A Narrative Review on Maternal Choline Intake and Liver Function of the Fetus and the Infant; Implications for Research, Policy, and Practice.

Dietary choline is needed to maintain normal health, including normal liver function in adults. Fatty liver induced by a choline-deficient diet has been consistently observed in human and animal studies. The effect of insufficient choline intake on hepatic fat accumulation is specific and reversible when choline is added to the diet. Choline requirements are higher in women during pregnancy and lactation than in young non-pregnant women. We reviewed the evidence on whether choline derived from the maternal diet is necessary for maintaining normal liver function in the fetus and breastfed infants. Studies have shown that choline from the maternal diet is actively transferred to the placenta, fetal liver, and human milk. This maternal-to-child gradient can cause depletion of maternal choline stores and increase the susceptibility of the mother to fatty liver. Removing choline from the diet of pregnant rats causes fatty liver both in the mother and the fetus. The severity of fatty liver in the offspring was found to correspond to the severity of fatty liver in the respective mothers and to the duration of feeding the choline-deficient diet to the mother. The contribution of maternal choline intake in normal liver function of the offspring can be explained by the role of phosphatidylcholine in lipid transport and as a component of cell membranes and the function of choline as a methyl donor that enables synthesis of phosphatidylcholine in the liver. Additional evidence is needed on the effect of choline intake during pregnancy and lactation on health outcomes in the fetus and infant. Most pregnant and lactating women are currently not achieving the adequate intake level of choline through the diet. Therefore, public health policies are needed to ensure sufficient choline intake through adding choline to maternal multivitamin supplements.

Cerebral Gray and White Matter Monogalactosyl Diglyceride Levels Rise with the Progression of Alzheimer's Disease.

BACKGROUND: Multiple studies have reported brain lipidomic abnormalities in Alzheimer's disease (AD) that affect glycerophospholipids, sphingolipids, and fatty acids. However, there is no consensus regarding the nature of these abnormalities, and it is unclear if they relate to disease progression. OBJECTIVE: Monogalactosyl diglycerides (MGDGs) are a class of lipids which have been recently detected in the human brain. We sought to measure their levels in postmortem human brain and determine if these levels correlate with the progression of the AD-related traits. METHODS: We measured MGDGs by ultrahigh performance liquid chromatography tandem mass spectrometry in postmortem dorsolateral prefrontal cortex gray matter and subcortical corona radiata white matter samples derived from three cohorts of participants: the Framingham Heart Study, the Boston University Alzheimer's Disease Research Center, and the Arizona Study of Aging and Neurodegenerative Disorders/Brain and Body Donation Program (total n = 288). RESULTS: We detected 40 molecular species of MGDGs (including diacyl and alkyl/acyl compounds) and found that the levels of 29 of them, as well as total MGDG levels, are positively associated with AD-related traits including pathologically confirmed AD diagnosis, clinical dementia rating, Braak and Braak stage, neuritic plaque score, phospho-Tau AT8 immunostaining density, levels of phospho-Tau396 and levels of Aß40. Increased MGDG levels were present in both gray and white matter, indicating that they are widespread and likely associated with myelin-producing oligodendrocytes-the principal cell type of white matter. CONCLUSIONS: Our data implicate the MGDG metabolic defect as a central correlate of clinical and pathological progression in AD.

Accelerated Breakdown of Phosphatidylcholine and Phosphatidylethanolamine Is a Predominant Brain Metabolic Defect in Alzheimer's Disease.

Numerous studies have demonstrated defects in multiple metabolic pathways in Alzheimer's disease (AD), detected in autopsy brains and in the cerebrospinal fluid in vivo. However, until the advent of techniques capable of measuring thousands of metabolites in a single sample, it has not been possible to rank the relative magnitude of these abnormalities. A recent study provides evidence that the abnormal turnover of the brain's most abundant phospholipids: phosphatidylcholine and phosphatidylethanolamine, constitutes a major metabolic pathology in AD. We place this observation in a historical context and discuss the implications of a central role for phospholipid metabolism in AD pathogenesis.

Is dietary choline intake related to dementia and Alzheimer's disease risks? Results from the Framingham Heart Study.

BACKGROUND: The positive association of choline for cognition has been reported in both animal and human studies, yet the associations of choline with the risks of incident dementia or Alzheimer's disease (AD) in humans is unclear. OBJECTIVES: Our objective was to test the hypothesis that lower or higher dietary choline intake is associated with increased or decreased, respectively, risks of incident dementia and AD. METHODS: Data from the Framingham Heart Study Offspring Cohort exam 5 to exam 9 were used. Participants were free of dementia and stroke, with a valid self-reported 126-item Harvard FFQ at exam 5. The intakes of total choline, its contributing compounds, and betaine were estimated based on a published nutrient database. The intakes were updated at each exam to represent the cumulative average intake across the 5 exams. The associations between dietary choline intakes and incident dementia and AD were examined in mixed-effect Cox proportional hazard models, adjusting for covariates. RESULTS: A total of 3224 participants (53.8% female; mean ± SD age, 54.5 ± 9.7 y) were followed up for a mean ± SD of 16.1 ± 5.1 y (1991-2011). There were 247 incident dementia cases, of which 177 were AD. Dietary choline intake showed nonlinear relationships with incident dementia and AD. After adjusting for covariates, low choline intake (defined as ≤ 219 and ≤ 215 mg/d for dementia and AD, respectively) was significantly associated with incident dementia and incident AD. CONCLUSIONS: Low choline intake was associated with increased risks of incident dementia and AD.

The Expression of Activin Receptor-Like Kinase 1 (ACVRL1/ALK1) in Hippocampal Arterioles Declines During Progression of Alzheimer's Disease.

Cerebral amyloid angiopathy (CAA) in Alzheimer's disease (AD)-deposition of beta amyloid (Aß) within the walls of cerebral blood vessels-typically accompanies Aß buildup in brain parenchyma and causes abnormalities in vessel structure and function. We recently demonstrated that the immunoreactivity of activin receptor-like kinase 1 (ALK1), the type I receptor for circulating BMP9/BMP10 (bone morphogenetic protein) signaling proteins, is reduced in advanced, but not early stages of AD in CA3 pyramidal neurons. Here we characterize vascular expression of ALK1 in the context of progressive AD pathology accompanied by amyloid angiopathy in postmortem hippocampi using immunohistochemical methods. Hippocampal arteriolar wall ALK1 signal intensity was 35% lower in AD patients (Braak and Braak Stages IV and V [BBIV-V]; clinical dementia rating [CDR1-2]) as compared with subjects with early AD pathologic changes but either cognitively intact or with minimal cognitive impairment (BBIII; CDR0-0.5). The intensity of Aß signal in arteriolar walls was similar in all analyzed cases. These data suggest that, as demonstrated previously for specific neuronal populations, ALK1 expression in blood vessels is also vulnerable to the AD pathophysiologic process, perhaps related to CAA. However, cortical arterioles may remain responsive to the ALK1 ligands, such as BMP9 and BMP10 in early and moderate AD.

Choline: The Neurocognitive Essential Nutrient of Interest to Obstetricians and Gynecologists.

Choline is an essential nutrient for proper liver, muscle, and brain functions as well as for lipid metabolism and cellular membrane composition and repair. Humans can produce small amounts of choline via the hepatic phosphatidylethanolamine N-methyltransferase pathway; however, most individuals must consume this vitamin through the diet to prevent deficiency. An individual's dietary requirement for choline is dependent on common genetic variants in genes required for choline, folate, and one-carbon metabolism. Both the American Academy of Pediatrics and American Medical Association have recently reinforced the importance of maternal choline intake during pregnancy and lactation and recognize that failure to provide choline and other key essential nutrients during the first 1,000 days postconception may result in lifelong deficits in brain function despite subsequent nutrient repletion. Given that dietary intake for the majority of the US population, including subpopulations such as pregnant women, women of childbearing age, and vegetarians, falls well below the current adequate intake, there is a need to develop better policies and improve consumer education around the importance of this essential nutrient for human health. This comprehensive expert review summarizes the current scientific evidence on choline and health in relation to interests of obstetricians and gynecologists.

Immunohistochemical Analysis of Activin Receptor-Like Kinase 1 (ACVRL1/ALK1) Expression in the Rat and Human Hippocampus: Decline in CA3 During Progression of Alzheimer's Disease.

The pathophysiology of Alzheimer's disease (AD) includes signaling defects mediated by the transforming growth factor ß-bone morphogenetic protein-growth and differentiation factor (TGFß-BMP-GDF) family of proteins. In animal models of AD, administration of BMP9/GDF2 improves memory and reduces amyloidosis. The best characterized type I receptor of BMP9 is ALK1. We characterized ALK1 expression in the hippocampus using immunohistochemistry. In the rat, ALK1 immunoreactivity was found in CA pyramidal neurons, most frequently and robustly in the CA2 and CA3 fields. In addition, there were sporadic ALK1-immunoreactive cells in the stratum oriens, mainly in CA1. The ALK1 expression pattern in human hippocampus was similar to that of rat. Pyramidal neurons within the CA2, CA3, and CA4 were strongly ALK1-immunoreactive in hippocampi of cognitively intact subjects with no neurofibrillary tangles. ALK1 signal was found in the axons of alveus and fimbria, and in the neuropil across CA fields. Relatively strongest ALK1 neuropil signal was observed in CA1 where pyramidal neurons were occasionally ALK1-immunoractive. As in the rat, horizontally oriented neurons in the stratum oriens of CA1 were both ALK1- and GAD67-immunoreactive. Analysis of ALK1 immunoreactivity across stages of AD pathology revealed that disease progression was characterized by overall reduction of the ALK1 signal in CA3 in advanced, but not early, stages of AD. These data suggest that the CA3 pyramidal neurons may remain responsive to the ALK1 ligands, e.g., BMP9, during initial stages of AD and that ALK1 may constitute a therapeutic target in early and moderate AD.

Protective effects of 7,8-dihydroxyflavone on neuropathological and neurochemical changes in a mouse model of Alzheimer's disease.

Interest in brain-derived neurotrophic factor (BDNF) was greatly enhanced when it was recognized that its expression is reduced in neurodegenerative disorders, especially in Alzheimer's disease (AD). BDNF signaling through the TrkB receptor has a central role in promoting synaptic transmission, synaptogenesis, and facilitating synaptic plasticity making the BDNF-TrkB signaling pathway an attractive candidate for targeted therapies. Here we investigated the early effect of the small molecule TrkB agonist, 7,8 dihydroxyflavone (7,8-DHF), on AD-related pathology, dendritic arborization, synaptic density, and neurochemical changes in the 5xFAD mouse model of AD. We treated 5xFAD mice with 7,8-DHF for 2 months beginning at 1 month of age. We found that, in this model of AD, 7,8-DHF treatment decreased cortical Aß plaque deposition and protected cortical neurons against reduced dendritic arbor complexity but had no significant impact on the density of dendritic spines. In addition 7,8-DHF treatment protected against hippocampal increase in the level of choline-containing compounds and glutamate loss, but had no significant impact on hippocampal neurogenesis.

Pramlintide: The Effects of a Single Drug Injection on Blood Phosphatidylcholine Profile for Alzheimer's Disease.

Studies suggest that a single injection of pramlintide, an amylin analog, induces changes in Alzheimer's disease (AD) biomarkers in the blood of AD mouse models and AD patients. The aim of this study was to examine whether a pramlintide challenge combined with a phosphatidylcholine (PC) profile diagnoses of AD and mild cognitive impairment (MCI) better than PC alone. Non-diabetic subjects with cognitive status were administered a single subcutaneous injection of 60 mcg of pramlintide under fasting condition. A total of 71 PCs, amyloid-ß peptide (Aß), and total tau (t-tau) in plasma at different time points were measured and treated as individual variables. A single injection of pramlintide altered the levels of 7 PCs in the blood, while a pramlintide injection plus food modulated the levels of 10 PCs in the blood (p < 0.05). The levels of 2 PCs in MCI and 12 PCs in AD in the pramlintide challenge were significantly lower than the ones in controls. We found that while some PCs were associated with only Aß levels, other PCs were associated with both Aß and t-tau levels. A receiver operating characteristic analysis of the PCs was combined with the Aß and t-tau data to produce an area under the curve predictive value of 0.9799 between MCI subjects and controls, 0.9794 between AD subjects and controls, and 0.9490 between AD and MCI subjects. A combination of AD biomarkers and a group of PCs post a pramlintide challenge may provide a valuable diagnostic and prognostic test for AD and MCI.

Anxiety, neuroinflammation, cholinergic and GABAergic abnormalities are early markers of Gulf War illness in a mouse model of the disease.

Gulf War Illness (GWI) is a chronic disease that affects the 1991 Gulf War (GW) veterans for which treatment is lacking. It has been hypothesized that drugs used to protect military personnel from chemical attacks and insects during the war: pyridostigmine bromide (PB),N, N-diethyl-m-toluamide (DEET), and permethrin (PER) together with stress may have contributed collectively and synergistically to generate GWI. There is a need to find markers of pathology to be used in pre-clinical trials. For this purpose we employed a previously validated mouse model of GWI evoked by daily exposure to PB (1.3 mg/kg), DEET (40 mg/kg), PER (0.13 mg/kg), and 5 min of restraint stress for 28 days to analyze behavior, brain pathology and neurochemical outcomes three months later. GWI-model mice were characterized by increased anxiety, decreased hippocampal levels of N-acetyl aspartate, GABA, the GABA-producing enzyme GAD-67 and microglial activation. We also observed that GWI model was sexually dimorphic on some measures: males had increased while females had decreased protein levels of the acetylcholine-synthesizing enzyme, choline acetyltransferase, in the septum and hippocampus and decreased levels of the receptor for brain-derived neurotrophic factor, TrkB140, in the hippocampus. Increased hippocampal levels of nerve growth factor were detected in males only. Together the data show behavioral and neuropathological abnormalities detected at 3 months post-exposure and that some of them are sexually dimorphic. Future preclinical studies for GWI may take advantage of this short latency model and should include both males and females as their response to treatment may differ.

Choline: The Underconsumed and Underappreciated Essential Nutrient.

Choline has been recognized as an essential nutrient by the Food and Nutrition Board of the National Academies of Medicine since 1998. Its metabolites have structural, metabolic, and regulatory roles within the body. Humans can endogenously produce small amounts of choline via the hepatic phosphatidylethanolamine N-methyltransferase pathway. However, the nutrient must be consumed exogenously to prevent signs of deficiency. The Adequate Intake (AI) for choline was calculated at a time when dietary intakes across the population were unknown for the nutrient. Unlike the traditional National Academy of Medicine approach of calculating an AI based on observed or experimentally determined approximations or estimates of intake by a group (or groups) of healthy individuals, calculation of the AI for choline was informed in part by a depletion-repletion study in adult men who, upon becoming deficient, developed signs of liver damage. The AI for other gender and life-stage groups was calculated based on standard reference weights, except for infants 0 to 6 months, whose AI reflects the observed mean intake from consuming human breast milk. Recent analyses indicate that large portions of the population (ie, approximately 90% of Americans), including most pregnant and lactating women, are well below the AI for choline. Moreover, the food patterns recommended by the 2015-2020 Dietary Guidelines for Americans are currently insufficient to meet the AI for choline in most age-sex groups. An individual's requirement for choline is dependent on common genetic variants in genes required for choline, folate, and 1-carbon metabolism, potentially increasing more than one-third of the population's susceptibly to organ dysfunction. The American Medical Association and American Academy of Pediatrics have both recently reaffirmed the importance of choline during pregnancy and lactation. New and emerging evidence suggests that maternal choline intake during pregnancy, and possibly lactation, has lasting beneficial neurocognitive effects on the offspring. Because choline is found predominantly in animal-derived foods, vegetarians and vegans may have a greater risk for inadequacy. With the 2020-2025 Dietary Guidelines for Americans recommending expansion of dietary information for pregnant women, and the inclusion of recommendations for infants and toddlers 0 to 2 years, better communication of the role that choline plays, particularly in the area of neurocognitive development, is critical. This narrative review summarizes the peer-reviewed literature and discussions from the 2018 Choline Science Summit, held in Washington, DC, in February 2018.

Methionine Sulfoxide Reductase-B3 (MsrB3) Protein Associates with Synaptic Vesicles and its Expression Changes in the Hippocampi of Alzheimer's Disease Patients.

Genome-wide association studies (GWAS) identified susceptibility loci associated with decreased hippocampal volume, and found hippocampal subfield-specific effects at MSRB3 (methionine sulfoxide reductase-B3). The MSRB3 locus was also linked to increased risk for late onset Alzheimer's disease (AD). In this study, we uncovered novel sites of MsrB3 expression in CA pyramidal layer and arteriolar walls by using automated immunohistochemistry on hippocampal sections from 23 individuals accompanied by neuropathology reports and clinical dementia rating scores. Controls, cognitively intact subjects with no hippocampal neurofibrillary tangles, exhibited MsrB3 signal as distinct but rare puncta in CA1 pyramidal neuronal somata. In CA3, however, MsrB3-immunoreactivity was strongest in the neuropil of the pyramidal layer. These patterns were replicated in rodent hippocampi where ultrastructural and immunohistofluorescence analysis revealed MsrB3 signal associated with synaptic vesicles and colocalized with mossy fiber terminals. In AD subjects, the number of CA1 pyramidal neurons with frequent, rather than rare, MsrB3-immunoreactive somatic puncta increased in comparison to controls. This change in CA1 phenotype correlated with the occurrence of AD pathological hallmarks. Moreover, the intensity of MsrB3 signal in the neuropil of CA3 pyramidal layer correlated with the signal pattern in neurons of CA1 pyramidal layer that was characteristic of cognitively intact individuals. Finally, MsrB3 signal in the arteriolar walls in the hippocampal white matter decreased in AD patients. This characterization of GWAS-implicated MSRB3 protein expression in human hippocampus suggests that patterns of neuronal and vascular MsrB3 protein expression reflect or underlie pathology associated with AD.

Neuroprotective Actions of Dietary Choline.

Choline is an essential nutrient for humans. It is a precursor of membrane phospholipids (e.g., phosphatidylcholine (PC)), the neurotransmitter acetylcholine, and via betaine, the methyl group donor S-adenosylmethionine. High choline intake during gestation and early postnatal development in rat and mouse models improves cognitive function in adulthood, prevents age-related memory decline, and protects the brain from the neuropathological changes associated with Alzheimer's disease (AD), and neurological damage associated with epilepsy, fetal alcohol syndrome, and inherited conditions such as Down and Rett syndromes. These effects of choline are correlated with modifications in histone and DNA methylation in brain, and with alterations in the expression of genes that encode proteins important for learning and memory processing, suggesting a possible epigenomic mechanism of action. Dietary choline intake in the adult may also influence cognitive function via an effect on PC containing eicosapentaenoic and docosahexaenoic acids; polyunsaturated species of PC whose levels are reduced in brains from AD patients, and is associated with higher memory performance, and resistance to cognitive decline.

Amylin Treatment Reduces Neuroinflammation and Ameliorates Abnormal Patterns of Gene Expression in the Cerebral Cortex of an Alzheimer's Disease Mouse Model.

Our recent study has demonstrated that peripheral amylin treatment reduces the amyloid pathology in the brain of Alzheimer's disease (AD) mouse models, and improves their learning and memory. We hypothesized that the beneficial effects of amylin for AD was beyond reducing the amyloids in the brain, and have now directly tested the actions of amylin on other aspects of AD pathogenesis, especially neuroinflammation. A 10-week course of peripheral amylin treatment significantly reduced levels of cerebral inflammation markers, Cd68 and Iba1, in amyloid precursor protein (APP) transgenic mice. Mechanistic studies indicated the protective effect of amylin required interaction with its cognate receptor because silencing the amylin receptor expression blocked the amylin effect on Cd68 in microglia. Using weighted gene co-expression network analysis, we discovered that amylin treatment influenced two gene modules linked with amyloid pathology: 1) a module related to proinflammation and transport/vesicle process that included a hub gene of Cd68, and 2) a module related to mitochondria function that included a hub gene of Atp5b. Amylin treatment restored the expression of most genes in the APP cortex toward levels observed in the wild-type (WT) cortex in these two modules including Cd68 and Atp5b. Using a human dataset, we found that the expression levels of Cd68 and Atp5b were significantly correlated with the neurofibrillary tangle burden in the AD brain and with their cognition. These data suggest that amylin acts on the pathological cascade in animal models of AD, and further supports the therapeutic potential of amylin-type peptides for AD.

Comment on "Multiple repressive mechanisms in the hippocampus during memory formation".

Cho et al. (Reports, 2 October 2015, p. 82) report that gene repression after contextual fear conditioning regulates hippocampal memory formation. We observe low levels of expression for many of the top candidate genes in the hippocampus and robust expression in the choroid plexus, as well as repression at 4 hours after contextual fear conditioning, suggesting the inclusion of choroid plexus messenger RNAs in Cho et al. hippocampal samples.

Intrinsic Cholinergic Neurons in the Hippocampus: Fact or Artifact?

It is generally agreed that hippocampal acetylcholine (ACh) is synthesized and released exclusively from the terminals of the long-axon afferents whose cell bodies reside in the medial septum and diagonal band. The search for intrinsic cholinergic neurons in the hippocampus has a long history; however evidence for the existence of these neurons has been inconsistent, with most investigators failing to detect them using in situ hybridization or immunohistochemical staining of the cholinergic markers, choline acetyltransferase (ChAT) or vesicular acetylcholine transporter (VAChT). Advances in the use of bacterial artificial chromosome (BAC) transgenic mice expressing a reporter protein under the control of the genomic elements of the Chat gene (Chat-BAC mice) have facilitated studies of cholinergic neurons. Such mice show robust and faithful expression of the reporter proteins in all known cholinergic cell populations. The availability of the Chat-BAC mice re-ignited interest in hippocampal cholinergic interneurons, because a small number of such reporter-expressing cells is frequently observed in the hippocampus of these mice. However, to date, attempts to confirm that these neurons co-express the endogenous cholinergic marker ChAT, or release ACh, have been unsuccessful. Without such confirmatory evidence it is best to conclude that there are no cholinergic neurons in the hippocampus. Similar considerations apply to other BAC transgenic lines, whose utility as a discovery tool for cell populations heretofore not known to express the genes of interest encoded by the BACs, must be validated by methods that detect expression of the endogenous genes.

High maternal choline consumption during pregnancy and nursing alleviates deficits in social interaction and improves anxiety-like behaviors in the BTBR T+Itpr3tf/J mouse model of autism.

Autism is a neurodevelopmental disorder with multiple genetic and environmental risk factors. Choline is a fundamental nutrient for brain development and high choline intake during prenatal and/or early postnatal periods is neuroprotective. We examined the effects of perinatal choline supplementation on social behavior, anxiety, and repetitive behaviors in the BTBR T+Itpr3tf/J (BTBR) mouse model of autism. The BTBR or the more "sociable" C57BL/6J (B6) strain females were fed a control or choline-supplemented diet from mating, throughout pregnancy and lactation. After weaning to a control diet, all offspring were evaluated at one or two ages [postnatal days 33-36 and 89-91] using open field (OF), elevated plus maze (EPM), marble burying (MB), and three-chamber social interaction tests. As expected, control-diet BTBR mice displayed higher OF locomotor activity, impaired social preference, and increased digging behavior during the MB test compared to control-diet B6 mice. Choline supplementation significantly decreased digging behavior, elevated the percentage of open arm entries and time spent in open arms in the EPM by BTBR mice, but had no effect on locomotion. Choline supplementation did not alter social interaction in B6 mice but remarkably improved impairments in social interaction in BTBR mice at both ages, indicating that the benefits of supplementation persist long after dietary choline returns to control levels. In conclusion, our results suggest that high choline intake during early development can prevent or dramatically reduce deficits in social behavior and anxiety in an autistic mouse model, revealing a novel strategy for the treatment/prevention of autism spectrum disorders.

IGF2 ameliorates amyloidosis, increases cholinergic marker expression and raises BMP9 and neurotrophin levels in the hippocampus of the APPswePS1dE9 Alzheimer's disease model mice.

The development of an effective therapy for Alzheimer's disease (AD) is a major challenge to biomedical sciences. Because much of early AD pathophysiology includes hippocampal abnormalities, a viable treatment strategy might be to use trophic factors that support hippocampal integrity and function. IGF2 is an attractive candidate as it acts in the hippocampus to enhance memory consolidation, stimulate adult neurogenesis and upregulate cholinergic marker expression and acetylcholine (ACh) release. We performed a seven-day intracerebroventricular infusion of IGF2 in transgenic APPswe.PS1dE9 AD model mice that express green fluorescent protein in cholinergic neurons (APP.PS1/CHGFP) and in wild type WT/CHGFP littermates at 6 months of age representing early AD-like disease. IGF2 reduced the number of hippocampal Aß40- and Aß42-positive amyloid plaques in APP.PS1/CHGFP mice. Moreover, IGF2 increased hippocampal protein levels of the ACh-synthesizing enzyme, choline acetyltransferase in both WT/CHGFP and APP.PS1/CHGFP mice. The latter effect was likely mediated by increased protein expression of the cholinergic differentiating factor, BMP9, observed in IGF2-treated mice as compared to controls. IGF2 also increased the protein levels of hippocampal NGF, BDNF, NT3 and IGF1 and of doublecortin, a marker of neurogenesis. These data show that IGF2 administration is effective in reversing and preventing several pathophysiologic processes associated with AD and suggest that IGF2 may constitute a therapeutic target for AD.

BMP9 ameliorates amyloidosis and the cholinergic defect in a mouse model of Alzheimer's disease.

Bone morphogenetic protein 9 (BMP9) promotes the acquisition of the cholinergic phenotype in basal forebrain cholinergic neurons (BFCN) during development and protects these neurons from cholinergic dedifferentiation following axotomy when administered in vivo. A decline in BFCN function occurs in patients with Alzheimer's disease (AD) and contributes to the AD-associated memory deficits. We infused BMP9 intracerebroventricularly for 7 d in transgenic AD model mice expressing green fluorescent protein specifically in cholinergic neurons (APP.PS1/CHGFP) and in wild-type littermate controls (WT/CHGFP). We used 5-mo-old mice, an age when the AD transgenics display early amyloid deposition and few cholinergic defects, and 10-mo-old mice, by which time these mice exhibit established disease. BMP9 infusion reduced the number of Aß42-positive amyloid plaques in the hippocampus and cerebral cortex of 5- and 10-mo-old APP.PS1/CHGFP mice and reversed the reductions in choline acetyltransferase protein levels in the hippocampus of 10-mo-old APP.PS1/CHGFP mice. The treatment increased cholinergic fiber density in the hippocampus of both WT/CHGFP and APP.PS1/CHGFP mice at both ages. BMP9 infusion also increased hippocampal levels of neurotrophin 3, insulin-like growth factor 1, and nerve growth factor and of the nerve growth factor receptors, tyrosine kinase receptor A and p75/NGFR, irrespective of the genotype of the mice. These data show that BMP9 administration is effective in reducing the Aß42 amyloid plaque burden, reversing cholinergic neuron abnormalities, and generating a neurotrophic milieu for BFCN in a mouse model of AD and provide evidence that the BMP9-signaling pathway may constitute a therapeutic target for AD.