Rice bran derivatives alleviate microglia activation: possible involvement of MAPK pathway.

BACKGROUND: Hyperactivation of microglia is considered to be a key hallmark of brain inflammation and plays a critical role in regulating neuroinflammatory events. Neuroinflammatory responses in microglia represent one of the major risk factors for various neurodegenerative diseases. One of the strategies to protect the brain and slow down the progression of these neurodegenerative diseases is by consuming diet enriched in anti-oxidants and polyphenols. Therefore, the present study aimed to evaluate the anti-inflammatory effects of rice bran extract (RBE), one of the rich sources of vitamin E forms (tocopherols and tocotrienols) and gamma-oryzanols, in primary rat microglia. METHODS: The vitamin E profile of the RBE was quantified by high-performance liquid chromatography (HPLC). Microglia were stimulated with lipopolysaccharide (LPS) in the presence or absence of RBE. Release of prostaglandins (prostaglandin (PG) E2, 8-iso-prostaglandin F2α (8-iso-PGF2α)) were determined with enzyme immunoassay (EIA). Protein levels and genes related to PGE2 synthesis (Cyclooxygenase-2 (COX-2), microsomal prostaglandin E synthase-1 (mPGES-1)) and various pro- and anti-inflammatory cytokines (TNF-α, IL-1ß, IL-6, and IL-10), were assessed by western blot, ELISA, and quantitative real-time PCR. Furthermore, to elucidate the molecular targets of RBE, the phosphorylated state of various mitogen-activated protein kinase (MAPK) signaling molecules (p38 MAPK, ERK 1/2, and JNK) and activation of NF-kB pathway was studied. RESULTS: RBE significantly inhibited the release of PGE2 and free radical formation (8-iso-PGF2α) in LPS-activated primary microglia. Inhibition of PGE2 by RBE was dependent on reduced COX-2 and mPGES-1 immunoreactivity in microglia. Interestingly, treatment of activated microglia with RBE further enhanced the gene expression of the microglial M2 marker IL-10 and reduced the expression of pro-inflammatory M1 markers (TNF-α, IL-1ß). Further mechanistic studies showed that RBE inhibits microglial activation by interfering with important steps of MAPK signaling pathway. Additionally, microglia activation with LPS leads to IkB-α degradation which was not affected by the pre-treatment of RBE. CONCLUSIONS: Taken together, our data demonstrate that RBE is able to affect microglial activation by interfering in important inflammatory pathway. These in vitro findings further demonstrate the potential value of RBE as a nutraceutical for the prevention of microglial dysfunction related to neuroinflammatory diseases, including Alzheimer's disease.

MH84: A Novel γ-Secretase Modulator/PPARγ Agonist--Improves Mitochondrial Dysfunction in a Cellular Model of Alzheimer's Disease.

Developing new therapeutic strategies for Alzheimer's disease (AD) is a current challenge. Approved drugs merely act symptomatically and delay the progression of the disease for a relatively short period of time. Here, we investigated the effectiveness of MH84 in a cellular HEK293APPwt model of AD, characterized by elevated beta amyloid protein levels (Aß1-42) and mitochondrial dysfunction. MH84 is a derivate of pirinixic acid belonging to a novel class of γ-secretase modulators, which combines γ-secretase modulation with activation of peroxisome proliferator-activator receptor gamma (PPARγ). The mitochondria modifying Dimebon, the γ-secretase blocker DAPT, and the PPARγ agonist pioglitazone were used as controls. MH84 protects against nitrosative stress, increased mitochondrial respiration, citrate synthase (CS) activity and protein levels of PGC1α indicating enhanced mitochondrial content at nano-molar concentrations. Concurrently, MH84 decreased protein levels of APP, Aß1-42, and C-terminal fragments at micro-molar concentrations. Both Dimebon and DAPT reduced cellular Aß1-42 levels. Dimebon improved mitochondrial functions and DAPT decreased mitochondrial membrane potential. Pioglitazone had no effects on APP processing and mitochondrial function. Our data emphasizes MH84 as possible novel therapeutic agent with mitochondria-based mode of action.

Rice bran extract improves mitochondrial dysfunction in brains of aged NMRI mice.

OBJECTIVES: Aging represents a major risk factor for neurodegenerative diseases such as Alzheimer's disease. Mitochondria are significantly involved in both the aging process and neurodegeneration. One strategy to protect the brain and to prevent neurodegeneration is a healthy lifestyle including a diet rich in antioxidants and polyphenols. Rice bran extract (RBE) contains various antioxidants including natural vitamin E forms (tocopherols and tocotrienols) and gamma-oryzanol. In this work, we examined the effects of a stabilized RBE on mitochondrial function in 18-month-old Naval Medical Research Institute mice (340 mg/kg body weight/day), which received the extract for 3 weeks via oral gavage. METHODS: Mitochondrial parameters were measured using high-resolution respirometry (Oroboros Oxygraph-2k), Western blot analysis, and photometric methods in dissociated brain cells, isolated mitochondria, and brain homogenate. Vitamin E concentrations in blood plasma and brain tissue were measured using HPLC with fluorescence detection. RESULTS: Aging leads to decreased mitochondrial function (decreased mitochondrial respiration and ATP production) and decreased protein expression of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1alpha). RBE administration increased alpha-tocopherol concentrations in the brain and compensated for age-related mitochondrial dysfunction by increasing mitochondrial respiration, membrane potential, PGC1alpha protein expression, and citrate synthase activity. Furthermore, resistance of brain cells to sodium nitroprusside-induced nitrosative stress was improved. DISCUSSION: According to these results, RBE is a promising candidate nutraceutical for the prevention of age-related neurodegenerative diseases.

Beneficial Effects of Ethanolic and Hexanic Rice Bran Extract on Mitochondrial Function in PC12 Cells and the Search for Bioactive Components.

Mitochondria are involved in the aging processes that ultimately lead to neurodegeneration and the development of Alzheimer's disease (AD). A healthy lifestyle, including a diet rich in antioxidants and polyphenols, represents one strategy to protect the brain and to prevent neurodegeneration. We recently reported that a stabilized hexanic rice bran extract (RBE) rich in vitamin E and polyphenols (but unsuitable for human consumption) has beneficial effects on mitochondrial function in vitro and in vivo (doi:10.1016/j.phrs.2013.06.008, 10.3233/JAD-132084). To enable the use of RBE as food additive, a stabilized ethanolic extract has been produced. Here, we compare the vitamin E profiles of both extracts and their effects on mitochondrial function (ATP concentrations, mitochondrial membrane potential, mitochondrial respiration and mitochondrial biogenesis) in PC12 cells. We found that vitamin E contents and the effects of both RBE on mitochondrial function were similar. Furthermore, we aimed to identify components responsible for the mitochondria-protective effects of RBE, but could not achieve a conclusive result. α-Tocotrienol and possibly also γ-tocotrienol, α-tocopherol and δ-tocopherol might be involved, but hitherto unknown components of RBE or a synergistic effect of various components might also play a role in mediating RBE's beneficial effects on mitochondrial function.

Rice bran extract protects from mitochondrial dysfunction in guinea pig brains.

Mitochondrial dysfunction plays a major role in the development of age-related neurodegenerative diseases and recent evidence suggests that food ingredients can improve mitochondrial function. In the current study we investigated the effects of feeding a stabilized rice bran extract (RBE) on mitochondrial function in the brain of guinea pigs. Key components of the rice bran are oryzanols, tocopherols and tocotrienols, which are supposed to have beneficial effects on mitochondrial function. Concentrations of α-tocotrienol and γ-carboxyethyl hydroxychroman (CEHC) but not γ-tocotrienol were significantly elevated in brains of RBE fed animals and thus may have provided protective properties. Overall respiration and mitochondrial coupling were significantly enhanced in isolated mitochondria, which suggests improved mitochondrial function in brains of RBE fed animals. Cells isolated from brains of RBE fed animals showed significantly higher mitochondrial membrane potential and ATP levels after sodium nitroprusside (SNP) challenge indicating resistance against mitochondrial dysfunction. Experimental evidence indicated increased mitochondrial mass in guinea pig brains, e.g. enhanced citrate synthase activity, increased cardiolipin as well as respiratory chain complex I and II and TIMM levels. In addition levels of Drp1 and fis1 were also increased in brains of guinea pigs fed RBE, indicating enhanced fission events. Thus, RBE represents a potential nutraceutical for the prevention of mitochondrial dysfunction and oxidative stress in brain aging and neurodegenerative diseases.

Liposome-incorporated DHA increases neuronal survival by enhancing non-amyloidogenic APP processing.

The fluidity of neuronal membranes plays a pivotal role in brain aging and neurodegeneration. In this study, we investigated the role of the omega-3 fatty acid docosahexaenoic acid (DHA) in modulation of membrane fluidity, APP processing, and protection from cytotoxic stress. To this end, we applied unilamellar transfer liposomes, which provided protection from oxidation and effective incorporation of DHA into cell membranes. Liposomes transferring docosanoic acid (DA), the completely saturated form of DHA, to the cell cultures served as controls. In HEK-APP cells, DHA significantly increased membrane fluidity and non-amyloidogenic processing of APP, leading to enhanced secretion of sAPPα. This enhanced secretion of sAPPα was associated with substantial protection against apoptosis induced by ER Ca(2+) store depletion. sAPPα-containing supernatants obtained from HEK-APP cells exerted similar protective effects as DHA in neuronal PC12 cells and HEK293 control cells. Correlating to further increased sAPPα levels, supernatants obtained from DHA-treated HEK-APP cells enhanced protection, whereas supernatants obtained from DHA-treated HEK293 control cells did not inhibit apoptosis, likely due to the low expression of endogenous APP and negligible sAPPα secretion in these cells. Further experiments with the small molecule inhibitors LY294002 and SP600125 indicated that sAPPα-induced cytoprotection relied on activation of the anti-apoptotic PI3K/Akt pathway and inhibition of the stress-triggered JNK signaling pathway in PC12 cells. Our data suggest that liposomal DHA is able to restore or maintain physiological membrane properties, which are required for neuroprotective sAPPα secretion and autocrine modulation of neuronal survival.

Impact of Silibinin A on Bioenergetics in PC12APPsw Cells and Mitochondrial Membrane Properties in Murine Brain Mitochondria.

Age-related multifactorial diseases, such as the neurodegenerative Alzheimer's disease (AD), still remain a challenge to today's society. One mechanism associated with AD and aging in general is mitochondrial dysfunction (MD). Increasing MD is suggested to trigger other pathological processes commonly associated with neurodegenerative diseases. Silibinin A (SIL) is the main bioactive compound of the Silymarin extract from the Mediterranean plant Silybum marianum (L.) (GAERTN/Compositae). It is readily available as a herbal drug and well established in the treatment of liver diseases as a potent radical scavenger reducing lipid peroxidation and stabilize membrane properties. Recent data suggest that SIL might also act on neurological changes related to MD. PC12APPsw cells produce low levels of human Aß and thus act as a cellular model of early AD showing changed mitochondrial function. We investigated whether SIL could affect mitochondrial function by measuring ATP, MMP, as well as respiration, mitochondrial mass, cellular ROS and lactate/pyruvate concentrations. Furthermore, we investigated its effects on the mitochondrial membrane parameters of swelling and fluidity in mitochondria isolated from the brains of mice. In PC12APPsw cells, SIL exhibits strong protective effects by rescuing MMP and ATP levels from SNP-induced mitochondrial damage and improving basal ATP levels. However, SIL did not affect mitochondrial respiration and mitochondrial content. SIL significantly reduced cellular ROS and pyruvate concentrations. Incubation of murine brain mitochondria with SIL significantly reduces Ca2+ induced swelling and improves membrane fluidity. Although OXPHOS activity was unaffected at this early stage of a developing mitochondrial dysfunction, SIL showed protective effects on MMP, ATP- after SNP-insult and ROS-levels in APPsw-transfected PC12 cells. Results from experiments with isolated mitochondria imply that positive effects possibly result from an interaction of SIL with mitochondrial membranes and/or its antioxidant activity. Thus, SIL might be a promising compound to improve cellular health when changes to mitochondrial function occur.

Olesoxime improves cerebral mitochondrial dysfunction and enhances Aß levels in preclinical models of Alzheimer's disease.

BACKGROUND: Approved drugs for Alzheimer's disease (AD) only have a symptomatic effects and do not intervene causally in the course of the disease. Olesoxime (TRO19622) has been tested in AD disease models characterized by improved amyloid precursor protein processing (AßPP) and mitochondrial dysfunction. METHODS: Three months old Thy-1-AßPPSL (tg) and wild type mice (wt) received TRO19622 (100 mg/kg b.w.) in supplemented food pellets for 15 weeks (tg TRO19622). Mitochondrial membrane potential (MMP) and adenosine triphosphate (ATP) levels were determined in dissociated brain cells (DBC). Respiration was analyzed in mitochondria isolated from brain tissue. Citrate synthase (CS) activity and beta-amyloid peptide (Aß1-40) levels were determined in brain tissue. Malondialdehyde (MDA) levels were determined as an indicator for lipid peroxidation. DBC and brain homogenates were additionally stressed with Rotenone and FeCl2, respectively. Mitochondrial respiration and Aß1-40 levels were also determined in HEK-AßPPsw-cells. RESULTS: Treatment of mice did not affect the body weight. TRO19622 was absorbed after oral treatment (plasma levels: 6,2 µg/ml). Mitochondrial respiration was significantly reduced in brains of tg-mice. Subsequently, DBC isolated from brains of tg-mice showed significantly lower MMP but not ATP levels. TRO19622 increased the activity of respiratory chain complexes and reversed complex IV (CIV) activity and MMP. Moreover, DBC isolated from brains of tg TRO19622 mice were protected from Rotenone induced inhibition of complex I activity. TRO19622 also increased the respiratory activity in HEKsw-cells. MDA basal levels were significantly higher in brain homogenates isolated from tg-mice. TRO19622 treatment had no effects on lipid peroxidation. TRO19622 increased cholesterol levels but did not change membrane fluidity of synaptosomal plasma and mitochondrial membranes isolated from brain of mice. TRO19622 significantly increased levels of Aß1-40 in both, in brains of tg TRO19622 mice and in HEKsw cells. CONCLUSIONS: TRO19622 improves mitochondrial dysfunction but enhances Aß levels in disease models of AD. Further studies must evaluate whether TRO19622 offers benefits at the mitochondrial level despite the increased formation of Aß, which could be harmful.

Differential Effects of Silibinin A on Mitochondrial Function in Neuronal PC12 and HepG2 Liver Cells.

The Mediterranean plant Silybum marianum L., commonly known as milk thistle, has been used for centuries to treat liver disorders. The flavonolignan silibinin represents a natural antioxidant and the main bioactive ingredient of silymarin (silybin), a standard extract of its seeds. Mitochondrial dysfunction and the associated generation of reactive oxygen/nitrogen species (ROS/RNS) are involved in the development of chronic liver and age-related neurodegenerative diseases. Silibinin A (SIL A) is one of two diastereomers found in silymarin and was used to evaluate the effects of silymarin on mitochondrial parameters including mitochondrial membrane potential and ATP production with and without sodium nitroprusside- (SNP-) induced nitrosative stress, oxidative phosphorylation, and citrate synthase activity in HepG2 and PC12 cells. Both cell lines were influenced by SIL A, but at different concentrations. SIL A significantly weakened nitrosative stress in both cell lines. Low concentrations not only maintained protective properties but also increased basal mitochondrial membrane potential (MMP) and adenosine triphosphate (ATP) levels. However, these effects could not be associated with oxidative phosphorylation. On the other side, high concentrations of SIL A significantly decreased MMP and ATP levels. Although SIL A did not provide a general improvement of the mitochondrial function, our findings show that SIL A protects against SNP-induced nitrosative stress at the level of mitochondria making it potentially beneficial against neurological disorders.

MH84 improves mitochondrial dysfunction in a mouse model of early Alzheimer's disease.

BACKGROUND: Current approved drugs for Alzheimer's disease (AD) only attenuate symptoms, but do not cure the disease. The pirinixic acid derivate MH84 has been characterized as a dual gamma-secretase/proliferator activated receptor gamma (PPARγ) modulator in vitro. Pharmacokinetic studies in mice showed that MH84 is bioavailable after oral administration and reaches the brain. We recently demonstrated that MH84 improved mitochondrial dysfunction in a cellular model of AD. In the present study, we extended the pharmacological characterization of MH84 to 3-month-old Thy-1 AßPPSL mice (harboring the Swedish and London mutation in human amyloid precursor protein (APP)) which are characterized by enhanced AßPP processing and cerebral mitochondrial dysfunction, representing a mouse model of early AD. METHODS: Three-month-old Thy-1 AßPPSL mice received 12 mg/kg b.w. MH84 by oral gavage once a day for 21 days. Mitochondrial respiration was analyzed in isolated brain mitochondria, and mitochondrial membrane potential and ATP levels were determined in dissociated brain cells. Citrate synthase (CS) activity was determined in brain tissues and MitoTracker Green fluorescence was measured in HEK293-AßPPwt and HEK293-AßPPsw cells. Soluble Aß1-40 and Aß1-42 levels were determined using ELISA. Western blot analysis and qRT-PCR were used to measure protein and mRNA levels, respectively. RESULTS: MH84 reduced cerebral levels of the ß-secretase-related C99 peptide and of Aß40 levels. Mitochondrial dysfunction was ameliorated by restoring complex IV (cytochrome-c oxidase) respiration, mitochondrial membrane potential, and levels of ATP. Induction of PPARγ coactivator-1α (PGC-1α) mRNA and protein expression was identified as a possible mode of action that leads to increased mitochondrial mass as indicated by enhanced CS activity, OXPHOS levels, and MitoTracker Green fluorescence. CONCLUSIONS: MH84 modulates ß-secretase processing of APP and improves mitochondrial dysfunction by a PGC-1α-dependent mechanism. Thus, MH84 seems to be a new promising therapeutic agent with approved in-vivo activity for the treatment of AD.

Effects of Grape Skin Extract on Age-Related Mitochondrial Dysfunction, Memory and Life Span in C57BL/6J Mice.

Dementia contributes substantially to the burden of disability experienced at old age, and mitochondrial dysfunction (MD) was identified as common final pathway in brain aging and Alzheimer's disease. Due to its early appearance, MD is a promising target for nutritional prevention strategies and polyphenols as potential neurohormetic inducers may be strong neuroprotective candidates. This study aimed to investigate the effects of a polyphenol-rich grape skin extract (PGE) on age-related dysfunctions of brain mitochondria, memory, life span and potential hormetic pathways in C57BL/6J mice. PGE was administered at a dose of 200 mg/kg body weight/d in a 3-week short-term, 6-month long-term and life-long study. MD in the brains of aged mice (19-22 months old) compared to young mice (3 months old) was demonstrated by lower ATP levels and by impaired mitochondrial respiratory complex activity (except for mice treated with antioxidant-depleted food pellets). Long-term PGE feeding partly enhanced brain mitochondrial respiration with only minor beneficial effect on brain ATP levels and memory of aged mice. Life-long PGE feeding led to a transient but significant shift of survival curve toward higher survival rates but without effect on the overall survival. The moderate effects of PGE were associated with elevated SIRT1 but not SIRT3 mRNA expressions in brain and liver tissue. The beneficial effects of the grape extract may have been influenced by the profile of bioavailable polyphenols and the starting point of interventions.

Effects of Long-Term Rice Bran Extract Supplementation on Survival, Cognition and Brain Mitochondrial Function in Aged NMRI Mice.

Aging represents a major risk factor for the development of neurodegenerative diseases like Alzheimer's disease (AD). As mitochondrial dysfunction plays an important role in brain aging and occurs early in the development of AD, the prevention of mitochondrial dysfunction might help to slow brain aging and the development of neurodegenerative diseases. Rice bran extract (RBE) contains high concentrations of vitamin E congeners and γ-oryzanol. We have previously shown that RBE increased mitochondrial function and protected from mitochondrial dysfunction in vitro and in short-term in vivo feeding studies. To mimic the use of RBE as food additive, we have now investigated the effects of a long-term (6 months) feeding of RBE on survival, behavior and brain mitochondrial function in aged NMRI mice. RBE administration significantly increased survival and performance of aged NMRI mice in the passive avoidance and Y-maze test. Brain mitochondrial dysfunction found in aged mice was ameliorated after RBE administration. Furthermore, data from mRNA and protein expression studies revealed an up-regulation of mitochondrial proteins in RBE-fed mice, suggesting an increase in mitochondrial content which is mediated by a peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α)-dependent mechanism. Our findings suggest that a long-term treatment with a nutraceutical containing RBE could be useful for slowing down brain aging and thereby delaying or even preventing AD.

Curcumin micelles improve mitochondrial function in neuronal PC12 cells and brains of NMRI mice - Impact on bioavailability.

Curcumin, a polyphenolic compound abundant in the rhizome of Curcuma longa, has been reported to have various beneficial biological and pharmacological activities. Recent research revealed that curcumin might be valuable in the prevention and therapy of numerous disorders including neurodegenerative diseases like Alzheimer's disease. Due to its low absorption and quick elimination from the body, curcumin bioavailability is rather low which poses major problems for the use of curcumin as a therapeutic agent. There are several approaches to ameliorate curcumin bioavailability after oral administration, amongst them simultaneous administration with secondary plant compounds, micronization and micellation. We examined bioavailability in vivo in NMRI mice and the effects of native curcumin and a newly developed curcumin micelles formulation on mitochondrial function in vitro in PC12 cells and ex vivo in isolated mouse brain mitochondria. We found that curcumin micelles improved bioavailability of native curcumin around 10- to 40-fold in plasma and brain of mice. Incubation with native curcumin and curcumin micelles prevented isolated mouse brain mitochondria from swelling, indicating less mitochondrial permeability transition pore (mPTP) opening and prevention of injury. Curcumin micelles proved to be more efficient in preventing mitochondrial swelling in isolated mouse brain mitochondria and protecting PC12 cells from nitrosative stress than native curcumin. Due to their improved effectivity, curcumin micelles might be a suitable formulation for the prevention of mitochondrial dysfunction in brain aging and neurodegeneration.

Omega-3 polyunsaturated fatty acids improve mitochondrial dysfunction in brain aging--impact of Bcl-2 and NPD-1 like metabolites.

The present study investigated the effects of orally administered long chain omega-3 polyunsaturated fatty acids (PUFA) on mitochondrial function and processing of the amyloid precursor protein (APP) in brains of young (3 months old) and aged (24 months old) NMRI-mice. Neuroprotective properties of fish oil (FO) (1.6 ml/kg p.o.) were assessed ex vivo after 21 days in dissociated brain cells (DBC) and isolated mitochondria. Docosahexaenoic acid (DHA) levels were significantly lower in blood and brains of aged mice which were compensated by FO administration. Isolated DBC and mitochondria from aged mice showed significantly lower adenosine triphosphate (ATP) levels and reduced activity of complexes I+II and IV of the mitochondrial respiration system, respectively. FO restored the age-related decrease in respiration and improved ATP production. Moreover, FO increased the levels of anti-apoptotic Bcl-2 protein. Cell membrane fractions isolated from the brain of aged mice exhibited lower membrane fluidity, which was partially improved under FO treatment. In comparison to young animals, levels of neuroprotective sAPPα were significantly lower in the brain of aged mice. However, levels of sAPPα, Aß and C-terminal APP fragments (CTF) were largely unchanged after FO treatment in aged mice. Neuroprotectin D-1 (NPD-1) represents a neuroprotective compound that is derived from unesterified DHA. Levels of NPD1-like metabolites (NPD1-like) and of unesterified DHA were significantly increased in brains of aged mice. FO treatment further strongly increased NPD1-like levels indicating an accelerated conversion rate of free DHA to NPD1-like. Our findings provide new mechanisms underlying the neuroprotective actions of omega-3 PUFA and identified FO as a promising nutraceutical to delay age-related mitochondrial dysfunction in the brain.

Rice bran extract compensates mitochondrial dysfunction in a cellular model of early Alzheimer's disease.

Mitochondrial dysfunction plays an important role in brain aging and has emerged to be an early event in Alzheimer's disease (AD), contributing to neurodegeneration and the loss of physical abilities seen in patients suffering from this disease. We examined mitochondrial dysfunction in a cell culture model of AD (PC12APPsw cells) releasing very low amyloid-ß (Aß40) levels and thus mimicking early AD stages. Our data show that these cells have impaired energy metabolism, low ATP levels, and decreased endogenous mitochondrial respiration. Furthermore, protein levels of PGC1α as well as of Mitofusin 1 were decreased. PC12APPsw cells also showed increased mitochondrial content, probably due to an attempt to compensate the impaired mitochondrial function. Recent data showed that stabilized rice bran extract (RBE) protects from mitochondrial dysfunction in vivo Pharmacol Res. (2013) 76C, 17-27. To assess the effect of RBE on mitochondrial function, we treated PC12APPsw cells for 24 h with RBE. Key components of RBE are oryzanols, tocopherols, and tocotrienols, all substances that have been found to exert beneficial effects on mitochondrial function. RBE incubation elevated ATP production and respiratory rates as well as PGC1α protein levels in PC12APPsw cells, thus improving the impaired mitochondrial function assessed in our cell culture AD model. Therefore, RBE represents to be a promising nutraceutical for the prevention of AD.

Adenosine triphosphate concentrations are higher in the brain of APOE3- compared to APOE4-targeted replacement mice and can be modulated by curcumin.

Curcumin from Curcuma longa may exert putative neuroprotective properties in the brain. Impaired mitochondrial function is implicated in Alzheimer's disease and the presence of the apolipoprotein (APO) E4 genotype, which is a risk factor for late-onset Alzheimer's disease, may aggravate mitochondrial malfunction. Here, we report that in the brain of 16-month-old APOE4-targeted replacement mice, adenosine triphosphate (ATP) concentrations were significantly lower than in APOE3 mice. A 3-month dietary supplementation of 0.2 % curcumin numerically increased ATP concentrations in APOE3 and significantly in APOE4 mice compared to the respective controls. Curcumin significantly induced the transcription of peroxisome proliferator-activated receptor (PPAR) γ and mitochondrial transcription factor A (TFAM) in APOE3, but not in APOE4 mice. Moreover, PPARγ coactivator (PGC)-1α and guanine-adenine repeat binding protein α (GABPa) mRNA was only increased in APOE3 mice. Consistent with these observations, protein expression of mitochondrial respiratory complexes, especially of complex IV, also appeared to be increased in APOE3 mice. In conclusion, we provide evidence that curcumin affects mitochondrial function and gene and protein expression in the murine brain despite its low bioavailability and carriers of the Alzheimer's disease-risk genotype APOE4 may be less responsive to dietary curcumin than APOE3 carriers.

Mitochondrial membrane fluidity is consistently increased in different models of Huntington disease: restorative effects of olesoxime.

Huntington disease (HD) is a fatal neurodegenerative disorder caused by a CAG repeat expansion in exon 1 of the huntingtin gene (HTT). One prominent target of the mutant huntingtin protein (mhtt) is the mitochondrion, affecting its morphology, distribution, and function. Thus, mitochondria have been suggested as potential therapeutic targets for the treatment of HD. Olesoxime, a cholesterol-like compound, promotes motor neuron survival and neurite outgrowth in vitro, and its effects are presumed to occur via a direct interaction with mitochondrial membranes (MMs). We examined the properties of MMs isolated from cell and animal models of HD as well as the effects of olesoxime on MM fluidity and cholesterol levels. MMs isolated from brains of aged Hdh Q111/Q111 knock-in mice showed a significant decrease in 1,6-diphenyl-hexatriene (DPH) anisotropy, which is inversely correlated with membrane fluidity. Similar increases in MM fluidity were observed in striatal STHdh Q111/Q111 cells as well as in MMs isolated from brains of BACHD transgenic rats. Treatment of STHdh cells with olesoxime decreased the fluidity of isolated MMs. Decreased membrane fluidity was also measured in olesoxime-treated MMs isolated from brains of HD knock-in mice. In both models, treatment with olesoxime restored HD-specific changes in MMs. Accordingly, olesoxime significantly counteracted the mhtt-induced increase in MM fluidity of MMs isolated from brains of BACHD rats after 12 months of treatment in vivo, possibly by enhancing MM cholesterol levels. Thus, olesoxime may represent a novel pharmacological tool to treat mitochondrial dysfunction in HD.

Curcumin prevents mitochondrial dysfunction in the brain of the senescence-accelerated mouse-prone 8.

The aging brain suffers mitochondrial dysfunction and a reduced availability of energy in the form of ATP, which in turn may cause or promote the decline in cognitive, sensory, and motor function observed with advancing age. There is a need for animal models that display some of the pathological features of human brain aging in order to study their prevention by e.g. dietary factors. We thus investigated the suitability of the fast-aging senescence-accelerated mouse-prone 8 (SAMP8) strain and its normally aging control senescence-accelerated mouse-resistant 1 (SAMR1) as a model for the age-dependent changes in mitochondrial function in the brain. To this end, 2-months old male SAMR1 (n=10) and SAMP8 mice (n=7) were fed a Western type diet (control groups) for 5months and one group of SAMP8 mice (n=6) was fed an identical diet fortified with 500mg curcumin per kg. Dissociated brain cells and brain tissue homogenates were analyzed for malondialdehyde, heme oxygenase-1 mRNA, mitochondrial membrane potential (MMP), ATP concentrations, protein levels of mitochondrial marker proteins for mitochondrial membranes (TIMM, TOMM), the mitochondrial permeability transition pore (ANT1, VDAC1, TSPO), respiration complexes, and fission and fusion (Fis, Opa1, Mfn1, Drp1). Dissociated brain cells isolated from SAMP8 mice showed significantly reduced MMP and ATP levels, probably due to significantly diminished complex V protein expression, and increased expression of TSPO. Fission and fusion marker proteins indicate enhanced mitochondrial fission in brains of SAMP8 mice. Treatment of SAMP8 mice with curcumin improved MMP and ATP and restored mitochondrial fusion, probably by up-regulating nuclear factor PGC1α protein expression. In conclusion, SAMP8 compared to SAMR1 mice are a suitable model to study age-dependent changes in mitochondrial function and curcumin emerges as a promising nutraceutical for the prevention of neurodegenerative diseases that are accompanied or caused by mitochondrial dysfunction.

Mitochondrial dysfunction--a pharmacological target in Alzheimer's disease.

Increasing evidences suggest that mitochondrial dysfunction plays an important role in the pathogenesis of neurodegenerative diseases including Alzheimer's disease (AD). Alterations of mitochondrial efficiency and function are mainly related to alterations in mitochondrial content, amount of respiratory enzymes, or changes in enzyme activities leading to oxidative stress, mitochondrial permeability transition pore opening, and enhanced apoptosis. More recently, structural changes of the network are related to bioenergetic function, and its consequences are a matter of intensive research. Several mitochondria-targeting compounds with potential efficacy in AD including dimebon, methylene blue, piracetam, simvastatin, Ginkgo biloba, curcumin, and omega-3 polyunsaturated fatty acids have been identified. The majority of preclinical data indicate beneficial effects, whereas most controlled clinical trials did not meet the expectations. Since mitochondrial dysfunction represents an early event in disease progression, one reason for the disappointing clinical results could be that pharmacological interventions might came too late. Thus, more studies are needed that focus on therapeutic strategies starting before severe disease progress.

Colonic availability of polyphenols and D-(-)-quinic acid after apple smoothie consumption.

SCOPE: The aim of this study was to determine the amounts of polyphenols and D-(-)-quinic acid reaching the ileostomy bags of probands (and thus the colon in healthy humans) after ingestion of apple smoothie, a beverage containing 60% cloudy apple juice and 40% apple puree. METHODS AND RESULTS: Ten healthy ileostomy subjects each ingested 0.7 L of apple smoothie (a bottle). Their ileostomy bags were collected directly before and 1, 2, 4, 6 and 8 h after smoothie consumption, and the polyphenol and D-(-)-quinic acid contents of the ileostomy fluids were examined using HPLC-DAD and HPLC-MS/MS. The total polyphenol and D-(-)-quinic acid content of the apple smoothie was determined to be 1955.6±124.6 mg/0.7 L, which is very high compared to cloudy apple juices. The most abundant substances found in the ileostomy bags were oligomeric procyanidins (705.6±197.9 mg), D-(-)-quinic acid (363.4±235.5 mg) and 5-caffeoylquinic acid (76.7±26.8 mg). Overall recovery of ingested polyphenols and D-(-)-quinic acid in the ileostomy bags was 63.3±16.1%. CONCLUSIONS: The amounts of polyphenol and D-(-)-quinic acids reaching the ileostomy bags are considerably higher after apple smoothie consumption than after the consumption of cloudy apple juice or cider. These results suggest that the food matrix might affect the colonic availability of polyphenols, and apple smoothies could be more effective in the prevention of chronic colon diseases than both cloudy apple juice and apple cider.