title: Role of Akt signaling pathway in delayed cerebral vasospasm after subarachnoid hemorrhage in rats.
abstract: BACKGROUND
  Akt plays an important role in cell survival, proliferation, apoptosis and other activities. It also has been involved in maintaining smooth muscle cell contraction phenotypes in vitro and in vivo. Recent studies have focused on the inhibition of Akt in acute vasospasm and neuronal apoptosis after subarachnoid hemorrhage (SAH). However, its role in delayed cerebral vasospasm (DCVS) has not been reported.
  
  
  METHODS
  In this study, using a "two-hemorrhage" rat model of SAH, we examined the expression of p-Akt and the formation of vasospasm in the basilar arteries. To investigate the possible role of Akt in phenotypic switching, we performed immunohistochemical staining to examine expressions of SMα-actin and proliferating cell nuclear antigen (PCNA), markers of smooth muscle phenotypic switching.
  
  
  RESULTS
  We found that the basilar arteries exhibited vasospasm after SAH and that vasospasm became most severe on day 7 after SAH. Elevated protein expression of p-Akt was detected 4 days after SAH induction, peaked on day 7, and recovered on day 21, which was in a parallel time course to the development of DCVS. Moreover, results of immunohistochemical staining revealed enhanced expression of PCNA but gradual reduction in expression of SMα-actin from day 1 to day 7 after SAH; then, the expressions of PCNA and SMα-actin gradually recovered until day 21.
  
  
  CONCLUSIONS
  These results support a novel mechanism in which the Akt signaling pathway plays an important role in the proliferation of smooth muscle cells (SMCs) rather than inducing phenotype switching in basilar arteries, which promotes the development of DCVS after SAH.
authors.affiliation: Department of Neurosurgery, First Affiliated Hospital of Medical College, Xi'an Jiaotong University, Xi'an, Shaanxi, People's Republic of China, jinningsong@126.com.
authors.forename: Jin-Ning
authors.initials: JN
authors.lastname: Song
authors.forename: Ji-Yang
authors.initials: JY
authors.lastname: An
authors.forename: Guang-Shan
authors.initials: GS
authors.lastname: Hao
authors.forename: Dan-Dong
authors.initials: DD
authors.lastname: Li
authors.forename: Peng
authors.initials: P
authors.lastname: Sun
authors.forename: Yu
authors.initials: Y
authors.lastname: Li
authors.forename: Jun-Gang
authors.initials: JG
authors.lastname: Xue
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology; D001488:Basilar Artery / Q000378:metabolism; D049109:Cell Proliferation; D004195:Disease Models, Animal; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000502:physiology*; D013345:Subarachnoid Hemorrhage / Q000378:metabolism*; D020301:Vasospasm, Intracranial / Q000378:metabolism*
chemical_list: D051057:Proto-Oncogene Proteins c-akt