title: Cholestasis induced antinociception and decreased gene expression of MOR1 in rat brain.
abstract: We examined antinociception and gene expression of mu-opioid receptor 1 (MOR1) in some brain areas of cholestatic rats, 21 days after common bile duct ligation (BDL). Cholestasis was induced in male Wistar rats during laparotomy and common BDL. Pain behavior was assessed on days 7, 14 or 21 of BDL using a hotplate test in control, sham and cholestatic groups. On day 21 of BDL, other groups of rats were sacrificed, whole brains were extracted, and the hypothalamus, prefrontal cortex (PFC), hippocampus and striatum in control, sham and cholestatic rats were dissected. We used a semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) method for evaluating MOR1 gene expression. The results revealed that cholestatic rats showed significant antinociception on days 14 and 21 of ligation with the most significant effect on day 21, which was prevented by naloxone (1 mg/kg). On the other hand, the expression of MOR1 gene compared to the sham group was decreased by 42% in the hypothalamus, 41% in the PFC, and 67% in the hippocampus after 21 days of BDL, while no significant change in its expression in the striatum was observed. It can be concluded that a change in endogenous opioid levels and its subsequent influence on the gene expression of MOR in some areas of the rat brain may underlie the altered nociception and other possible pathological changes such as pruritus after induction of cholestasis.
authors.affiliation: Department of Biological Science and Biotechnology, Faculty of Science, University of Kurdistan, Sanandaj, Iran. Electronic address: sh.ahmadi@uok.ac.ir.
authors.forename: S
authors.initials: S
authors.lastname: Ahmadi
authors.affiliation: Department of Biological Science and Biotechnology, Faculty of Science, University of Kurdistan, Sanandaj, Iran.
authors.forename: Z
authors.initials: Z
authors.lastname: Karami
authors.affiliation: Department of Biological Science and Biotechnology, Faculty of Science, University of Kurdistan, Sanandaj, Iran.
authors.forename: A
authors.initials: A
authors.lastname: Mohammadian
authors.affiliation: Department of Biological Science and Biotechnology, Faculty of Science, University of Kurdistan, Sanandaj, Iran.
authors.forename: F
authors.initials: F
authors.lastname: Khosrobakhsh
authors.affiliation: Department of Biological Science and Biotechnology, Faculty of Science, University of Kurdistan, Sanandaj, Iran.
authors.forename: J
authors.initials: J
authors.lastname: Rostamzadeh
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001649:Bile Duct Diseases / Q000209:etiology / Q000503:physiopathology*; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D004195:Disease Models, Animal; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D007813:Laparotomy / Q000009:adverse effects; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D010146:Pain / Q000209:etiology / Q000473:pathology*; D010147:Pain Measurement / Q000187:drug effects; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D017450:Receptors, Opioid, mu / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors
chemical_list: D009292:Narcotic Antagonists; C485765:Oprm1 protein, rat; D012333:RNA, Messenger; D017450:Receptors, Opioid, mu; D009270:Naloxone
keywords: antinociception; cholestasis; gene expression; semi-quantitative RT-PCR