title: Heme oxygenase-1 dependant pathway contributes to protection by tetramethylpyrazine against chronic hypoxic injury on medulla oblongata in rats.
abstract: Tetramethylpyrazine (TMP), one of the active ingredients of the Chinese herb Lingusticum Wallichii (Chuan Xiong) has been proved to protect the medulla oblongata from chronic hypoxia injury. However, the underlying mechanism remains unclear. The purpose of this study was to determine whether the protective effects of TMP are associated with the heme oxygenase-1 (HO-1) dependant pathway in adult rats. The morphological changes of neurons in the hypoglossal nucleus (12N), the nucleus ambiguus (Amb), the nucleus tractus solitarius (NTS), and the pre-Bötzinger complex (pre-BötC) were investigated by Nissl staining; the malondialdehyde (MDA) content and superoxide dismutase (SOD) activity were measured to evaluate the anti-oxidant effect; some apoptosis parameters, Bax mRNA and Bcl-2 mRNA, were tested; and the double immunochemistry staining of active caspase-3/NeuN was performed. Meanwhile, the HO-1 protein expression and heme oxygenase (HO) activity were examined. Tin-protoporphyrin (SnPP), a potent inhibitor of HO, was used to further confirm the effect of HO-1. We found that TMP ameliorated the neuron loss in 12N, Amb and NTS, the decrease in SOD activity and the increase in MDA content, the decrease in Bcl-2 mRNA of medulla oblongata (P<0.05), and the increase in percentage of apoptotic neurons in Amb (P<0.05) induced by chronic hypoxia. Co-administration with SnPP abolished the beneficial effects above of TMP to some extent (P<0.05). Moreover, TMP significantly increased HO activity and HO-1 protein expression, which was most likely enhanced in the neurons (P<0.05), and co-administration of SnPP reduced these up-regulated effects (P<0.05). This study demonstrated that HO-1 dependant pathway may be involved in the protective action of TMP against chronic hypoxic damage on medulla oblongata in the rats.
authors.affiliation: Department of Histology, Embryology and Neurobiology, Sichuan University, Chengdu, Sichuan 610041, PR China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Ding
authors.affiliation: Department of Physiology, West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu, Sichuan 610041, PR China.
authors.forename: Xuefei
authors.initials: X
authors.lastname: Hou
authors.affiliation: Department of Physiology, West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu, Sichuan 610041, PR China.
authors.forename: Li
authors.initials: L
authors.lastname: Chen
authors.affiliation: Department of Physiology, West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu, Sichuan 610041, PR China.
authors.forename: Hua
authors.initials: H
authors.lastname: Zhou
authors.affiliation: Department of Histology, Embryology and Neurobiology, Sichuan University, Chengdu, Sichuan 610041, PR China.
authors.forename: Yanju
authors.initials: Y
authors.lastname: Gong
authors.affiliation: Department of Histology, Embryology and Neurobiology, Sichuan University, Chengdu, Sichuan 610041, PR China.
authors.forename: Liqun
authors.initials: L
authors.lastname: Dai
authors.affiliation: Department of Physiology, West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu, Sichuan 610041, PR China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Zheng
mesh_terms: D000818:Animals; D051547:Heme Oxygenase-1 / Q000378:metabolism*; D002534:Hypoxia, Brain / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D008297:Male; D008315:Malondialdehyde / Q000378:metabolism; D008526:Medulla Oblongata / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D018696:Neuroprotective Agents / Q000494:pharmacology / Q000627:therapeutic use*; D018384:Oxidative Stress / Q000187:drug effects; D011719:Pyrazines / Q000494:pharmacology / Q000627:therapeutic use*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D018696:Neuroprotective Agents; D011719:Pyrazines; D008315:Malondialdehyde; D051547:Heme Oxygenase-1; D013482:Superoxide Dismutase; C017953:tetramethylpyrazine
keywords: Chronic hypoxia; Heme oxygenase-1; Medulla oblongata; Neuroprotection; Tetramethylpyrazine; The rat