FGF-2 Attenuates Neuronal Apoptosis via FGFR3/PI3k/Akt Signaling Pathway After Subarachnoid Hemorrhage
Neuronal apoptosis is a common and critical pathology following subarachnoid hemorrhage (SAH). We investigated the anti-apoptotic property of fibroblast growth factor (FGF)-2 after SAH in rats. A total of 289 rats underwent endovascular perforation to induce SAH or sham operation. Three dosages (3, 9, or 27 μg) of recombinant FGF-2 (rFGF-2) or vehicle was administered intranasally to rats 30 min after SAH induction. The pan-FGF receptor (FGFR) inhibitor PD173074 or vehicle was administered intracerebroventricularly (i.c.v.) 1 h before modeling, in addition to rFGF-2 treatment. Small interfering ribonucleic acid (siRNA) for FGFR1 and FGFR3 or scrambled siRNA was administered i.c.v. 48 h before SAH induction in addition to rFGF-2 treatment. Anti-FGF-2 neutralizing antibody or normal mouse immunoglobulin G (IgG) was administered i.c.v. 1 h before SAH model. Neurobehavioral tests, SAH severity, brain water content, immunofluorescence, Fluoro-Jade C, TUNEL staining, and western blot were evaluated. The expression of FGF-2, FGFR1, and FGFR3 increased after SAH. FGFR1 and FGFR3 were expressed in the neurons. Nine micrograms of FGF-2 alleviated neurological impairments, brain edema, and neuronal apoptosis following SAH. A rFGF-2 treatment improved motor skill learning and spatial memory and increased the number of surviving neurons postinjury to 28 days after SAH. PD173074 abolished the anti-apoptotic effects of rFGF-2 via suppression of the expression of PI3k, phosphorylated Akt (p-Akt), and Bcl-2 leading to enhancement of the expression of Bax. FGFR3 siRNA worsened neurobehavioral function and suppressed the expression of PI3k, p-Akt, and Bcl-2 rather than FGFR1 siRNA in SAH rats treated with rFGF-2. Anti-FGF-2 neutralizing antibody suppressed the expression of PI3k and p-Akt after SAH. FGF-2 may be a promising therapy to reduce post-SAH neuronal apoptosis via activation of the FGFR3/PI3k/Akt signaling pathway.
KeywordsAkt Early brain injury Fibroblast growth factor-2 Fibroblast growth factor receptor 3 Neuronal apoptosis Subarachnoid hemorrhage
brain water content
central nervous system
early brain injury
extracellular signal-regulated kinase
fibroblast growth factor
fibroblast growth factor receptor
growth factor receptor-bound protein 2
neuron-specific nuclear protein
phosphorylated fibroblast growth factor receptor
recombinant fibroblast growth factor-2
revolutions per minute
- Scr siRNA
scrambled small interfering ribonucleic acid
small interfering ribonucleic acid
son of sevenless
terminal deoxynucleotidyl transferase dUTP nick end labeling
The authors acknowledge the technical assistance provided by Desislava Doycheva, Jerry Flores, Marcin Gamdzyk, Helen Huang, Prativa Sherchan, Orhan Altay, Weilin Xu, Yuchun Zuo, Ganz Zuo, and Jun Peng.
TO, BE, SH, JT, and JHZ were involved in the study design. TO, BE, and JHZ were involved in data interpretation and writing of the manuscript; TO performed the majority of the laboratory work and contributed to the analysis of data; BE was responsible for the animal model; ZDT was involved in manuscript editing. UO was responsible for the rotarod and water maze test; ZDT was involved in manuscript editing.
This article is supported partially by grants from the National Institutes of Health (NS081740 and NS082184) to Dr. Zhang.
Compliance with Ethical Standards
Ethics Approval and Consent to Participate
The Institutional Animal Care and Use Committee (IACUC) of Loma Linda University approved the study protocol, and all experiments were conducted in accordance with the NIH Guidelines for Use of Animals in Neuroscience Research. All authors have read and approved the submitted manuscript.
The authors declare that they have no competing interests.
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