Neurotrophic Peptide Research Articles

Increased opioid dependence in a mouse model of panic disorder

Panic disorder is a highly prevalent neuropsychiatric disorder that shows co-occurrence with substance abuse. Here, we demonstrate that TrkC, the high-affinity receptor for neurotrophin-3, is a key molecule involved in panic disorder and opiate dependence, using a transgenic mouse model (TgNTRK3). Constitutive TrkC overexpression in TgNTRK3 mice dramatically alters spontaneous firing rates of locus coeruleus (LC) neurons and the response of the noradrenergic system to chronic opiate exposure, possibly related to the altered regulation of neurotrophic peptides observed. Notably, TgNTRK3 LC neurons showed an increased firing rate in saline-treated conditions and profound abnormalities in their response to met5-enkephalin. Behaviorally, chronic morphine administration induced a significantly increased withdrawal syndrome in TgNTRK3 mice. In conclusion, we show here that the NT-3/TrkC system is an important regulator of neuronal firing in LC and could contribute to the adaptations of the noradrenergic system in response to chronic opiate exposure. Moreover, our results indicate that TrkC is involved in the molecular and cellular changes in noradrenergic neurons underlying both panic attacks and opiate dependence and support a functional endogenous opioid deficit in panic disorder patients.

Effect of an NCAM mimetic peptide FGL on impairment in spatial learning and memory after neonatal phencyclidine treatment in rats

The FGL peptide is a neural cell adhesion molecule-derived fibroblast growth factor receptor agonist. FGL has both neurotrophic and memory enhancing properties. Neonatal phencyclidine (PCP) treatment on postnatal days 7, 9, and 11 has been shown to result in long-lasting behavioral abnormalities, including cognitive impairment relevant to schizophrenia. The present study investigated the effect of FGL on spatial learning and memory deficits induced by neonatal PCP treatment. Rat pups were treated with 30 mg/kg PCP on postnatal days 7, 9, and 11. Additionally, the rats were subjected to a chronic FGL treatment regimen where FGL was administered throughout development. Rats were tested as adults for spatial reference memory, reversal learning, and working memory in the Morris water maze. The PCP-treated rats demonstrated a robust impairment in working memory and reversal learning. However, the long-term memory component of the reference memory task was not affected by PCP. Chronic FGL treatment had no effect on the reversal learning impairment but ameliorated the working memory deficits almost to the levels of the control groups. In conclusion, the results suggest that the neonatal PCP treatment produced deficits in cognition relevant to schizophrenia. Moreover, working memory function was selectively protected by the neurotrophic peptide, FGL.

Isolation of Peptide Transport System-6 from Brain Endothelial Cells: Therapeutic Effects with Antisense Inhibition in Alzheimer and Stroke Models

By isolating for the first time ever a peptide transporter from the blood-brain barrier (BBB) and developing an antisense that selectively targets the brain-to-blood efflux component, we were able to deliver a therapeutic concentration of the neurotrophic peptide pituitary adenylate cyclase-activating polypeptide (PACAP) 27 to brain in animal models of Alzheimer's and stroke. Efflux pumps at the BBB are major causes of BBB impermeability to peptides. PACAP is neuroprotective in vitro in femtomole amounts, but brain uptake of PACAP27 is limited by an efflux component of peptide transport system-6 (PTS-6). Here, we characterized, isolated, and sequenced this component of PTS-6, identifying it as beta-F1 ATPase, and colocalized it with PACAP27 on BBB endothelial cells. Antisenses targeting the BBB inhibited PACAP27 efflux, thus increasing brain uptake of PACAP27. Treatment with antisense+PACAP27 improved cognition in a mouse model of Alzheimer's disease and reduced infarct size after cerebral ischemia. This represents the first isolation from BBB tissue of a peptide transporter and shows that inhibition of peptide efflux pumps is a potential strategy for drug delivery to brain.

GSK3β modulates PACAP-induced neuritogenesis in PC12 cells by acting downstream of Rap1 in a caveolae-dependent manner

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a neurotrophic peptide. Here, we show that PACAP recruits Rap1 into caveolin-enriched membrane subdomains in PC12 cells and activates Rap1, nuclear ERK1/2, Elk-1 and CREB in a caveolae-dependent manner. We reveal that GSK3β is a novel modulator in PACAP signalling. PACAP induces phosphorylation of serine 9 in GSK3β, which is inhibited by silencing Rap1. Lithium and valproate promote but wortmannin and LY294002 attenuate PACAP-induced phosphorylation of both GSK3β and ERK1/2, whereas MEK inhibitor PD98059 inhibits nerve growth factor- but not PACAP-induced phosphorylation of GSK3β, suggesting that GSK3β operates downstream of Rapt 1 but upstream of ERK1/2 in PACAP signalling. Inhibition or stimulation of GSK3β results in a 2-fold increase and 6-fold decrease in PACAP-induced neurite outgrowth, respectively. These results reveal an important role of caveolae in the signal transduction of PACAP and that GSK3β is a critical regulator in PACAP-induced neuronal differentiation.

Neurotrophic effects of Cerebrolysin in the Mecp2308/Y transgenic model of Rett syndrome

Rett syndrome is a childhood neurodevelopmental disorder caused by mutations in the gene encoding for methyl-CpG-binding protein (MeCP2). Neuropathological studies in patients with Rett syndrome and in MeCP2 mutant models have shown reduced dendritic arborization and abnormal neuronal packing. We have previously shown that Cerebrolysin (CBL), a neurotrophic peptide mixture, ameliorates the synaptic and dendritic pathology in models of aging and neurodegeneration. This study aimed to determine whether CBL was capable of reducing behavioral and neuronal alterations in Mecp2(308/Y) mutant mice. Two sets of experiments were performed, the first with 4-month-old male Mecp2(308/Y) mutant mice treated with CBL or vehicle for 3 months (Group A) and the second with 1-month-old mice treated for 6 months (Group B). Behavioral analysis showed improved motor performance with CBL in Group A and a trend toward improvement in Group B. Consistent with behavioral findings, neuropathological analysis of the basal ganglia showed amelioration of dendritic simplification in CBL-treated Mecp2(308/Y) mutant mice. CBL treatment also ameliorated dendritic pathology and neuronal loss in the hippocampus and neocortex in Mecp2(308/Y) mutant mice. In conclusion, this study demonstrates that CBL promotes recovery of dendritic and neuronal damage and behavioral improvements in young adult Mecp2(308/Y) mutant mice and suggests that CBL may have neurotrophic effects in this model. These findings support the possibility that CBL may have beneficial effects in the management of Rett syndrome.

P2-445: Enhancement of dentate gyrus neurogenesis and associated memory by a neurotrophic peptide

P2-445: Enhancement of dentate gyrus neurogenesis and associated memory by a neurotrophic peptide

DREAM Mediates cAMP-Dependent, Ca2+-Induced Stimulation of GFAP Gene Expression and Regulates Cortical Astrogliogenesis

In the developing mouse brain, once the generation of neurons is mostly completed during the prenatal period, precisely coordinated signals act on competent neural precursors to direct their differentiation into astrocytes, which occurs mostly after birth. Among these signals, those provided by neurotrophic cytokines and bone morphogenetic proteins appear to have a key role in triggering the neurogenic to gliogenic switch and in regulating astrocyte numbers. In addition, we have reported previously that the neurotrophic peptide pituitary adenylate cyclase-activating polypeptide (PACAP) is able to promote astrocyte differentiation of cortical precursors via activation of a cAMP-dependent pathway. Signals acting on progenitor cells of the developing cortex to generate astrocytes activate glial fibrillary acidic protein (GFAP) gene expression, but the transcriptional mechanisms that regulate this activation are unclear. Here, we identify the previously known transcriptional repressor downstream regulatory element antagonist modulator (DREAM) as an activator of GFAP gene expression. We found that DREAM occupies specific sites on the GFAP promoter before and after differentiation is initiated by exposure of cortical progenitor cells to PACAP. PACAP raises intracellular calcium concentration via a mechanism that requires cAMP, and DREAM-mediated transactivation of the GFAP gene requires the integrity of calcium-binding domains. Cortical progenitor cells from dream(-/-) mice fail to express GFAP in response to PACAP. Moreover, the neonatal cortex of dream(-/-) mice exhibits a reduced number of astrocytes and increased number of neurons. These results identify the PACAP-cAMP-Ca(2+)-DREAM cascade as a new pathway to activate GFAP gene expression during astrocyte differentiation.

Therapeutic Potential of Fluoxetine in Neurological Disorders

The selective serotonin reuptake inhibitor (SSRI) fluoxetine, which is registered for a variety of psychiatric disorders, has been found to stimulate the cAMP-responsive element binding protein (CREB), increase the production of brain-derived neurotrophic factor (BNDF) and the neurotrophic peptide S100beta, enhance glycogenolysis in astrocytes, block voltage-gated calcium and sodium channels, and decrease the conductance of mitochondrial voltage-dependent anion channels (VDACs). These mechanisms of actions suggest that fluoxetine may also have potential for the treatment of a number of neurological disorders. We performed a Pubmed search to review what is known about possible therapeutic effects of fluoxetine in animal models and patients with neurological disorders. Beneficial effects of fluoxetine have been noted in animal models of stroke, multiple sclerosis, and epilepsy. Fluoxetine was reported to improve neurological manifestations in patients with Alzheimer's disease, stroke, Huntington's disease, multiple sclerosis, traumatic brain injury, and epilepsy. Clinical studies so far were small and often poorly designed. Results were inconclusive and contradictory. However, the available preclinical data justify further clinical trials to determine the therapeutic potential of fluoxetine in neurological disorders.

A cAMP-Dependent, Protein Kinase A-Independent Signaling Pathway Mediating Neuritogenesis through Egr1 in PC12 Cells

The neurotrophic peptide PACAP (pituitary adenylate cyclase-activating polypeptide) elevates cAMP in PC12 cells. Forskolin and dibutyryl cAMP mimic PACAP's neuritogenic and cell morphological effects, suggesting that they are driven by cAMP. Comparison of microarray expression profiles after exposure of PC12 cells to either forskolin, dibutyryl cAMP, or PACAP revealed a small group of cAMP-dependent target genes. Neuritogenesis induced by all three agents is protein kinase A (PKA)-independent [not blocked by N-[2-(4-bromocinnamylamino)ethyl]-5-isoquinoline (H89)] and extracellular signal-regulated kinase (ERK)-dependent [blocked by 1,4-diamino-2,3-dicyano-1,4-bis(methylthio) butadiene (U0126)], and therefore cAMP-dependent target genes potentially mediating neuritogenesis were selected for further analysis based on the pharmacological profile of their induction by PACAP (i.e., mimicking that of neuritogenesis). Small interfering RNA (siRNA) targeting one of these genes, Egr1, blocked PACAP-induced neuritogenesis, and siRNA targeting another, Vil2, blocked a component of the cell size increase elicited by PACAP. Neither siRNA blocked PACAP's PKA-dependent antiproliferative effects. PACAP signaling to neuritogenesis was also impaired by dominant-negative Rap1 expression but was not affected by inhibition of protein kinase C (PKC), indicating a G-protein-coupled receptor-mediated differentiation pathway distinct from the one activated by receptor tyrosine kinase ligands such as nerve growth factor (NGF), that involves both Rap1 and PKC. We have thus identified a cAMP-dependent, PKA-independent pathway proceeding through ERK that functions to up-regulate the transcription of two genes, Egr1 and Vil2, required for PACAP-dependent neuritogenesis and increased cell size, respectively. Dominant-negative Rap1 expression impairs both PACAP-induced neuritogenesis and Egr1 activation by PACAP, suggesting that cAMP elevation and ERK activation by PACAP are linked through Rap1.

Activity‐dependent neurotrophic factor, ADNF, determines the structure characteristics of Colivelin, a fusion protein of ADNF9 and Humanin analog

A 24-amino acid long peptide, Humanin, protects neurons from Alzheimer's disease (AD)-related cell toxicities at sub-nM-uM concentrations. Activity-dependent neurotrophic factor (ADNF) is a glia-derived neurotrophic peptide, which protects neurons from tetrodoxin treatment and AD-related and amyotrophic lateral sclerosis-related insults at fM concentrations. An attempt was made to further improve the activity of Humanin by fusing this peptide to ADNF9, a 9-amino acid long core peptide of the ADNF. This fusion resulted in a novel molecule, termed Colivelin, with the neuroprotective activity at fM range, which is approximately 10(3)-10(7) fold higher than the activity of Humanin and Humanin analogs and follows the activity profile of fM-active ADNF9. We have characterized the structural properties of Colivelin and compared with those of ADNF9 and Humanin in water and phosphate-buffered saline (PBS). The secondary structure of Colivelin was similar to that of ADNF9, but not that of Humanin, and hence was not the average of the contributions of the two peptides fused. Colivelin was stable and monomeric in PBS, consistent with the monomeric property of ADNF9, while Humanin showed strong tendency to self-associate. Thus, it is evident that the structural properties of Colivelin resemble those of ADNF9, rather than those of Humanin.

Ectopic expression of neurotrophic peptide derived from saposin C increases proliferation and upregulates androgen receptor expression and transcriptional activity in human prostate cancer cells

To determine the effects of the functional domain of saposin C (neurotrophic peptide [NP]) on androgen receptor (AR) expression and transcriptional activity. We constructed DNA vectors expressing NP or a chimeric peptide of the viral TAT transduction domain and NP (TAT-NP) using gene cloning technology. The effects of ectopic expression of NP or TAT-NP on cell growth were examined by 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. Reverse transcription-polymerase chain reaction (RT-PCR), Western blot, transient transfection and reporter gene assays were used to determine the effects of NP on AR expression and activation. NP stimulated proliferation of androgen responsive LNCaP cells in the absence of androgens. RT-PCR and Western blot analyses showed that ectopic expression of NP resulted in induction of AR gene expression, and that the NP-stimulated expression of AR could be synergistically enhanced in the presence of androgens. Furthermore, reporter gene assay results showed that NP could enhance AR transactivation by increasing androgen-inducible gene reporter activity. We provided evidence that ectopic expression of saposin C-originated NP could upregulate AR gene expression and activate the AR transcriptional function in an androgen-independent manner in prostate cancer cells.

Understanding the mechanism of learning enhancement: NMDA and GABA receptor expression

The administration of neurotrophic peptides NAPVSIPQ (NAP) + SALLRSIPA (SAL) to aged mice resulted in significant learning enhancement. N-methyl-D-aspartate (NMDA) and gamma-aminobutyric acid (GABA) receptors are fundamental for learning because they are the major modulators of the long-term potentiation, the electrophysiologic mechanism for learning. Also, these receptors have been shown to be involved in NAP + SAL prevention of learning deficit in a mouse model for fetal alcohol syndrome, when administered prenatally during development. Our objective was to test whether NMDA and GABA receptors contribute to the learning enhancement that is induced by the peptides after adult administration. Aged (14.5 months) male mice were treated for 10 consecutive days with placebo or D-NAP + D-SAL (20 microg, by gavage). At the end of the treatment, brains were harvested. Calibrator-normalized relative real-time polymerase chain reaction was performed with primers for GABA-(A)beta3, GABA-(A)alpha5, and the NMDA receptor subunits NR2A and NR2B, with GAPDH standardization. Statistical analysis included analysis of variance, with a probability value that was considered significant at <.05. Five control brains and 6 brains from animals that were treated with NAP + SAL were collected. There was no difference in GABA-(A)beta3, GABA-(A)alpha5, NR2A, and NR2B subunits after adult administration of NAP + SAL, as compared with the controls (P > .05). Postnatal treatment with NAP + SAL induced learning enhancement in aged mice with a mechanism that does not involve alteration in NMDA and GABA receptor expression. Thus, the mechanism of learning enhancement might be different for a developing fetus than an adult or in the absence of a perturbing agent.

Structure Analysis of Activity-dependent Neurotrophic Factor 9 by Circular Dichroism and Sedimentation Equilibrium

Activity-dependent neurotrophic factor (ADNF) is a glia-derived neurotrophic peptide, which protects neurons from tetrodoxin treatment and Alzheimer's disease-related and amyotrophic-lateral-sclerosis-related insults at femto-molar concentrations. However, the mechanism of the femto-molar neuroprotection by the peptide has not been elucidated. The characterization of the peptide structure in solution at molecular level should shed light in the mechanism of such extremely high biological activity. From that point of view, the secondary and quaternary structure analysis of ADNF9, an active core fragment peptide of ADNF, was performed by circular dichroism (CD) and sedimentation equilibrium. ADNF9 has also been shown to exhibit a neurotrophic activity in femto-molar concentrations; in this study it showed sub-pM neuroprotective activity against V642I-APP-induced cytotoxity in the mouse primary cortical neuron. CD analysis showed that the secondary structure of ADNF9 is identical in water and phosphate-buffered saline (PBS) and is independent of the peptide concentration. The CD spectra appear to be characterized most likely as disordered. The sedimentation equilibrium experiments demonstrated monomeric structure of the protein over the wide range of peptide concentration. There is a slight enhancement of CD intensity at 37 degrees C relative to 20 degrees C, suggesting a possible hydrophobic association of the peptide. There is no change in the secondary structure in PBS upon freeze-thaw treatment, which has previously been suggested to cause activity loss.

Adult administration of peptides resulting in learning enhancement is not mediated through NMDA and GABA receptor expression

IS NOT MEDIATED THROUGH NMDA AND GABA RECEPTOR EXPRESSION LAURA TOSO, ROBIN ROBERSON, DANIEL ABEBE, CATHERINE SPONG, National Institutes of Health (NIH), Unit on Perinatal and Develomental Neurobiology, NICHD&NIAAA, Bethesda, Maryland, National Institutes of Health (NIH), Unit on Perinatal and Develomental Neurobiology, Bethesda, Maryland OBJECTIVE: Administration of neurotrophic peptides NAPCSAL to aged mice resulted in significant learning enhancement (Toso 2006). NMDA and GABA receptors are fundamental for learning as they are the major modulators of the Long Term Potentiation, the electrophisiologic mechanism for learning. Also, these receptors have been shown to be involved in NAPCSAL prevention of learning deficit in a mouse model for fetal alcohol syndrome when administered prenatally during development(Toso 2006). Our objective was to test if NMDA and GABA receptors contribute to the learning enhancement induced by the peptides after adult administration. STUDY DESIGN: Aged (14.5 months) males were treated for 10 consecutive days with placebo or D-NAPCD-SAL (20mg, via gavage). At the end of the treatment brains were harvested. Calibrator-normalized relative real time PCR was performed using primers for GABA-Ab3, GABA-Aa5, NR2A and NR2B with GAPDH standardization. Statistical analysis included ANOVA with p!0.05 significant. RESULTS: 5 control brains and 6 brains from animals treated with NAPCSAL were collected. There was no difference in GABA-Ab3, GABAAa5, NR2A and NR2B subunits after adult administration of NAPCSAL as compared to the controls (pO0.05). CONCLUSION: Postnatal treatment with NAPCSAL induced learning enhancement in aged mice with mechanism that does not involve NMDA and GABA receptor expression. Treatment with the peptides does not acutely alter expression, although it may have an effect on the function of these receptors. Alternatively, the mechanism of learning enhancement may differ when administered to a developing fetus vs an adult.

Noncompensation in peptide/receptor gene expression and distinct behavioral phenotypes in VIP‐ and PACAP‐deficient mice

Pituitary adenylate cyclase-activating polypeptide (PACAP) and vasoactive intestinal peptide (VIP) are closely related neurotrophic peptides of the secretin/glucagon family. The two peptides are derived from a common ancestral gene and share many functional attributes in neuronal development/regeneration which occur not only from overlapping receptor subtype signaling but also through common mechanisms regulating their expression. Although PACAP or VIP null mice have been generated for study, it is unclear whether the expression of the complementary peptide or their receptor systems are altered in a compensatory manner during nervous system development. By radioimmunoassay and quantitative PCR measurements, we first show that PACAP and VIP have very different temporal patterns of expression in developing postnatal mouse brain. In wild-type animals, PACAP transcript and peptide levels increased rapidly 2- and 5-fold, respectively, within 1 week of age. These levels at 1 week of age were maintained through adulthood. VIP transcript and peptide levels, by contrast, increased 25- and 50-fold, respectively, over a later time course. In parallel studies of development, there were no apparent compensatory increases in brain VIP expression in the PACAP knockout animals, PACAP expression in the VIP-deficient animals, or receptor mRNA levels in either genotype. To the contrary, there was evidence for developmental delays in the expression of peptide and receptor transcripts in the knockout animals. A series of behavioral and neurological tests demonstrated differences between the knockout genotypes, revealing some functional distinctions between the two genes. These results suggest that the PACAP and VIP have evolved to possess distinct biological activities and intimate that the respective knockout phenotypes represent deficits unmitigated by the actions of the complementary related peptide.

Neurotrophic peptide aldehydes: Solid phase synthesis of fellutamide B and a simplified analog

A combination of solid phase and solution phase synthetic methods have been used to complete the total synthesis of the neurotrophic lipopeptide aldehyde fellutamide B ( 2). The β-hydroxy aliphatic tail was prepared by regioselective reductive opening of a cyclic sulfate, and later coupled to a solid phase resin. The synthetic compound was then examined in cytotoxicity and nerve growth factor (NGF) induction assays. A simplified analog of fellutamide B also showed activity.

Gene therapy for the treatment of sensory neuropathy

Sensory polyneuropathy can be a serious problem, but for the majority of clinically important neuropathies there are no available therapies. Neurotrophic and neuroprotective peptide factors have been identified that prevent or reverse neuropathy in rodent models of disease, but delivery of these highly pleiotropic peptides has posed an obstacle for translation into effective human therapies. Gene transfer into muscle using viral or non-viral vectors, or into neurons of the dorsal root ganglion using herpes simplex virus-based vectors, provides an alternative means to achieve this end. Studies in animal models have been promising, and the first human trial, using a plasmid to transfer the gene coding for vascular endothelial growth factor into muscle for the treatment of diabetic neuropathy, is now underway. Evidence supporting the trial and the challenges facing this therapy are reviewed.

Colivelin prolongs survival of an ALS model mouse

Amyotrophic lateral sclerosis (ALS) is the most common motor neuron disease for which there is no sufficiently effective therapy. We have reported in our earlier study that intracerebroventricular (i.c.v.) injection of activity-dependent neurotrophic factor (ADNF) improves motor performance of G93A-SOD1 transgenic mice without significant prolongation in survival. Here, we found that i.c.v. injection of a synthetic hybrid peptide named Colivelin composed of ADNF and AGA-(C8R)HNG17, a potent derivative of Humanin that is a bioactive peptide with anti-Alzheimer’s disease activity, dose-dependently improved motor performance and prolonged survival of ALS mice. Histological analysis, performed at the age of 120 days, demonstrated increased motoneuronal survival in spinal cords of Colivelin-treated mice as compared with saline- or ADNF-treated mice, indicating that Colivelin is a promising neurotrophic peptide for treatment of ALS.

Dynamic reorganization of the astrocyte actin cytoskeleton elicited by cAMP and PACAP: a role for phosphatidylInositol 3‐kinase inhibition

Cyclic AMP (cAMP)-raising agents induce astrocytes grown in vitro to adopt a stellate morphology resembling their in vivo appearance, through the depolymerization of actomyosin stress fibres. The signalling pathways responsible for cAMP-induced astrocyte stellation have thus far remained largely elusive. We showed in this study that the neurotrophic peptide PACAP (pituitary adenylate cyclase-activating polypeptide) mimicked the effect of forskolin, a direct activator of adenylate cyclase, on the actin cytoskeleton of primary rat astrocytes. The depolymerization of stress fibres induced by PACAP or forskolin was prevented by the expression of a constitutively active mutant of RhoA, but not by a protein kinase A (PKA) blocker, indicating that cAMP-raising agents act upstream of RhoA, in a PKA-independent manner. In addition, PACAP and forskolin inhibited basal Akt phosphorylation, and basal and epidermal growth factor (EGF)-stimulated phosphatidylinositol 3-kinase (PI 3-K) activities. Incubation with a PI 3-K blocker resulted in the depolymerization of stress fibres. This effect was blocked by the expression of a constitutively active mutant of RhoA, indicating that PI 3-K inhibition acted upstream of RhoA. Together, these data demonstrate for the first time that depolymerization of stress fibres, and the resulting astrocyte stellation, induced by stimulation of cAMP production involves the inhibition of the PI 3-K-RhoA pathway.

A novel neurotrophic peptide: APP63-73

The objective of this study was to find out which N-terminal segment/s of amyloid precursor protein (APP) has any neurotrophic properties, since soluble APP-alpha (sAPP-alpha) has neurotrophic effects. We investigated neurotrophic properties of eight peptide segments of N-terminal APP. The APP63-73 was able to enhance neuronal growth; augment axonal and cell body growth in human neuroblastoma cell line, SH-SY5Y. Neurotrophic effects of chronic APP63-73 treatment were assessed in vivo using streptozotocin-induced diabetes and ovariectomized rats. Thus, this study demonstrated that APP63-73 peptide has neurotrophic effects both in vivo and in vitro.