Intranasal administration of recombinant Netrin-1 attenuates neuronal apoptosis by activating DCC/APPL-1/AKT signaling pathway after subarachnoid hemorrhage in rats.

Neuronal apoptosis is a crucial pathological process in early brain injury after subarachnoid hemorrhage (SAH). The effective therapeutic strategies to ameliorate neuronal apoptosis are still absent. We intended to determine whether intranasal administration of exogenous Netrin-1 (NTN-1) could attenuate neuronal apoptosis after experimental SAH, specifically via activating DCC-dependent APPL-1/AKT signaling cascade. Two hundred twenty-five male Sprague-Dawley rats were subjected to the endovascular perforation model of SAH. Recombinant human NTN-1 (rNTN-1) was administered intranasally. NTN-1 small interfering RNA (siRNA), APPL-1 siRNA, and AKT inhibitor MK2206 were administered through intracerebroventricular (i.c.v.) injection. SAH grade, neurological score, neuronal apoptosis assessed by cleaved caspase-3 (CC-3) expression and Fluoro-Jade C (FJC) staining, double immunofluorescence staining, and Western blot were examined. Our results revealed that endogenous NTN-1 level was increased after SAH. Administration of rNTN-1 improved neurological outcomes at 24 h and 72 h after SAH, while knockdown of endogenous NTN-1 worsened neurological impairments. Furthermore, exogenous rNTN-1 treatment promoted APPL-1 activation, increased phosphorylated-AKT and Bcl-2 expression, as well as decreased apoptotic marker CC-3 expression and the number of FJC-positive neurons, thereby alleviated neuronal apoptosis. Conversely, APPL-1 siRNA and MK2206 abolished the anti-apoptotic effect of exogenous rNTN-1 at 24 h after SAH. Collectively, intranasal administration of exogenous rNTN-1 attenuated neuronal apoptosis and improved neurological function in SAH rats, at least in apart via activating DCC/APPL-1/AKT signaling pathway.

Xie Z ，Huang L ，Enkhjargal B ，Reis C ，Wan W ，Tang J ，Cheng Y ，Zhang JH ... -  《-》

FGF-2 Attenuates Neuronal Apoptosis via FGFR3/PI3k/Akt Signaling Pathway After Subarachnoid Hemorrhage.

Okada T ，Enkhjargal B ，Travis ZD ，Ocak U ，Tang J ，Suzuki H ，Zhang JH ... -  《-》

Tetramethylpyrazine Protects Against Early Brain Injury and Inhibits the PERK/Akt Pathway in a Rat Model of Subarachnoid Hemorrhage.

Shao Z ，Wu P ，Wang X ，Jin M ，Liu S ，Ma X ，Shi H ... -  《-》

Standardized Ginkgo biloba extract EGb 761® attenuates early brain injury following subarachnoid hemorrhage via suppressing neuronal apoptosis through the activation of Akt signaling.

Early brain injury (EBI) plays a critical role in determining the outcome of subarachnoid hemorrhage (SAH). The present study was designed to investigate the role of EGb 761, a standardized extract of Ginkgo biloba, in SAH-induced EBI and to explore its potential mechanism of action. A rat SAH model was established by the endovascular perforation process. Doses of 10, 50 and 100 mg/kg EGb 761 were injected intraperitoneally 2 h after SAH was induced. Mortality, SAH grade, neurological score and brain water content were measured 24 h after SAH was induced. A Western blot assay was performed to assess the expression of the apoptosis-related proteins Bax, Bcl-2, cleaved caspase-3, Akt and phosphorylated Akt (p-Akt). Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) and neuronal nuclei (NeuN) double immunofluorescence staining were used to detect apoptotic neurons. Animals suffered from serious neurological deficits and increased brain water content after induction of SAH. Rats treated with EGb 761 experienced dose-dependent attenuation of neurological dysfunction and decreased brain water content. In addition, EGb 761 significantly activated Akt signaling accompanied by increased Bcl-2 levels and decreased expression of Bax and cleaved caspase-3. Moreover, EGb 761 decreased the number of TUNEL/NeuN-positive cells in a dose-dependent manner. However, all the beneficial effects of EGb 761 for SAH were abolished by the Akt inhibitor MK2206. Our results indicated that EGb 761 could ameliorate SAH-induced EBI and that the neuroprotective effects of EGb 761 against SAH were exerted via suppression of neuronal apoptosis through activation of the Akt pathway.

Yu T ，Fan Y ，Xu Y ，Xu L ，Xu G ，Cao F ，Jiang H ... -  《-》

LAMC1 attenuates neuronal apoptosis via FAK/PI3K/AKT signaling pathway after subarachnoid hemorrhage.

The poor prognosis in patients with subarachnoid hemorrhage (SAH) is often attributed to neuronal apoptosis. Recent evidence suggests that Laminin subunit gamma 1 (LAMC1) is essential for cell survival and proliferation. However, the effects of LAMC1 on early brain injury after SAH and the underlying mechanisms are unknown. The current study aimed to reveal the anti-neuronal apoptotic effect and the potential mechanism of LAMC1 in the rat and in the in vitro SAH models. The SAH model of Sprague-Dawley rats was established by endovascular perforation. Recombinant LAMC1 (rLAMC1) was administered intranasally 30 min after modeling. LAMC1 small interfering RNA (LAMC1 siRNA), focal adhesion kinase (FAK)-specific inhibitor Y15 and PI3K-specific inhibitor LY294002 were administered before SAH modeling to explore the neuroprotection mechanism of rLAMC1. HT22 cells were cultured and stimulated by oxyhemoglobin to establish an in vitro model of SAH. Subsequently, SAH grades, neurobehavioral tests, brain water content, blood-brain barrier permeability, western blotting, immunofluorescence, TUNEL, and Fluoro-Jade C staining were performed. The expression of endogenous LAMC1 was markedly decreased after SAH, both in vitro and in vivo. rLAMC1 significantly reduced the brain water content and blood-brain barrier permeability, improved short- and long-term neurobehavior, and decreased neuronal apoptosis. Furthermore, rLAMC1 treatment significantly increased the expression of p-FAK, p-PI3K, p-AKT, Bcl-XL, and Bcl-2 and decreased the expression of Bax and cleaved caspase -3. Conversely, knockdown of endogenous LAMC1 aggravated the neurological impairment, suppressed the expression of Bcl-XL and Bcl-2, and upregulated the expression of Bax and cleaved caspase-3. Additionally, the administration of Y15 and LY294002 abolished the protective roles of rLAMC1. In vitro, rLAMC1 significantly reduced neuronal apoptosis, and the protective effects were also abolished by Y15 and LY294002. Exogenous LAMC1 treatment improved neurological deficits after SAH in rats, and attenuated neuronal apoptosis in both in vitro and in vivo SAH models, at least partially through the FAK/PI3K/AKT pathway.

Wu Q ，Yuan K ，Yao Y ，Yao J ，Shao J ，Meng Y ，Wu P ，Shi H ... -  《-》