The dopamine D2 antagonist eticlopride accelerates extinction and delays reacquisition of food self-administration in rats

Abstract

Dopamine receptors are implicated in the reinforcing effects of food and drug reinforcement. The purpose of this study was to evaluate whether blocking D2 dopamine receptors during extinction (secondary reinforcement) would affect reacquisition of responding for food pellets (primary reinforcement). Food-restricted rats self-administered (FR1) food pellets in 1-h daily sessions for seven days. For the next seven days rats responded in extinction conditions. Prior to each extinction session rats were injected with saline or the dopamine D2 antagonist eticlopride (0.03 mg/kg, cs.c.). After the extinction phase, rats were allowed to reacquire food pellet self-administration in seven daily sessions, and received saline or eticlopride prior to each session. Four treatment groups were represented: (saline extinction, saline reacquisition); (eticlopride extinction, saline reacquisition); (saline extinction, eticlopride reacquisition); (eticlopride extinction, eticlopride reacquisition). Locomotor activity did not differ between eticlopride-treated and saline-treated rats throughout the study. Extinction was accelerated in eticlopride-treated rats. Eticlopride also delayed reacquisition of food self-administration compared to saline-treated rats. Rats administered eticlopride during extinction showed delayed reacquisition and a decreased response rate for food during the reacquisition phase. Indirectly reducing the value of a reinforcer in this way may provide a novel approach for reducing addiction-related food or drug self-administration behaviors.

D2-Like Receptors Mediate Dopamine-Inhibited Insulin Secretion via Ion Channels in Rat Pancreatic β-Cells

“…Eticlopride is a potent and selective D2-like receptor antagonist. Previous studies showed that eticlopride was more specific for D2-like receptors than pimozide or haloperidol (18). Quinpirole has been used as a selective D2-like receptor agonist in various experiments (17,19).…”

Dopamine relieves inflammatory responses through the D2 receptor after electroacupuncture at ST36 in a mouse model of chronic obstructive pulmonary disease

“…During the last 2 weeks of CS exposure, EA was applied to mice in the ST36, chlorpromazine, SCH 23390 and eticlopride hydrochloride groups, as described above. Half an hour prior to every EA session, chlorpromazine (10 mg/kg), 21 SCH 23390 (10 μg/kg), 22 or eticlopride hydrochloride (0.03 mg/kg) 23 were administered in the respective groups by intraperitoneal (i.p.) injection.…”