colivelin and Memory-Disorders

Alzheimer's disease (AD) is characterized with progressive memory loss and severe cognitive impairments, which affect everyday life and human health in the elderly. It is required that an effective and safe protective reagent against AD should be developed. It has been reported that humanin (HN) exerts neuroprotective effects against AD. In this study, we investigated the effect of a novel and more effective HN derivative, Colivelin (CLN) on AD.. PDAPP(V717I) transgenic AD model mice (derived from parental C57/BL6 mice) were used in our study as AD model. Morris water maze test was used to test the memory impairment of AD mice and the levels of Aβ40 and Aβ42 were determined by an Elisa assay. We used an Immunohistochemistry and Immunofluorescence staining method to check the GFAP and MAP2 positive cells, and TUNEL to assess the apoptotic cells. Western blot assay was used to check the expression and phosphorylation level of p38.. We found that CLN improved the memory impairment induced by AD and reduced the deposit of Aβ40 and Aβ42. CLN also inhibited cell apoptosis and activation of caspase 3 in brain tissues of AD mice. Inflammation in AD mice was alleviated by CLN treatment, including the accumulation of GFAP positive cells and the inflammatory cytokines. With both structure of AGA-HNG and ANDF, CLN exhibited significantly stronger effects than synchronously administration of AGA-HNG and ADNF, suggesting CLN as a novel potential effective therapeutic reagent for AD patients. Finally, we found that CLN inhibited phosphorylation of p38 in AD mice and p38 inhibitor, SB203580 weakened the therapeutic effect of CLN.. CLN effectively improved the memory dysfunction in PDAPP mice, and our data suggests CLN as a novel and effective reagent which may have great potentials in AD therapy.

Topics: Alzheimer Disease; Amyloid beta-Peptides; Animals; Apoptosis; Disease Models, Animal; Gene Expression Regulation; Humans; Intracellular Signaling Peptides and Proteins; Memory; Memory Disorders; Mice; Mice, Transgenic; Neuroprotective Agents; p38 Mitogen-Activated Protein Kinases; Peptide Fragments; Phosphorylation

Amyloid β peptide (Aβ) has been thought to be neurotoxic and responsible for the impairment of learning and memory in Alzheimer's disease (AD). Humanin (HN), a 24 amino acid polypeptide first identified from the unaffected occipital lobe of an AD patient, is believed to be neuroprotective against the AD-related neurotoxicity. In this study, we investigated the neuroprotective effects of Colivelin (CLN), a novel HN derivative, against Aβ by using behavioral test, in vivo electrophysiological recording, and intracellular calcium imaging. Our results showed that intrahippocampal injection of CLN (0.2 nmol) effectively prevented Aβ25-35 (4 nmol)-induced deficits in spatial learning and memory of rats in Morris water maze test; the suppression of in vivo hippocampal long term potentiation (LTP) by Aβ25-35 was nearly completely prevented by CLN; in addition, CLN pretreatment also effectively inhibited Aβ25-35-induced calcium overload in primary cultured hippocampal neurons. These results indicate that CLN has significant neuroprotective properties against Aβ, and CLN may holds great promise for the treatment and prevention of AD.

Topics: Amyloid beta-Peptides; Animals; Calcium; Cells, Cultured; Hippocampus; Homeostasis; Intracellular Signaling Peptides and Proteins; Long-Term Potentiation; Maze Learning; Memory Disorders; Neuronal Plasticity; Neurons; Peptide Fragments; Rats; Rats, Sprague-Dawley

Elevation of intracranial soluble amyloid-beta (Abeta) levels has been implicated in the pathogenesis of Alzheimer's disease (AD). Intracellular events in neurons, which lead to memory loss in AD, however, remain elusive. Humanin (HN) is a short neuroprotective peptide abolishing Abeta neurotoxicity. Recently, we found that HN derivatives activate the Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) signaling axis. We here report that an HN derivative named colivelin completely restored cognitive function in an AD model (Tg2576) by activating the JAK2/STAT3 axis. In accordance, immunofluorescence staining using a specific antibody against phospho- (p-) STAT3 revealed that p-STAT3 levels in hippocampal neurons age-dependently decreased in both AD model mice and AD patients. Intracerebroventricular administration of Abeta1-42 downregulated p-STAT3 whereas passive immunization with anti-Abeta antibody conversely restored hippocampal p-STAT3 levels in Tg2576 mice, paralleling the decrease in the brain Abeta burden. Abeta1-42 consistently modulated p-STAT3 levels in primary neurons. Pharmacological inhibition of the JAK2/STAT3 axis not only induced significant loss of spatial working memory by downregulating an acetylcholine-producing enzyme choline acetyltransferase but also desensitized the M(1)-type muscarinic acetylcholine receptor. Thus, we propose a novel theory accounting for memory impairment related to AD: Abeta-dependent inactivation of the JAK2/STAT3 axis causes memory loss through cholinergic dysfunction. Our findings provide not only a novel pathological hallmark in AD but also a novel target in AD therapy.

Topics: Age Factors; Alzheimer Disease; Amyloid beta-Peptides; Amyloid beta-Protein Precursor; Animals; Disease Models, Animal; Enzyme Inhibitors; Exploratory Behavior; Gene Expression Regulation; Hippocampus; Humans; Intracellular Signaling Peptides and Proteins; Janus Kinase 2; Maze Learning; Memory Disorders; Mice; Mice, Inbred ICR; Mice, Transgenic; Mutation; Nerve Tissue Proteins; Neurons; Peptide Fragments; Presenilin-1; Receptor, Muscarinic M1; STAT3 Transcription Factor

Humanin (HN) and its derivatives, such as Colivelin (CLN), suppress neuronal death induced by insults related to Alzheimer's disease (AD) by activating STAT3 in vitro. They also ameliorate functional memory impairment of mice induced by anticholinergic drugs or soluble toxic amyloid-beta (Abeta) in vivo when either is directly administered into the cerebral ventricle or intraperitoneally injected. However, the mechanism underlying the in vivo effect remains uncharacterized. In addition, from the standpoint of clinical application, drug delivery methods that are less invasive and specific to the central nervous system (CNS) should be developed. In this study, we show that intranasally (i.n.) administered CLN can be successfully transferred to CNS via the olfactory bulb. Using several behavioral tests, we have demonstrated that i.n. administered CLN ameliorates memory impairment of AD models in a dose-responsive manner. Attenuation of AD-related memory impairment by HN derivatives such as CLN appears to be correlated with an increase in STAT3 phosphorylation levels in the septohippocampal region, suggesting that anti-AD activities of HN derivatives may be mediated by activation of STAT3 in vivo as they are in vitro. We further demonstrate that CLN treatment inhibits an Abeta induced decrease in the number of choline acetyltransferase (ChAT)-positive neurons in the medial septum. Combined with the finding that HN derivatives upregulate mRNA expression of neuronal ChAT and vesicular acetylcholine transporter (VAChT) in vitro, it is assumed that CLN may ameliorate memory impairment of AD models by supporting cholinergic neurotransmission, which is at least partly mediated by STAT3-mediated transcriptional upregulation of ChAT and VAChT.

Topics: Acetylcholinesterase; Administration, Intranasal; Alzheimer Disease; Amyloid beta-Peptides; Animals; Behavior, Animal; Cholinergic Antagonists; Immunohistochemistry; Injections, Intraventricular; Intracellular Signaling Peptides and Proteins; Maze Learning; Memory Disorders; Mice; Mice, Inbred ICR; Muscarinic Antagonists; Olfactory Bulb; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Scopolamine; STAT3 Transcription Factor; Up-Regulation