Neurogenesis In Rats With Experimental Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) is a common and often fatal stroke subtype. Most of these patients will suffer neurological impairment. There is currently no proven therapy for ICH other than supportive care. Neurogenesis is modulated by both physiological stimuli and pathological conditions, where it may contribute to brain recovery. Neurogenesis has been well studied in ischemic stroke, but neurogenesis in ICH has not been well investigated.Purpose: To investigate neurogenesis in adult rat after intracerebral hemorrhage. Intracerebral hemorrhage is mostly a disease of the elderly, and age is an important factor in neurogenesis after brain injury. The present study investigated neurogenesis in aged rats after intracerebral hemorrhage. To explore the role of iron and thrombin in ICH-related neurogenesis, that come from blood and are important in ICH-induced brain injury. To exam whether EPO treatment can affect ICH-induced neurogenesis and improve behavioral recovery in adult rat.Methods: This study was divided into four parts. (1) Rats received either an intracerebral infusion of 100uL autologous blood or a needle insertion (sham). Some rats received intraperitoneal injections of BrdU. Western blot analysis and histological examination were performed to check doublecortin (DCX), GFAP and Bromodeoxyuridine (BrdU). (2) Aged rats received an intracerebral infusion of 100μL autologous blood or a needle insertion (sham). The rats were killed for DCX, GFAP and polysialylated neural cell adhesion protein (PSA-NCAM) western blot analysis and immunohistochemistry. Some rats received intraperitoneal injections of BrdU. Brains were perfused to identify BrdU-positive cells. Compare the aged rats with adult rats. (3) Rats had an ICH treated with deferoxamine. Rats had an ICH with or without a thrombin inhibitor, hirudin. The brains were sampled for DCX quantitation. Rats had an intracaudate injection of thrombin (1U) and brains were sampled for Western blots. (4) Rats had an ICH treated with EPO. Behavioral tests (corner turn test, forelimb placing test, forelimb limb-use asymmetry test) were used to examine neurological deficits. The brains were sampled for DCX quantitation.Results: DCX levels in the ipsilateral basal ganglia started to increase as early as seven days after ICH, peaked at 14 days, and then gradually decreased at one month. Immunohistochemistry also demonstrated that DCX immunoreactivity was increased in the ipsilateral subventricular zone and basal ganglia at 2 weeks after ICH. Most DCX positive cells were BrdU positive. There were many reactive astrocytes around the hematoma at day 14 after ICH, and decreased gradually. In aged rats, DCX content in the ICH ipsilateral basal ganglia was much higher than the sham ipsilateral basal ganglia, but it was lower compare with that of ipsilateral basal ganglia in adult rats. The time course of DCX content in ICH aged rat was similar to that of adult rat. Reactive astrocytes around hematoma in aged rats were less than that of adult rats. Deferoxamine treatment can't change DCX content in adult rat with intracerebral hemorrhage. Hirudin can blocked ICH-induced upregulation of DCX. One unit thrombin, which can not cause marked brain injury, was injected into the caudate. Thrombin increased DCX levels in the ipsilateral basal ganglia in adult rats. There was no significant change in DCX level with EPO treatment in adult rat following intracerebral hemorrhage. To assess functional deficits after EPO treatment behavioral tests were used. Over 2 weeks after ICH, EPO treatment enhanced behavioral recovery in adult rats with intracerebral hemorrhage.Conclusion: The results demonstrated that neurogenesis occurs from subventricular zone in the adult rat brain following intracerebral hemorrhage. Neurogenesis is preserved but reduced in the aged rat brain. Thrombin may play a role in ICH-induced neurogenesis. Treat the adult rat following intracerebral hemorrhage with EPO improve recovery of function but there was no evidence that EPO enhance neurogenesis in present study.