calpain and Subarachnoid-Hemorrhage

Excessive glutamate-mediated overactivation of metabotropic glutamate receptor 1 (mGluR1) plays a leading role in neuronal apoptosis following subarachnoid hemorrhage (SAH). TAT-mGluR1, a fusion peptide consisting of a peptide spanning the calpain cleavage site of mGluR1α and the trans-activating regulatory protein (TAT) of HIV, effectively blocks mGluR1α truncation and protects neurons against excitotoxic damage. This study investigated the effects of TAT-mGluR1 on neuronal apoptosis in the rat SAH model. Here, we report that SAH caused activation of calpain and truncation of mGluR1α; intraperitoneally administered TAT-mGluR1 did not affect calpain activity, while it blocked truncation of mGluR1α after SAH. Intraperitoneally administered FITC-labeled TAT-mGluR1 was colocalized with mGluR1α in thecortex after SAH. Furthermore, TAT-mGluR1 significantly improved the neurological deficit, increased p-PI3K, p-Akt, and p-GSK3β, downregulated Bax, upregulated Bcl-2, and reduced cortical apoptosis in the basal cortex at 24 h after SAH. These findings indicated that TAT-mGluR1 acted against SAH-induced cell apoptosis through preventing mGluR1α truncation.

Topics: Animals; Apoptosis; Calpain; Male; Neurons; Neuroprotective Agents; Rats, Sprague-Dawley; Receptors, Metabotropic Glutamate; Signal Transduction; Subarachnoid Hemorrhage

Aneurysmal subarachnoid hemorrhage (ASAH) is a serious event with grave consequences. Delayed ischemic neurological deficits caused by cerebral arterial vasospasm contribute significantly to death and disability. Biomarkers may reflect brain injury and provide an early warning of impending neurological decline and stroke from ASAH-induced vasospasm. Alpha-II spectrin is a cytoskeletal protein whose breakdown products are candidate surrogate markers of injury magnitude, treatment efficacy, and outcome. In addition, all spectrin breakdown products (SBDPs) can provide information on the proteolytic mechanisms of injury.. Twenty patients who received a diagnosis of Fisher Grade 3 ASAH were enrolled in this study to examine the clinical utility of SBDPs in the detection of cerebral vasospasm in patients with ASAH. All patients underwent placement of a ventriculostomy for continual cerebrospinal fluid drainage within 72 hours of ASAH onset. Cerebrospinal fluid samples were collected every 6 hours and analyzed using Western Blotting for SBDPs. Onset of vasospasm was defined as an acute onset of a focal neurological deficit or a change in Glasgow Coma Scale score of two or more points. All suspected cases of vasospasm were confirmed on imaging studies.. Both calpain- and caspase-mediated SBDP levels are significantly increased in patients suffering ASAH. The concentration of SBDPs was found to increase significantly over baseline level up to 12 hours before the onset of cerebral arterial vasospasm.. Differential expression of SBDPs suggests oncotic necrotic proteolysis may be predominant in acute brain injury after ASAH and cerebral arterial vasospasm.

Topics: Adult; Aged; Angiography, Digital Subtraction; Biomarkers; Calpain; Caspases; Cerebral Angiography; Female; Humans; Male; Middle Aged; Necrosis; Spectrin; Subarachnoid Hemorrhage; Tomography, X-Ray Computed; Vasospasm, Intracranial

Increases in intracellular calcium and subsequent activation of calcium-activated proteases (e.g., calpains) may play a critical role in central nervous system injury. Several studies have implicated calpain activation following subarachnoid hemorrhage (SAH). This study evaluated the effect of a calpain inhibitor administration following SAH in the rat on behavioral deficits (postinjury days 1-5, employing a battery of well-characterized assessment tasks), and blood-brain barrier permeability changes (48 h post-SAH, quantifying the microvascular alterations according to the extravasation of protein-bound Evans Blue using a spectrophotofluorimetric technique). Rats were injected with 400 microl of autologous blood into the cisterna magna to induce SAH. Within 5 min after the surgical procedure, Calpain Inhibitor II or vehicle was continuously administered intravenously for 2 days. Results indicated that Calpain Inhibitor II treatment after SAH significantly improved (a) beam balance time (day 1, p < 0.05), but not beam balance score, (b) latency to traverse the beam on days 1-4 (day 1-3, p < 0.001; day 4, p < 0.01), and (c) loss in body weight on days 4-5 (p < 0.05). Evans Blue dye extravasation was significantly less in SAH Calpain Inhibitor II-treated rats compared to SAH vehicle-treated rats in seven out of the eight brain regions studied (p < 0.001, 0.01, and 0.05). These results suggest that pharmacological inhibition of a relatively selective, membrane-permeant calpain inhibitor can significantly reduce some pathophysiological SAH consequences, and indicate that the inhibition of calpain may be a beneficial therapeutic approach to reduce post-SAH global brain dysfunction.

Topics: Animals; Behavioral Symptoms; Blood-Brain Barrier; Body Weight; Calpain; Male; Motor Skills; Oligopeptides; Permeability; Rats; Rats, Sprague-Dawley; Subarachnoid Hemorrhage