title: ERK1/2 inhibition attenuates cerebral blood flow reduction and abolishes ET(B) and 5-HT(1B) receptor upregulation after subarachnoid hemorrhage in rat.
abstract: Upregulation of endothelin B (ET(B)) and 5-hydroxytryptamine 1B (5-HT(1B)) receptors via transcription has been found after experimental subarachnoid hemorrhage (SAH), and this is associated with enhanced phosphorylation of the mitogen-activated protein kinase (MAPK) extracellular signal-regulated kinase (ERK1/2). In the present study, we hypothesized that inhibition of ERK1/2 alters the ET(B) and 5-HT(1B) receptor upregulation and at the same time prevents the sustained cerebral blood flow (CBF) reduction associated with SAH. The ERK1/2 inhibitor SB386023-b was injected intracisternally in conjunction with and after the induced SAH in rats. At 2 days after the SAH, cerebral arteries were harvested for quantitative real-time polymerase chain reaction, immunohistochemistry and analysis of contractile responses to endothelin-1 (ET-1; ET(A) and ET(B) receptor agonist) and 5-carboxamidotryptamine (5-CT; 5-HT1 receptor agonist) in a sensitive myograph. To investigate if ERK1/2 inhibition had an influence on the local and global CBF after SAH, an autoradiographic technique was used. At 48 h after induced SAH, global and regional CBF were reduced by 50%. This reduction was prevented by treatment with SB386023-b. The ERK1/2 inhibition also decreased the maximum contraction elicited by application of ET-1 and 5-CT in cerebral arteries compared with SAH. In parallel, ERK1/2 inhibition downregulated ET(B) and 5-HT(1B) receptor messenger ribonucleic acid and protein levels compared with the SAH. Cerebral ischemia after SAH involves vasoconstriction and subsequent reduction in the CBF. The results suggest that ERK1/2 inhibition might be a potential treatment for the prevention of cerebral vasospasm and ischemia associated with SAH.
authors.affiliation: Department of Clinical Sciences, Division of Experimental Vascular Research, Lund University Hospital, Lund, Sweden. saema.beg@med.lu.se
authors.forename: Saema A S
authors.initials: SA
authors.lastname: Beg
authors.forename: Jacob A
authors.initials: JA
authors.lastname: Hansen-Schwartz
authors.forename: Petter J
authors.initials: PJ
authors.lastname: Vikman
authors.forename: Cang-Bao
authors.initials: CB
authors.lastname: Xu
authors.forename: Lars I H
authors.initials: LI
authors.lastname: Edvinsson
mesh_terms: D000818:Animals; D001345:Autoradiography; D001921:Brain / Q000098:blood supply* / Q000503:physiopathology; D002536:Cerebral Arteries / Q000187:drug effects / Q000502:physiology; D002560:Cerebrovascular Circulation / Q000187:drug effects / Q000502:physiology*; D004195:Disease Models, Animal; D019332:Endothelin-1 / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000378:metabolism*; D007150:Immunohistochemistry; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D044023:Receptor, Endothelin B / Q000378:metabolism*; D044302:Receptor, Serotonin, 5-HT1B / Q000378:metabolism*; D012039:Regional Blood Flow; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D013345:Subarachnoid Hemorrhage / Q000378:metabolism / Q000503:physiopathology*; D015854:Up-Regulation; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology
chemical_list: D019332:Endothelin-1; D004791:Enzyme Inhibitors; D012333:RNA, Messenger; D044023:Receptor, Endothelin B; D044302:Receptor, Serotonin, 5-HT1B; D017366:Serotonin Receptor Agonists; D048049:Extracellular Signal-Regulated MAP Kinases