Recombinant tissue plasminogen activator induces long-term anxiety-like behaviors via the ERK1/2-GAD1-GABA cascade in the hippocampus of a rat model.

OBJECTIVES: Recombinant tissue plasminogen activator (rtPA) is widely used for patients with thromboembolic disease, and increasing evidence indicates that it can directly induce neurotoxicity independent of its thrombolysis property. Here, we aimed to confirm the long-term effect of rtPA on animal's behavior, and investigate the underlying pathogenesis. METHODS AND RESULTS: Male Sprague-Dawley rats randomly received a dose of rtPA (10 mg/kg) or sterile saline. Three months later, the animals receiving rtPA displayed anxiety-like behaviors in the open field and novelty-suppressed feeding tests. To investigate the possible pathogenesis, gas chromatography-mass spectrometry-based metabolomics analysis was performed, with 18 differential metabolites identified in the hippocampus 24 h after the treatments. Based upon these differential metabolites, a metabolite-protein integrated network was generated, which indicated that ERK1/2-glutamic acid decarboxylase (GAD) 1-γ aminobutyric acid (GABA) cascade may be related to long-term anxiety-like behaviors. The GABA levels in hippocampus were decreased 24 h post-treatment and three months later, confirmed by a high performance liquid chromatography method. We also examined the expression of GAD1 and GAD2 using western blotting or immunohistochemical staining. Levels of GAD1 were persistently decreased after treatment, while GAD2 levels, GAD1-immunoreactive, and GAD2-immunoreactive neurons showed no significant differences. The underlying pathogenesis also involved activation of ERK1/2, confirmed by increased phospho-ERK1/2 24 h post-treatment. CONCLUSIONS: RtPA can induce long-term anxiety-like behaviors after a clinical injected dose. The underlying pathogenesis involves the ERK1/2-GAD1-GABA cascade in the hippocampus. This pharmacological side effect of rtPA may further exacerbate post-stroke anxiety disorder for stroke patients.

Recombinant Tissue Plasminogen Activator Induces Neurological Side Effects Independent on Thrombolysis in Mechanical Animal Models of Focal Cerebral Infarction: A Systematic Review and Meta-Analysis.

BACKGROUND AND PURPOSE: Recombinant tissue plasminogen activator (rtPA) is the only effective drug approved by US FDA to treat ischemic stroke, and it contains pleiotropic effects besides thrombolysis. We performed a meta-analysis to clarify effect of tissue plasminogen activator (tPA) on cerebral infarction besides its thrombolysis property in mechanical animal stroke. METHODS: Relevant studies were identified by two reviewers after searching online databases, including Pubmed, Embase, and ScienceDirect, from 1979 to 2016. We identified 6, 65, 17, 12, 16, 12 and 13 comparisons reporting effect of endogenous tPA on infarction volume and effects of rtPA on infarction volume, blood-brain barrier, brain edema, intracerebral hemorrhage, neurological function and mortality rate in all 47 included studies. Standardized mean differences for continuous measures and risk ratio for dichotomous measures were calculated to assess the effects of endogenous tPA and rtPA on cerebral infarction in animals. The quality of included studies was assessed using the Stroke Therapy Academic Industry Roundtable score. Subgroup analysis, meta-regression and sensitivity analysis were performed to explore sources of heterogeneity. Funnel plot, Trim and Fill method and Egger's test were obtained to detect publication bias. RESULTS: We found that both endogenous tPA and rtPA had not enlarged infarction volume, or deteriorated neurological function. However, rtPA would disrupt blood-brain barrier, aggravate brain edema, induce intracerebral hemorrhage and increase mortality rate. CONCLUSIONS: This meta-analysis reveals rtPA can lead to neurological side effects besides thrombolysis in mechanical animal stroke, which may account for clinical exacerbation for stroke patients that do not achieve vascular recanalization with rtPA.