Elsevier

Neuroscience Letters

Volume 599, 10 July 2015, Pages 133-139
Neuroscience Letters

Research article
Impaired adult hippocampal neurogenesis and cognitive ability in a mouse model of intrastriatal hemorrhage

https://doi.org/10.1016/j.neulet.2015.05.049Get rights and content

Highlights

  • Neurogenesis was damaged in thrombin induced ICH.

  • The impaired adult neurogenesis correlated with cognitive deficits.

  • Apoptosis at SVZ and SGZ is not related to ICH-induced neurogenesis reduction.

Abstract

Thrombin released by hematoma is an important mediator of the secondary injury of intracerebral hemorrhage (ICH), however, the effect of thrombin on adult neurogenesis and cognitive ability remains elusive. In this study, intrastriatal injection of 0.05 U thrombin didn't affect the neurogenesis at the subgranular zone (SGZ), which was distal to the injection site. 0.1 U thrombin increased the 5-bromo-2-deoxyuridine+ (BrdU+, S-phase proliferating cells)/doublecortin+ (DCX+, immature neurons) double labelled neurons, but decreased BrdU+/NeuN+ double labelled mature neurons. Higher doses of thrombin (1 U, 2 U, and 5 U) significantly decreased the BrdU+/DCX+ and BrdU+/NeuN+ double labelled cells. After 1 U thrombin injection, cell apoptosis was found at the dentate gyrus of hippocampus at 3–24 h, but not 5 d post-injury. Thrombin infusion (1U) induced spatial memory deficits in Morris water maze test; whereas, hirudin, the thrombin antagonist, significantly reversed both neurogenesis loss and spatial learning and memory impairment. In conclusion, at least at short term (5 days) after striatum ICH, the effect of high dose of thrombin on neurogenesis of SGZ, and the spatial learning and memory ability, is detrimental.

Introduction

Cognitive impairment has been reported in up to 50% survivors of intracerebral hemorrhage (ICH), which is related to poor life quality [1]. To date, no effective therapeutic achievements have been developed for the treatment of cognitive impairment [2]. Cognitive ability, usually represented by spatial learning and memory in mice, is related to the neurogenesis at subgranular zone (SGZ) of hippocampus [3]. The decline of the adult neurogenesis is correlated with a significant reduction in Morris water maze performance [4].

ICH induced brain injury is composed of primary and secondary mechanisms [5]. The primary mechanism, such as space-occupying effect of hematomas, does not constitute the whole injury [2]. The secondary injuries, which are mainly mediated by the enzymes or cytokines released by hematoma, are largely responsible for the injuries in ICH, and can't be stopped or reversed by current available medications.

Much evidence shows that thrombin is one of the main detrimental molecules in ICH-induced secondary injury [5]. Thrombin injection into the brain tissues causes lysis of vascular basement membrane, injury of neurons and astrocytes, disruption of BBB [6], and brain edema [5] in animal models. Hirudin can inhibit thrombin activity after ICH and effectively reduce the damage mentioned above [6], [7].

The striatum is the most common site of ICH in patients. Striatum injury has also been produced and examined in animal ICH models [8]. However, the range of injury induced by intrastriatal thrombin injection is still unclear. SGZ is the region in the adult brain that maintains the neurogenesis ability throughout life [9]. The effects of intrastriatal thrombin injection on the adult neurogenesis in the SGZ and therefor the cognitive ability are still unknown.

One in vivo study demonstrates that intrastriatal thrombin injection can activate microglial cells in the midbrain and cause dopaminergic neuronal death [10]. Along the rostral to caudal axis of the brain, the substantial nigra is located further away from the thrombin injection site than hippocampus. So we can only speculate that intrastriatal thrombin injection may have impact on the adult neurogenesis at the SGZ.

In this study, we investigated the effect of striatal thrombin injection on the adult neurogenesis at SGZ, as well as hippocampal dependent learning and memory. We found that thrombin injection posed dose-dependent effects on the adult neurogenesis at the SGZ. Higher dose of thrombin is detrimental to the spatial learning and memory ability.

Section snippets

Materials and methods

All animal experiments were performed in accordance with the guidelines approved by the ethics committee of Chinese PLA General Hospital.

To measure the neurogenesis and cognitive ability after thrombin injection, a total of 56 male C57BL/6 mice, 6 weeks of age and weighting 20–22 g, were divided into 7 groups. Each group contained 8 mice.

Sham (group 1): saline was injected into the striatum.

ICH (group 2–6): injection of 0.05, 0.1, 1, 2 or 5 U of thrombin respectively into the striatum.

ICH and

Thrombin caused tissue damage near lateral ventricles

The experiment paradigm was schematically represented in Fig. 1A. The needle tract was identified by the presence of blood, tissue rarefaction, and hematoma (Fig. 1B). On the coronal section containing lateral ventricle, the right lateral ventricles was located in the vicinity of the thrombin infusion site (Fig. 1C). Along the rostral to caudal axis, the SGZ is far away from the injection tract. No coronal sections containing both DG and injection tract was found in our experiments.

Effect of thrombin injection on BrdU and DCX double labeled newborn neurons

In our

Discussion

The role of thrombin in ICH remains controversial. It has been reported that high concentrations of thrombin induce neuronal damage in vitro; however, low concentrations of thrombin are neuroprotective in ischemia or oxidative stress [16]. Injury-induced neurogenesis should be taken into consideration when investigating the effect of thrombin on cerebral injury [17].

In this study, we focused on the effect of intrastriatal injection of thrombin on the neurogenesis at SGZ. We found that 0.05 U

References (20)

  • M.V. Springer et al.

    Predictors of global cognitive impairment 1 year after subarachnoid hemorrhage

    Neurosurgery

    (2009)
  • R.F. Keep et al.

    Intracerebral haemorrhage: mechanisms of injury and therapeutic targets

    Lancet. Neurol.

    (2012)
  • D.T. Balu et al.

    Adult hippocampal neurogenesis: regulation, functional implications, and contribution to disease pathology

    Neurosci. Biobehav. Rev.

    (2009)
  • A. Garthe et al.

    An old test for new neurons: refining the Morris water maze to study the functional relevance of adult hippocampal neurogenesis

    Front. Neurosci.

    (2013)
  • Y. Hua et al.

    Brain injury after intracerebral hemorrhage: the role of thrombin and iron

    Stroke

    (2007)
  • D.Z. Liu et al.

    Blood–brain barrier breakdown and repair by Src after thrombin-induced injury

    Ann. Neurol.

    (2010)
  • M. Xue et al.

    Injections of blood, thrombin, and plasminogen more severely damage neonatal mouse brain than mature mouse brain

    Brain Pathol.

    (2005)
  • M. Xue et al.

    Acute tissue damage after injections of thrombin and plasmin into rat striatum

    Stroke

    (2001)
  • E. Bruel-Jungerman et al.

    Long-term potentiation enhances neurogenesis in the adult dentate gyrus

    J. Neurosci.

    (2006)
  • S.H. Choi et al.

    Thrombin-induced microglial activation produces degeneration of nigral dopaminergic neurons in vivo

    J. Neurosci.

    (2003)
There are more references available in the full text version of this article.

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    In brief, a low dose of thrombin reduced cell damage, which is induced by a large dose of thrombin [12,16], and the low doses of thrombin (less than 1 U) promoted angiogenesis and neurogenesis after ICH [28]. However, the effect of high dose of thrombin (e.g.5 U) impaired neurogenesis at the subgranular zone, and damaged the spatial learning and memory ability [29,30]. Our results revealed that high doses of thrombin (e.g. 5U) significantly inhibited neurogenesis in EnNSCs both in vivo and in vitro.

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