry” animals pressed the pedal forhypothalamic self-stimulation and did not distract to the feeding trough. Food reactions were observed only when using the threshold current. Then rats received a free access to food, but the animals, pressing the pedal for self-stimulation, continued food intakes for many times and eat up to 60 seeds in 10 minutes of the experiment. Dopamine receptor D2/D3 antagonist sulpiride at doses of 5 and 20 mg/kg ip and orexin receptor antagonists OX1RSB-408124 and OX2R TCS 29 0.5 mg/ml, 20 μl intranasally were used. Sulpiride administration in “fed” rats decreased both the eating behavior and the reinforcing properties of electrical stimulation in food self-deprivation testing. At the same time, SB-408124 administration induced a decrease in the number of seeds eaten, but the number of pedal presses increased. Administration of OX2R TCS 29 had no effect.

CONCLUSIONS: The conclusion was made about the selectivity of the orexin A OX1RSB-408124 antagonist for emotional eating forms compared with the D2/D3 receptor antagonist dopamine sulpiride.