Effects of thrombin on neurogenesis after intracerebral hemorrhage.
OBJECTIVE
Neurogenesis in intracerebral hemorrhage (ICH) has not been investigated. Thrombin formation causes acute brain injury after ICH, but thrombin also can stimulate cell proliferation. The present study examined whether neurogenesis takes place in ICH and the role of thrombin in ICH-related neurogenesis.


METHODS
This study was divided into four parts. (1) Rats received either an ICH or a needle insertion (sham). The rats were killed for doublecortin (DCX) Western blot analysis and immunohistochemistry. (2) Rats had an ICH or a sham operation, and then received intraperitoneal injections of 5-bromo-2'-deoxyuridine (BrdU) at day-7 and day-9 later. Brains were perfused to identify BrdU-positive cells. (3) Rats had an intracaudate injection of thrombin (1 U) and brains were sampled for Western blots. (4) Rats had an ICH with or without a thrombin inhibitor, hirudin. The brains were sampled for DCX quantitation.


RESULTS
DCX levels in the ipsilateral basal ganglia started to increase as early as 7 days after ICH, peaked at 14 days, and then gradually decreased at 1 month. Immunohistochemistry also demonstrated that DCX immunoreactivity was increased in the ipsilateral subventricular zone and basal ganglia at 2 weeks after ICH. Some DCX-positive cells were BrdU-positive. One unit thrombin, which does not cause marked brain injury, was injected into the caudate. Thrombin increased DCX levels in the ipsilateral basal ganglia and hirudin blocked ICH-induced upregulation of DCX.


CONCLUSIONS
Our results demonstrated that neurogenesis occurs in the brain after ICH and that thrombin may play a role in ICH-induced neurogenesis.
Yang
Shuxu
S
Department of Neurosurgery, University of Michigan, Ann Arbor 48109, USA.
Song
Shuijiang
S
Hua
Ya
Y
Nakamura
Takehiro
T
Keep
Richard F
RF
Xi
Guohua
G
D000818:Animals; D001921:Brain / Q000378:metabolism; D001973:Bromodeoxyuridine / Q000494:pharmacology; D049109:Cell Proliferation; D002543:Cerebral Hemorrhage / Q000188:drug therapy* / Q000473:pathology*; D000089622:Doublecortin Domain Proteins; D000089662:Doublecortin Protein; D006629:Hirudins / Q000378:metabolism; D007150:Immunohistochemistry / Q000379:methods; D008297:Male; D008869:Microtubule-Associated Proteins / Q000235:genetics; D008954:Models, Biological; D009474:Neurons / Q000378:metabolism*; D009479:Neuropeptides / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D013917:Thrombin / Q000378:metabolism*; D013997:Time Factors
C000714848:Dcx protein, rat; D000089622:Doublecortin Domain Proteins; D000089662:Doublecortin Protein; D006629:Hirudins; D008869:Microtubule-Associated Proteins; D009479:Neuropeptides; D013917:Thrombin; D001973:Bromodeoxyuridine