humanin and Disease-Models--Animal

Mitochondrial-derived peptides (MDPs) are encoded within the mitochondrial genome. They signal within the cell or are released to act as autocrine/paracrine/endocrine cytoprotective factors playing a key role in the cellular stress response. The first reported and better characterized MDP is humanin (HN), which exerts robust protective effects against a myriad of cytotoxic stimuli in many cell types. These effects have led to the evaluation of HN and its analogs as therapeutic targets for several chronic diseases. Areas covered: We describe the latest findings on the mechanism of action of HN and discuss the role of HN as therapeutic target for neurodegenerative and cardiovascular diseases, diabetes, male infertility, and cancer. Since HN can be detected in circulation, we also depict its value as a biomarker for these diseases. Expert opinion: HN analogs and peptide mimetics have been developed over the last decade and show promising results in preclinical models of degenerative diseases. Local administration of gene therapy vectors that overexpress or silence endogenous HN could also hold therapeutic potential. Controversy on the role of HN in cancer progression and chemoresistance should be addressed before the translation of these therapeutic approaches.

Topics: Animals; Cardiovascular Diseases; Disease Models, Animal; Genetic Therapy; Humans; Intracellular Signaling Peptides and Proteins; Mitochondria; Molecular Targeted Therapy; Neoplasms; Neurodegenerative Diseases

Polycystic ovary syndrome (PCOS) is the most common endocrinological pathology among women of reproductive age, whereas the pathogenesis is still not fully understood. Systemic and ovarian oxidative stress (OS) imbalance is a pivotal feature of PCOS. Humanin, a mitochondria-derived peptide, has been reported to function as an antioxidant in cardiomyocytes, pancreatic beta cells and other cells, but how this function is regulated remains unclear. In this study, we investigated whether humanin expression differs in the granulosa cells (GCs) of PCOS patients versus controls, and whether humanin alleviates OS in PCOS ovaries. Sixteen PCOS patients and 28 age- and BMI-matched controls undergoing IVF were recruited, and their serum, follicular fluid and GCs were collected for humanin analysis. Dehydroepiandrosterone-induced rat PCOS models, and vitamin K3-induced OS COV434 cell lines were applied to investigate the mechanism. Humanin expression was significantly down-regulated in the ovaries of PCOS patients relative to those of non-PCOS patients. Exogenous humanin supplementation significantly attenuated body weight gain, ovarian morphological abnormalities, endocrinological disorders and ovarian and systemic OS in PCOS rat models. Our study further demonstrated that this attenuation effect was involved in the modulation of the Kelch-like ECH-associated protein 1 (Keap1)/nuclear factor-erythroid 2-related factor 2 (Nrf2) signalling pathway. In summary, this study reported for the first time that decreased expression of humanin in the GCs was associated with oxidative imbalance in PCOS. Humanin alleviates OS in ovarian GCs of PCOS patients via modulation of the Keap1/Nrf2 signalling pathway.

Topics: Adult; Animals; Case-Control Studies; Cell Line, Tumor; Disease Models, Animal; Female; Granulosa Cells; Humans; Intracellular Signaling Peptides and Proteins; Kelch-Like ECH-Associated Protein 1; NF-E2-Related Factor 2; Ovary; Oxidative Stress; Polycystic Ovary Syndrome; Rats, Sprague-Dawley; Signal Transduction; Young Adult

Polycystic ovary syndrome (PCOS), the most common endocrine disorder in women of reproductive age, is characterized by hyperandrogenism and insulin resistance (IR); however, the pathogenesis of local ovarian IR in PCOS remains largely unclear. Humanin, a mitochondria-derived peptide, has been reported to be associated with IR. Our previous study confirmed that humanin is expressed in multiple cell types in the ovary and is present in follicular fluid. However, it remains unknown whether humanin participates in the pathogenesis of local ovarian IR or whether humanin supplementation can improve IR in PCOS patients. In this study, we compared humanin concentrations in follicular fluid from PCOS patients with and without IR. We further investigated the effect of humanin analogue (HNG) supplementation on IR in a rat model of dehydroepiandrosterone-induced PCOS. Humanin concentrations in the follicular fluid were found to be significantly lower in PCOS patients with IR than in those without IR. HNG supplementation attenuated both the increases in the levels of fasting plasma glucose and fasting insulin in rats with PCOS and the decreases in phosphorylation of IRS1, PI3K, AKT, and GLUT4 proteins in the granulosa cells of these rats. Combined supplementation with HNG and insulin significantly improved glucose consumption in normal and humanin-siRNA-transfected COV434 cells. In conclusion, downregulated humanin in the ovaries may be involved in the pathogenesis of IR in PCOS, and exogenous supplementation with HNG improved local ovarian IR through modulation of the IRS1/PI3K/Akt signaling pathway in a rat model. This finding supports the potential future use of HNG as a therapeutic drug for PCOS.

Topics: Adult; Animals; Case-Control Studies; Cell Line; Disease Models, Animal; Drug Evaluation, Preclinical; Female; Follicular Fluid; Glucose Transporter Type 4; Granulosa Cells; Humans; Insulin Receptor Substrate Proteins; Insulin Resistance; Intracellular Signaling Peptides and Proteins; Phosphatidylinositol 3-Kinases; Polycystic Ovary Syndrome; Primary Cell Culture; Proto-Oncogene Proteins c-akt; Rats, Sprague-Dawley; Signal Transduction; Young Adult

Although the gold standard treatment for acute myocardial infarction is reperfusion therapy, reperfusion itself can cause myocardial damage via induction of cardiac mitochondrial dysfunction. This can lead to increased myocardial infarct size, arrhythmias, and left ventricular (LV) dysfunction. Recently, a newly discovered peptide, Humanin, has been shown to exert several beneficial effects including antioxidative and antiapoptosis effects. We recently reported that a Humanin analogue (HNG, 84 μg/kg) given prior to cardiac ischemia exerted cardioprotection against I/R injury, but failed to do so when it was given after ischemia was induced. However, in a clinical setting, patients can only be treated after the onset of ischemia. In this study, we investigated the potential benefit of various doses of HNG therapy (84, 168, 252 μg/kg) against myocardial I/R injury when applied during ischemia on cardiac arrhythmia, myocardial infarct size, cardiac mitochondrial function, and LV function.. Myocardial I/R injury was induced in rats by 30-minute left anterior descending coronary artery occlusion, followed by 120-minute of reperfusion. HNG at the different doses were given intravenously at 15 minutes after ischemic onset and also at the onset of reperfusion.. HNG (252 μg/kg) applied during the ischemic period not only increased HN levels in the damaged myocardium, but also significantly decreased cardiac arrhythmia, myocardial infarct size, cardiac mitochondrial dysfunction, and left ventricular dysfunction. These benefits were mediated through the attenuation of cardiac mitochondrial dysfunction.. High-dose HN applied during ischemia in rats could exert cardioprotection against I/R injury-induced mitochondrial dysfunction.

Topics: Animals; Arrhythmias, Cardiac; Disease Models, Animal; Dose-Response Relationship, Drug; Intracellular Signaling Peptides and Proteins; Male; Mitochondria, Heart; Myocardial Infarction; Myocardial Reperfusion Injury; Myocytes, Cardiac; Protective Agents; Rats, Wistar; Signal Transduction; Ventricular Function, Left

Humanin (HN) is an endogenous 24-residue peptide. A highly potent HN derivative, S14G-HN, which has a substitution of serine 14 to glycine, reduced amyloid burden and suppressed cognitive impairment in a mouse model of Alzheimer's disease. S14G-HN also suppressed amnesia induced by a muscarinic receptor antagonist in rodents. To understand the effects of HN on brain function, we tested the effect of S14G-HN on diazepam (DZP)-induced memory impairment and anxiety in mice using the object recognition test and zero-maze test, respectively. Intraperitoneal injection of S14G-HN reversed the DZP-induced memory deficit, whereas no significant change was observed in behavioral markers of anxiety. S14G-HN had no effect on locomotor activity in either test, indicating that S14G-HN did not affect physical functioning or motivation. These results suggest that HN preferentially influences cognitive function but not emotional function in the central nervous system.

Topics: Alzheimer Disease; Animals; Anticonvulsants; Cognition; Diazepam; Disease Models, Animal; Intracellular Signaling Peptides and Proteins; Male; Maze Learning; Memory Disorders; Mice; Neuroprotective Agents

The 24-residue peptide humanin (HN) has been proposed as a peptide-based inhibitor able to interact directly with amyloid-β (Aβ) oligomers and interfere with the formation and/or biological properties of toxic Aβ species. When administered exogenously, HN, or its synthetic S14G-derivative (HNG), exerted multiple cytoprotective effects, counteracting the Aβ-induced toxicity. Whether these peptides interact directly with Aβ, particularly with the soluble oligomeric assemblies, remains largely unknown. We here investigated the ability of HN and HNG to interact directly with highly aggregating Aβ42, and interfere with the formation and toxicity of its oligomers. Experiments were run in cell-free conditions and in vivo in a transgenic C. elegans strain in which the Aβ toxicity was specifically due to oligomeric species. Thioflavin-T assay indicated that both HN and HNG delay the formation and reduce the final amount of Aβ42 fibrils. In vitro surface plasmon resonance studies indicated that they interact with Aβ42 oligomers favoring the formation of amorphous larger assemblies, observed with turbidity and electron microscopy. In vivo studies indicated that both HN and HNG decrease the relative abundance of A11-positive prefibrillar oligomers as well as OC-positive fibrillar oligomers and had similar protective effects. However, while HN possibly decreased the oligomers by promoting their assembly into larger aggregates, the reduction of oligomers caused by HNG can be ascribed to a marked decrease of the total Aβ levels, likely the consequence of the HNG-induced overexpression of the Aβ-degrading enzyme neprilysin. These findings provide information on the mechanisms underlying the anti-oligomeric effects of HN and HNG and illustrate the role of S14G substitution in regulating the in vivo mechanism of action.

Topics: Amyloid beta-Peptides; Animals; Animals, Genetically Modified; Caenorhabditis elegans; Caenorhabditis elegans Proteins; Circular Dichroism; Disease Models, Animal; Dose-Response Relationship, Drug; Gene Expression Regulation; Humans; Intracellular Signaling Peptides and Proteins; Microscopy, Atomic Force; Microscopy, Electron, Transmission; Neprilysin; Paralysis; Peptide Fragments; Surface Plasmon Resonance

What is the central question of this study? Myocardial ischaemia-reperfusion (I/R) injury causes interference in the systemic circulation and damages not only the heart but also several vital organs, including the brain. Recently, a novel peptide called humanin has been shown to exert potent neuroprotective effects. However, the effect of humanin on the brain during cardiac I/R injury has not yet been investigated. What is the main finding and its importance? The I/R injury caused blood-brain barrier breakdown, increased brain oxidative stress and resulted in mitochondrial dysfunction. Only the humanin treatment before ischaemia attenuated brain mitochondrial dysfunction, but it did not prevent blood-brain barrier breakdown or brain oxidative stress. Humanin treatment during ischaemia and in the reperfusion period provided no neuroprotection. These findings indicate that humanin exerted neuroprotection during cardiac I/R injury via improved brain mitochondrial function. Myocardial ischaemia-reperfusion (I/R) injury causes interference in the systemic circulation and damages not only the heart but also several vital organs, including the brain. Nevertheless, limited information is available regarding the effect of cardiac I/R injury on the brain, including blood-brain barrier (BBB) breakdown, brain oxidative stress and mitochondrial function. Recently, a novel peptide called humanin has been shown to exert potent neuroprotective effects. However, the effect of humanin on the brain during cardiac I/R injury has not yet been investigated. Forty-two male Wistar rats were divided into the following two groups: an I/R group, which was subjected to a 30 min left anterior descending coronary artery occlusion followed by 120 min reperfusion (I/R group; n = 36); and a sham group (n = 6). The I/R group was divided into six subgroups. Each subgroup was given either vehicle or humanin analogue (84 μg kg(-1) , i.v.) at three different time points, namely before ischaemia, during ischaemia or at the onset of reperfusion. At the end of the experimental protocol, animals were killed and the brains removed for determination of mitochondrial function, oxidative stress and Western blot analyses. The I/R injury caused BBB breakdown, increased brain oxidative stress and resulted in mitochondrial dysfunction. Only the humanin treatment before ischaemia attenuated brain mitochondrial dysfunction, but it did not prevent BBB breakdown or brain oxidative stress. Humanin treatment d

Topics: Animals; Blood-Brain Barrier; Brain; Coronary Artery Disease; Coronary Vessels; Disease Models, Animal; Heart; Intracellular Signaling Peptides and Proteins; Male; Mitochondria; Mitochondrial Diseases; Myocardial Ischemia; Myocardial Reperfusion Injury; Myocardium; Oxidative Stress; Rats; Rats, Wistar

Myocardial reperfusion via the re-canalization of occluded coronary arteries is gold standard for the treatment of acute myocardial infarction. However, reperfusion itself can cause myocardial damage due to increased reactive oxygen species (ROS) production, a process known as ischemia/reperfusion (I/R) injury. Cardiac mitochondria are the major organelle of ROS production in the heart. Cardiac mitochondrial dysfunction caused by an increased ROS production can increase cardiac arrhythmia incidence, myocardial infarct size, and cardiac dysfunction. Thus, preservation of cardiac mitochondrial function is a promising pharmacological approach to reduce cardiac I/R injury. Humanin (HN), a newly discovered 24-amino acid polypeptide, has been shown to exert antioxidative stress and antiapoptotic effects. Although the cardioprotective effects of HN against I/R injury has been reported, the effect of HN on cardiac mitochondrial function has not yet been investigated. Thus, we tested the hypothesis that HN exerts its cardioprotective effects against I/R injury through the attenuation of cardiac mitochondrial dysfunction.. I/R protocol was carried out using a 30-minutes occlusion of a left anterior descending coronary artery followed by a 120-minutes of reperfusion. The plasma HN level, infarct size, arrhythmia incidence, left ventricular function, and cardiac mitochondrial function were determined.. Endogenous HN level before I/R injury showed no difference between groups, but was markedly decreased after I/R injury. HN analogue pretreatment decreased arrhythmia incidence and infarct size, improved cardiac mitochondrial function, and attenuated cardiac dysfunction.. Humanin analogue pretreatment exerted cardioprotective effects against I/R injury through the attenuation of cardiac mitochondrial dysfunction.

Topics: Animals; Arrhythmias, Cardiac; Cardiotonic Agents; Disease Models, Animal; Drug Administration Schedule; Intracellular Signaling Peptides and Proteins; Male; Mitochondria, Heart; Mitochondrial Diseases; Myocardial Infarction; Myocardial Reperfusion Injury; Myocardium; Oxidative Stress; Rats, Wistar; Reactive Oxygen Species; Time Factors; Ventricular Function, Left

Oligodendrocytes are the predominant cell type in white matter and are highly vulnerable to ischemic injury. The role of oligodendrocyte dysfunction in ischemic brain injury is unknown. In this study, we used a 24-amino acid peptide S14G-Humanin (HNG) to examine oligodendrogenesis and neurological functional recovery in a hypoxic/ischemic (H/I) neonatal model. Intraperitoneal HNG pre-treatment decreased infarct volume following H/I injury. Delayed HNG treatment 24 h after H/I injury did not reduce infarct volume but did decrease neurological deficits and brain atrophy. Delayed HNG treatment did not attenuate axonal demyelination at 48 h after H/I injury. However, at 14 d after H/I injury, delayed HNG treatment increased axonal remyelination, the thickness of corpus callosum at the midline, the number of Olig2(+) /BrdU(+) cells, and levels of brain-derived neurotrophic factor (BDNF). Our results suggest that targeting oligodendrogenesis via delayed HNG treatment may represent a promising approach for the treatment of stroke.

Topics: Animals; Animals, Newborn; Atrophy; Axons; Brain-Derived Neurotrophic Factor; Cerebral Infarction; Disease Models, Animal; Hypoxia-Ischemia, Brain; Intracellular Signaling Peptides and Proteins; Neurogenesis; Oligodendroglia; Random Allocation; Rats; Rats, Sprague-Dawley; Recovery of Function

Amyloid β-peptide (Aβ) has been implicated as a key molecule in the neurodegenerative cascades of Alzheimer's disease (AD). Humanin (HN) is a secretory peptide that inhibits the neurotoxicity of Aβ. However, the mechanism(s) by which HN exerts its neuroprotection against Aβ-induced AD-like pathological changes and memory deficits are yet to be completely defined. In the present study, we provided evidence that treatment of rats with HN increases the number of dendritic branches and the density of dendritic spines, and upregulates pre- and post-synaptic protein levels; these effects lead to enhanced long-term potentiation and amelioration of the memory deficits induced by Aβ(1-42). HN also attenuated Aβ(1-42)-induced tau hyperphosphorylation, apparently by inhibiting the phosphorylation of Tyr307 on the inhibitory protein phosphatase-2A (PP2A) catalytic subunit and thereby activating PP2A. HN also inhibited apoptosis and reduced the oxidative stress induced by Aβ(1-42). These findings provide novel mechanisms of action for the ability of HN to protect against Aβ(1-42)-induced AD-like pathological changes and memory deficits.

Topics: Alzheimer Disease; Amyloid beta-Peptides; Animals; Brain; Cognition; Cognition Disorders; Dendrites; Dendritic Spines; Disease Models, Animal; Hippocampus; Intracellular Signaling Peptides and Proteins; Male; Maze Learning; Neurons; Oxidative Stress; Phosphorylation; Rats; Rats, Wistar

Perihematomal brain edema formation and consequent cell death contribute to second brain injury resulting in severe neurological deficits and sometimes delayed fatality after intracerebral hemorrhage (ICH). [Gly14]-Humanin (HNG), a variant of Humanin (HN) in which the 14th amino acid serine is replaced with glycine, reduced Alzheimer's disease-relevant insults and improved neurological deficits in an ischemia stroke model. In the study, we aimed to evaluate whether HNG posttreatment attenuated early brain injury after ICH and whether the protective effect was associated with regulation of apoptosis via phosphatidylinositol 3-kinase (PI3K)-Akt/GSK-3β signaling. Male ICR mice were subjected to infusion of Type IV collagenase (to induce ICH) of saline (for shams) into the left striatum. ICH animals received vehicle, HNG (1 or 2.5 μg in 100 μl saline) administration intraperitoneally 1h post injury. Compared with vehicle, HNG-2.5 μg treatment improved neurological outcome and reduced brain edema at 24 and 72 h after surgery (P<0.05), but wortmannin (15 μg/kg, 90 min before HNG-2.5 μg, intravenously) obliterated the effect. HNG-2.5 μg also reduced cell insults and injury volume at 24 and 72 h after surgery (P<0.05, vs. vehicle). Furthermore, HNG-2.5 μg treatment increased p-Akt and Bcl-2 and decreased p-GSK-3β, cleaved caspase-3 and cleaved poly (ADP-ribose) polymerase expressions in the ipsilateral hemisphere (P<0.05, vs. vehicle), however, the effect was reversed by wortmannin. In conclusion, HNG treatment improved functional and morphological outcomes after experimental ICH in mice and the protective effect was associated with suppressing apoptosis through PI3K-Akt/GSK-3β signaling pathway.

Topics: Animals; Apoptosis; Cerebral Hemorrhage; Corpus Striatum; Disease Models, Animal; Glycogen Synthase Kinase 3; Glycogen Synthase Kinase 3 beta; Intracellular Signaling Peptides and Proteins; Male; Mice; Mice, Inbred ICR; Neurons; Neuroprotective Agents; Proto-Oncogene Proteins c-akt; Proto-Oncogene Proteins c-bcl-2; Signal Transduction

Inhibition of the early intracellular event that triggers neurodegenerative cascades and reversal of neuronal cell death are essential for effective treatment of Alzheimer's disease (AD). In this study, a novel therapeutic for AD, a transducible humanin with an extended caspase-3 cleavage sequence (tHN-C3), was developed and showed multiple mechanisms of therapeutic action. These included targeted delivery of anti-apoptotic protein humanin through the blood-brain barrier (BBB) to neuronal cells, specific inhibition of caspase-3 activation to inhibit the early triggering of AD progression, and delivery of humanin into the cytoplasm of neuronal cells undergoing apoptosis where it exerts its anti-apoptotic functions effectively. The tHN-C3 prevented neuronal cell death induced by H2O2, or soluble Aβ42, via Bax binding. In animal models of AD induced by amyloid beta, in Tg2576 mice, and in the rat middle cerebral artery occlusion model of stroke, tHN-C3 effectively prevented neuronal cell death, inflammatory cell infiltration into the brain, and improved cognitive memory. The therapeutic effectiveness of tHN-C3 was comparable to that of Aricept, a clinically approved drug for AD treatment. Therefore, tHN-C3 may be a new remedy with multiple therapeutic functions targeting the early and late stages of neurodegeneration in AD and other brain injuries.

Topics: Animals; Animals, Newborn; Apoptosis; Caspase 3; Cell Death; Cell Line, Tumor; Cytoplasm; Cytoprotection; Disease Models, Animal; Female; Flow Cytometry; Green Fluorescent Proteins; Humans; Immunohistochemistry; Intracellular Signaling Peptides and Proteins; Mice; Mice, Inbred C57BL; Mice, Transgenic; Neurodegenerative Diseases; Neurons; Neuroprotective Agents; Rats

Because of the immunogenicity and toxicity in vivo of large molecules such as lectins, the application of these molecules is remarkably restricted in drug delivery systems. In this study, to improve the brain drug delivery and reduce the immunogenicity of traditional lectin modified delivery system, Odorranalectin (OL, 1700 Da), a novel non-immunogenic small peptide, was selected to establish an OL-modified cubosomes (Cubs) system. The streptavidin (SA)-conjugated Cubs were prepared by incorporating maleimide-PEG-oleate and taking advantage of its thiol group binding reactivity to conjugate with 2-iminothiolane thiolated SA; mono-biotinylated OL was then coupled with the SA-modified Cubs. The OL-decorated Cubs (OL-Cubs) devised via a non-covalent SA-biotin "bridge" made it easy to conjugate OL and determine the number of ligands on the surface of the Cubs using sensitive chemiluminescent detection. Retention of the bio-recognitive activity of OL after covalent coupling was verified by hemagglutination testing. Nose-to-brain delivery characteristic of OL-Cubs was investigated by in vivo fluorescent biodistribution using coumarin-6 as a marker. The relative uptake of coumarin carried by OL-Cubs was 1.66- to 3.46-fold in brain tissues compared to that incorporated in the Cubs. Besides, Gly14-Humanin (S14G-HN) as a model peptide drug was loaded into cubosomes and evaluated for its pharmacodynamics on Alzheimer's disease (AD) rats following intranasal administration by Morris water maze test and acetylcholinesterase activity determination. The results suggested that OL functionalization enhanced the therapeutic effects of S14G-HN-loaded cubosomes on AD. Thus, OL-Cubs might offer a novel effective and noninvasive system for brain drug delivery, especially for peptides and proteins.

Topics: Administration, Intranasal; Alzheimer Disease; Amyloid beta-Peptides; Animals; Brain; Coumarins; Disease Models, Animal; Drug Carriers; Drug Delivery Systems; Glycine; Intracellular Signaling Peptides and Proteins; Lectins; Maze Learning; Peptide Fragments; Rats; Rats, Sprague-Dawley; Streptavidin; Thiazoles; Tissue Distribution

Since several different pathways are involved in cerebral ischemia/reperfusion injury, combination therapy rather than monotherapy may be required for efficient neuroprotection. In this study, we examined the protective effects of an apoptosis inhibitor Gly(14)-humanin (HNG) and a necroptosis inhibitor necrostatin-1 (Nec-1) on hypoxia/ischemia/reperfusion injury. Cultured mouse primary cortical neurons were incubated with Nec-1, HNG or both in a hypoxia chamber for 60 min. Cell viability was determined by MTS assay at 24h after oxygen-glucose deprivation (OGD) treatment. Mice underwent middle cerebral artery occlusion for 75 min followed by 24h reperfusion. Mice were administered HNG and/or Nec-1 (i.c.v.) at 4h after reperfusion. Neurological deficits were evaluated and the cerebral infarct volume was determined by TTC staining. Nec-1 or HNG alone had protective effects on OGD-induced cell death. Combined treatment with Nec-1 and HNG resulted in more neuroprotection than Nec-1 or HNG alone. Treatment with HNG or Nec-1 reduced cerebral infarct volume from 59.3 ± 2.6% to 47.0 ± 2.3% and 47.1 ± 1.5%, respectively. Combined treatment with HNG and Nec-1 improved neurological scores and decreased infarct volume to 38.6 ± 1.5%. In summary, we demonstrated that the combination treatment of HNG and Nec-1 conferred synergistic neuroprotection on hypoxia/ischemia/reperfusion injury in vitro and in vivo. These findings provide a novel therapeutic strategy for the treatment of stroke by combining anti-apoptosis and anti-necroptosis therapy.

Topics: Animals; Apoptosis; Cells, Cultured; Disease Models, Animal; Drug Synergism; Drug Therapy, Combination; Hypoxia-Ischemia, Brain; Imidazoles; Indoles; Intracellular Signaling Peptides and Proteins; Mice; Neuroprotective Agents; Reperfusion Injury; Signal Transduction; Treatment Outcome

Humanin (HN) is a 24-amino acid peptide that protects neuronal cells from death caused by Alzheimer's disease (AD)-related genes and amyloid-beta (Abeta). Multiple studies have revealed its biochemical and neuroprotective characteristics in vitro; however, little has been known regarding whether HN is effective in vivo in AD model systems. We examined the effect of S14G-HN, a 1,000-fold more potent derivative of HN in vitro, on amnesia induced by Abeta25-35 in mice. The Y-maze test revealed that at least 50 pmol of S14G-HN by intracerebroventricular injection prevented Abeta-induced impairment of short-term/spatial working memory; however, 5 nmol of S14A-HN, a neuroprotection-defective mutant in vitro, did not prevent Abeta-induced amnesia. These results are in agreement with the structure-function correlation shown previously in vitro. In the water-finding task, S14G-HN prevented prolongation of finding latency (the time to find water) observed in Abeta-amnesic mice, indicating that S14G-HN also blocked Abeta-induced impairment of latent learning. In accordance with these observations, immunohistochemical analysis showed that S14G-HN sustained the number of cholinergic neurons in the basal forebrain and the striata nearly to the normal level. Furthermore, genistein, a specific inhibitor of tyrosine kinases, blocked recovery from scopolamine-induced amnesia by S14G-HN, suggesting that certain tyrosine kinase(s) are involved in the inhibitory function of S14G-HN in vivo. Taking these findings together, we conclude that S14G-HN has rescue activity against memory impairment caused by AD-related insults in vivo by activating the same intracellular neuroprotective machinery as elucidated previously in vitro.

Topics: Amnesia; Amyloid beta-Peptides; Analysis of Variance; Animals; Behavior, Animal; Brain; Cell Count; Choline O-Acetyltransferase; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Interactions; Enzyme Inhibitors; Exploratory Behavior; Genistein; Humans; Immunohistochemistry; Injections, Intraventricular; Intracellular Signaling Peptides and Proteins; Male; Maze Learning; Memory Disorders; Memory, Short-Term; Mice; Neuroprotective Agents; Proteins; Reaction Time; Scopolamine; Space Perception