title: Effects of dopamine receptor agonist and antagonists on cholestasis-induced anxiolytic-like behaviors in rats.
abstract: Dysfunctions in the dopamine transmission system have been suggested to contribute to the pathogenesis of hepatic encephalopathy. In an experimental animal model, cholestasis induction through bile duct ligation may present several main pathological features of hepatic encephalopathy. Dopaminergic systems are shown to play pivotal roles in regulation of anxiety-like behaviors. The main bile duct in male Wistar rats, weighing 220-240 g, was ligated using two ligatures plus duct transection in between. Anxiety-like behaviors were measured using the elevated plus maze task. Cholestasis increased the open arm time percentage (%OAT), 13 but not 10 days after bile duct ligation, indicating an anxiolytic-like effect. Sole intraperitoneal injection of apomorphine (dopamine D1/D2 receptor agonist, 0.25 mg/kg), SCH23390 (dopamine D1 receptor antagonist, 0.005, 0.01 and 0.02 mg/kg) or sulpiride (dopamine D2 receptor antagonist, 0.125, 0.25 and 0.5 mg/kg) did not alter %OAT, open arm entries percentage (%OAE) and locomotor activity in the sham-operated rats. Meanwhile, the higher dose apomorphine (0.5 mg/kg) induced anxiolytic-like behaviors in this group. The subthreshold dose injection of SCH23390 or sulpiride, partially reversed the anxiolytic-like behaviors induced by cholestasis (13 days after bile duct ligation). On the other hand, subthreshold dose of apomorphine in cholestatic rats (10 days post bile duct ligation) induced anxiolytic-like effects which could be blocked by SCH23390 or sulpiride. The effective doses of above drugs did not alter locomotor activity, number of rearings, groomings and defections. These findings suggested that the dopaminergic system may potentially be involved in the modulation of cholestasis-induced anxiolytic-like behaviors in rats.
authors: Department of Neuroscience, School of Advanced Medical Technologies, Tehran University of Medical Sciences, Tehran, Iran. zarinmr@ams.ac.ir
authors: Mohammad
authors: M
authors: Reza Zarrindast
authors: Delaram
authors: D
authors: Eslimi Esfahani
authors: Shahrbano
authors: S
authors: Oryan
authors: Mohammad
authors: M
authors: Nasehi
authors: Mohammad
authors: M
authors: Torabi Nami
mesh_terms: D000818:Animals; D001007:Anxiety / Q000209:etiology / Q000503:physiopathology*; D001522:Behavior, Animal / Q000187:drug effects; D002779:Cholestasis / Q000150:complications / Q000503:physiopathology*; D018491:Dopamine Agonists / Q000494:pharmacology*; D018492:Dopamine Antagonists / Q000494:pharmacology*; D065127:Dopamine D2 Receptor Antagonists; D005106:Exploratory Behavior / Q000187:drug effects; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D017447:Receptors, Dopamine D1 / Q000819:agonists / Q000037:antagonists & inhibitors / Q000502:physiology*; D017448:Receptors, Dopamine D2 / Q000819:agonists / Q000502:physiology*
chemical_list: D018491:Dopamine Agonists; D018492:Dopamine Antagonists; D065127:Dopamine D2 Receptor Antagonists; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2