Effects of a high n-3 fatty acid diet on membrane lipid composition of heart and skeletal muscle in normal swine and in swine with the genetic mutation for malignant hyperthermia

Membrane binding of Neuronal Calcium Sensor-1 (NCS1)

Neuronal Calcium Sensor-1 (NCS1) belongs to the family of Neuronal Calcium Sensor (NCS) proteins. NCS1 is composed of four EF-hand motifs and an N-terminal myristoylation. However, the presence of a calcium-myristoyl switch in NCS1 and its role in the membrane binding are controversial. The model of Langmuir lipid monolayers is thus used to mimic the cell membrane in order to characterize the membrane interactions of NCS1. Two binding parameters are calculated from monolayer measurements: the maximum insertion pressure, up to which protein binding is energetically favorable, and the synergy, reporting attractive or repulsive interactions with the lipid monolayers. Binding membrane measurements performed in the presence of myristoylated NCS1 reveal better binding interactions for phospholipids composed of phosphoethanolamine polar head groups and unsaturated fatty acyl chains. In the absence of calcium, the membrane binding measurements are drastically modified and suggest that the protein is more strongly bound to the membrane. Indeed, the binding of calcium by three EF-hand motifs of NCS1 leads to a conformation change. NCS1 arrangement at the membrane could thus be reshuffled for better interactions with its substrates. The N-terminal peptide of NCS1 is composed of two amphiphilic helices involved in the membrane interactions of NCS1. Moreover, the presence of the myristoyl group has a weak influence on the membrane binding of NCS1 suggesting the absence of a calcium-myristoyl switch mechanism in this protein. The myristoylation could thus have a structural role required in the folding/unfolding of NCS1 which is essential to its multiple biological functions.

Membrane-stabilizing copolymers confer marked protection to dystrophic skeletal muscle in vivo

Duchenne muscular dystrophy (DMD) is a fatal disease of striated muscle deterioration. A unique therapeutic approach for DMD is the use of synthetic membrane stabilizers to protect the fragile dystrophic sarcolemma against contraction-induced mechanical stress. Block copolymer-based membrane stabilizer poloxamer 188 (P188) has been shown to protect the dystrophic myocardium. In comparison, the ability of synthetic membrane stabilizers to protect fragile DMD skeletal muscles has been less clear. Because cardiac and skeletal muscles have distinct structural and functional features, including differences in the mechanism of activation, variance in sarcolemma phospholipid composition, and differences in the magnitude and types of forces generated, we speculated that optimized membrane stabilization could be inherently different. Our objective here is to use principles of pharmacodynamics to evaluate membrane stabilization therapy for DMD skeletal muscles. Results show a dramatic differential effect of membrane stabilization by optimization of pharmacodynamic-guided route of poloxamer delivery. Data show that subcutaneous P188 delivery, but not intravascular or intraperitoneal routes, conferred significant protection to dystrophic limb skeletal muscles undergoing mechanical stress in vivo. In addition, structure-function examination of synthetic membrane stabilizers further underscores the importance of copolymer composition, molecular weight, and dosage in optimization of poloxamer pharmacodynamics in vivo.

Essential fatty acids and psychiatric disorders

Psychiatric disorders are a significant source of disability worldwide. Increasing evidence indicates that disturbances of fatty acids and phospholipid metabolism can play a part in a wide range of psychiatric, neurological, and developmental disorders in adults. Essential fatty acids, ω-3 and ω-6 polyunsaturated fatty acids, play a central role in the normal development and functioning of the brain and central nervous system. The aim of this article is to discuss the overall insight into roles of essential fatty acids in the development of mental disorders (depression, schizophrenia, bipolar disorder) and, in light of the fact that disturbances of fatty acid metabolism can play a part in the above-mentioned disorders, to investigate the current knowledge of lipid abnormalities in posttraumatic stress disorder. The information in this review was obtained after extensive MEDLINE searching of each topic area through relevant published studies from the past 20 years. References from the obtained studies were also used. This review summarizes the knowledge in terms of essential fatty acids intake and metabolism, as well as evidence pointing to potential mechanisms of essential fatty acids in normal brain functioning and development of neuropsychiatric disorders. The literature shows that ω-3 fatty acids provide numerous health benefits and that changes in their concentration in organisms are connected to a variety of psychiatric symptoms and disorders, including stress, anxiety, cognitive impairment, mood disorders, and schizophrenia. Further studies are necessary to confirm ω-3 fatty acids' supplementation as a potential rational treatment in psychiatric disorders.

Electrophysiological mechanisms of the anti-arrhythmic effects of omega-3 fatty acids

Heart rhythm disorders, or arrhythmias, are a leading cause of morbidity and mortality worldwide. Omega-3 polyunsaturated fatty acids (ω3PUFAs), commonly found in fish oils and plant seeds, have recently emerged as potential anti-arrhythmic agents. The purpose of this review is to summarize the electrophysiological basis of the anti-arrhythmic properties of ω3PUFAs from clinical, animal, and cellular research. Evidence of the anti-arrhythmic effects of ω3PUFAs originated from epidemiological studies that correlated a low incidence of sudden cardiac death with high dietary ω3PUFA intake. Subsequently, multiple clinical trials have confirmed the therapeutic effects of ω3PUFAs in preventing sudden cardiac death and multiple other arrhythmia-related disorders. This has led basic scientists to investigate the effects of ω3PUFAs on several ion channels including sodium, potassium, and calcium channels, as well as Na/Ca exchangers. Therefore, ω3PUFAs may hold promise as safe and effective anti-arrhythmic agents. Nevertheless, further research is needed in areas such as: (1) identifying which form(s) of ω3PUFAs (i.e., phospholipid, triglyceride, or free) is (are) responsible for anti-arrhythmic actions; and (2) developing reproducible methods for delivery so that the appropriate form and concentration may be present at the target site to prevent and treat arrhythmias.

Omega-3 fatty acid deficiency in major depressive disorder is caused by the interaction between diet and a genetically determined abnormality in phospholipid metabolism

Omega-3 fatty acids are a type of polyunsaturated fatty acid (PUFA). A growing body of evidence suggests that this form PUFA is a useful and well tolerated treatment for major depressive disorder, a common and serious mental illness. The efficacy of omega-3 PUFA is routinely explained as being due to a deficiency caused by inadequate dietary intake of this class of fatty acid. The hypothesis considered states that low omega-3 PUFA abundance in patients with major depressive and related disorders is due to an underlying genetically determined abnormality. The hypothesis can explain why although a specific and consistent deficit in omega-3, but not omega-6, PUFA occurs in major depressive and related disorders, the literature does not consistently support the notion that this is due to deficient dietary intake. Specifically it is hypothesized that having genetically determined low activity of fatty acid CoA ligase 4 and/or Type IV phospholipase A(2) combined with the low dietary availability of omega-3 PUFA results in reduced cellular uptake of omega-3 PUFA and constitutes a risk factor for depression. The hypothesis also has important consequences for the pharmacological treatment of depression in that it predicts that administering agents which enhance phospholipid synthesis, particularly those containing ethanolamine such as CDP-ethanolamine, should be effective antidepressants especially when co-administered with omega-3 PUFA.

Essential fatty acids and the brain: possible health implications

Linoleic and alpha-linolenic acid are essential for normal cellular function, and act as precursors for the synthesis of longer chained polyunsaturated fatty acids (PUFAs) such as arachidonic (AA), eicosapentaenoic (EPA) and docosahexaenoic acids (DHA), which have been shown to partake in numerous cellular functions affecting membrane fluidity, membrane enzyme activities and eicosanoid synthesis. The brain is particularly rich in PUFAs such as DHA, and changes in tissue membrane composition of these PUFAs reflect that of the dietary source. The decline in structural and functional integrity of this tissue appears to correlate with loss in membrane DHA concentrations. Arachidonic acid, also predominant in this tissue, is a major precursor for the synthesis of eicosanoids, that serve as intracellular or extracellular signals. With aging comes a likely increase in reactive oxygen species and hence a concomitant decline in membrane PUFA concentrations, and with it, cognitive impairment. Neurodegenerative disorders such as Parkinson's and Alzheimer's disease also appear to exhibit membrane loss of PUFAs. Thus it may be that an optimal diet with a balance of n-6 and n-3 fatty acids may help to delay their onset or reduce the insult to brain functions which these diseases elicit.