Antioxidant Roles of Heme Oxygenase, Carbon Monoxide, and Bilirubin in Cerebral Circulation during Seizures

• Published in: Journal of cerebral blood flow and metabolism 2012-06, Vol.32 (6), p.1024-1034
• Main Authors: Parfenova, Helena, Leffler, Charles W, Basuroy, Shyamali, Liu, Jianxiong, Fedinec, Alexander L
• Format: Article
• Language: English
• Subjects: Animals; Antioxidants; Antioxidants - metabolism; Astrocytes; Astrocytes - metabolism; Bicuculline; Bilirubin; Bilirubin - metabolism; Biological and medical sciences; Bradykinin; Bradykinin - metabolism; Brain; Carbon monoxide; Carbon Monoxide - metabolism; Cerebral blood flow; Cerebral circulation. Blood-brain barrier. Choroid plexus. Cerebrospinal fluid. Circumventricular organ. Meninges; Cerebrovascular Circulation; Cobalt; Cortex; Data processing; Enzyme Inhibitors - pharmacology; Fundamental and applied biological sciences. Psychology; Glutamic Acid - metabolism; Heme oxygenase (decyclizing); Heme Oxygenase (Decyclizing) - metabolism; Medical sciences; Metalloporphyrins - pharmacology; Nerve Tissue Proteins - metabolism; Neurology; Original; Oxidative Stress; Protoporphyrin; Protoporphyrins - pharmacology; Reactive oxygen species; Reactive Oxygen Species - metabolism; Seizures; Seizures - metabolism; Seizures - physiopathology; Side effects; sodium nitroprusside; Swine; Vascular diseases and vascular malformations of the nervous system; Vertebrates: nervous system and sense organs
• ISSN: 0271-678X; 1559-7016
• DOI: 10.1038/jcbfm.2012.13

Postictal cerebrovascular dysfunction is an adverse effect of seizures in newborn piglets. The brain heme oxygenase (HO) provides protection against cerebrovascular dysfunction. We investigated the contribution of reactive oxygen species (ROS) to seizure-induced vascular damage and the mechanism of HO vasoprotection. In a bicuculline model of seizures, we addressed the hypotheses: (1) seizures increase brain ROS; (2) ROS contribute to cerebral vascular dysfunction; (3) ROS initiate a vasoprotective mechanisms by activating endogenous HO; and (4) HO products have antioxidant properties. As assessed by dihydroethidium oxidation (ox-DHE), seizures increased ROS in cerebral vessels and cortical astrocytes; ox-DHE elevation was prevented by tiron and apocynin. An HO inhibitor, tin protoporphyrin, potentiated, whereas an HO-1 inducer, cobalt protoporphyrin, blocked seizure-induced increase in DHE oxidation. Heme oxygenase products carbon monoxide (CO) (CORM-A1) and bilirubin attenuated ox-DHE elevation during seizures. Antioxidants tiron and bilirubin prevented the loss of postictal cerebrovascular dilations to bradykinin, glutamate, and sodium nitroprusside. Tiron and apocynin abrogated activation of the brain HO during seizures. Overall, these data suggest that long-term adverse cerebrovascular effects of seizures are attributed to oxidative stress. On the other hand, seizure-induced ROS are required for activation of the endogenous antioxidant HO/CO/bilirubin system that alleviates oxidative stress-induced loss of postictal cerebrovascular function in piglets.