mk-2206 and Brain-Injuries

Phosphodiesterase-4 (PDE4) plays a fundamental role in a range of central nervous system (CNS) insults, however, the role of PDE4 in early brain injury (EBI) after subarachnoid hemorrhage (SAH) remains unclear. The current study was designed to investigate the role of PDE4 in EBI after SAH and explore the potential mechanism. The SAH model in Sprague-Dawley rat was established by endovascular perforation process. Rats were randomly divided into: sham group, SAH?+?vehicle group, SAH?+?rolipram (PDE4 inhibitor) group, SAH?+?rolipram?+?sirtinol (SIRT1 inhibitor) group and SAH?+?rolipram+MK2206 (Akt inhibitor) group. Mortality, SAH grades, neurological function, brain edema, immunofluorescence staining and western blotting were performed. Double fluorescence labeling staining indicated that PDE4 was located predominately in neurons after SAH. Rolipram reduced brain edema, improved neurological function in the rat model of SAH. Moreover, rolipram increased the expression of Sirtuin1 (SIRT1) and up-regulated the phosphorylation of Akt, which was accompanied by the reduction of neuronal apoptosis. Administration of sirtinol inhibited the phosphorylation of Akt. Moreover, all the beneficial effects of rolipram against SAH were abolished by both sirtinol and MK2206. These data indicated that PDE4 inhibition by rolipram protected rats against EBI after SAH via suppressing neuronal apoptosis through the SIRT1/Akt pathway. Rolipram might be an important therapeutic drug for SAH.

Topics: Animals; Apoptosis; Benzamides; Brain Edema; Brain Injuries; Cyclic Nucleotide Phosphodiesterases, Type 4; Heterocyclic Compounds, 3-Ring; Male; Naphthols; Neuroprotective Agents; Phosphodiesterase 4 Inhibitors; Phosphorylation; Proto-Oncogene Proteins c-akt; Rats; Rats, Sprague-Dawley; Rolipram; Sirtuin 1; Subarachnoid Hemorrhage

Neuronal apoptosis is a central pathological process in subarachnoid hemorrhage (SAH)-induced early brain injury. Endoplasmic reticulum (ER) stress was reported to have a vital role in the pathophysiology of neuronal apoptosis in the brain. The present study was designed to investigate the potential effects of ER stress and its downstream signals in early brain injury after SAH. One hundred thirty-four rats were subjected to an endovascular perforation model of SAH. The RNA-activated protein kinase-like ER kinase (PERK) inhibitor GSK2606414 and the Akt inhibitor MK2206 were injected intracerebroventricularly. SAH grade, neurologic scores, and brain water content were measured 72 h after subarachnoid hemorrhage. Expression of PERK and its downstream signals, Akt, Bcl-2, Bax, and cleaved caspase-3, were examined using Western blot analysis. Specific cell types that expressed PERK were detected with double immunofluorescence staining. Neuronal cell death was demonstrated with terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL). Our results showed that the expression of p-PERK and its downstream targets, p-eIF2α and ATF4, increased after SAH and peaked at 72 h after SAH. PERK was expressed mostly in neurons. The inhibition of PERK with GSK2606414 reduced p-PERK, p-eIF2α, and ATF4 expression. Furthermore, GSK2606414 treatment increased p-Akt levels and the Bcl-2/Bax ratio as well as decreased cleaved caspase-3 expression and neuronal death, thereby improving neurological deficits at 72 h after SAH. The selective Akt inhibitor MK2206 abolished the beneficial effects of GSK2606414. PERK, the major transducer of ER stress, is involved in neuronal apoptosis after SAH. The inhibition of PERK reduces early brain injury via Akt-related anti-apoptosis pathways. PERK may serve as a promising target for future therapeutic intervention.

Topics: Adenine; Animals; Brain Injuries; eIF-2 Kinase; Heterocyclic Compounds, 3-Ring; Indoles; Male; Proto-Oncogene Proteins c-akt; Rats; Rats, Sprague-Dawley; Subarachnoid Hemorrhage