Hinton, David J.

Aging and other cardiovascular risk factors are associated with increased incidence of Alzheimer's disease (AD). A common feature of cardiovascular risk factors is decreased endothelial nitric oxide (NO). We studied the effect of a loss of endothelial NO on amyloid precursor protein (APP) related phenotype in aged (14–15 month) endothelial nitric oxide synthase deficient (eNOS −/− ) mice. APP, β‐site APP cleaving enzyme 1, and amyloid beta (Aβ) levels were significantly higher in the brains of aged eNOS −/− mice as compared to aged wild type mice. APP and Aβ 1–40 were increased in hippocampal tissue of eNOS −/− mice as compared to wild type mice. Aged eNOS −/− mice displayed an increased inflammatory phenotype as compared to aged wild type mice. Importantly, aged eNOS −/− mice performed worse in a radial arm maze test of spatial learning and memory as compared to aged wild type mice. These data suggest that chronic loss of endothelial NO may be an important contributor to both Aβ related pathology and cognitive decline. Research was supported by NIH grants HL‐111062 and HL‐91867, the Mayo Alzheimer's Disease Research Center (Z.S.K.), AHA scientist development grant (0835436N, A.V.S.), AHA postdoctoral fellowship 12POST8550003 (S.A.A.), Clinical Pharmacology Training Grant (T32 GM08685) (Trainee S.A.A.), the Samuel Johnson Foundation for Genomics of Addiction Program at Mayo Clinic (D.‐S.C.) and the Mayo Foundation.

AbstractAcamprosate is an FDA‐approved medication for the treatment of alcoholism that is unfortunately only effective in certain patients. Although acamprosate is known to stabilize the hyper‐glutamatergic state in alcoholism, pharmacological mechanisms of action in brain tissue remains unknown. To investigate the mechanism of acamprosate efficacy, the authors employ a pharmacoproteomics approach using an animal model of alcoholism, type 1 equilibrative nucleoside transporter (ENT1) null mice. The results demonstrate that acamprosate treatment significantly decreased both ethanol drinking and preference in ENT1 null mice compared to that of wild‐type mice. Then, to elucidate acamprosate efficacy mechanism in ENT1 null mice, the authors utilize label‐free quantification proteomics comparing both genotype and acamprosate treatment effects in the nucleus accumbens (NAc). A total of 1040 protein expression changes are identified in the NAc among 3634 total proteins detected. The proteomics and Western blot result demonstrate that acamprosate treatment decreased EAAT expression implicating stabilization of the hyper‐glutamatergic condition in ENT1 null mice. Pathway analysis suggests that acamprosate treatment in ENT1 null mice seems to rescue glutamate toxicity through restoring of RTN4 and NF‐κB medicated neuroimmune signaling compared to wild‐type mice. Overall, pharmacoproteomics approaches suggest that neuroimmune restoration is a potential efficacy mechanism in the acamprosate treatment of certain sub‐populations of alcohol dependent subjects.

Abstract Although the precise drug mechanism of action of acamprosate remains unclear, its antidipsotropic effect is mediated in part through glutamatergic neurotransmission. We evaluated the effect of 4 weeks of acamprosate treatment in a cohort of 13 subjects with alcohol dependence (confirmed by a structured interview, Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision) on proton magnetic resonance spectroscopy glutamate levels in the midline anterior cingulate cortex (MACC). We compared levels of metabolites with a group of 16 healthy controls. The Pennsylvania Alcohol Craving Scale was used to assess craving intensity. At baseline, before treatment, the mean cerebrospinal fluid–corrected MACC glutamate (Glu) level was significantly elevated in subjects with alcohol dependence compared with controls (P = 0.004). Four weeks of acamprosate treatment reduced glutamate levels (P = 0.025), an effect that was not observed in subjects who did not take acamprosate. At baseline, there was a significant positive correlation between cravings, measured by the Pennsylvania Alcohol Craving Scale, and MACC (Glu) levels (P = 0.019). Overall, these data would suggest a normalizing effect of acamprosate on a hyperglutamatergic state observed in recently withdrawn patients with alcohol dependence and a positive association between MACC glutamate levels and craving intensity in early abstinence. Further research is needed to evaluate the use of these findings for clinical practice, including monitoring of craving intensity and individualized selection of treatment with antidipsotropic medications in subjects with alcohol dependence.

BackgroundQuantifying craving longitudinally during the course of withdrawal, early abstinence, and relapse is essential for optimal management of alcohol use disorder (AUD). In an effort to identify biological correlates of craving, we used proton magnetic resonance spectroscopy (1H‐MRS) to investigate the correlation between craving and glutamate levels in the left dorsolateral prefrontal cortex (LDLPFC) of patients with AUD.MethodsParticipants underwent 1H‐MRS of the LDLPFC with 2‐dimensional J‐resolved (2DJ) averaged PRESS. MRS data were processed with LCModel and cerebrospinal fluid (CSF)‐corrected to generate metabolite concentrations. The Penn Alcohol Craving Scale (PACS) and the 30‐day time line follow‐back (TLFB 30) were used to quantify craving for alcohol and drinking patterns, respectively.ResultsThere was a statistically significant positive correlation between CSF‐corrected glutamate ([Glu]) levels and PACS scores (n = 14; p = 0.005). When PACS scores were dichotomized (< or ≥median = 16), [Glu] levels were significantly higher in the high‐ versus low‐craving group (p = 0.007). In addition, there was a significant negative correlation between CSF‐corrected N‐acetyl aspartic acid ([NAA]) levels and mean number of drinks per drinking day in the past month (n = 13; TLFB 30; p = 0.012). When mean TLFB 30 was dichotomized (< or ≥median = 7.86), [NAA] levels were significantly lower in subjects that consumed more alcoholic beverages. There was no significant correlation between [Glu] and [NAA] levels with other measures of drinking behavior and or depression symptom severity.ConclusionsWhile limited by small sample size, these data suggest that glutamate levels in LDLPFC are associated with alcohol craving intensity in patients with AUD. Further study with larger sample size is needed to replicate this finding and evaluate the merits of glutamate spectroscopy as a biological correlate of alcohol craving intensity and a guide to treatment interventions.

AbstractBackgroundAdenosine signaling has been implicated in several neurological and psychiatric disorders. Previously, we found that astrocytic excitatory amino acid transporter 2 (EAAT2) and aquaporin 4 (AQP4) are downregulated in the striatum of mice lacking type 1 equilibrative nucleoside transporter (ENT1).MethodsTo further investigate the gene expression profile in the striatum, we preformed Illumina Mouse Whole Genome BeadChip microarray analysis of the caudate–putamen (CPu) and nucleus accumbens (NAc) inENT1 null mice. Gene expression was validated byRT‐PCR, Western blot, and immunofluorescence. Using transgenic mice expressing enhanced green fluorescence protein (EGFP) under the control of the glial fibrillary acidic protein (GFAP) promoter, we examinedEGFPexpression in anENT1 null background.ResultsGlial fibrillary acidic protein was identified as a top candidate gene that was reduced in ENT1 null mice compared to wild‐type littermates. Furthermore, EGFP expression was significantly reduced in GFAP‐EGFP transgenic mice in an ENT1 null background in both the CPu and NAc. Finally, pharmacological inhibition or siRNA knockdown of ENT1 in cultured astrocytes also reduced GFAPmRNAlevels.ConclusionsOverall, our findings demonstrate thatENT1 regulatesGFAPexpression and possibly astrocyte function.

Abstract Aging and the presence of cerebrovascular disease are associated with increased incidence of Alzheimer's disease. A common feature of aging and cerebrovascular disease is decreased endothelial nitric oxide (NO). We studied the effect of a loss of endothelium derived NO on amyloid precursor protein (APP) related phenotype in late middle aged (LMA) (14–15 month) endothelial nitric oxide synthase deficient ( eNOS −/− ) mice. APP, β‐site APP cleaving enzyme (BACE) 1, and amyloid beta (Aβ) levels were significantly higher in the brains of LMA eNOS −/− mice as compared with LMA wild‐type controls. APP and Aβ 1‐40 were increased in hippocampal tissue of eNOS −/− mice as compared with wild‐type mice. LMA eNOS −/− mice displayed an increased inflammatory phenotype as compared with LMA wild‐type mice. Importantly, LMA eNOS −/− mice performed worse in a radial arm maze test of spatial learning and memory as compared with LMA wild‐type mice. These data suggest that chronic loss of endothelial NO may be an important contributor to both Aβ related pathology and cognitive decline. image Cardiovascular risk factors are associated with increased incidence of Alzheimer's disease (AD). A common feature of these risk factors is decreased endothelial nitric oxide (NO). We observed, in mice deficient in endothelial nitric oxide synthase, increased amyloid precursor protein (APP), β‐site APP cleaving enzyme 1, amyloid beta levels, microglial activation, and impaired spatial memory. This suggests chronic loss of endothelial NO may be an important contributor to the pathogenesis of sporadic AD.

Recent studies have demonstrated that the function of glia is not restricted to the support of neuronal function. Especially, astrocytes are essential for neuronal activity in the brain. Astrocytes actively participate in synapse formation and brain information processing by releasing or uptaking gliotransmitters such as glutamate, d ‐serine, adenosine 5′‐triphosphate ( ATP ), and adenosine. In the central nervous system, adenosine plays an important role in regulating neuronal activity as well as in controlling other neurotransmitter systems such as GABA , glutamate, and dopamine. Ethanol ( E t OH ) increases extracellular adenosine levels, which regulates the ataxic and hypnotic/sedative (somnogenic) effects of E t OH . Adenosine signaling is also involved in the homeostasis of major inhibitory/excitatory neurotransmission (i.e., GABA or glutamate) through neuron–glial interactions, which regulates the effect of E t OH and sleep. Adenosine transporters or astrocytic SNARE ‐mediated transmitter release regulates extracellular or synaptic adenosine levels. Adenosine then exerts its function through several adenosine receptors and regulates glutamate levels in the brain. This review presents novel findings on how neuron–glial interactions, particularly adenosinergic signaling and glutamate uptake activity involving glutamate transporter 1 ( GLT 1), are implicated in alcoholism and sleep disorders.