Blueberry-induced changes in spatial working memory correlate with changes in hippocampal CREB phosphorylation and brain-derived neurotrophic factor (BDNF) levels

Phytochemical-rich foods have been shown to be effective at reversing age-related deficits in memory in both animals and humans. We show that a supplementation with a blueberry diet (2% w/w) for 12 weeks improves the performance of aged animals in spatial working memory tasks. This improvement emerged within 3 weeks and persisted for the remainder of the testing period. Memory performance correlated well with the activation of cAMP-response element-binding protein (CREB) and increases in both pro- and mature levels of brain-derived neurotrophic factor (BDNF) in the hippocampus. Changes in CREB and BDNF in aged and blueberry-supplemented animals were accompanied by increases in the phosphorylation state of extracellular signal-related kinase (ERK1/2), rather than that of calcium calmodulin kinase (CaMKII and CaMKIV) or protein kinase A. Furthermore, age and blueberry supplementation were linked to changes in the activation state of Akt, mTOR, and the levels of Arc/Arg3.1 in the hippocampus, suggesting that pathways involved in de novo protein synthesis may be involved. Although causal relationships cannot be made among supplementation, behavior, and biochemical parameters, the measurement of anthocyanins and flavanols in the brain following blueberry supplementation may indicate that changes in spatial working memory in aged animals are linked to the effects of flavonoids on the ERK-CREB-BDNF pathway. (c) 2008 Elsevier Inc. All Fights reserved.

Dietary levels of pure flavonoids improve spatial memory performance and increase hippocampal brain-derived neurotrophic factor.

Evidence suggests that flavonoid-rich foods are capable of inducing improvements in memory and cognition in animals and humans. However, there is a lack of clarity concerning whether flavonoids are the causal agents in inducing such behavioral responses. Here we show that supplementation with pure anthocyanins or pure flavanols for 6 weeks, at levels similar to that found in blueberry (2% w/w), results in an enhancement of spatial memory in 18 month old rats. Pure flavanols and pure anthocyanins were observed to induce significant improvements in spatial working memory (p = 0.002 and p = 0.006 respectively), to a similar extent to that following blueberry supplementation (p = 0.002). These behavioral changes were paralleled by increases in hippocampal brain-derived neurotrophic factor (R = 0.46, p<0.01), suggesting a common mechanism for the enhancement of memory. However, unlike protein levels of BDNF, the regional enhancement of BDNF mRNA expression in the hippocampus appeared to be predominantly enhanced by anthocyanins. Our data support the claim that flavonoids are likely causal agents in mediating the cognitive effects of flavonoid-rich foods.

Striatum brain-derived neurotrophic factor levels are decreased in dystrophin-deficient mice

Brain dystrophin is enriched in the postsynaptic densities of pyramidal neurons specialized regions of the subsynaptic cytoskeletal network, which are critical for synaptic transmission and plasticity. Lack of dystrophin in brain structures have been involved with impaired cognitive functions. The brain-derived neurotrophic factor (BDNF) is a regulator of neuronal survival, fast synaptic transmission, and activity-dependent synaptic plasticity. The present study investigated BDNF protein levels by Elisa analysis in prefrontal cortex, cerebellum, hippocampus, striatum and cortex tissues from male dystrophic mdx (n = 5) and normal C57BL10 mouse (n = 5). We observed that the mdx mouse display diminution in BDNF levels in striatum (t = 6.073; df = 6; p = 0.001), while a tendency of decrease in BDNF levels was observed in the prefrontal cortex region (t = 1.962; df = 6; p = 0.096). The cerebellum (t = 1.258; df = 7; p = 0.249), hippocampus (t = 0.631; df = 7; p = 0.548) and cortex (t = 0.572; df = 7; p = 0.586) showed no significant alterations as compared to wt mouse. In conclusion, we demonstrate that only striatum decreased BDNF levels compared with wild-type (wt) mouse, differently to the other areas of the brain. This dystrophin deficiency may be affecting BDNF levels in striatum and contributing, in part, in memory storage and restoring. (C) 2009 Elsevier Ireland Ltd. All rights reserved.

Effects of voluntary running on spatial memory and mature brain-derived neurotrophic factor expression in mice hippocampus after status epilepticus

Voluntary physical activity improves memory and learning ability in rodents, whereas status epilepticus has been associated with memory impairment. Physical activity and seizures have been associated with enhanced hippocampal expression of BDNF, indicating that this protein may have a dual role in epilepsy. The influence of voluntary physical activity on memory and BDNF expression has been poorly studied in experimental models of epilepsy. In this paper, we have investigated the effect of voluntary physical activity on memory and BDNF expression in mice with pilocarpine-incluced epilepsy. Male Swiss mice were assigned to four experimental groups: pilocarpine sedentary (PS), pilocarpine runners (PRs), saline sedentary (SS) and saline runners (SRs). Two days after pilocarpine-induced status epilepticus, the affected mice (PR) and their running controls (SR) were housed with access to a running wheel for 28 days. After that, the spatial memory and the expression of the precursor and mature forms of hippocampal BDNF were assessed. PR mice performed better than PS mice in the water maze test. In addition, PR mice had a higher amount of mature BDNF (14 kDa) relative to the total BDNF (14 kDa + 28 kDa + 32 kDa forms) content when compared with PS mice. These results show that voluntary physical activity improved the spatial memory and increased the hippocampal content of mature BDNF of mice with pilocarpine-induced status epilepticus. (C) 2009 Elsevier B.V. All rights reserved.

Physical exercise modulates peripheral levels of brain-derived neurotrophic factor (BDNF): A systematic review of experimental studies in the elderly

The objective of this study was to conduct a systematic review of studies that analyzed the effect of physical exercise on the peripheral levels of BDNF in elderly individuals. Method: We conducted a search in PsycINFO, Biological Abstracts, Pubmed, Web of Science, and Science Direct from 1990 to 2011, using the following keywords: physical exercise , physical activity , physical therapy , training , BDNF , neuroplasticity , neurotrophins , neuroplasticity proteins , aged , older , elderly The articles were considered for inclusion in the review if they were studies with elderly, assessed peripheral (serum and/or plasma) BDNF and evaluated an acute exercise or chronic exercise (training). Results: Five randomized controlled trial and one randomized non-controlled trial studies were analyzed. Five out of six studies reported a significantly higher BDNF response to aerobic acute exercise and to aerobic or strength training program in healthy elderly and elderly with different pathologies. Conclusion: It was not possible to establish a recommendation protocol for the type and intensity of physical exercise required to produce an increase in levels BDNF. However, physical exercise, particularly, moderate-intensity exercises seem to be more effective to promote increase the peripheral levels of BDNF in the elderly. © 2012 Elsevier B.V.

Acute Aerobic Exercise Increases Brain-Derived Neurotrophic Factor Levels in Elderly with Alzheimer's Disease

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Intrahippocampal injection of brain-derived neurotrophic factor increases anxiety-related, but not panic-related defensive responses: involvement of serotonin

Changes in brain-derived neurotrophic factor (BDNF)mediated signaling in the hippocampus have been implicated in the etiology of depression and in the mode of action of antidepressant drugs. There is also evidence from animal studies to suggest that BDNF-induced changes in the hippocampus may play a role in another stress-related pathology: anxiety. However, it is still unknown whether this neurotrophin plays a differential role in defensive responses associated with distinguished subtypes of anxiety disorders found in the clinic, such as generalized anxiety and panic disorder. In the present study, we investigated the effect of an acute BDNF injection into the rat dorsal hippocampus (DH) on inhibitory avoidance acquisition and escape expression measured in the elevated T-maze (ETM). We also assessed whether serotonergic neurotransmission may account for such effects. Intra-DH BDNF injection (200 pg) facilitated inhibitory avoidance in ETM. BDNF was equally anxiogenic in the light/dark transition test. Preadministration of the 5-HT1A receptor antagonist WAY-100635 fully counteracted the anxiogenic effect of BDNF in both tests. Intra-DH midazolam administration (10 nmol) impaired avoidance acquisition in ETM, suggesting an anxiolytic effect. Therefore, in the DH, facilitation of BDNF signaling seems to enhance 5-HT1A receptor-mediated neurotransmission to exert an anxiogenic effect associated with generalized anxiety. Behavioural Pharmacology 23:80-88 (C) 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins.

Interactions between the NO-Citrulline Cycle and Brain-derived Neurotrophic Factor in Differentiation of Neural Stem Cells

The diffusible messenger NO plays multiple roles in neuroprotection, neurodegeneration, and brain plasticity. Argininosuccinate synthase (AS) is a ubiquitous enzyme in mammals and the key enzyme of the NO-citrulline cycle, because it provides the substrate L-arginine for subsequent NO synthesis by inducible, endothelial, and neuronal NO synthase (NOS). Here, we provide evidence for the participation of AS and of the NO-citrulline cycle in the progress of differentiation of neural stem cells (NSC) into neurons, astrocytes, and oligodendrocytes. AS expression and activity and neuronal NOS expression, as well as L-arginine and NOx production, increased along neural differentiation, whereas endothelial NOS expression was augmented in conditions of chronic NOS inhibition during differentiation, indicating that this NOS isoform is amenable to modulation by extracellular cues. AS and NOS inhibition caused a delay in the progress of neural differentiation, as suggested by the decreased percentage of terminally differentiated cells. On the other hand, BDNF reversed the delay of neural differentiation of NSC caused by inhibition of NOx production. Alikely cause is the lack of NO, which up-regulated p75 neurotrophin receptor expression, a receptor required for BDNF-induced differentiation of NSC. We conclude that the NO-citrulline cycle acts together with BDNF for maintaining the progress of neural differentiation.

Effects of local continuous release of brain derived neurotrophic factor (BDNF) on peripheral nerve regeneration in a rat model

The purpose of this study was to evaluate the effect of continuously released BDNF on peripheral nerve regeneration in a rat model. Initial in vitro evaluation of calcium alginate prolonged-release-capsules (PRC) proved a consistent release of BDNF for a minimum of 8 weeks. In vivo, a worst case scenario was created by surgical removal of a 20-mm section of the sciatic nerve of the rat. Twenty-four autologous fascia tubes were filled with calcium alginate spheres and sutured to the epineurium of both nerve ends. The animals were divided into 3 groups. In group 1, the fascial tube contained plain calcium alginate spheres. In groups 2 and 3, the fascial tube contained calcium alginate spheres with BDNF alone or BDNF stabilized with bovine serum albumin, respectively. The autocannibalization of the operated extremity was clinically assessed and documented in 12 additional rats. The regeneration was evaluated histologically at 4 weeks and 10 weeks in a blinded manner. The length of nerve fibers and the numbers of axons formed in the tube was measured. Over a 10-week period, axons have grown significantly faster in groups 2 and 3 with continuously released BDNF compared to the control. The rats treated with BDNF (groups 2 and 3) demonstrated significantly less autocannibalization than the control group (group 1). These results suggest that BDNF may not only stimulate faster peripheral nerve regeneration provided there is an ideal, biodegradable continuous delivery system but that it significantly reduces the neuropathic pain in the rat model.

Blocking brain-derived neurotrophic factor inhibits injury-induced hyperexcitability of hippocampal CA3 neurons

Brain trauma can disrupt synaptic connections, and this in turn can prompt axons to sprout and form new connections. If these new axonal connections are aberrant, hyperexcitability can result. It has been shown that ablating tropomyosin-related kinase B (TrkB), a receptor for brain-derived neurotrophic factor (BDNF), can reduce axonal sprouting after hippocampal injury. However, it is unknown whether inhibiting BDNF-mediated axonal sprouting will reduce hyperexcitability. Given this, our purpose here was to determine whether pharmacologically blocking BDNF inhibits hyperexcitability after injury-induced axonal sprouting in the hippocampus. To induce injury, we made Schaffer collateral lesions in organotypic hippocampal slice cultures. As reported by others, we observed a 50% reduction in axonal sprouting in cultures treated with a BDNF blocker (TrkB-Fc) 14 days after injury. Furthermore, lesioned cultures treated with TrkB-Fc were less hyperexcitable than lesioned untreated cultures. Using electrophysiology, we observed a two-fold decrease in the number of CA3 neurons that showed bursting responses after lesion with TrkB-Fc treatment, whereas we found no change in intrinsic neuronal firing properties. Finally, evoked field excitatory postsynaptic potential recordings indicated an increase in network activity within area CA3 after lesion, which was prevented with chronic TrkB-Fc treatment. Taken together, our results demonstrate that blocking BDNF attenuates injury-induced hyperexcitability of hippocampal CA3 neurons. Axonal sprouting has been found in patients with post-traumatic epilepsy. Therefore, our data suggest that blocking the BDNF-TrkB signaling cascade shortly after injury may be a potential therapeutic target for the treatment of post-traumatic epilepsy.

Brain-derived neurotrophic factor-deficient mice develop aggressiveness and hyperphagia in conjunction with brain serotonergic abnormalities

Brain-derived neurotrophic factor (BDNF) has trophic effects on serotonergic (5-HT) neurons in the central nervous system. However, the role of endogenous BDNF in the development and function of these neurons has not been established in vivo because of the early postnatal lethality of BDNF null mice. In the present study, we use heterozygous BDNF+/− mice that have a normal life span and show that these animals develop enhanced intermale aggressiveness and hyperphagia accompanied by significant weight gain in early adulthood; these behavioral abnormalities are known to correlate with 5-HT dysfunction. Forebrain 5-HT levels and fiber density in BDNF+/− mice are normal at an early age but undergo premature age-associated decrements. However, young adult BDNF+/− mice show a blunted c-fos induction by the specific serotonin releaser-uptake inhibitor dexfenfluramine and alterations in the expression of several 5-HT receptors in the cortex, hippocampus, and hypothalamus. The heightened aggressiveness can be ameliorated by the selective serotonin reuptake inhibitor fluoxetine. Our results indicate that endogenous BDNF is critical for the normal development and function of central 5-HT neurons and for the elaboration of behaviors that depend on these nerve cells. Therefore, BDNF+/− mice may provide a useful model to study human psychiatric disorders attributed to dysfunction of serotonergic neurons.

Virus-mediated gene transfer into hippocampal CA1 region restores long-term potentiation in brain-derived neurotrophic factor mutant mice.

Long-term potentiation (LTP) has been shown to be impaired in mice deficient in the brain-derived neurotrophic factor (BDNF) gene, as well as in a number of other knockout animals. Despite its power the gene-targeting approach is always fraught with the danger of looking at the cumulative direct and indirect effects of the absence of a particular gene rather than its immediate function. The re-expression of a specific gene at a selective time point and at a specific site in gene-defective mutants presents a potent procedure to overcome this limitation and to evaluate the causal relationship between the absence of a particular gene and the impairment of a function in gene-defective animals. Here we demonstrate that the re-expression of the BDNF gene in the CA1 region almost completely restores the severely impaired LTP in hippocampal slices of BDNF-deficient mice. The results therefore provide strong evidence for the direct involvement of BDNF in the process of LTP.

Amyloid beta-protein reduces acetylcholine synthesis in a cell line derived from cholinergic neurons of the basal forebrain.

The characteristic features of a brain with Alzheimer disease (AD) include the presence of neuritic plaques composed of amyloid beta-protein (Abeta) and reductions in the levels of cholinergic markers. Neurotoxic responses to Abeta have been reported in vivo and in vitro, suggesting that the cholinergic deficit in AD brain may be secondary to the degeneration of cholinergic neurons caused by Abeta. However, it remains to be determined if Abeta contributes to the cholinergic deficit in AD brain by nontoxic effects. We examined the effects of synthetic Abeta peptides on the cholinergic properties of a mouse cell line, SN56, derived from basal forebrain cholinergic neurons. Abeta 1-42 and Abeta 1-28 reduced the acetylcholine (AcCho) content of the cells in a concentration-dependent fashion, whereas Abeta 1-16 was inactive. Maximal reductions of 43% and 33% were observed after a 48-h treatment with 100 nM of Abeta 1-42 and 50 pM of Abeta 1-28, respectively. Neither Abeta 1-28 nor Abeta 1-42 at a concentration of 100 nM and a treatment period of 2 weeks was toxic to the cells. Treatment of the cells with Abeta 25-28 (48 h; 100 nM) significantly decreased AcCho levels, suggesting that the sequence GSNK (aa 25-28) is responsible for the AcCho-reducing effect of Abeta. The reductions in AcCho levels caused by Abeta 1-42 and Abeta 1-28 were accompanied by proportional decreases in choline acetyltransferase activity. In contrast, acetylcholinesterase activity was unaltered, indicating that Abeta specifically reduces the synthesis of AcCho in SN56 cells. The reductions in AcCho content caused by Abeta 1-42 could be prevented by a cotreatment with all-trans-retinoic acid (10 nM), a compound previously shown to increase choline acetyltransferase mRNA expression in SN56 cells. These results demonstrate a nontoxic, suppressive effect of Abeta on AcCho synthesis, an action that may contribute to the cholinergic deficit in AD brain.