title: Ischemic preconditioning protects neurons from damage and maintains the immunoreactivity of kynurenic acid in the gerbil hippocampal CA1 region following transient cerebral ischemia.
abstract: Pyramidal neurons in region I of hippocampus proper (CA1) are particularly vulnerable to excitotoxic processes following transient forebrain ischemia. Kynurenic acid (KYNA) is a small molecule derived from tryptophan when this amino acid is metabolized through the kynurenine pathway. In the present study, we examined the effects of ischemic preconditioning (IPC) on the immunoreactivity and protein levels of KYNA following 5 min of transient forebrain ischemia in gerbils. The animals were randomly assigned to 4 groups (sham-operated group, ischemia-operated group, IPC + sham-operated group and IPC + ischemia-operated group). IPC was induced by subjecting the gerbils to 2 min of ischemia followed by 1 day of recovery. In the ischemia-operated group, we observed a significant loss of pyramidal neurons in the CA1 stratum pyramidale (SP) at 5 days post-ischemia; however, in the IPC + ischemia-operated group, the pyramidal neurons were well protected. KYNA immunoreactivity in the SP of the ischemia-operated group was significantly altered following ischemia-reperfusion and was very low 5 days following ischemia-reperfusion. In the IPC + ischemia-operated group, however, KYNA immunoreactivity was constitutively detected in the SP of the CA1 region after the ischemic insult. We also found that the alteration pattern of the KYNA protein level in the CA1 region following ischemia was generally similar to the immunohistochemical changes observed. In brief, our findings demonstrated that IPC maintained and even increased KYNA immunoreactivity in the SP of the CA1 region following ischemia-reperfusion. The data from the present study thus indicate that the enhancement of KYNA expression by IPC may be necessary for neuronal survival following transient ischemic injury.
authors: Department of Neurobiology, School of Medicine, Kangwon National University, Chuncheon 200-701, Republic of Korea.
authors: Jae-Chul
authors: JC
authors: Lee
authors: Department of Biomedical Science and Research Institute for Bioscience and Biotechnology, Hallym University, Chuncheon 200-702, Republic of Korea.
authors: Hyun-Jin
authors: HJ
authors: Tae
authors: Department of Neuroscience, College of Medicine, Korea University, Seoul 136-705, Republic of Korea.
authors: Geum-Sil
authors: GS
authors: Cho
authors: Department of Neurobiology, School of Medicine, Kangwon National University, Chuncheon 200-701, Republic of Korea.
authors: In Hye
authors: IH
authors: Kim
authors: Department of Neurobiology, School of Medicine, Kangwon National University, Chuncheon 200-701, Republic of Korea.
authors: Ji Hyeon
authors: JH
authors: Ahn
authors: Department of Neurobiology, School of Medicine, Kangwon National University, Chuncheon 200-701, Republic of Korea.
authors: Joon Ha
authors: JH
authors: Park
authors: Department of Physiology, College of Medicine, and Institute of Neurodegeneration and Neuroregeneration, Hallym University, Chuncheon 200-702, Republic of Korea.
authors: Bai Hui
authors: BH
authors: Chen
authors: Department of Neurobiology, School of Medicine, Kangwon National University, Chuncheon 200-701, Republic of Korea.
authors: Jeong-Hwi
authors: JH
authors: Cho
authors: Department of Physiology, College of Medicine, and Institute of Neurodegeneration and Neuroregeneration, Hallym University, Chuncheon 200-702, Republic of Korea.
authors: Bich Na
authors: BN
authors: Shin
authors: Department of Emergency Medicine, School of Medicine, Kangwon National University, Chuncheon 200-701, Republic of Korea.
authors: Jun Hwi
authors: JH
authors: Cho
authors: Department of Pediatrics, Chuncheon Sacred Heart Hospital, College of Medicine, Hallym University, Chuncheon 200-701, Republic of Korea.
authors: Eun Joo
authors: EJ
authors: Bae
authors: Department of Biomedical Science and Research Institute for Bioscience and Biotechnology, Hallym University, Chuncheon 200-702, Republic of Korea.
authors: Jinseu
authors: J
authors: Park
authors: Department of Molecular and Cellular Biochemistry, School of Medicine, Kangwon National University, Chuncheon 200-701, Republic of Korea.
authors: Young-Myeong
authors: YM
authors: Kim
authors: Department of Biomedical Science and Research Institute for Bioscience and Biotechnology, Hallym University, Chuncheon 200-702, Republic of Korea.
authors: Soo Young
authors: SY
authors: Choi
authors: Department of Neurobiology, School of Medicine, Kangwon National University, Chuncheon 200-701, Republic of Korea.
authors: Moo-Ho
authors: MH
authors: Won
mesh_terms: D000818:Animals; D056547:CA1 Region, Hippocampal / Q000378:metabolism* / Q000473:pathology; D005849:Gerbillinae; D019194:Ischemic Preconditioning; D007736:Kynurenic Acid / Q000378:metabolism*; D017966:Pyramidal Cells / Q000378:metabolism* / Q000473:pathology
chemical_list: D007736:Kynurenic Acid