Time interval after ischaemic preconditioning affects neuroprotection and gliosis in the gerbil hippocampal CA1 region induced by transient cerebral ischaemia.
OBJECTIVE
Ischaemic preconditioning (IPC) can increase ischaemic tolerance of the central nervous system (CNS) to a subsequent longer or lethal period of transient ischaemia. In this study, we examined neuroprotective effects of time intervals after IPC against ischaemic insult in the hippocampus.


METHODS
Animals were randomly assigned to six groups; sham-operated-group, ischaemia-operated-group, and three IPC (12 hours, 1- and 2-day intervals after IPC) plus ischaemia-groups (IPC-12 hour, 1 and 2-day interval-ischaemia-operated-groups). For neuroprotection, we carried out cresyl violet (CV) staining neuronal nuclei (NeuN) immunohistochemistry and Fluoro-Jade B histofluorescence staining. In addition, we examined gliosis using immunohistochemistry for GFAP (a marker for astrocytes) and Iba-1 (a marker for microglia).


RESULTS
A significant loss of neurons was observed in the stratum pyramidale (SP) of the hippocampal CA1 region (CA1) in the ischaemia-operated-group and IPC-12 hours interval-ischaemia-operated-groups. In the IPC-1 day interval-ischaemia-operated-group, CA1 pyramidal neurons were well protected from ischaemic insult; the neuroprotective effect in the IPC-2 day interval-ischaemia-operated-group was less than that in the IPC-1 day interval-ischaemia-operated-group. On the other hand, we observed changes in glial cells (astrocytes and microglia) in the CA1 of all groups. The distribution pattern of glial cells only in the IPC-1 day interval-ischaemia-operated-group was similar to that in the sham-group.


CONCLUSIONS
In brief, our findings indicate that 1 day after IPC displays a mighty neuroprotection and shows an inhibition of glial activation in the CA1 induced by transient ischaemic insult.
a Department of Neurobiology, School of Medicine , Kangwon National University , Chuncheon , South Korea.
In
I
Hye Kim
a Department of Neurobiology, School of Medicine , Kangwon National University , Chuncheon , South Korea.
Jae-Chul
JC
Lee
a Department of Neurobiology, School of Medicine , Kangwon National University , Chuncheon , South Korea.
Joon
J
Ha Park
a Department of Neurobiology, School of Medicine , Kangwon National University , Chuncheon , South Korea.
Ji
J
Hyeon Ahn
a Department of Neurobiology, School of Medicine , Kangwon National University , Chuncheon , South Korea.
Jeong-Hwi
JH
Cho
b Department of Physiology, College of Medicine , Hallym University , Chuncheon , South Korea.
Bai
B
Hui Chen
b Department of Physiology, College of Medicine , Hallym University , Chuncheon , South Korea.
Bich
B
Na Shin
c Institute of Integrative Traditional & Western Medicine, Medical College , Yangzhou University , China.
Bing
B
Chun Yan
d Department of Internal Medicine, School of Medicine , Kangwon National University , Chuncheon , South Korea.
Dong
D
Rueol Ryu
e Department of Surgery, School of Medicine , Kangwon National University , Chuncheon , South Korea.
Seongkweon
S
Hong
f Department of Emergency Medicine, School of Medicine , Kangwon National University , Chuncheon , South Korea.
Jun
J
Hwi Cho
b Department of Physiology, College of Medicine , Hallym University , Chuncheon , South Korea.
Yun
Y
Lyul Lee
g Department of Molecular and Cellular Biochemistry, School of Medicine , Kangwon National University , Chuncheon , South Korea.
Young-Myeong
YM
Kim
d Department of Internal Medicine, School of Medicine , Kangwon National University , Chuncheon , South Korea.
Byung-Ryul
BR
Cho
a Department of Neurobiology, School of Medicine , Kangwon National University , Chuncheon , South Korea.
Moo-Ho
MH
Won
D000704:Analysis of Variance; D000818:Animals; D056547:CA1 Region, Hippocampal / Q000378:metabolism / Q000473:pathology*; D002135:Calcium-Binding Proteins; D002452:Cell Count; D004268:DNA-Binding Proteins / Q000378:metabolism; D004195:Disease Models, Animal; D005452:Fluoresceins / Q000493:pharmacokinetics; D005849:Gerbillinae; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D005911:Gliosis / Q000209:etiology* / Q000517:prevention & control*; D002546:Ischemic Attack, Transient / Q000150:complications* / Q000473:pathology*; D019194:Ischemic Preconditioning / Q000379:methods*; D008297:Male; D008840:Microfilament Proteins; D010751:Phosphopyruvate Hydratase / Q000378:metabolism; D013997:Time Factors
C112986:AIF1 protein, human; D002135:Calcium-Binding Proteins; D004268:DNA-Binding Proteins; D005452:Fluoresceins; D005904:Glial Fibrillary Acidic Protein; D008840:Microfilament Proteins; C435731:fluoro jade; D010751:Phosphopyruvate Hydratase
Delayed neuronal death; Gliosis; Ischaemia–reperfusion; Neuroprotection; Pyramidal neurons; Time intervals after IPC