Fish Oil Toxicity
Women, Estrogen, and Circulating DHA
PUFA – Accumulation & Aging
Fat Deficient Animals – Activity of Cytochrome Oxidase
“Curing” a High Metabolic Rate with Unsaturated Fats
Glucocorticoids, Cytochrome Oxidase, and Metabolism
Dietary PUFA Reflected in Human Subcutaneous Fat Tissue
Benefits of Red Light
Quotes by Ray Peat, PhD:
“The most highly unsaturated fats, including DHA, accumulate with aging, and their toxic fragments are increased in Alzheimer’s disease.”
“General aging, and especially aging of the brain, is increasingly seen as being closely associated with lipid peroxidation.”
“Our innate immune system is perfectly competent for handling our normal stress induced exposures to bacterial endotoxin, but as we accumulate the unstable fats, each exposure to endotoxin creates additional inflammatory stress by liberating stored fats. The brain has a very high concentration of complex fats, and is highly susceptible to the effects of lipid peroxidative stress, which become progressively worse as the unstable fats accumulate during aging.”
“Some types of dementia, such as Alzheimer’s disease, involve a life-long process of degeneration of the brain, with an inflammatory component, that probably makes them comparable to osteoporosis and muscle-wasting. (In the brain, the microglia, which are similar to macrophages, and the astrocytes, can produce TNF.) The importance of the inflammatory process in Alzheimer’s disease was appreciated when it was noticed that people who used aspirin regularly had a low incidence of that dementia. Aspirin inhibits the formation of TNF, and aspirin has been found to retard bone loss. In the case of osteoporosis (A. Murrillo-Uribe, 1999), as in Alzheimer’s disease, the incidence is two or three times as high in women as in men. In both Alzheimer’s disease and osteoporosis, the estrogen industry is arguing that the problems are caused by a suddenly developing estrogen deficiency, rather than by prolonged exposure to estrogen.”
“The shorter chain fatty acids of coconut oil are more easily oxidized for energy than long chain fatty acids, and their saturation makes them resistant to the random oxidation produced by inflammation, so they don’t support their production of acrolein or age pigment; along with their reported antiinflammatory effect, these properties might be responsible for their beneficial effects that have been seen in Alzheimer’s disease.”
“The brain has a very high concentration of complex fats, and is highly susceptible to the effects of lipid peroxidative stress, which become progressively worse as the unstable fats accumulate during aging.”
Acrolein and hydroxynonenal (HNE) are lipid peroxides or breakdown products from consumption of polyunsaturated fatty acids (PUFA). Isoprostanes and neuroprostanes are inflammatory prostaglandin-like mediators (eicosanoids) formed from omega-3 PUFA fish oil (DHA/EPA). These substances are accurate markers of lipid peroxidation/oxidative stress and are implicated in a variety of brain degenerative conditions.
“Other new knowledge of the ways in which polyunsaturated fats break down become available in this same period. For example, acrolein, which is elevated in Alzheimer’s disease, is from 10 to 100 times more reactive than some of the better know oxidative fragments, and it is formed mainly from omega -3 polyunsaturated fatty acids, especially, DHA and EPA.” -Ray Peat, PhD
Neurosci Lett. 2006 Apr 24;397(3):170-3. Epub 2006 Jan 4.
Elevated protein-bound levels of the lipid peroxidation product, 4-hydroxy-2-nonenal, in brain from persons with mild cognitive impairment.
Butterfield DA, Reed T, Perluigi M, De Marco C, Coccia R, Cini C, Sultana R.
Oxidative damage is a feature of many age-related neurodegenerative diseases, including Alzheimer’s disease (AD). 4-Hydroxy-2-nonenal (HNE) is a highly reactive product of the free radical-mediated lipid peroxidation of unsaturated lipids, particularly arachidonic acid, in cellular membranes. In the present study we show for the first time in brain obtained at short postmortem intervals that the levels of HNE are elevated in mild cognitive impairment (MCI) hippocampus and inferior parietal lobules compared to those of control brain. Thus, increased levels of HNE in MCI brain implicate lipid peroxidation as an early event in AD pathophysiology and also suggest that the pharmacologic intervention to prevent lipid peroxidation at the MCI stage or earlier may be a promising therapeutic strategy to delay or prevent progression to AD.
J Biol Chem. 1998 May 29;273(22):13605-12.
Formation of isoprostane-like compounds (neuroprostanes) in vivo from docosahexaenoic acid.
Roberts LJ 2nd, Montine TJ, Markesbery WR, Tapper AR, Hardy P, Chemtob S, Dettbarn WD, Morrow JD.
F2-isoprostanes are prostaglandin F2-like compounds that are formed nonenzymatically by free radical-induced oxidation of arachidonic acid. We explored whether oxidation of docosahexaenoic acid (C22:6omega3), which is highly enriched in the brain, led to the formation of F2-isoprostane-like compounds, which we term F4-neuroprostanes. Oxidation of docosahexaenoic acid in vitro yielded a series of compounds that were structurally established to be F4-neuroprostanes using a number of mass spectrometric approaches. The amounts formed exceeded levels of F2-isoprostanes generated from arachidonic acid by 3.4-fold. F4-neuroprostanes were detected esterified in normal whole rat brain and newborn pig cortex at a level of 7.0 +/- 1.4 ng/g and 13.1 +/- 8 ng/g, respectively. Furthermore, F4-neuroprostanes could be detected in normal human cerebrospinal fluid and levels in patients with Alzheimer’s disease (110 +/- 12 pg/ml) were significantly higher than age-matched controls (64 +/- 8 pg/ml) (p < 0.05). F4-neuroprostanes may provide a unique marker of oxidative injury to the brain and could potentially exert biological activity. Furthermore, the formation of F4-neuroprostane-containing aminophospholipids might adversely effect neuronal function as a result of alterations they induce in the biophysical properties of neuronal membranes.
J Nutr Health Aging. 2003;7(1):24-9.
Lipoproteins and lipid peroxidation in Alzheimer’s disease.
Bassett CN, Montine TJ.
Alzheimer’s Disease (AD) is a clinical-pathological entity that probably derives from different causes. Mounting evidence strongly implicates regionally increased oxidative damage to brain beyond what occurs with aging as one of the processes that may contribute to AD progression. While several different classes of molecules may be affected, lipid peroxidation is thought to be a prominent and especially deleterious form of oxidative damage in brain due to this organ’s relative enrichment in polyunsaturated fatty acids. Our laboratory recently has demonstrated that lipoproteins in AD brain extracellular fluid are more vulnerable to oxidation than lipoproteins in control brain extracellular fluid. Apolipoprotein E (apoE) is the principal apolipoprotein in the central nervous system (CNS), and it serves as the major apolipoprotein that is capable of lipid transport and regulation of lipid metabolism through known receptor-mediated processes. Moreover, inheritance of the APOE4 allele represents the strongest genetic risk factor for sporadic AD. Evidence suggests that apoE isoforms may specifically influence the cellular distribution of lipid peroxidation products in brain and may therefore contribute to the stratification of risk for AD associated with APOE. Here, we review possible mechanisms whereby lipoprotein trafficking and lipid peroxidation converge to contribute to neurodegeneration in AD brain.
Neurobiol Aging. 2002 Sep-Oct;23(5):655-64.
Evidence that amyloid beta-peptide-induced lipid peroxidation and its sequelae in Alzheimer’s disease brain contribute to neuronal death.
Butterfield DA, Castegna A, Lauderback CM, Drake J.
Amyloid beta-peptide [Abeta(1-42)] is central to the pathogenesis of Alzheimer’s disease (AD), and the AD brain is under intense oxidative stress, including membrane lipid peroxidation. Abeta(1-42) causes oxidative stress in and neurotoxicity to neurons in mechanisms that are inhibited by Vitamin E and involve the single methionine residue of this peptide. In particular, Abeta induces lipid peroxidation in ways that are inhibited by free radical antioxidants. Two reactive products of lipid peroxidation are the alkenals, 4-hydroxynonenal (HNE) and 2-propenal (acrolein). These alkenals covalently bind to synaptosomal protein cysteine, histidine, and lysine residues by Michael addition to change protein conformation and function. HNE or acrolein binding to proteins introduces a carbonyl to the protein, making the protein oxidatively modified as a consequence of lipid peroxidation. Immunoprecipitation of proteins from AD and control brain, obtained no longer than 4h PMI, showed selective proteins are oxidatively modified in the AD brain. Creatine kinase (CK) and beta-actin have increased carbonyl groups, and Glt-1, a glutamate transporter, has increased binding of HNE in AD. Abeta(1-42) addition to synaptosomes also results in HNE binding to Glt-1, thereby coupling increased Abeta(1-42) in AD brain to increased lipid peroxidation and its sequelae and possibly explaining the mechanism of glutamate transport inhibition known in AD brain. Abeta also inhibits CK. Implications of these findings relate to decreased energy utilization, altered assembly of cytoskeletal proteins, and increased excitotoxicity to neurons by glutamate, all reported for AD. The epsilon-4 allele of the lipid carrier protein apolipoprotein E (APOE) allele is a risk factor for AD. Synaptosomes from APOE knock-out mice are more vulnerable to Abeta-induced oxidative stress (protein oxidation, lipid peroxidation, and ROS generation) than are those from wild-type mice. Further, synaptosomes from allele-specific APOE knock-in mice have tiered vulnerability to Abeta(1-42)-induced oxidative stress, with APOE4 more vulnerable to Abeta(1-42) than are those from APOE2 or APOE3 mice. These results are consistent with the notion of a coupling of the oxidative environment in AD brain and increased risk of developing this disorder. Taken together, the findings from in-vitro studies of lipid peroxidation induced by Abeta(1-42) and postmortem studies of lipid peroxidation (and its sequelae) in AD brain may help explain the APOE allele-related risk for AD, some of the functional and structural alterations in AD brain, and strongly support a causative role of Abeta(1-42)-induced oxidative stress in AD neurodegeneration.
Neurotox Res. 2003;5(7):515-20.
Acrolein inhibits NADH-linked mitochondrial enzyme activity: implications for Alzheimer’s disease.
Pocernich CB, Butterfield DA.
In Alzheimer’s disease (AD) brain increased lipid peroxidation and decreased energy utilization are found. Mitochondria membranes contain a significant amount of arachidonic and linoleic acids, precursors of lipid peroxidation products, 4-hydroxynonenal (HNE) and 2-propen-1-al (acrolein), that are extremely reactive. Both alkenals are increased in AD brain. In this study, we examined the effects of nanomolar levels of acrolein on the activities of pyruvate dehydrogenase (PDH) and Alpha-ketoglutarate dehydrogenase (KGDH), both reduced nicotinamide adenine dinucleotide (NADH)-linked mitochondrial enzymes. Acrolein decreased PDH and KGDH activities significantly in a dose-dependent manner. Using high performance liquid chromatography coupled to mass spectrometry (HPLC-MS), acrolein was found to bind lipoic acid, a component in both the PDH and KGDH complexes, most likely explaining the loss of enzyme activity. Acrolein also interacted with oxidized nicotinamide adenine dinucleotide (NAD(+)) in such a way as to decrease the production of NADH. Acrolein, which is increased in AD brain, may be partially responsible for the dysfunction of mitochondria and loss of energy found in AD brain by inhibition of PDH and KGDH activities, potentially contributing to the neurodegeneration in this disorder.
Free Radical Biology and Medicine
Volume 29, Issue 8, 15 October 2000, Pages 714-720
Acrolein, a product of lipid peroxidation, inhibits glucose and glutamate uptake in primary neuronal cultures.
Mark A Lovell, Chengsong Xie, William R Markesbery
Oxidative stress has been implicated in the pathogenesis of several neurodegenerative disorders including Alzheimer’s disease (AD). Increased lipid peroxidation, decreased levels of polyunsaturated fatty acids, and increased levels of 4-hydroxynonenal (HNE), F2-isoprostanes, and F4-neuroprostanes are present in the brain in patients with AD. Acrolein, an α,β-unsaturated aldehydic product of lipid peroxidation has been demonstrated to be approximately 100 times more reactive than HNE and is present in neurofibrillary tangles in the brain in AD. We recently demonstrated statistically significant elevated concentrations of extractable acrolein in the hippocampus/parahippocampal gyrus and amygdala in AD compared with age-matched control subjects. Concentrations of acrolein were two to five times those of HNE in the same samples. Treatment of hippocampal cultures with acrolein led to a time- and concentration-dependent decrease in cell survival as well as a concentration-dependent increase in intracellular calcium. In cortical neuron cultures, we now report that acrolein causes a concentration-dependent impairment of glutamate uptake and glucose transport in cortical neuron cultures. Treatment of cortical astrocyte cultures with acrolein led to the same pattern of impairment of glutamate uptake as observed in cortical neuron cultures. Collectively, these data demonstrate neurotoxicity mechanisms of arolein that might be important in the pathogenesis of neuron degeneration in AD.
Neurobiol Aging. 2001 Mar-Apr;22(2):187-94.
Acrolein is increased in Alzheimer’s disease brain and is toxic to primary hippocampal cultures.
Lovell MA, Xie C, Markesbery WR.
Accumulating evidence implicates oxidative stress in the pathogenesis of several neurodegenerative diseases including Alzheimer’s disease (AD). Increased lipid peroxidation, decreased levels of polyunsaturated fatty acids, and increased levels of 4-hydroxynonenal (HNE), F(2)-isoprostanes, and F(4)-neuroprostanes are present in the brain in AD. Acrolein, an alpha,beta-unsaturated aldehydic product of lipid peroxidation, is approximately 100 times more reactive than HNE and recently was demonstrated in neurofibrillary tangles in the brain in AD. In three brain regions of 10 AD patients compared with 8 age-matched control subjects, we found increased mean extractable acrolein, with the increases reaching statistical significance in the amygdala and hippocampus/parahippocampal gyrus. In hippocampal neuron cultures, acrolein was neurotoxic in a time- and concentration-dependent manner and more toxic than HNE at 5 microM concentrations of each. Acrolein exposure led to a significant concentration-dependent increase in intracellular calcium concentrations. Collectively, these data show that acrolein is increased in the brain in AD and demonstrate neurotoxicity mechanisms that might be important in the pathogenesis of neuron degeneration in AD.
Neurobiol Aging. 2006 Aug;27(8):1094-9. Epub 2005 Jul 1.
Increased levels of 4-hydroxynonenal and acrolein, neurotoxic markers of lipid peroxidation, in the brain in Mild Cognitive Impairment and early Alzheimer’s disease.
Williams TI, Lynn BC, Markesbery WR, Lovell MA.
Previous studies show increased levels of lipid peroxidation and neurotoxic by-products of lipid peroxidation including 4-hydroxynonenal (HNE) and acrolein in vulnerable regions of the Alzheimer’s disease (AD) brain. To determine if lipid peroxidation occurs early in progression of AD, we analyzed levels of HNE and acrolein in the hippocampus/parahippocampal gyrus (HPG), superior and middle temporal gyrus (SMTG) and cerebellum (CER) of 7 subjects with Mild Cognitive Impairment (MCI), six subjects with early AD (EAD) and sevem age-matched control subjects using liquid chromatography electrospray ionization tandem mass spectrometry (LC/ESI/MS/MS). Our data show that there is a statistically significant (P<0.05) increase in HNE in HPG, SMTG and CER in MCI compared to age-matched control subjects. Specimens of SMTG also showed a significant increase in levels of acrolein in MCI. Comparison of EAD and control subjects showed a statistically significant increase in HNE in HPG and SMTG and a significant increase in acrolein in all three brain regions studied. We did not observe any statistically significant differences between MCI and EAD specimens. These results suggest that lipid peroxidation occurs early in the pathogenesis of AD.
Brain Res. 2009 Jun 5;1274:66-76. Epub 2009 Apr 15.
Proteomic identification of HNE-bound proteins in early Alzheimer disease: Insights into the role of lipid peroxidation in the progression of AD.
Reed TT, Pierce WM, Markesbery WR, Butterfield DA.
Early Alzheimer’s disease (EAD) is the intermediary stage between mild cognitive impairment (MCI) and late-stage Alzheimer’s disease (AD). The symptoms of EAD mirror the disease advancement between the two phases. Dementia, memory deficits, and cognitive decline are more pronounced as the disease progresses. Oxidative stress in brain is reported in MCI and AD, including lipid peroxidation indexed by protein-bound 4-hydroxy-2-nonenal (HNE). There are limited data regarding the proteomics analysis of brain from subjects with EAD and even less concerning the possible relationship of EAD HNE-modified brain proteins with HNE-modified proteins in MCI and AD. Proteomics was utilized to investigate excessively HNE-bound brain proteins in EAD compared to those in control. These new results provide potentially valuable insight into connecting HNE-bound brain proteins in EAD to those previously identified in MCI and AD, since EAD is a transitional stage between MCI and late-stage AD. In total, six proteins were found to be excessively covalently bound by HNE in EAD inferior parietal lobule (IPL) compared to age-related control brain. These proteins play roles in antioxidant defense (manganese superoxide dismutase), neuronal communication and neurite outgrowth (dihydropyriminidase-related protein 2), and energy metabolism (alpha-enolase, malate dehydrogenase, triosephosphate isomerase, and F1 ATPase, alpha subunit). This study shows that there is an overlap of brain proteins in EAD with previously identified oxidatively modified proteins in MCI and late-stage AD. The results are consistent with the hypothesis that oxidative stress, in particular lipid peroxidation, is an early event in the progression of AD, and is the first to identify in EAD identical brain proteins previously identified as HNE-modified in MCI and late-state AD.
Neurobiol Dis. 2008 Apr;30(1):107-20. Epub 2008 Jan 5.
Redox proteomic identification of 4-hydroxy-2-nonenal-modified brain proteins in amnestic mild cognitive impairment: insight into the role of lipid peroxidation in the progression and pathogenesis of Alzheimer’s disease.
Reed T, Perluigi M, Sultana R, Pierce WM, Klein JB, Turner DM, Coccia R, Markesbery WR, Butterfield DA.
Numerous investigations point to the importance of oxidative imbalance in mediating AD pathogenesis. Accumulated evidence indicates that lipid peroxidation is an early event during the evolution of the disease and occurs in patients with mild cognitive impairment (MCI). Because MCI represents a condition of increased risk for Alzheimer’s disease (AD), early detection of disease markers is under investigation. Previously we showed that HNE-modified proteins, markers of lipid peroxidation, are elevated in MCI hippocampus and inferior parietal lobule compared to controls. Using a redox proteomic approach, we now report the identity of 11 HNE-modified proteins that had significantly elevated HNE levels in MCI patients compared with controls that span both brain regions: Neuropolypeptide h3, carbonyl reductase (NADPH), alpha-enolase, lactate dehydrogenase B, phosphoglycerate kinase, heat shock protein 70, ATP synthase alpha chain, pyruvate kinase, actin, elongation factor Tu, and translation initiation factor alpha. The enzyme activities of lactate dehydrogenase, ATP synthase, and pyruvate kinase were decreased in MCI subjects compared with controls, suggesting a direct correlation between oxidative damage and impaired enzyme activity. We suggest that impairment of target proteins through the production of HNE adducts leads to protein dysfunction and eventually neuronal death, thus contributing to the biological events that may lead MCI patients to progress to AD.
J Cell Mol Med. 2008 Jun;12(3):987-94.
Elevated levels of pro-apoptotic p53 and its oxidative modification by the lipid peroxidation product, HNE, in brain from subjects with amnestic mild cognitive impairment and Alzheimer’s disease.
Cenini G, Sultana R, Memo M, Butterfield DA.
Oxidative stress has been implicated in the pathogenesis of Alzheimer’s disease (AD). Both AD and arguably its earlier form, mild cognitive impairment (MCI), have elevated membrane oxidative damage in brain. The tumor suppressor and transcription factor p53 plays a pivotal function in neuronal apoptosis triggered by oxidative stress. Apoptosis contributes to neuronal death in many neurological disorders, including AD. In this study, we investigated p53 expression in a specific region of the cerebral cortex, namely the inferior parietal lobule (IPL), in MCI and AD brain, to test the hypothesis that alterations of this pro-apoptotic protein may be involved in neuronal death in the progression of AD. By immunoprecipitation assay, we also investigated whether 4-hydroxy-2-transnonenal (HNE), an aldehydic product of lipid peroxidation, was bound in excess to p53 in IPL from subjects with MCI and AD compared to control. Overall, the data provide evidence that p53 is involved in the neuronal death in both MCI and AD, suggesting that the observed alterations are early events in the progression of AD. In addition, HNE may be a novel non-protein mediator of oxidative stress-induced neuronal apoptosis.
Brain Pathol. 1999 Jan;9(1):133-46.
Oxidative alterations in Alzheimer’s disease.
Markesbery WR, Carney JM.
There is increasing evidence that free radical damage to brain lipids, carbohydrates, proteins, and DNA is involved in neuron death in neurodegenerative disorders. The largest number of studies have been performed in Alzheimer’s disease (AD) where there is considerable support for the oxidative stress hypothesis in the pathogenesis of neuron degeneration. In autopsied brain there is an increase in lipid peroxidation, a decline in polyunsaturated fatty acids (PUFA) and an increase in 4-hydroxynonenal (HNE), a neurotoxic aldehyde product of PUFA oxidation. Increased protein oxidation and a marked decline in oxidative-sensitive enzymes, glutamine synthetase and creatinine kinase, are found in the brain in AD. Increased DNA oxidation, especially 8-hydroxy-2′-deoxyguanosine (8-OHdG) is present in the brain in AD. Immunohistochemical studies show the presence of oxidative stress products in neurofibrillary tangles and senile plaques in AD. Markers of lipid peroxidation (HNE, isoprostanes) and DNA (8-OHdG) are increased in CSF in AD. In addition, inflammatory response markers (the complement cascade, cytokines, acute phase reactants and proteases) are present in the brain in AD. These findings, coupled with epidemiologic studies showing that anti-inflammatory agents slow the progression or delay the onset of AD, suggest that inflammation plays a role in AD. Overall these studies indicate that oxidative stress and the inflammatory cascade, working in concert, are important in the pathogenetic cascade of neurodegeneration in AD, suggesting that therapeutic efforts aimed at both of these mechanisms may be beneficial.
Neurochem Res. 2004 Dec;29(12):2215-20.
Oxidatively modified GST and MRP1 in Alzheimer’s disease brain: implications for accumulation of reactive lipid peroxidation products.
Sultana R, Butterfield DA.
Alzheimer disease (AD) is a neurodegenerative disorder characterized pathologically by intracellular inclusions including neurofibrillary tangles (NFT) and senile plaques. Several lines of evidence implicate oxidative stress with the progression of AD. 4-hydroxy-2-trans-nonenal (HNE), an aldehydic product of membrane lipid peroxidation, is increased in AD brain. The alpha class of glutathione S-transferase (GST) can detoxify HNE and plays an important role in cellular protection against oxidative stress. The export of the glutathione conjugate of HNE is required to fully potentiate the GST-mediated protection. The multidrug resistance protein-1 (MRP1) and GST proteins may act in synergy to confer cellular protection. In the present study, we studied oxidative modification of GST and MRP1 in AD brain by immunoprecipitation of GST and MRP1 proteins followed by Western blot analysis using anti-HNE antibody. The results suggested that HNE is covalently bound to GST and MRP1 proteins in excess in AD brain. Collectively, the data suggest that HNE may be an important mediator of oxidative stress-induced impairment of this detoxifying system and may thereby play a role in promoting neuronal cell death. The results from this study also imply that augmenting endogenous oxidative defense capacity through dietary or pharmacological intake of antioxidants may slow down the progression of neurodegenerative processes in AD.
Ann Neurol. 2002 Aug;52(2):175-9.
Peripheral F2-isoprostanes and F4-neuroprostanes are not increased in Alzheimer’s disease.
Montine TJ, Quinn JF, Milatovic D, Silbert LC, Dang T, Sanchez S, Terry E, Roberts LJ 2nd, Kaye JA, Morrow JD.
Quantitative biomarkers of oxidative damage, such as the F(2)-isoprostanes (IsoPs) and F(4)-neuroprostanes (F(4)-NeuroPs), may be useful in assessing progression and response to therapeutics in patients with Alzheimer’s disease. F(2)-IsoPs and F(4)-NeuroPs are reproducibly increased in brain and cerebrospinal fluid of Alzheimer’s disease patients; however, results in blood and urine have been conflicting. We tested the hypothesis that F(2)-IsoPs and F(4)-NeuroPs in plasma or urine quantitatively reflect oxidative damage to the central nervous system. Our results showed that urine levels of F(2)-IsoPs or their major metabolite were not significantly different between 56 Alzheimer’s disease patients and 34 controls. In addition, urine and cerebrospinal fluid F(2)-IsoP levels in 32 Alzheimer’s disease patients did not correlate. Supporting these conclusions, elevated rat cerebral F(2)-IsoPs and F(4)-NeuroPs after systemic exposure to kainic acid were not associated with a significant change in their plasma or urine levels. These results show that plasma and urine F(2)-IsoPs and F(4)-NeuroPs do not accurately reflect central nervous system levels of these biomarkers and are not reproducibly elevated in body fluids outside of central nervous system in Alzheimer’s disease patients. These results should guide the organization of clinical trials now being planned for patients with Alzheimer’s disease.
Ann Neurol. 1998 Sep;44(3):410-3.
Cerebrospinal fluid F2-isoprostane levels are increased in Alzheimer’s disease.
Montine TJ, Markesbery WR, Morrow JD, Roberts LJ 2nd.
Postmortem studies have associated Alzheimer’s disease (AD) with regionally increased oxidative damage to brain. Lacking, however, is a specific marker of oxidative damage to brain that may be measured during life. We tested the hypothesis that cerebrospinal fluid (CSF) concentrations of F2-isoprostanes (F2-IsoPs), stable products of arachidonate peroxidation, are increased in CSF of AD patients. CSF from lateral ventricles (VF) was analyzed from 11 AD patients and 11 control subjects who participated in a rapid autopsy program. VF F2-IsoP concentrations were significantly elevated in AD patients compared with control subjects (72 +/- 7 vs 46 +/- 4 pg/ml) and were significantly linearly correlated with brain weight (-0.3 pg/ml/g, r2 = 0.32). These results suggest that quantification of CSF F2-IsoP concentrations may provide a useful biomarker of central nervous system oxidative damage in AD.
JPET June 1, 2000 vol. 293 no. 3 912-920
Isoprostanes, Novel Eicosanoids That Produce Nociception and Sensitize Rat Sensory Neurons1
Angela R. Evans, Heidi Junger, Michael D. Southall, Grant D. Nicol, Linda S. Sorkin, James T. Broome, Timothy W. Bailey, Michael R. Vasko
Isoprostanes are a novel class of eicosanoids primarily formed by peroxidation of arachidonic acid. Because of their potential as inflammatory and/or hyperalgesic agents whose formation is largely independent of cyclooxygenases, we examined whether 8-iso prostaglandin E2 (8-iso PGE2) or 8-iso prostaglandin F2α (8-iso PGF2α) reduces mechanical and thermal withdrawal threshold in rats, and whether they sensitize rat sensory neurons. Injection of 1 μg of 8-iso PGE2 (in 2.5 μl) into the hindpaw of rats significantly reduced mechanical and thermal withdrawal thresholds, whereas 1 μg of 8-iso PGF2α elicited a transient decrease in only the mechanical withdrawal threshold. Both isoprostanes enhanced the firing of C-nociceptors in a concentration-dependent manner when injected into peripheral receptive fields. Exposing sensory neurons grown in culture to 1 μM 8-iso PGE2 or 8-iso PGF2α augmented the number of action potentials elicited by a ramp of depolarizing current. In contrast, 8-iso PGE2 but not 8-iso PGF2α enhanced the release of substance P- and calcitonin gene-related peptide-like immunoreactivity from isolated sensory neurons. Ten micromolar 8-iso PGE2 stimulated peptide release directly, whereas treatment with 1 μM 8-iso PGE2 augmented the release evoked by either bradykinin or capsaicin. Pretreating neuronal cultures with the nonsteroidal anti-inflammatory drug ketorolac did not alter the sensitizing action of 8-iso PGE2 on peptide release, suggesting that this action of the isoprostane was not secondary to the production of prostaglandins via the cyclooxygenase pathway. These data support the notion that isoprostanes are an important class of inflammatory mediators that augment nociception.
The amount of DHA in the brain (and other tissues) increases with aging and its breakdown products, including neuroprostanes, are associated with dementia. Higher levels of DHA and total PUFA are found in the plasma of demented patients (Laurin, et al., 2003). -Ray Peat, PhD
J Alzheimers Dis. 2003 Aug;5(4):315-22.
Omega-3 fatty acids and risk of cognitive impairment and dementia.
Laurin D, Verreault R, Lindsay J, Dewailly E, Holub BJ.
It has been suggested that the dietary intake of omega-3 polyunsaturated fatty acids could be inversely related to the risk of dementia and cognitive decline. This analysis examined the association between plasma concentration of omega-3 polyunsaturated fatty acids and prevalence and incidence of cognitive impairment and dementia. Data are reported on subjects 65 years or older who had a complete clinical evaluation at the first two waves (1991-1992 and 1996-1997) of the Canadian Study of Health and Aging. Main outcome measures were cognitive impairment and dementia by mean relative plasma concentrations of fatty acids in the phospholipid fraction at baseline. Results were adjusted for age, sex, education, smoking, alcohol intake, body mass index, history of cardiovascular disease, and apolipoprotein E e4 genotype. In the cross-sectional analysis, no significant difference in omega-3 polyunsaturated fatty acid concentrations was observed between controls and both prevalent cases of cognitive impairment and dementia. In the prospective analysis, a higher eicosapentaenoic acid (p < 0.01) concentration was found in cognitively impaired cases compared to controls while higher docosahexaenoic acid (p < 0.07), omega-3 (p < 0.04) and total polyunsaturated fatty acid (p < 0.03) concentrations were found in dementia cases. These findings do not support the hypothesis that omega-3 polyunsaturated fatty acids play a protective role in cognitive function and dementia.
Women, estrogen, DHA, acrolein, Alzheimer’s:
“For example, the brain toxic effects of estrogen were usually neglected, and the much higher incidence of Alzheimer’s disease in women was usually interpreted as evidence that the disease is caused by a deficiency of estrogen. The neurotoxic effects of lipid peroxides and prostaglandins were ignored, while fish oil was advocated to prevent and treat dementia. The toxic effects of serotonin and nitric oxide were seldom considered, whle drugs to increase those were advocated to treat Alzheimer’s.” -Ray Peat, PhD
“Acrolein’s self-stimulating production from DHA is another factor that could account for the predominance of Alzheimer’s disease in women, since, under the influence of estrogen, women accumulate significantly more DHA than men (Giltay, et al., 2004), and similar effects can be seen in animal studies (McNamara, et al., 2008).” -Ray Peat, PhD
Am J Clin Nutr. 2004 Nov;80(5):1167-74.
Docosahexaenoic acid concentrations are higher in women than in men because of estrogenic effects.
Giltay EJ, Gooren LJ, Toorians AW, Katan MB, Zock PL.
During pregnancy there is a high demand for docosahexaenoic acid (DHA), which is needed for formation of the fetal brain. Women who do not consume marine foods must synthesize DHA from fatty acid precursors in vegetable foods.
We studied sex differences in DHA status and the role of sex hormones.
First, DHA status was compared between 72 male and 103 female healthy volunteers who ate the same rigidly controlled diets. Second, the effects of sex hormones were studied in 56 male-to-female transsexual subjects, who were treated with cyproterone acetate alone or randomly assigned to receive oral ethinyl estradiol or transdermal 17beta-estradiol combined with cyproterone acetate, and in 61 female-to-male transsexual subjects, who were treated with testosterone esters or randomly assigned for treatment with the aromatase inhibitor anastrozole or placebo in addition to the testosterone regimen.
The proportion of DHA was 15 +/- 4% (x +/- SEM; P < 0.0005) higher in the women than in the men. Among the women, those taking oral contraceptives had 10 +/- 4% (P = 0.08) higher DHA concentrations than did those not taking oral contraceptives. Administration of oral ethinyl estradiol, but not transdermal 17beta-estradiol, increased DHA by 42 +/- 8% (P < 0.0005), whereas the antiandrogen cyproterone acetate did not affect DHA. Parenteral testosterone decreased DHA by 22 +/- 4% (P < 0.0005) in female-to-male transsexual subjects. Anastrozole decreased estradiol concentrations significantly and DHA concentrations nonsignificantly (9 +/- 6%; P = 0.09).
Estrogens cause higher DHA concentrations in women than in men, probably by upregulating synthesis of DHA from vegetable precursors.
Psychoneuroendocrinology. 2009 May;34(4):532-9. Epub 2008 Nov 28.
Gender differences in rat erythrocyte and brain docosahexaenoic acid composition: role of ovarian hormones and dietary omega-3 fatty acid composition.
McNamara RK, Able J, Jandacek R, Rider T, Tso P.
The two-fold higher prevalence rate of major depression in females may involve vulnerability to omega-3 fatty acid deficiency secondary to a dysregulation in ovarian hormones. However, the role of ovarian hormones in the regulation of brain omega-3 fatty acid composition has not been directly evaluated. Here we determined erythrocyte and regional brain docosahexaenoic acid (DHA, 22:6n-3) composition in intact male and female rats, and in chronically ovariectomized (OVX) rats with or without cyclic estradiol treatment (2 microg/4d). All groups were maintained on diets with or without the DHA precursor alpha-linolenic acid (ALA, 18:3n-3). We report that both male (-21%) and OVX (-19%) rats on ALA+ diet exhibited significantly lower erythrocyte DHA composition relative to female controls. Females on ALA+ diet exhibited lower DHA composition in the prefrontal cortex (PFC) relative males (-5%). OVX rats on ALA+ diet exhibited significantly lower DHA composition in the hippocampus (-6%), but not in the PFC, hypothalamus, or midbrain. Lower erythrocyte and hippocampus DHA composition in OVX rats was not prevented by estrogen replacement. All groups maintained on ALA- diet exhibited significantly lower erythrocyte and regional brain DHA composition relative to groups on ALA+ diet, and these reductions were greater in males but not in OVX rats. These preclinical data corroborate clinical evidence for gender differences in peripheral DHA composition (female>male), demonstrate gender differences in PFC DHA composition (male>female), and support a link between ovarian hormones and erythrocyte and region-specific brain DHA composition.
Connecting hypothyroidism and Alzheimer’s:
P R Health Sci J. 1993 Jun;12(2):85-7.
[Alzheimer's disease: the untold story].
[Article in Spanish]
Alzheimer’s Disease. The untold story. After considering the potential relationship between amyloid deposits and myxedematous infiltrations, the hypothesis is formulated that Alzheimer’s disease may be due to functional hypothyroidism and may thus respond to thyroid therapy.
Energy production suppression and oxidative stress in brain degenerative diseases.
Life Sci. 1995;56(14):1151-71.
Bioenergetic and oxidative stress in neurodegenerative diseases.
Bowling AC, Beal MF.
Aging is a major risk factor for several common neurodegenerative diseases, including Parkinson’s disease (PD), amyotrophic lateral sclerosis (ALS), Alzheimer’s disease (AD), and Huntington’s disease (HD). Recent studies have implicated mitochondrial dysfunction and oxidative stress in the aging process and also in the pathogenesis of neurodegenerative diseases. In brain and other tissues, aging is associated with progressive impairment of mitochondrial function and increased oxidative damage. In PD, several studies have demonstrated decreased complex I activity, increased oxidative damage, and altered activities of antioxidant defense systems. Some cases of familial ALS are associated with mutations in the gene for Cu, Zn superoxide dismutase (Cu, Zn SOD) and decreased Cu, Zn SOD activity, while in sporadic ALS oxidative damage may be increased. Defects in energy metabolism and increased cortical lactate levels have been detected in HD patients. Studies of AD patients have identified decreased complex IV activity, and some patients with AD and PD have mitochondrial DNA mutations. The age-related onset and progressive course of these neurodegenerative diseases may be due to a cycling process between impaired energy metabolism and oxidative stress.
J Neuropathol Exp Neurol. 1994 Sep;53(5):508-12.
Functional alterations in Alzheimer’s disease: selective loss of mitochondrial-encoded cytochrome oxidase mRNA in the hippocampal formation.
Simonian NA, Hyman BT.
The activity of cytochrome oxidase (CO), the terminal enzyme of the electron transport chain, has been reported to be decreased in the brains of individuals with Alzheimer’s disease (AD). In experimental models, CO activity decreases following functional deafferentation of neural circuits. CO is a holoenzyme composed of 13 nuclear- and mitochondrial-encoded subunits and experimental data indicate that the change in CO activity following deafferented is controlled primarily by regulation of mitochondrial CO gene expression. It has been proposed that the hippocampal formation is deafferented in AD. We therefore hypothesized that an alteration in mitochondrial CO gene expression might underlie the reduction in CO activity in AD. Using in situ hybridization, we found a selective reduction in mRNA levels for a mitochondrial-encoded subunit, CO II, with preservation of mRNA for a nuclear-encoded subunit, CO IV, in the hippocampal formation of individuals with AD. The reduction in CO II mRNA levels was seen both in regions with neurofibrillary tangles, senile plaques, and neuronal loss and regions relatively spared from these neuropathological changes. These data suggest that the reduction in CO activity in brain regions from individuals with AD may be a result of an alteration in mitochondrial CO gene expression that extends beyond neurons directly affected by structural pathology.