Re: Ketogenic Diet - Path To Transformation?
Below is another paper, available at: http://www.ncbi.nlm.nih.gov/pubmed/19049599
It was a study on epilepsy, but you will see several clues that might concern everybody, and answers to some of the questions you have been asking.
I don't know about you all, but I had to look several terms up. One that caught my attention was this PCr-Cr ratio. Here's a simple definition from Wikipedia:
So, as an explanation for "dummies", could we say that this PCr is an essential "backup battery" ? Think of times of duress, high intensity exercise, high peaks of stress, etc. Think of having al energy available from healthy mitochondria, plus this reserve of potential ATP and its regulation in case of need.
Another important "backup" soucer of energy would be ADP, aslo mentioned above:
Lastly, another term mentioned above and in the paper about Mitochondria and Bioenergetics recommended by Laura is "Oxidative phosphorylation"
It's still kind of hard to understand how all these processes take place, but I think we can get a general idea from this paper, and IMO it is quite motivating and promissing :D.
Below is another paper, available at: http://www.ncbi.nlm.nih.gov/pubmed/19049599
It was a study on epilepsy, but you will see several clues that might concern everybody, and answers to some of the questions you have been asking.
Energy Metabolism as Part of the Anticonvuslant Mechanism of the Ketogenic Diet
Kristopher Bough, PhDNIH – National Institute on Drug Abuse, Division of Pharmacotherapies and MedicalConsequences, 6001 Executive Boulevard – Room 4122, Bethesda, MD 20852
Published in final edited form as:
Epilepsia. 2008 November ; 49(Suppl 8): 91–93. doi:10.1111/j.1528-1167.2008.01846.x.
Summary
The efficacy of the ketogenic diet (KD) develops gradually over a period of 1-3 weeks, suggesting that adaptive changes in gene expression are involved in its anticonvulsant effects. Previously, we employed microarrays to define patterns of gene expression in the hippocampus of rats maintained on either a KD or control diet for three weeks. The density of mitochondria in hippocampal tissue was assessed by electron microscopy. Levels of selected energy metabolites, enzyme activities, and the effect of low glucose on synaptic transmission were also investigated in hippocampal tissue taken from either KD- or control-fed animals. We found a coordinated upregulation of transcripts encoding energy metabolism enzymes and a dramatic 46% increase in the density of mitochondria observed in neuronal processes. These changes were accompanied by an increased phosphocreatine (PCr):creatine (Cr) energy-store ratio. Consistent with heightened energy eserves, hippocampal synaptic transmission in KD-fed animals was maintained ∼50% longer compared to controls after exposure to a mild metabolic stressor. Taken together, several lines of evidence indicate that the KD enhances energy production in the brain. As a consequence, brain tissue appears to become more resistant to metabolic stress. We propose that the observed KD induced enhancements in energy metabolism help to compensate for the metabolic deficits exhibited (interictally) within epileptic foci and transient failures of GABAergic inhibition, which would otherwise favor the initiation and propagation of seizure activity.
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The ketogenic diet (KD) has long been used as an alternative treatment for intractable, pediatric epilepsy and is remarkably effective against multiple seizure types. It is comprised of >90% fat by weight, is low in carbohydrates, adequate in proteins, vitamins and minerals, and typically calorie restricted by 10-25%. During diet treatment, the body synthesizes ketone bodies as an energy supplement to the brain, since dietary sources of glucose are dramatically reduced. Despite its successful use for nearly a century, we still do not know how the KD results in improved seizure control.
Both clinical and experimental data suggest that adaptations to the KD underlie its anticonvulsant effects. In rodents, maximal seizure control develops gradually over a period of 10-14 days (Appleton & De Vivo, 1974). Similarly, in most human patients, maximal seizure control is not achieved until after two weeks of dietary therapy (Freeman et al.,2000). Therefore, we hypothesized that the adaptive changes in gene expression are involved in the anticonvulsant mechanisms of the KD.
Microarrays were employed to identify coordinated patterns of gene expression in rats maintained on a calorie-restricted KD for three weeks (Bough et al., 2006). Three hundred eighty-four transcripts were upregulated after KD treatment, whereas 274 were downregulated.[The fact that this diet can have such effects in only 3 weeks is fascinating! I wish they had given more explanations about which genes got upregulated and with downregulated, but it was probably too technical. (I'm not sure I understand the concept fully, but Laura helped me a bit and she'll probably be able to explain it better. From what I understand, upregulation means that more genes of a kind get activated, or rather, the gene transcription increases, and the opposite for downregulation. Upregulation implies that more mRNA is produced for a gene in particular, which then activates following a stimulus when needed (which is the way it is supposed to work.) But it gets better below.] Seventy percent of these transcripts could be assigned to one of eight functional categories. These included metabolism (16%), signal transduction (15.3%), growth & development (11%), biosynthesis (10%), synaptic transport (8%), transport (8%), protein biosynthesis (6.5%), miscellaneous (6.5%), immune function (5%), transcriptional regulation (4.5%), cytoskeleton (3.8%), homeostasis (3.2%) and apoptosis (2.2%). The most prominent category of genes differentially expressed following chronic KD treatment was functionally attributed to energy metabolism. Of these, remarkably, 33 of the 34 transcripts were upregulated and 21 encoded genes involve oxidative phosphorylation.
We subsequently asked whether this coordinated increase in energy metabolism transcripts was accompanied by mitochondrial biogenesis. We visually scored electron micrographs of hippocampal tissue taken from animals maintained on either a control or ketogenic diet for at least three weeks. The inter-animal variability was consistent across treatment groups(i.e., coefficient of variation, CV = 3% for both KD and controls), indicating a striking 46% increase in the density of mitochondrial profiles in tissue taken from KD-fed animals compared to controls. Most mitochondria appeared to be located in neuronal processes (i.e., dendrites or axon terminals). In support of this result, we found that 39 of the 42 genes encoding mitochondrial proteins were upregulated after the KD.
In light of these findings, we next investigated whether the production of energy metabolites was heightened within hippocampal tissue. Although ATP, ADP and AMP levels did not change appreciably after the KD, there was an increase in the phosphocreatine (PCr)–creatine (Cr) energy-store ratio and tissue levels of beta-hydroxybutyrate (BHB)[I find this, again, fascinating. Below you'll see in the notes the possible importance of PCr]. Somewhat surprisingly, concentrations of glutamate and glutamine were also elevated in hippocampal tissue from KD-fed animals versus controls. However, because most glutamate in the brain is used as an energy substrate rather than neurotransmitter, these results are consistent with notion that energy reserves in hippocampus are elevated after KD treatment.
Because neuronal energy consumption is largely dependent upon action potential and postsynaptic depolarizing activity (Attwell & Laughlin, 2001), we then asked whether the observed genetic and biochemical changes could produce a functional change in synaptic transmission. We found that reducing the glucose concentration in the perfusion mediumfrom 10 to 2 mM for 7-10 minutes reversibly depressed the slope of the field EPSP by 53±9% in control tissue; this was nearly twice that exhibited in slices made from KD-fed animals (27±8%). The latency to a −25% reduction of the fEPSP took nearly 50% longer in hippocampal KD slices than it did in controls.
How might these observed genetic, biochemical, and functional changes lead to improved seizure control? Human imaging studies have shown that interictally, epileptic foci are hypometabolic areas. More specifically, there is a concomitant loss of “metabolically inexpensive” inwardly-rectifying potassium channels and an increase in Na+/K+-ATPase activity at the same time that there is a net reduction in glucose transport via GLUT-1, perhaps uncoupling metabolic supply and demand (Janigro, 1999). These data suggest that metabolic perturbations contribute significantly to synaptic instability, epileptic hyperexcitability, and the development of seizures.[And, one would think, a lot more mental disorders] We propose that the ∼50% increase in the density of neuronal mitochondria increases ATP production capacity, where the excess high-energy phosphates are stored as PCr. The enhanced ability of neurons to produce and sustain ATP levels during heightened levels of activity should allow neurons to more readily re-fuel the energy-requiring transporters (e.g., the Na+/K+-ATPase) and stabilize the membrane potential. This action would be expected to maintain ionic homeostasis and normal synaptic function in a time of need. Indeed, our finding that hippocampal synaptic transmission in slices taken from KD-fed animals could be maintained for approximately 60% longer when exposed to a mild metabolic stressor compared to synaptic transmission in slices taken from controls is consistent with the notion that KD enhances energy production capacity and energy stores.[Given what we know about the possible future, this seems to be REALLY important. From toxins in the atmosphere to water, to the unbearable stress factors that can accompany food shortages, cataclysms, repression, the death of loves ones, etc., stress may take a huge toll on people's bodies. So, a higher tolerance to stress seems to be a major factor in being prepared and "transforming". We know how much EE helps with that, but combined with genetic changes and the wok on ourselves, we migth be much more able to cope, see and help others.]
Another consideration is that the KD-induced enhancement in energy metabolism compensates for a metabolic deficiency that compromises, in particular, GABAergic inhibition. [And what else does it compensate for? They don't know because they didn't test it. But they are talking about literally being able to compensate for genetic glitches.]This may occur via three synergistic mechanisms. First, the KD may re-establish energy stores important for GABAergic output. In cases of human temporal lobe epilepsy, the PCr/ATP energy-store ratio has been inversely correlated with the recovery of the membrane potential following a stimulus train of neuronal bursting (Williamson et al.,2005); because the creatine kinase enzyme is predominantly localized within GABAergic interneurons (Boero et al., 2003), it has been proposed that PCr and energy stores are especially critical to the maintenance of GABAergic inhibitory output. Consistent with this possibility, we found that the KD induced an elevation in the PCr/Cr energy-store ratio in rats, and a similar finding was observed previously in humans (Pan et al., 1999). These results suggest that the KD may act to metabolically re-establish energy stores and, in so doing, help maintain network GABAergic inhibitory output that might have otherwise become compromised during non-accommodating bursts of activity.
Second, the KD-induced enhancement in energy production may help prevent rundown of post-synaptic GABA A receptors. Endogenous phosphorylation of the GABA A receptor prevents rundown of GABAergic inhibitory responses (Stelzer et al., 1988). Notably, theglyceraldehyde-3-phosphate dehydrogenase (GAPDH) metabolic enzyme has been shown to be physically associated with the GABAA receptor and autophosphorylate the alpha-1subunit using ATP (Pumain & Laschet, 2006). This energy-dependent mechanism of GABA receptor phosphorylation is significantly reduced in human epileptic tissue. We found that GAPDH was significantly upregulated after KD. Furthermore, in earlier studies, electrophysiological recordings performed in KD-fed animals in vivo demonstrated that paired-pulse inhibition was enhanced at the 30-ms time point compared to controls, a measure consistent with enhanced fast, GABAA-mediated inhibition (Bough et al., 2003).
These data are consistent with the notion that the postsynaptic GABAA receptor is better able to withstand functional rundown as it likely remains in a phosphorylated state. Third, the KD-induced changes in energy metabolism also seem likely to modify the metabolism of brain amino acids (Yudkoff et al., 2007). Treatment with the KD may limit the availability of oxaloacetate to the aspartate aminotransferase reaction. As a result, glutamate becomes more accessible to the glutamate decarboxylase (GAD) reaction. This would be expected to increase the production of GABA, and, presumably, functional inhibition. Although we did not note an increase in hippocampal GABA concentration, the concentrations of both glutamate and glutamine – the essential precursors to GABA synthesis – were elevated following the KD. Diet therapy has been shown to increase the abundance of GAD in several brain regions (Cheng et al., 2004), and, in mice, KD treatment modified amino acid metabolism in a manner consistent with enhanced GABA production (Yudkoff et al., 2001).
Taken together, several lines of evidence indicate that the KD dramatically enhances energy production in the brain. This effect appears to result from adaptive changes to chronic dietary treatment which produces a coordinated upregulation of several energy metabolism genes, mitochondrial biogenesis, and an increase in energy reserves. As a consequence, brain tissue appears to become more resistant to metabolic stress. It is noteworthy that the KD only increases seizure threshold; it does not appear to terminate breakthrough seizure activity, and may actually provide a greater energy supply that exacerbates the spread ofictal activity once it has been initiated (Bough et al, 2000). We propose that KD-induced enhancements in metabolism compensate for metabolic deficits exhibited (interictally)within epileptic foci and transient failures of GABAergic inhibition (e.g., GABAA receptor rundown), which would otherwise favor the initiation and propagation of seizure activity.
Although many questions remain, the fact that a dietary regimen can have such profound therapeutic effects on neurological disease and cellular metabolism underscores the importance of elucidating the mechanistic underpinnings of the KD. Future studies will undoubtedly lead to a better understanding of the roles of cellular metabolism in normal neurological function, as well as disease, and should pave the way for the development of potent new treatment strategies for the intractable epilepsies.[In other words, they know it works, and it must be so confusing for them to imagine that ketogenic diet is good for humans, that they just can't understand why it works. But we have several clues, at least.]
I don't know about you all, but I had to look several terms up. One that caught my attention was this PCr-Cr ratio. Here's a simple definition from Wikipedia:
Phosphocreatine, also known as creatine phosphate or PCr (Pcr), is a phosphorylated creatine molecule that serves as a rapidly mobilizable reserve of high-energy phosphates in skeletal muscle and brain.
Chemistry
Phosphocreatine is formed from parts of three amino acids: arginine (Arg), glycine (Gly), and methionine (Met). It can be synthesized by formation of guanidinoacetate from Arg and Gly (in kidney) followed by methylation (S-adenosyl methionine is required) to creatine (in liver), and phosphorylation by creatine kinase (ATP is required) to phosphocreatine (in muscle); catabolism: dehydration to form the cyclic Schiff base creatinine. Phosphocreatine is synthesized in the liver and transported to the muscle cells, via the bloodstream, for storage.
The creatine phosphate shuttle facilitates transport of high energy phosphate from mitochondria.
Function
Phosphocreatine can anaerobically donate a phosphate group to ADP to form ATP during the first 2 to 7 seconds following an intense muscular or neuronal effort. Conversely, excess ATP can be used during a period of low effort to convert creatine to phosphocreatine. The reversible phosphorylation of creatine (i.e., both the forward and backward reaction) is catalyzed by several creatine kinases. The presence of creatine kinase (CK-MB, MB for muscle/brain) in plasma is indicative of tissue damage and is used in the diagnosis of myocardial infarction.[1] The cell's ability to generate phosphocreatine from excess ATP during rest, as well as its use of phosphocreatine for quick regeneration of ATP during intense activity, provides a spatial and temporal buffer of ATP concentration. In other words, phosphocreatine acts as high-energy reserve in a coupled reaction; the energy given off from donating the phosphate group is used to regenerate the other compound - in this case, ATP. Phosphocreatine plays a particularly important role in tissues that have high, fluctuating energy demands such as muscle and brain.
So, as an explanation for "dummies", could we say that this PCr is an essential "backup battery" ? Think of times of duress, high intensity exercise, high peaks of stress, etc. Think of having al energy available from healthy mitochondria, plus this reserve of potential ATP and its regulation in case of need.
Another important "backup" soucer of energy would be ADP, aslo mentioned above:
Adenosine diphosphate, abbreviated ADP, is a nucleoside diphosphate. It is an ester of pyrophosphoric acid with the nucleoside adenosine. ADP consists of the pyrophosphate group, the pentose sugar ribose, and the nucleobase adenine.
ADP is the product of ATP dephosphorylation by ATPases. ADP is converted back to ATP by ATP synthases. ATP is an important energy transfer molecule in cells.
ADP is stored in dense bodies inside blood platelets and is released upon platelet activation. ADP interacts with a family of ADP receptors found on platelets (P2Y1, P2Y12 and P2X1), leading to further platelet activation.[1] ADP in the blood is converted to adenosine by the action of ecto-ADPases, inhibiting further platelet activation via adenosine receptors.
ADP is the end-product that results when ATP loses one of its phosphate groups located at the end of the molecule.[2] The conversion of these two molecules plays a critical role in supplying energy for many processes of life.[2] The deletion of one of ATP’s phosphorus bonds generates approximately 31 kilojoules per Mole of ATP (7.3 kcal).[3] ADP can be converted, or powered back to ATP through the process of releasing the chemical energy available in food; in humans this is constantly performed via aerobic respiration in the mitochondria.[2] Plants use photosynthetic pathways to convert and store the energy from sunlight, via conversion of ADP to ATP.[3] Animals use the energy released in the breakdown of glucose and other molecules to convert ADP to ATP, which can then be used to fuel necessary growth and cell maintenance.[2]
Lastly, another term mentioned above and in the paper about Mitochondria and Bioenergetics recommended by Laura is "Oxidative phosphorylation"
Oxidative phosphorylation (or OXPHOS in short) is a metabolic pathway that uses energy released by the oxidation of nutrients to produce adenosine triphosphate (ATP). Although the many forms of life on earth use a range of different nutrients, almost all aerobic organisms carry out oxidative phosphorylation to produce ATP, the molecule that supplies energy to metabolism. This pathway is probably so pervasive because it is a highly efficient way of releasing energy, compared to alternative fermentation processes such as anaerobic glycolysis.
During oxidative phosphorylation, electrons are transferred from electron donors to electron acceptors such as oxygen, in redox reactions. These redox reactions release energy, which is used to form ATP. In eukaryotes, these redox reactions are carried out by a series of protein complexes within the cells intermembrane wall mitochondria, whereas, in prokaryotes, these proteins are located in the cells' intermembrane space. These linked sets of proteins are called electron transport chains. In eukaryotes, five main protein complexes are involved, whereas in prokaryotes many different enzymes are present, using a variety of electron donors and acceptors.
The energy released by electrons flowing through this electron transport chain is used to transport protons across the inner mitochondrial membrane, in a process called chemiosmosis. This generates potential energy in the form of a pH gradient and an electrical potential across this membrane. This store of energy is tapped by allowing protons to flow back across the membrane and down this gradient, through a large enzyme called ATP synthase. This enzyme uses this energy to generate ATP from adenosine diphosphate (ADP), in a phosphorylation reaction. This reaction is driven by the proton flow, which forces the rotation of a part of the enzyme; the ATP synthase is a rotary mechanical motor.
[The next remak is important, IMO, because althout OXPHOS is very important, too much of it can be dangerous, Thus, too much aerobic exercise(which increases OXPHOS) and not enough resistance exercise can be detrimental. And it can be counterproductive at times when a need for protection against "poisons" is necessary.] Although oxidative phosphorylation is a vital part of metabolism, it produces reactive oxygen species such as superoxide and hydrogen peroxide, which lead to propagation of free radicals, damaging cells and contributing to disease and, possibly, aging (senescence). The enzymes carrying out this metabolic pathway are also the target of many drugs and poisons that inhibit their activities.
It's still kind of hard to understand how all these processes take place, but I think we can get a general idea from this paper, and IMO it is quite motivating and promissing :D.