The rise and fall of insulin signaling in Alzheimer's disease.

The prevalence of both diabetes and Alzheimer's disease (AD) are reaching epidemic proportions worldwide. Alarmingly, diabetes is also a risk factor for Alzheimer's disease. The AD brain is characterised by the accumulation of peptides called Aß as plaques in the neuropil and hyperphosphorylated tau protein in the form of neurofibrillary tangles within neurons. How diabetes confers risk is unknown but a simple linear relationship has been proposed whereby the hyperinsulinemia associated with type 2 diabetes leads to decreased insulin signaling in the brain, with downregulation of the PI3K/AKT signalling pathway and its inhibition of the major tau kinase, glycogen synthase kinase 3ß. The earliest studies of post mortem AD brain tissue largely confirmed this cascade of events but subsequent studies have generally found either an upregulation of AKT activity, or that the relationship between insulin signaling and AD is independent of glycogen synthase kinase 3ß altogether. Given the lack of success of beta-amyloid-reducing therapies in clinical trials, there is intense interest in finding alternative or adjunctive therapeutic targets for AD. Insulin signaling is a neuroprotective pathway and represents an attractive therapeutic option. However, this incredibly complex signaling pathway is not fully understood in the human brain and particularly in the context of AD. Here, we review the ups and downs of the research efforts aimed at understanding how diabetes modifies AD risk.

High Fat Diet Mediated Alterations in Serum Sphingolipid Profiles in An Experimental Mouse Model Measured by Matrix-Assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry.

Non-alcoholic fatty liver disease (NAFLD) is associated with hepatic steatosis, a benign condition caused by accumulation of lipids in hepatocytes, which may progress to steatohepatitis and cirrhosis. Recent studies suggest that sphingolipids are involved in the development and severity of NAFLD. The goal of this study is to identify the circulating sphingolipid species that are altered by chronic high fat diet (HFD) feeding and correlate these abnormalities with hepatic sphingolipids. We utilized a previously established experimental model of NAFLD generated by HFD feeding of 8-week-old male mice for 16 weeks. Lipids were extracted from serum samples by Folch method and analyzed with matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) in the positive and negative ion modes. MALDI-TOF detected a total of 47 serum sphingolipids including sphingomyelins, sulfatides, ceramides, phosphosphingolipids, and glycosphingolipids within the mass range of 600-2000 Da. Principle component analysis demonstrated clear separation of hepatic sphingolipids from low fat diet (LFD) and HFD groups and partial overlap of serum sphingolipids with a variance of 53.5% and 15.1%, and 11.7% in PC1, PC2, and PC3, respectively. Chronic HFD feeding significantly increased expression of SM (40:0), SM(42:2), ST(42:2), Hex(6)-Cer (40:1), and Hex(4)-HexNAc (2)-Cer (34:1) in both serum and liver. In addition, HFD mediated percent changes in hepatic sphingolipids correlate linearly with the percent changes in serum sphingolipids as determined by Pearson correlation (P = 0.0002). Elevated levels of serum and hepatic sphingomyelins and glycoceramides are key factors mediating NAFLD development and may serve as peripheral markers of hepatic steatosis.

Rapid Peak Alignment for MALDI-TOF Lipid Analysis.

The ability to measure structural and functional alterations in cellular and tissue lipids with small footprint, accessible instrumentation has sparked interest in their role in disease pathology. However, various lipidomic analytical tools tend to be cumbersome and time-consuming. A rapid, accurate, and straight forward peak alignment software routine would greatly facilitate the analysis of large datasets, such as those produced by matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Herein, we describe a novel Rapid Peak Alignment Method (RPAM) which allows untargeted analysis of lipids expressed in brain white matter following chronic ethanol exposure in an established experimental model. The RPAM outputs data comparable to manual peak alignments but the processing time requires only 90 minutes instead of 8-10 hours. This method is readily adapted to a broad range of models, tissue types, and human diseases.

reply: Neurobiologyp25 protein in neurodegeneration.

Yoo and Lubec show that the amount of p25 is decreased in the brains they studied from patients with Alzheimer's disease or Down's syndrome. Their results persuaded us to conduct a more extensive survey of the p25/p35 ratio in AD brains (to be published elsewhere), as the number of samples was small in both of our studies (eight AD brains in our original study and six in theirs). After analysing a further 25 AD brains and those from 25 age-matched controls, we found that p25 levels are consistently higher in AD brains and that the difference is statistically significant (Student's t-test). This is in agreement with our original observations, as well as being consistent with earlier reports of increased Cdk5 kinase activity in AD brain and of increased amounts of p25 in an animal model of neurodegeneration.

Cloning of human GAP-43: growth association and ischemic resurgence.

GAP-43 is a growth cone protein expressed in neurons especially during periods of axonal elongation. Poor repair in the adult mammalian CNS has been ascribed to restraints upon its expression. We have cloned human GAP-43 cDNA to investigate its potential involvement in neurological illness. Analysis of postmortem human brain tissue disclosed uniformly high expression of GAP-43 throughout the neonatal brain, whereas in the adult brain high levels of GAP-43 persist only in discrete regions. However, in the wake of ischemic injury in the adult brain, regions normally low in GAP-43 reexpress it at high levels, suggesting a role for GAP-43 in remodeling and repair of mature CNS neurons.

Impaired placentation in fetal alcohol syndrome.

Intrauterine growth restriction (IUGR) is one of the key features of fetal alcohol syndrome (FAS), and IUGR can be mediated by impaired placentation. Insulin-like growth factors (IGF) regulate placentation due to stimulatory effects on extravillous trophoblasts, which are highly motile and invasive. Previous studies demonstrated that extravillous trophoblasts express high levels of aspartyl-(asparaginyl) beta-hydroxylase (AAH), a gene that is regulated by IGF and has a critical role in cell motility and invasion. The present study examines the hypothesis that ethanol impaired placentation is associated with inhibition of AAH expression in trophoblasts. Pregnant Long Evans rats were fed isocaloric liquid diets containing 0% or 37% ethanol by caloric content. Placentas harvested on gestation day 16 were used for histopathological, mRNA, and protein studies to examine AAH expression in relation to the integrity of placentation and ethanol exposure. Chronic ethanol feeding prevented or impaired the physiological conversion of uterine vessels required for expansion of maternal circulation into placenta, a crucial process for adequate placentation. Real-time quantitative RT-PCR analysis demonstrated significant reductions in IRS-1, IRS-2, and significant increases in IGF-II and IGF-II receptor mRNA levels in ethanol-exposed placentas. These abnormalities were associated with significantly reduced levels of AAH expression in trophoblastic cells, particularly within the mesometrial triangle (deep placental bed) as demonstrated by real time quantitative RT-PCR, Western blot analysis, ELISA, and immunohistochemical staining. Ethanol-impaired placentation is associated with inhibition of AAH expression in trophoblasts. This effect of chronic gestational exposure to ethanol may contribute to IUGR in FAS.

Therapeutic Advantages of Dual Targeting of PPAR-δ and PPAR-γ in an Experimental Model of Sporadic Alzheimer's Disease.

BACKGROUND: Alzheimer's disease (AD) is associated with progressive impairments in brain responsiveness to insulin and insulin-like growth factor (IGF). Although deficiencies in brain insulin and IGF could be ameliorated with trophic factors such as insulin, impairments in receptor expression, binding, and tyrosine kinase activation require alternative strategies. Peroxisome proliferator-activated receptor (PPAR) agonists target genes downstream of insulin/IGF stimulation. Furthermore, their anti-oxidant and anti-inflammatory effects address other pathologies contributing to neurodegeneration. OBJECTIVES: The goal of this research was to examine effects of dual delivery of L165, 041 (PPAR-δ) and F-L-Leu (PPAR-γ) agonists for remediating in the early stages of neurodegeneration. MODEL: Experiments were conducted using frontal lobe slice cultures from an intracerebral Streptozotocin (i.c. STZ) rat model of AD. RESULTS: PPAR-δ+ PPAR-γ agonist treatments increased indices of neuronal and myelin maturation, and mitochondrial proliferation and function, and decreased neuroinflammation, AßPP-Aß, neurotoxicity, ubiquitin, and nitrosative stress, but failed to restore choline acetyl transferase expression and adversely increased HNE(lipid peroxidation) and acetylcholinesterase, which would have further increased stress and reduced cholinergic function in the STZ brain cultures. CONCLUSION: PPAR-δ + PPAR-γ agonist treatments have substantial positive early therapeutic targeting effects on AD-associated molecular and biochemical brain pathologies. However, additional or alternative strategies may be needed to optimize disease remediation during the initial phases of treatment.

The role of inflammation in the association between gestational diabetes and obstructive sleep apnea: A pilot study.

BACKGROUND: Obstructive sleep apnea is associated with pregnancy complications including gestational diabetes. Mechanisms underlying the association between obstructive sleep apnea and gestational diabetes remain to be elucidated. METHODS: Twenty-three participants with gestational diabetes underwent home sleep apnea testing. Obstructive sleep apnea was defined as an apnea hypopnea index > 5. Fasting morning blood samples were measured using multianalyte profiling (xMAP) multiplexed bead array immunoassay for Interleukin 6, tumor necrosis factor-alpha, and Interleukin 8. RESULTS: Age, body mass index, and gestational age at enrollment were 31 + 4.4 years, 35.7 + 7.4 kg/m2, and 28 ± 4 weeks, respectively. Participants were 52% Caucasian and 16% had obstructive sleep apnea. We observed positive correlations between apnea hypopnea index and Interleukin 6 (r = 0.62, p = 0.005), Interleukin 8 (r = 0.56, p = .56), and tumor necrosis factor-alpha (r = .58, p = .009). Women with obstructive sleep apnea had higher levels of Interleukin 6 (F = 5.01, p = .037) and Interleukin 8 (F = 6.33, p = .021) vs. women without obstructive sleep apnea. CONCLUSION: These preliminary results indicate that in women with gestational diabetes, apnea hypopnea index is associated with an elevated inflammatory profile.

Enhanced expression of an exocrine pancreatic protein in Alzheimer's disease and the developing human brain.

Pancreatic thread protein (PTP) is a major exocrine secretory protein that in vitro forms filamentous bundles reminiscent of the paired helical filaments of Alzheimer's disease (AD). We previously described increased PTP immunoreactivity in AD brains and now report high levels in the developing human brain. Using a full-length cloned bovine PTP cDNA and synthetic oligonucleotides corresponding to human PTP cDNA, which is identical to human islet cell regeneration factor, we analyzed the expression of PTP in pancreas and brain. A major 0.9-kb as well as several minor transcripts were identified in human pancreas. In AD brain, the same size transcripts were detected by Northern analysis, primer extension assay, or polymerase chain reaction amplification of cDNAs generated by reverse transcriptase assay. There were significantly higher levels of PTP mRNA in brains with AD compared with aged controls, with increased amounts of 1.2-, 0.6-, and 0.4-kb transcripts by Northern analysis. In situ hybridization localized expression to pyramidal neurons in the cerebral cortex, the same population that contains neurofibrillary tangles and high levels of immunoreactive PTP. These findings suggest that AD is associated with enhanced expression of PTP-related transcripts with intraneuronal accumulation of PTP-like proteins.

Expression of the potent vasoconstrictor endothelin in the human central nervous system.

Endothelin is a potent vasoconstrictive peptide initially characterized as a product of endothelial cells. To examine the potential role of endothelin as a neuropeptide, we studied its distribution in the human central nervous system. RNA blot hybridization provided evidence of endothelin gene transcription in a variety of functional regions of the brain. In situ hybridization confirmed the widespread pattern of endothelin transcription and indicated that the highest density of cells containing endothelin mRNA is in the hypothalamus. This technique localized endothelin transcription to cells of the nervous system as well as the vascular endothelium. Immunocytochemical studies detected endothelin immunoreactivity in neurons, providing evidence of the synthesis of the peptide in this cell type and confirming that endothelin is a neuropeptide. Although the prominent expression of endothelin in the hypothalamus may indicate a central vasoregulatory role for the peptide, the widespread distribution of endothelin in neurons in other areas of the brain implies a more fundamental role in the regulation of nervous system function.

Overexpression of human aspartyl(asparaginyl)beta-hydroxylase in hepatocellular carcinoma and cholangiocarcinoma.

To characterize genes that become upregulated with malignant transformation of human hepatocytes, a library of monoclonal antibodies was produced against the FOCUS hepatocellular carcinoma cell line. Antibody FB-50 reacted with an antigen that was highly expressed in 4 of 10 primary hepatocellular carcinomas, in all 20 cholangiocarcinomas we studied, and in a variety of transformed cell lines. This antigen was also highly expressed in neoplastic epithelial cells of breast and colon carcinomas in contrast to its low level of expression in normal hepatocytes and in non-neoplastic epithelial cells. Among the normal adult tissues studied, high levels were observed only in proliferating trophoblastic cells of the placenta and in adrenal glands. A 636-bp partial cDNA, isolated from a gamma GT11 expression library generated with HepG2 human hepatoblastoma cells, and a complete cDNA, generated by reverse transcriptase-PCR, identified the antigen as the human form of aspartyl(asparaginyl)beta-hydroxylase. This enzyme catalyzes posttranslational hydroxylation of beta carbons of specific aspartyl and asparaginyl residues in EGF-like domains of certain proteins. Analyses of extracts prepared from several human tumor cell lines compared to their normal tissue counterparts indicate that the increase in hydroxylase, approximately 10-fold, is controlled at the level of transcription and the protein is expressed in an enzymatically active form. In similar analyses, comparing hepatocellular carcinomas to adjacent uninvolved liver from five patients, enzymatic activity was much higher in the tumor tissue from the four patients whose immunoblots revealed increased hydroxylase protein in the malignant tissue. EGF repeats in the extracellular domain of Notch or its homologs contain the consensus sequence for hydroxylation. Deletion mutants lacking this domain are gain-of-function mutants, suggesting that the domain modulates signal transduction by the cytoplasmic domain. While the function imparted by beta hydroxylation is unknown, our studies raise the possibility that beta hydroxylation is regulated in proteins like the mammalian Notch homologs, whose cytoplasmic domains have been shown to be oncogenic.

Structural and functional heterogeneity of nuclear bodies.

The nuclear body is a cellular structure that appears to be involved in the pathogenesis of acute promyelocytic leukemia and viral infection. In addition, the nuclear body is a target of autoantibodies in patients with the autoimmune disease primary biliary cirrhosis. Although the precise function of the nuclear body in normal cellular biology is unknown, this structure may have a role in the regulation of gene transcription. In a previous investigation, we identified a leukocyte-specific, gamma interferon (IFN-gamma)-inducible autoantigen designated Sp140. The objectives of the present study were to investigate the cellular location of Sp140 with respect to the nuclear-body components PML and Sp100 and to examine the potential role of Sp140 in the regulation of gene transcription. We used adenovirus-mediated gene transfer to express Sp140 in human cells and observed that the protein colocalized with PML and Sp100 in resting cells and associated with structures containing PML during mitosis. In cells infected with the adenovirus expressing Sp140 and incubated with IFN-gamma, the number of PML-Sp100 nuclear bodies per cell increased but immunoreactive Sp140 was not evenly distributed among the nuclear bodies. Sp140 associated with a subset of IFN-gamma-induced PML-Sp100 nuclear bodies. To examine the potential effect of Sp140 on gene transcription, a plasmid encoding Sp140 fused to the DNA-binding domain of GAL4 was cotransfected into COS cells with a chloramphenicol acetyltransferase (CAT) reporter gene containing five GAL4-binding sites and a simian virus 40 enhancer region. The GAL4-Sp140 fusion protein increased the expression of the reporter gene. In contrast, Sp100 fused to the GAL4 DNA-binding domain inhibited CAT activity in transfected mammalian cells. The results of this study demonstrate that Sp140 associates with a subset of PML-Sp100 nuclear bodies in IFN-gamma-treated cells and that Sp140 may activate gene transcription. Taken together, these observations suggest that the nuclear bodies within a cell may be heterogeneous with respect to both composition and function.

Sp110 localizes to the PML-Sp100 nuclear body and may function as a nuclear hormone receptor transcriptional coactivator.

The nuclear body is a multiprotein complex that may have a role in the regulation of gene transcription. This structure is disrupted in a variety of human disorders including acute promyelocytic leukemia and viral infections, suggesting that alterations in the nuclear body may have an important role in the pathogenesis of these diseases. In this study, we identified a cDNA encoding a leukocyte-specific nuclear body component designated Sp110. The N-terminal portion of Sp110 was homologous to two previously characterized components of the nuclear body (Sp100 and Sp140). The C-terminal region of Sp110 was homologous to the transcription intermediary factor 1 (TIF1) family of proteins. High levels of Sp110 mRNA were detected in human peripheral blood leukocytes and spleen but not in other tissues. The levels of Sp110 mRNA and protein in the human promyelocytic leukemia cell line NB4 increased following treatment with all-trans retinoic acid (ATRA), and Sp110 localized to PML-Sp100 nuclear bodies in ATRA-treated NB4 cells. Because of the structural similarities between Sp110 and TIF1 proteins, the effect of Sp110 on gene transcription was examined. An Sp110 DNA-binding domain fusion protein activated transcription of a reporter gene in transfected mammalian cells. In addition, Sp110 produced a marked increase in ATRA-mediated expression of a reporter gene containing a retinoic acid response element. Taken together, the results of this study demonstrate that Sp110 is a member of the Sp100/Sp140 family of nuclear body components and that Sp110 may function as a nuclear hormone receptor transcriptional coactivator. The predominant expression of Sp110 in leukocytes and the enhanced expression of Sp110 in NB4 cells treated with ATRA raise the possibility that Sp110 has a role in inducing differentiation of myeloid cells.

Patterned distribution of metastases from malignant melanoma in humans.

Malignant melanoma has an unpredictable clinical course in terms of metastatic behavior, and further understanding might lead to improved therapeutic intervention with immune agents or antagonists. To determine whether metastases show patterns or are randomly distributed, we analyzed the distributions of metastases in the 56 patients with metastatic malignant melanoma, subjected to complete autopsy at The Johns Hopkins Hospital, using parametric statistics and cluster analysis. Variables examined included age, race, sex, location of primary tumor, length of survival, mode of therapy, histology of tumor, location of metastases, and extent of tumor infiltration at each metastatic site. The results indicate that the distributions of metastases from malignant melanoma are patterned such that significant positive correlations (p less than 0.05 or better) were observed among various tissues and organs. We identified several aggregations with respect to the distributions of metastases: (a) central nervous system; (b) mesodermal; (c) endocrine; (d) reticuloendothelial; and (e) foregut. Organs and tissues comprising each aggregation were interrelated by their similar developmental origins or functions. A very highly significant negative correlation between central nervous system and hepatic metastases (p less than 0.001) was also demonstrated by cluster analysis. We concluded that the distributions of metastases from malignant melanoma are not random; the patterns of metastases may be related to the embryological derivation of tissues involved.

Overexpression of human aspartyl (asparaginyl) beta-hydroxylase is associated with malignant transformation.

The human aspartyl (asparaginyl) beta-hydroxylase (HAAH) is a highly conserved enzyme that hydroxylates epidermal growth factor-like domains in transformation-associated proteins. We previously reported overexpression of the HAAH gene in human hepatocellular carcinomas and cholangiocarcinomas (L. Lavaissiere et al., J. Clin. Investig., 98: 1313-1323, 1996). In the present study, we determined whether HAAH protein overexpression was linked to cellular proliferation or malignant transformation of bile ducts by using a human disease and rat model of bile duct proliferation. In addition, the transforming properties of the AAH genes were assessed by transient and stable transfection of NIH-3T3 cells with human and murine wild-type as well as mutant cDNA constructs that lacked hydroxylation activity. Cellular characteristics of the malignant phenotype were assessed by formation of transformed foci, growth in soft agar, and tumor development in nude mice. We found that HAAH gene expression was undetectable during bile duct proliferation in both human disease and rat models as compared with cholangiocarcinoma. Overexpression of HAAH in NIH-3T3 cells was associated with generation of a malignant phenotype, and enzymatic activity was required for cellular transformation. These findings suggest that overexpression of HAAH is linked to cellular transformation of biliary epithelial cells.

Characterization of thread proteins expressed in neuroectodermal tumors.

Neuronal thread protein is a novel 21-kDa protein that accumulates in brains with Alzheimer's disease and exhibits developmentally associated changes in the level of expression. Recently, we discovered that primary human primitive neuroectodermal tumor (PNETs), malignant astrocytomas, and several human PNET and glioblastoma cell lines also express thread protein immunoreactivity. However, in addition to the 21-kDa species, there are approximately 17- and approximately 14-kDa thread protein-immunoreactive molecules expressed in both PNET and glioblastoma cell lines and a fourth approximately 8-kDa thread protein detected in glioblastoma cell lines. Metabolic labeling studies demonstrated that the 21-kDa thread proteins are phosphorylated, whereas the approximately 17-, approximately 14-, and approximately 8-kDa thread proteins are not. Glycosylated residues were not detected in either the PNET- or glioblastoma-derived thread proteins. Using a panel of monoclonal antibodies, we observed differences between PNET and glioblastoma cells suggesting that the thread proteins expressed in neuronal and glial cells are distinct. The levels of thread protein immunoreactivity in both PNET and glial cells were highest during the log phase of cell growth and lowest in serum-starved, nonproliferating cultures. The findings suggest that there are several distinct neuronal and glial derived thread proteins expressed in the central nervous system and that their levels of expression may be modulated with cell growth.

Enzymatic Responses to Alcohol and Tobacco Nicotine-Derived Nitrosamine Ketone Exposures in Long Evans Rat Livers.

BACKGROUND: Chronic feeding plus binge administration of ethanol causes very high blood alcohol concentrations. However, its co-administration with tobacco Nicotine-Derived Nitrosamine Ketone (NNK) results in somewhat lower blood alcohol levels, suggesting that NNK and therefore smoking, alters alcohol metabolism in the liver. To explore this hypothesis, we examined effects of ethanol and/or NNK exposures on the expression and activity levels of enzymes that regulate their metabolism in liver. METHODS: This study utilized a 4-way model in which Long Evans rats were fed liquid diets containing 0% or 26% ethanol for 8 weeks, and respectively i.p injected with saline or 2 g/kg of ethanol 3 times/week during Weeks 7 and 8. The control and ethanol-exposed groups were each sub-divided and further i.p treated with 2 mg/kg of NNK or saline (3×/week) in Weeks 3-8. ADH, catalase and ALDH activities were measured using commercial kits. CYP450 mRNA levels (17 isoforms) were measured by qRT-PCR analysis. RESULTS: Ethanol significantly increased hepatic ADH but not catalase or ALDH activity. NNK had no effect on ADH, ALDH, or catalase, but when combined with ethanol, it increased ADH activity above the levels measured in all other groups. Ethanol increased CYP2C7, while NNK increased CYP2B1 and CYP4A1mRNA levels relative to control. In contrast, dual ethanol + NNK exposures inhibited CYP2B1 and CYP4A1 expression relative to NNK. Conclusion: Dual exposures to ethanol and NNK increase hepatic ethanol metabolism, and ethanol and/or NNK exposures alter the expression of CYP450 isoforms that are utilized in NNK and fatty acid metabolism.

Dose effect of gestational ethanol exposure on placentation and fetal growth.

INTRODUCTION: Prenatal ethanol exposure compromises fetal growth by impairing placentation. Invasive trophoblastic cells, which mediate placentation, express the insulin-IGF regulated gene, aspartyl-asparaginyl ß-hydroxylase (ASPH), which has a critical role in cell motility and invasion. The aims of this study were to characterize effects of ethanol on trophoblastic cell motility, and assess ethanol dose-dependent impairments in placentation and fetal development. METHODS: Pregnant Long Evans dams were fed with isocaloric liquid diets containing 0%, 8%, 18% or 37% ethanol (caloric content) from gestation day (GD) 6 to GD18. Fetal development, placental morphology, density of invasive trophoblasts at the mesometrial triangle, as well as placental and mesometrial ASPH and Notch-1 protein expression were evaluated. Directional motility of control and ethanol-exposed HTR-8/SVneo cells was assessed by ATP Luminescence-Based assay. RESULTS: Severity of fetal growth impairment correlated with increasing doses of ethanol. Ethanol exposure produced dose-dependent alterations in branching morphogenesis at the labyrinthine zone, and inhibited physiological transformation of maternal arteries. ASPH and Notch-1 protein expression levels were reduced, corresponding with impairments in placentation. DISCUSSION: Prenatal ethanol exposure compromises fetal growth and placentation in a dose-responsive manner. Ethanol's adverse effects on placental development are mediated by: (1) altered branching morphogenesis in labyrinthine zone; (2) suppression of invasive trophoblastic precursor cells; and (3) inhibition of trophoblastic cell adhesion and motility, corresponding with reduced ASPH and Notch-1 protein expression.

Leptin levels are reduced by intravenous ghrelin administration and correlated with cue-induced alcohol craving.

Increasing evidence supports the role of appetite-regulating pathways, including ghrelin and leptin, in alcoholism. This study tested the hypothesis that intravenous exogenous ghrelin administration acutely decreases endogenous serum leptin levels, and that changes in leptin levels negatively correlate with alcohol craving. This was a double-blind, placebo-controlled human laboratory study. Non-treatment-seeking, alcohol-dependent, heavy drinkers (n=45) were randomized to receive intravenous ghrelin or placebo, followed by a cue-reactivity procedure, during which participants were exposed to neutral (juice) and alcohol trial cues. There was a main effect for intravenous ghrelin administration, compared with placebo, in reducing serum leptin levels (P<0.01). Post hoc analysis showed significant differences in serum leptin levels at the alcohol trial (P<0.05) that persisted at the end of the experiment (P<0.05). By contrast, there were no significant differences in serum leptin levels at the juice trial (P=not significant (NS)). The change of serum leptin level at the alcohol trial correlated with the increase in alcohol urge (P<0.05), whereas urge to drink juice was not correlated with the leptin change at the juice trial (P=NS). These findings provide preliminary evidence of ghrelin-leptin cross-talk in alcoholic individuals and suggest that their relationship may have a role in alcohol craving.