title: The dopamine receptor antagonist levo-tetrahydropalmatine attenuates heroin  self-administration and heroin-induced reinstatement in rats.
abstract: Opiate addiction is a chronic recrudescent disorder characterized by a high rate of relapse. Levo-tetrahydropalmatine (l-THP) is an alkaloid substance extracted from Corydalis and Stephania and is contained in a number of traditional Chinese herbal preparations. Compared to other dopamine receptor antagonists, l-THP has lower affinity for D2 receptors than for D1 receptors, and a recent study showed that l-THP also binds to D3 receptors, possibly functioning as an antagonist. The unique pharmacological profile of l-THP suggests that l-THP may be effective for the treatment of opiate addiction. In this study, we investigated the effects of l-THP on heroin self-administration and reinstatement triggered by a priming injection of heroin in abstinent rats trained to stably self-administer heroin under an extinction/reinstatement protocol, and found that l-THP (2.5 and 5 mg/kg, i.p.) decreased heroin self-administration on the fixed-ratio 1 schedule and dose-dependently (1.25, 2.5 and 5 mg/kg, i.p.) inhibited heroin-induced reinstatement of heroin-seeking behavior. Importantly, l-THP (1.25 and 2.5 mg/kg, i.p.) did not affect locomotion, indicating that the observed effects of l-THP on reinstatement do not appear to be due to motor impairments. The present results demonstrated that dopamine receptor antagonist l-THP attenuates heroin self-administration and heroin-induced reinstatement.
authors: Wuhan Institutes of Biomedical Sciences, Jianghan University, Wuhan 430056, China.
authors: Kai
authors: K
authors: Yue
authors: Baomiao
authors: B
authors: Ma
authors: Qin
authors: Q
authors: Ru
authors: Lin
authors: L
authors: Chen
authors: Yongping
authors: Y
authors: Gan
authors: Daisong
authors: D
authors: Wang
authors: Guozhang
authors: G
authors: Jin
authors: Chaoying
authors: C
authors: Li
mesh_terms: D000818:Animals; D016739:Behavior, Addictive / Q000517:prevention & control* / Q000523:psychology; D001600:Berberine Alkaloids / Q000627:therapeutic use*; D018492:Dopamine Antagonists / Q000494:pharmacology / Q000627:therapeutic use*; D003932:Heroin / Q000008:administration & dosage* / Q000037:antagonists & inhibitors; D008297:Male; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012055:Reinforcement Schedule; D055502:Secondary Prevention; D012646:Self Administration
chemical_list: D001600:Berberine Alkaloids; D018492:Dopamine Antagonists; C014215:tetrahydropalmatine; D003932:Heroin