Changes in Reported Dietary Supplement Use in Cognitively Normal National Alzheimer's Coordinating Center Participants Aged 55 and Older From 2015 to 2019.

BACKGROUND: Although reported dietary supplement use is common in older adults, evaluations of dietary supplement use over the past 10 y are lacking. OBJECTIVE: This analysis determined changes in reported dietary supplement use in cognitively normal older adults (aged ≥ 55 y) using the National Alzheimer's Coordinating Center data from 2015 to 2019 using a serial cross-sectional study design. METHODS: The first available visit for cognitively normal participants aged ≥ 55 y from 2015 to 2019 with a complete medication form was used, resulting in 9357 participants. Associations between visit year categories and reported use of dietary supplement categories/individual supplements were tested using categorical statistics. To determine whether the probabilities of reported supplement use changed in 2019 compared with those of 2015, z-scores and two-sided P values were used. Weighted analyses were used to confirm analytical findings. RESULTS: When comparing 2015 and 2019, the reported use of any dietary supplement decreased from 77.7% in 2015 to 71.0% in 2019 (P < 0.0001); any vitamin from 72.5% to 65.5% (P < 0.0001); any mineral from 39.2% to 30.4% (P < 0.0001); "other" nonvitamin/nonmineral supplements from 34.4% to 26.9% (P < 0.0001), calcium from 31.2% to 21.7% (P < 0.0001), multivitamins from 48.4% to 38.4% (P < 0.0001), potassium from 5.6% to 3.5% (P = 0.001), vitamin C from 13.0% to 9.2% (P = 0.0002), chondroitin from 6.0% to 4.1% (P = 0.006), glucosamine from 11.1% to 6.5% (P < 0.0001), and all omega fatty acids from 25.2% to 17.0% (P < 0.0001). Reported use increased for vitamin B7/biotin from 3.1% in 2015 to 5.8% in 2019 (P = 0.0003), melatonin from 3.1% to 5.8% (P = 0.0002), and turmeric from 1.2% to 4.7% (P < 0.0001). CONCLUSION: Although the reported use of many major dietary supplement categories and individual supplements significantly decreased in older adults from 2015 to 2019, biotin, turmeric, and melatonin significantly increased. Because biotin may interfere with some laboratory tests, this may have important public health implications.

Synthesis and structure-activity relationships of 3,4,5-trisubstituted-1,2,4-triazoles: high affinity and selective somatostatin receptor-4 agonists for Alzheimer's disease treatment.

Somatostatin receptor-4 (SST4) is highly expressed in brain regions affiliated with learning and memory. SST4 agonist treatment may act to mitigate Alzheimer's disease (AD) pathology. An integrated approach to SST4 agonist lead optimization is presented herein. High affinity and selective agonists with biological efficacy were identified through iterative cycles of a structure-based design strategy encompassing computational methods, chemistry, and preclinical pharmacology. 1,2,4-Triazole derivatives of our previously reported hit (4) showed enhanced SST4 binding affinity, activity, and selectivity. Thirty-five compounds showed low nanomolar range SST4 binding affinity, 12 having a K i < 1 nM. These compounds showed >500-fold affinity for SST4 as compared to SST2A. SST4 activities were consistent with the respective SST4 binding affinities (EC50 < 10 nM for 34 compounds). Compound 208 (SST4 K i = 0.7 nM; EC50 = 2.5 nM; >600-fold selectivity over SST2A) display a favorable physiochemical profile, and was advanced to learning and memory behavior evaluations in the senescence accelerated mouse-prone 8 model of AD-related cognitive decline. Chronic administration enhanced learning with i.p. dosing (1 mg kg-1) compared to vehicle. Chronic administration enhanced memory with both i.p. (0.01, 0.1, 1 mg kg-1) and oral (0.01, 10 mg kg-1) dosing compared to vehicle. This study identified a novel series of SST4 agonists with high affinity, selectivity, and biological activity that may be useful in the treatment of AD.

Mfsd2a and Glut1 Brain Nutrient Transporters Expression Increase with 32-Week Low and High Lard Compared with Fish-Oil Dietary Treatment in C57Bl/6 Mice.

BACKGROUND: Diet-mediated alterations of critical brain nutrient transporters, major facilitator super family domain-containing 2a (Mfsd2a) and glucose transporter 1 (Glut1), have wide reaching implications in brain health and disease. OBJECTIVE: The aim of the study was to examine the impact of long-term low- and high-fat diets with lard or fish oil on critical brain nutrient transporters, Mfsd2a and Glut1. METHODS: Eight-week-old male C57BL/6 mice were fed 1 of the following 4 diets for 32 wk: 10% of kcal from lard, 10% of kcal from fish oil, 41% of kcal from lard, or 41% of kcal from fish oil. Body weight and blood chemistries delineated dietary effects. Cortical and subcortical Mfsd2a and Glut1 mRNA and protein expression were evaluated, with other supportive nutrient-sensitive targets also assessed for mRNA expression changes. RESULTS: Fish-oil diets increased cortical Mfsd2a mRNA expression compared with lard diets. Subcortical Mfsd2a mRNA expression decreased as the percentage of fat in the diet increased. There was an interaction between the type and percentage of fat with cortical and subcortical Mfsd2a and cortical Glut1 protein expression. In the lard diet groups, protein expression of cortical and subcortical Mfsd2a and cortical Glut1 significantly increased as fat percentage increased. As the fat percentage increased in the fish-oil diet groups, protein expression of cortical and subcortical Mfsd2a and cortical Glut1 did not change. When comparing the fish-oil groups with 10% lard, cortical Mfsd2a protein expression was significantly higher in the 10% and 41% fish-oil groups, whereas cortical Glut1 protein expression was significantly higher in only the 10% fish-oil group. A positive correlation between cortical peroxisome proliferator-activated receptor γ mRNA expression and Mfsd2a protein expression was shown. CONCLUSION: Corresponding to chronic dietary treatment, an interaction between the type of fat and the percentage of fat exists respective to changes in brain expression of the key nutrient transporters Mfsd2a and Glut1.

Peripheral Administration of GSK-3ß Antisense Oligonucleotide Improves Learning and Memory in SAMP8 and Tg2576 Mouse Models of Alzheimer's Disease.

Glycogen synthase kinase (GSK)-3ß is a multifunctional protein that has been implicated in the pathological characteristics of Alzheimer's disease (AD), including the heightened levels of neurofibrillary tangles, amyloid-beta (Aß), and neurodegeneration. We have previously shown that an antisense oligonucleotide directed at the Tyr 216 site on GSK-3ß (GAO) when injected centrally can decrease GSK-3ß levels, improve learning and memory, and decrease oxidative stress. In addition, we showed that GAO can cross the blood-brain barrier. Herein the impact of peripherally administered GAO in both the non-transgenic SAMP8 and transgenic Tg2576 (APPswe) models of AD were examined respective to learning and memory. Brain tissues were then evaluated for expression changes in the phosphorylated-Tyr 216 residue, which leads to GSK-3ß activation, and the phosphorylated-Ser9 residue, which reduces GSK-3ß activity. SAMP8 GAO-treated mice showed improved acquisition and retention using aversive T-maze, and improved declarative memory as measured by the novel object recognition (NOR) test. Expression of the phosphorylated-Tyr 216 was decreased and the phosphorylated-Ser9 was increased in GAO-treated SAMP8 mice. Tg2576 GAO-treated mice improved acquisition and retention in both the T-maze and NOR tests, with an increased phosphorylated-Ser9 GSK-3ß expression. Results demonstrate that peripheral administration of GAO improves learning and memory, corresponding with alterations in GSK-3ß phosphorylation state. This study supports peripherally administered GAO as a viable means to mediate GSK-3ß activity within the brain and a possible treatment for AD.

Steroids and the blood-brain barrier: therapeutic implications.

Steroids have a wide spectrum of impact, serving as fundamental regulators of nearly every physiological process within the human body. Therapeutic applications of steroids are equally broad, with a diverse range of medications and targets. Within the central nervous system (CNS), steroids influence development, memory, behavior, and disease outcomes. Moreover, steroids are well recognized as to their impact on the vascular endothelium. The blood-brain barrier (BBB) at the level of the brain microvascular endothelium serves as the principle interface between the peripheral circulation and the brain. Steroids have been identified to impact several critical properties of the BBB, including cellular efflux mechanisms, nutrient uptake, and tight junction integrity. Such actions not only influence brain homeostasis but also the delivery of CNS-targeted therapeutics. A greater understanding of the respective steroid-BBB interactions may shed further light on the differential treatment outcomes observed across CNS pathologies. In this chapter, we examine the current therapeutic implications of steroids respective to BBB structure and function, with emphasis on glucocorticoids and estrogens.

Somatostatin receptor subtype-4 agonist NNC 26-9100 mitigates the effect of soluble Aß(42) oligomers via a metalloproteinase-dependent mechanism.

Soluble amyloid-ß peptide (Aß) oligomers have been hypothesized to be primary mediators of Alzheimer's disease progression. In this regard, reduction of soluble Aß-oligomers levels within the brain may provide a viable means in which to treat the disease. Somatostatin receptor subtype-4 (SSTR4) agonists have been proposed to reduce Aß levels in the brain via enhancement of enzymatic degradation. Herein we evaluated the effect of selective SSTR4 agonist NNC 26-9100 on the changes in learning and soluble Aß42 oligomer brain content with and without co-administration of the M13-metalloproteinase family enzyme-inhibitor phosphoramidon, using the senescence-accelerated mouse prone-8 (SAMP8) model. NNC 26-9100 treatment (0.2 µg i.c.v. in 2 µL) improved learning, which was blocked by phosphoramidon (1 and 10mM, respectively). NNC 26-9100 decreased total soluble Aß42, an effect which was blocked by phosphoramidon (10mM). Extracellular, intracellular, and membrane fractions were then isolated from cortical tissue and assessed for soluble oligomer alterations. NNC 26-9100 decreased the Aß42 trimeric (12 kDa) form within the extracellular and intracellular fractions, and produced a band-split effect of the Aß42 hexameric (25 kDa) form within the extracellular fraction. These effects were also blocked by phosphoramdon (1 and 10mM, respectively). Subsequent evaluation of NNC 26-9100 in APPswe Tg2576 transgenic mice showed a similar learning improvement and corresponding reduction in soluble Aß42 oligomers within extracellular, intracellular, and membrane fractions. These data support the hypothesis that NNC 26-9100 reduces soluble Aß42 oligomers and enhances learning through a phosphoramidon-sensitive metalloproteinase-dependent mechanism.

Somatostatin receptor subtype-4 agonist NNC 26-9100 decreases extracellular and intracellular Aß1₋42 trimers.

Soluble amyloid ß-protein (Aß) oligomers are primary mediators of synaptic dysfunction associated with the progression of Alzheimer's disease. Such Aß oligomers exist dependent on their rates of aggregation and metabolism. Use of selective somatostatin receptor-subtype agonists have been identified as a potential means to mitigate Aß accumulation in the brain, via regulation of the enzyme neprilysin. Herein, we first evaluated the impact of the somatostatin receptor subtype-4 agonist 1-[3-[N-(5-Bromopyridin-2-yl)-N-(3,4-dichlorobenzyl)amino]propyl]-3-[3-(1H-imidazol-4-yl)propyl]thiourea (NNC 26-9100) on learning and memory in 12-month SAMP8 mice (i.c.v. injection). NNC 26-9100 (0.2 µg-dose) was shown to enhance both learning (T-maze) and memory (object recognition) compared to vehicle controls. Cortical and hippocampal tissues were evaluated subsequent to NNC 26-9100 (0.2 µg) or vehicle administration for changes in neprilysin activity, along with protein expression of amyloid-precursor protein (APP), neprilysin, and Aß1₋42 oligomers within respective cellular fractions (extracellular, intracellular and membrane). NNC 26-9100 increased neprilysin activity in cortical tissue, with an associated protein expression increase in the extracellular fraction and decreased in the intracellular fraction. A decrease in intracellular APP expression was found with treatment in both cortical and hippocampal tissues. NNC 26-9100 also significantly decreased expression of Aß1₋42 trimers within both the extracellular and intracellular cortical fractions. No expression changes were found in membrane fractions for any protein. These finding suggest the potential use of selective SSTR4 agonists to mitigate toxic oligomeric forms of Aß1₋42 in critical regions of the brain identified with learning and memory decline.

Age and 17ß-estradiol effects on blood-brain barrier tight junction and estrogen receptor proteins in ovariectomized rats.

Age and estrogen levels alter blood-brain barrier (BBB) tight junction (TJ) regulation, impacting brain homeostasis and pathological outcomes. This examination evaluated BBB TJ and estrogen receptor (ER) protein expression changes in young (8-10 week) and middle-aged (10-12 month) ovariectomized female Fisher-344 rats with chronic 17ß-estradiol or placebo treatment. Middle-aged rats showed decreased protein expression of occludin with 17ß-estradiol (55 kDa band) or placebo (45, 55, 60 kDa bands) treatment compared to respective young. In young animals, 17ß-estradiol treatment increased expression of the occludin 55 kDa band over placebo; however, this effect was lost in the middle-aged animals. In both young and middle-aged animals, expression of claudin-5 (23, 32 kDa bands) and ERα (66 kDa) increased with 17ß-estradiol treatment, while junctional adhesion molecule-A showed no change across all groups. However, ERα expression (66 kDa) was significantly reduced in the middle-aged animals compared to young placebo treated animals. Measurement of BBB TJ permeability via in situ perfusion of (14)C-sucrose showed no change with age or treatment. Our results show that increasing age and 17ß-estradiol treatment alters the expression of ERα and distinct BBB TJ protein isoforms without altering functional paracellular permeability.

Chronic peripheral administration of somatostatin receptor subtype-4 agonist NNC 26-9100 enhances learning and memory in SAMP8 mice.

Selective somatostatin receptor subtype agonists have been proposed as a means to mitigate learning and memory loss associated with Alzheimer's disease. The first aim of this study evaluated blood-to-brain transport and regional brain distribution of NNC 26-9100, a selective somatostatin subtype-4 (sst4) receptor agonist. The entry rate of (131)I-NNC 26-9100 was K(i)=0.25 µl/g min, with an ~93% association with the parenchymal component. The second goal of this study was to evaluate the effect of chronic NNC 26-9100 administration (i.p.) on learning and memory, brain Aß(x-42) levels, and protein expression of sst4 receptor and amyloid precursor protein (APP) in the senescence-accelerated mouse p8 (SAMP8) model of Alzheimer's disease. Mice chronically treated with NNC 26-9100 showed improved learning (day 21) and memory (day 28) using the T-maze paradigm (20 and 200 µg). Ex vivo tissue analyses showed a decline in Aß(x-42) levels at the 20 µg dose, while no alterations were observed in sst4 receptor or APP protein expression compared to vehicle controls. These findings indicate NNC 26-9100 is taken up into key brain regions associated with learning and memory. Furthermore, chronic administration of NNC 26-9100 improved learning and memory and decreased Aß(x-42) brain levels. These results suggest sst4 receptor agonists may provide a viable therapy in the treatment of Alzheimer's disease and other forms of cognitive impairment.

Blood-brain barrier tight junction permeability and ischemic stroke.

The blood-brain barrier (BBB) is formed by the endothelial cells of cerebral microvessels, providing a dynamic interface between the peripheral circulation and the central nervous system. The tight junctions (TJs) between the endothelial cells serve to restrict blood-borne substances from entering the brain. Under ischemic stroke conditions decreased BBB TJ integrity results in increased paracellular permeability, directly contributing to cerebral vasogenic edema, hemorrhagic transformation, and increased mortality. This loss of TJ integrity occurs in a phasic manner, which is contingent on several interdependent mechanisms (ionic dysregulation, inflammation, oxidative and nitrosative stress, enzymatic activity, and angiogenesis). Understanding the inter-relation of these mechanisms is critical for the development of new therapies. This review focuses on those aspects of ischemic stroke impacting BBB TJ integrity and the principle regulatory pathways, respective to the phases of paracellular permeability.

Reoxygenation stress on blood-brain barrier paracellular permeability and edema in the rat.

The blood-brain barrier (BBB) serves as a critical regulator of brain homeostasis. Following hypoxia (i.e. 6% oxygen/1 h) and reoxygenation (H/R), the BBB tight junctional complex is disrupted, resulting in increased BBB permeability and the development of vasogenic brain edema. In this study, we examined the effect of H/R on the in vivo rat BBB over a 36 h time course in conjunction with paracellular permeability, gray matter edema, and systemic inflammatory activity. A biphasic increase was observed in the brain uptake of (14)C-sucrose, a paracellular permeability marker; with the first increase at the 10 min reoxygenation time point, and the second increase at the 6-18 h time points. Increased brain water weight gain (edema) also showed a biphasic response with the first increase at the 10 min-1 h reoxygenation time points; and the second increase at only the 24 h time point. Analysis of serum derived cytokines (IL-1beta, TNFalpha, IL-6, IL-10, and IFNgamma) demonstrated that only IL-1beta and IL-6 were at detectable levels, but these levels were similar to controls. White blood cell counts showed significant decreases in lymphocytes (10 min-3 h), increases in monocytes (10 min-3 h and 12 h), and increases in polymorphonuclear cells (1 h and 3 h). We have shown that H/R elicits a biphasic increase in paracellular permeability and edema, which parallel to post-stroke sequelae, despite the lack of occlusion or complete depletion of oxygen.