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.