Elsevier

Molecular Brain Research

Volume 55, Issue 1, 30 March 1998, Pages 133-140
Molecular Brain Research

Research report
Reduction of cortical infarction and impairment of apoptosis in NGF-transgenic mice subjected to permanent focal ischemia

https://doi.org/10.1016/S0169-328X(97)00372-0Get rights and content

Abstract

The neuroprotective potential of the nerve growth factor (NGF) against permanent ischemic brain damage has been investigated in vivo using NGF-transgenic (tg) mice. The expression of the transgene is driven by part of the promoter of the proto-oncogene c-fos, which belongs to the first set of genes activated after brain ischemic insult. Wild-type (wt) mice and tg mice were subjected to permanent focal ischemia induced by electrocoagulation of the middle cerebral artery. Twenty four hours (h) after the ischemic shock, when compared to wt, tg mice displayed a 40% reduction of the infarcted area, which lasted up to 1 week. However, infarcted brain areas were similar in wt and tg mice within the first hours post-occlusion, indicating that NGF acted to block the progression of neuronal damage. Kinetics of NGF synthesis assessed by ELISA was in good agreement with the observed neuroprotective effect, since NGF content peaked 6 h post-ischemia. This was further correlated with the time-course of c-Fos immunoreactivity, detectable only from 6 h post-ischemia. The neuroprotective effect of NGF involved the impairment of apoptotic cell death, as evidenced by a marked decrease of the number of apoptotic profiles inside the ischemic zone in tg mice. These results underline the potential of c-fos-NGF-tg mice to study in vivo the molecular and cellular mechanisms of the NGF-induced neuroprotective effect against ischemic damage.

Introduction

`Neuropoietic' factors influence the survival, differentiation and connectivity of various neuronal populations. They belong to the neurotrophin, fibroblast growth factor (FGF), transforming growth factor (TGF), epidermal growth factor (EGF), insulin-like growth factor (IGF), and interleukin families (for a review, see e.g., Ref. [30]). Such factors, which are dynamically regulated in response to epileptic, hypoglycemic, ischemic and traumatic injuries, actively participate in the control of neuronal cell death (reviewed in Refs. 13, 21). In rodent models of focal cerebral ischemia based on middle cerebral artery occlusion (MCAO), ischemic brain damage results in neuronal loss within vulnerable regions of the striatum and cortex. Several mRNAs species exhibit enhanced levels following MCAO, including mRNAs of neuroprotective agents, such as nerve growth factor (NGF, [20]), brain-derived neurotrophic factor (BDNF, [2]), acidic and basic FGFs 11, 33, TGF-β1 [36], and neurotoxic agents, such as interleukin-1 (IL-1, [40]) and tumor necrosis factor-α (TNF-α, [24]).

The in vivo neuroprotective potential of NGF after either intracerebroventricular NGF injection 3, 4, 31or implantation of NGF-producing fibroblasts [28]has been demonstrated on hippocampal neurons, in different paradigms of experimental ischemia. However, in vitro, NGF can protect cultured hippocampal as well as cortical neurons against hypoglycemic damage, glutamate-induced neurotoxicity or iron-induced degeneration 5, 32, 41. To ascertain an in vivo neuroprotective effect of NGF on cortical neurons, we have used a model of pure cortical infarction following MCAO in mice [9]. The electrocoagulation of the left MCA in the mouse provokes a moderate and progressive infarct localized in the temporal and parietal cortices. Twenty four hours after the MCAO, the infarct is consolidated and about 20% of the brain volume is destroyed [9]. The availability of transgenic (tg) mice expressing the NGF gene after induction, has provided us with the opportunity to test the neuroprotective effect of NGF after permanent focal ischemia. MCAO was performed on a mouse strain transgenic for NGF in which encoding sequences are controlled by a part of the inducible promoter of the proto-oncogene c-fos [27]. Transcription of transgenic sequences and NGF protein synthesis can be notably increased after the stimulation of the promoter both in vitro and in vivo 27, 29. Considering that the c-fos gene is among the first set of genes activated in cortical structures by ischemic insults [15], we speculated that NGF synthesis could be rapidly and locally induced in tg mice after MCAO, thus, providing a useful tool to investigate the role of NGF in ischemia-related brain damage in vivo. We report here a major effect of NGF on the survival of cortical neurons following MCAO in mice resulting in an important reduction of brain infarction, mainly through modulation of the apoptotic cell death pathway.

Section snippets

Surgical procedure and measurement of the infarct volume

All the studies with mice have been conducted with respect to the EC legislation on animal care. Male tg mice homozygous for the transgene or wt mice of the same genetic background (C57Bl/6×DBA/2)F1 weighing 20–25 g were anesthetized intraperitoneally with chloral hydrate (500 mg/kg). Coagulation of the left middle cerebral artery was performed as described [9]. After surgery, animals were placed in a warm environment until they recovered from anesthesia. Three, 24 h and 7 days after MCAO, mice

Measurement of infarct volumes in wt and tg mice

Volumes of infarcted brain were measured in wt and tg groups, 3, 24 h and 7 days after MCAO (Fig. 1). Three hours post-occlusion, all mice showed cortical infarction and the measured volumes were equivalent between the two groups. On the contrary, 24 h after MCAO, the volume of the infarct had significantly increased in wt mice when compared to the volume measured at 3 h (t-test, p<0.05) whereas it was comparable to the 3 h-volume in tg mice. The comparison of infarct volumes between wt and tg

Discussion

The current study shows that tg mice subjected to unilateral MCAO exhibit a permanent 40% reduction of cortical infarction when compared to their wt counterpart. The neuroprotective effect of NGF has been unambiguously reported in animal models of epilepsy and degeneration induced by the administration of excitotoxic agents 8, 34. However, results obtained in models of transient ischemia are still controversial 3, 4, 28, 31and, to our knowledge, have never been reported for permanent ischemia

Acknowledgements

C.G. is a fellow of Ministère de l'Education Nationale, de la Recherche et de la Technologie. M.M.-B. is a fellow of France Parkinson. We thank Brigitte Hamon and Juliette Martin for critically reading the manuscript.

References (41)

Cited by (41)

  • Voltage-dependent potassium channel Kv4.2 alleviates the ischemic stroke impairments through activating neurogenesis

    2021, Neurochemistry International
    Citation Excerpt :

    Neurotrophins are important regulators of neuronal survival, development, function, and plasticity (Huang and Reichardt, 2001). Further experiments demonstrate that the administration of NGF can reduce apoptotic cell death and infarct volume (Cao et al., 2018; Guegan et al., 1998; Holtzman et al., 1996), ameliorate delayed neuronal death (Shigeno et al., 1991), steer microglia into neuroprotective phenotype (Rizzi et al., 2018), boost angiogenesis (Zhu et al., 2011), and promote neural regeneration and functional recovery (Zhu et al., 2011). BDNF is an alternative neurotrophin which also plays an important role in neuronal differentiation and learning memory after stroke (Soler-Llavina et al., 2003; Zhao et al., 2015).

  • Therapeutic Effects of Simultaneous Delivery of Nerve Growth Factor mRNA and Protein via Exosomes on Cerebral Ischemia

    2020, Molecular Therapy Nucleic Acids
    Citation Excerpt :

    NGF also has a broad spectrum of protective effects on various neurons, glial cells, and vascular endothelial cells under different pathological circumstances.3,4 Further experiments demonstrate that the administration of NGF can reduce apoptotic cell death and infarct volume,5–8 ameliorate delayed neuronal death,9 steer microglia into neuroprotective phenotype,10 boost angiogenesis,11 and promote neural regeneration and functional recovery.12 In the context of acute cerebral ischemia, the endogenous expression of NGF decreased significantly in infarcted cortex, highlighting the importance to deliver exogenous NGF.13

  • Amitriptyline is a TrkA and TrkB Receptor Agonist that Promotes TrkA/TrkB Heterodimerization and Has Potent Neurotrophic Activity

    2009, Chemistry and Biology
    Citation Excerpt :

    NGF, gambogic amide, or amitriptyline pretreatment significantly protected hippocampal neurons from apoptosis, while other tricyclic drugs tested had no effect (Figure 1D and data not shown). NGF reduces cortical infarction and apoptosis in transgenic mice and protects PC12 cells from apoptosis in oxygen-glucose deprivation (OGD) (Beck et al., 1992; Guegan et al., 1998). To explore whether amitriptyline and/or other tricyclics could protect hippocampal neurons from OGD-provoked apoptosis, we pretreated primary cultures with various tricyclic drugs, followed by OGD stimulation for 3 hr.

  • Neuroprotection by drug-induced growth factors

    2003, International Congress Series
View all citing articles on Scopus
1

Present address: UPRES-EA 2128, Faculté de Médecine, CHU Côte de Nacre, 14033 Caen Cedex, France.

View full text