apelin-13-peptide and Brain-Edema

Oxidative stress, an adverse consequence of brain ischemia-reperfusion injury (IRI), activates matrix metalloproteinase enzymes which cause to destruction of extracellular matrix and tight junction proteins. Oxidative stress during stroke increases serum endothelin-1 and endothelin B receptor (ETBR) expression. Apelin-13, an endogenous peptide, is expressed in numerous tissues that regulate diverse physiological and pathological processes. This study aimed to investigate the effect of intravenous (IV) injection of apelin-13 on cerebral vasogenic edema due to brain IRI. Animals were divided into sham, ischemia, and treat groups. IRI model was induced by middle cerebral artery occlusion (MCAO) for 60 min followed by 23 h reperfusion. Apelin-13 was injected into the tail vein 5 min before reperfusion. Neurological defects were evaluated with longa test. Brain water content and BBB permeability were assessed according to cerebral dry-wet weight and brain Evans blue extraction. Malondialdehyde (MDA), superoxide dismutase (SOD), and catalase (CAT) were measured using the colorimetric method. Expression of occludin and claudin-5, matrix metalloproteinase- 2 and 9 (MMP-2 & 9) and, ETBR were evaluated using Western blot. Brain IRI was associated with BBB breakdowns and vasogenic edema. Apelin-13 significantly reduced BBB permeability and vasogenic edema. Apelin-13 significantly attenuated IRI-related oxidative stress. Apelin-13 decreased expression of mmp-2, 9 and ETBR, prevented from decrement of occludin and claudin-5 expersion, which protected BBB integrity and reduced vasogenic edema. In conclusion, our results have suggested that an IV injection of apelin-13 could somehow reduce vasogenic edema via targeting oxidative stress and ETBR expression.

Topics: Animals; Antioxidants; Brain Chemistry; Brain Edema; Claudin-5; Infarction, Middle Cerebral Artery; Infusions, Intravenous; Intercellular Signaling Peptides and Proteins; Ischemic Stroke; Male; Matrix Metalloproteinase Inhibitors; Occludin; Oxidative Stress; Rats; Rats, Wistar; Receptor, Endothelin B

Neuronal apoptosis plays important roles in the early brain injury after subarachnoid hemorrhage (SAH). This study first showed that inhibition of activating transcription factor 6 (ATF6) by apelin-13 could reduce endoplasmic reticulum (ER)-stress-mediated apoptosis and blood-brain-barrier (BBB) disruption after SAH. We chose apelin-13, ATF6 and CCAAT/enhancer-binding protein (C/EBP) homologous protein (CHOP) siRNAs to verify the hypothesis. Brain water content, neurological behavior and Evans Blue (EB) were assessed at 24 h after SAH. Western blot analysis and reverse transcription-polymerase chain reaction (RT-PCR) were applied to evaluate the expression of targets in both protein and mRNA levels. Neuronal apoptosis was assessed with Terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) and caspase-3 staining. The results showed that the levels of ATF6, and its downstream protein, CHOP were upregulated and reached the peak at 24 h after SAH. ATF6 was highly expressed in neurons. The administration of apelin-13 could significantly reduce the mRNA and protein levels of ATF6, and its downstream targets, CHOP and caspase-3, but increase the Bcl-2/Bax ratio, Claudin-5, Occludin and ZO-1. What's more, the administration of apelin-13 could reduce brain edema, ameliorate BBB disruption and improve neurological functions. However, the CHOP siRNA could significantly reverse the pro-apoptotic effect induced by the increased ATF6 level after SAH. Apelin-13 could exert its neuroprotective effects via suppression of ATF6/CHOP arm of ER-stress-response pathway in the early brain injury after SAH.

Topics: Activating Transcription Factor 6; Animals; Apoptosis; Blood-Brain Barrier; Brain Edema; Brain Injuries; Disease Models, Animal; Intercellular Signaling Peptides and Proteins; Male; Neurons; Neuroprotective Agents; Rats, Sprague-Dawley; RNA, Messenger; Signal Transduction; Subarachnoid Hemorrhage; Time Factors; Transcription Factor CHOP

Adipocytokine apelin-13 is a peptide which could reportedly protect the brain against ischemic reperfusion injury and traumatic brain injury (TBI). Whether apelin-13 has any roles to play in intracerebral hemorrhage (ICH) has not been clarified. We aimed to investigate the roles of apelin-13 in ICH and effects on ICH-induced apoptosis. Firstly, CD-1 mice were subjected to infusion of Type IV collagenase (to induce ICH) or saline (for shams) into the left striatum. ICH animals received intracerebroventricular administration of vehicle, apelin-13 (50μg dissolved in 5μl saline) immediately after ICH. The motor function and the cerebral water content (CWC) as well as blood brain barrier (BBB) disruption were measured, coupled with determination of ICH-induced neural cell death by Terminal-deoxynucleoitidyl Transferase Mediated Nick End Labeling (TUNEL). The apoptosis-associated proteins caspase-3 and Bcl-2 as well as the brain edema-associated proteins aquaporin-4 (AQP4) and MMP-9 were all assessed with western blotting. The results showed that apelin-13 decreased CWC and reduced Evans blue leakage into injured hemispheres, with the motor function significantly improved. Additionally, apelin-13 also acutely decreased the number of ICH-induced TUNEL-positive (TUNEL(+)) cells at 48h after ICH. The expressions of AQP4, MMP-9, caspse-3 and Bcl-2 were all downregulated by apelin-13 at 24h and 48h after ICH. All these results revealed that apelin-13 attenuated brain edema and reduced cellular death by suppressing apoptosis after ICH in mice.

Topics: Animals; Apoptosis; Blood-Brain Barrier; Brain Edema; Cerebral Hemorrhage; Disease Models, Animal; Intercellular Signaling Peptides and Proteins; Male; Mice; Motor Activity; Neuroprotective Agents

To investigate the protective effect of Apelin-13 on focal cerebral ischemia-reperfusion injury in rats.. Focal transient cerebral ischemia-reperfusion injury was induced in male SD rats using modified suture occlusion technique. The rats were randomly divided into 5 groups: Sham group, Model group, Apelin-low dose (A) group, Apelin-middle dose (B) group and Apelin-high dose (C) group. Apelin-13 was injected into lateral cerebral ventricle, and the neurological function score, brain edema, infarct volume, apoptosis, malondialdehyde (MDA), superoxide dismutase (SOD) and extracellular regulated kinase1/2 (ERK1/2) protein were measured.. Neurological function scores, percentage of brain water content, infarct volumes and TUNEL-positive cells in B and C groups were lower than those in Model group (P<0.05). The level of MDA in the tissue bomogenate of brain tissue in the surrounding area of ischemia of B and C groups was lower than that of Model group, while the activity of SOD was higher (P<0.05). There was no significant difference in ERK1/2 protein expression among the groups (P>0.05). P-ERK1/2 increased in Model group and A, B, and C groups compared with Sham group (P<0.05), and that of A, B, and C group was higher than that of Model group (P<0.05).. Apelin-13 may play an important role by inhibiting oxidative stress to protect against focal cerebral ischemia-reperfusion injury; ERK1/2 signaling pathway may be involved in the protective mechanism of Apelin-13.

Topics: Animals; Apoptosis; Brain Edema; Brain Ischemia; Intercellular Signaling Peptides and Proteins; Male; Malondialdehyde; Oxidative Stress; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Signal Transduction; Superoxide Dismutase

Apelin has been proved to protect the heart against ischemia/reperfusion (I/R) injury via the activation of phosphatidylinositol 3-kinase (PI3K)/Akt and extracellular signal-regulated kinase (ERK) signaling pathways. Whether this protective effect applies to brain I/R injury needed to be explored. We therefore investigated the potential neuroprotective role of Apelin-13 and the underlying mechanisms. Focal transient cerebral I/R model in male ICR mice was induced by 60min of ischemia followed by reperfusion. Apelin-13 intracerebroventricular injection was performed 15 min before reperfusion. Neurological function, infarct volume, brain edema and apoptosis were measured at 24h after stroke. To further test the mechanism of Apelin-13, PI3K inhibitor LY294002 and ERK1/2 inhibitor PD98059 were injected into the lateral cerebral ventricle 15min before ischemia. Compared with the Vehicle group, Apelin-13 significantly ameliorated neurological deficit, infarct volume, brain edema and reduced TUNEL-positive cells. Bax, caspase-3 and cleaved caspase-3 were down-regulated and Bcl-2 up-regulated. While, the effect of Apelin-13 on Bax, Bcl-2, caspase-3 and cleaved caspase-3 was attenuated by LY294002 and PD98059. Apelin protected the brain against I/R insult injury, and this effect may be through activation of PI3K/Akt and ERK1/2 signaling pathways.

Topics: Animals; Apoptosis; Brain; Brain Edema; Brain Infarction; Brain Ischemia; Caspase 3; Chromones; Enzyme Activation; Flavonoids; Gene Expression Regulation; Intercellular Signaling Peptides and Proteins; Male; Mice, Inbred ICR; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Morpholines; Neuroprotective Agents; Phosphatidylinositol 3-Kinases; Phosphoinositide-3 Kinase Inhibitors; Phosphorylation; Proto-Oncogene Proteins c-akt; Proto-Oncogene Proteins c-bcl-2; Reperfusion Injury; Signal Transduction

The adipocytokine apelin is a peptide that was isolated from a bovine stomach for the first time. This peptide and its receptor are abundantly expressed in the nervous and cardiovascular systems. According to previous studies, apelin-13 protects cardiomyocytes from ischemic injury as well as apoptosis. In addition, this peptide has a neuroprotective effect on hippocampal and cultured mouse cortical neurons against NMDA receptor-mediated excitotoxicity. The present study was conducted to determine whether apelin-13 provides protection in transient focal cerebral ischemia. Focal ischemia was induced by 60-min middle cerebral artery occlusion (MCAO), followed by 23-h reperfusion. Saline as a vehicle and apelin-13 at doses of 25, 50, and 100 μg were injected intracerebroventriculary (ICV) at the beginning of ischemia. Infarct volume ,brain edema, motor dysfunction, and apoptosis were assessed 24 h after MCAO. Treatment with apelin-13 at doses of 50 and 100 μg ICV markedly reduced total infarct volumes by 45 and 55 %, respectively (P < 0.001), but injection of apelin at lower dose (25 μg) did not change infarct volume significantly (P > 0.05). In addition, apelin-13 at doses of 50 and 100 μg reduced brain edema (P < 0.001) and inhibited apoptosis by decreasing caspase-3 activation (P < 0.001). Apelin-13 did not significantly change neurological dysfunction (P > 0.05).

Topics: Animals; Apoptosis; Brain Edema; Brain Ischemia; Caspase 3; Cattle; Disease Models, Animal; Dose-Response Relationship, Drug; Infarction, Middle Cerebral Artery; Injections, Intraventricular; Intercellular Signaling Peptides and Proteins; Male; Neuroprotective Agents; Rats; Rats, Wistar; Severity of Illness Index