Sunday, August 18, 2013

FATTY ACID AMIDE (OEA) INVOLVED IN DOPAMINE REGULATION OF FEEDING BEHAVIORS

Until recently fats were considered mere sources of energy and as components of biological membranes. However, research over the past 10-15 years has demonstrated a widely diverse array of biological activities associated with fatty acids and fatty acid derivatives as well as other lipid compounds. Bioactive lipids span the gamut of structural entities from simple saturated fatty acids to complex molecules such as those derived from various omega-3 and omega-6 fatty acids and those derived from sphingosine. All bioactive lipids exert their effects through binding to specific receptors, many of which are members of the G-protein coupled receptor (GPCR) family and also many of which have just recently been characterized. Bioactive lipids play important roles in energy homeostasis, cell proliferation, metabolic homeostasis, and regulation of inflammatory processes.

Oleoylethanolamide (OEA) is very important and potent member of the bioactive lipid family. This molecule is a member of the fatty-acid ethanolamide family that includes palmitoylethanolamide (PEA) and N-arachidonoylethanolamide (anandamide). Anandamide was identified as an endogenous ligand (endocannabinoid) for the cannabinoid receptors.

For more details on anandamide and other endocannabinoid functions go to the Endocannabinoids page of my website.

OEA is produced by mucosal cells in the proximal small intestine from dietary oleic acid. Synthesis of OEA occurs on demand within the membrane of the cell. OEA has been shown to activate the fatty acid-sensing GPCR identified as GPR119 as well as the non-selective gated cation channel TRPV1 (transient receptor potential vanilloid 1), and to interact with intestinal fatty acid translocase (FAT/CD36) for uptake from the gut. Although the evidence is strong indicating that OEA may be the endogenous ligand for GPR119, its' interaction with FAT/CD36 is required for the satiety response elicited by this bioactive lipid. The demonstration that OEA is the most active endogenous ligand for GPR119 is of particular interest since previous work has demonstrated that OEA, when administered to laboratory animals, causes a significant reduction in food intake and body weight gain. These effects of OEA are the result of the activation of the nuclear receptor PPARĪ± resulting in increased expression of fatty acid translocase and modification of feeding behavior and motor activity.

For more details on oleoylethanolamide (OEA) go to the Bioactive Lipids page of my web site.

A recent paper just e-published in the journal Science demonstrates that OEA plays a critical role in the responses of the limbic system of the brain to the neurotransmitter, dopamine. Dopamine is known to exert a wide range of responses within the CNS and is of particular importance in the establishment of reward circuitry as relates to feeding behaviors and drug seeking behaviors.


Several studies in humans and in laboratory animals have shown a link between obesity, particularly associated with a high-fat diet, and a decrease in dopamine release within the brain. This decrease in dopamine release is suspected to exacerbate obesity by provoking compensatory overfeeding as one way to restore reward sensitivity. Precisely how a high fat diet exerts a negative effect on CNS dopamine release is not yet fully understood. What is now known as a result of the finding in this recent Science paper is that administration of OEA to rodents is sufficient to re-establish the release of dopamine in response to a high-fat diet. The OEA (or vehicle control) in these experiments was administered intraduodenally and then the effects of feeding either low-fat or high-fat diets on dopamine release was examined. As a starting point, dopamine release was assayed in mice fed the high-fat diet or the low-fat diet. The high-fat diet mice failed to elicit the typical calorie-dependent dopamine release. In the low-fat diet fed animals consumption of a high calorie bolus of food elicited a strong dopamine release that was not affected either way by prior administration of OEA. On the other hand the high-fat diet fed animals showed a level of dopamine release that was similar to that of the low-fat diet fed animals ONLY after OEA administration. In addition, OEA administration was shown to produce an anorectic effect (lack of desire for food intake) in both low-fat and high-fat diet animals fed a bolus of high-calorie food. However, OEA produced these anorectic effects during oral low-fat intake in the low-fat diet fed animals while stimulating low-fat intake in the high-fat diet animals. Another consistent result from these experiments was that OEA administration resulted in decreased weight gain and a desire for fat intake in the high-fat diet fed mice.

The take home from this study is that there is great potential for the use of compounds, such as OEA, to re-establish the gut-lipid signaling pathways that beneficially regulate dopamine-mediated reward behaviors related to food intake and appetite. Of particular interest to human diets is the fact that extra-virgin olive oil has a high concentration of oleic acid which if the precursor to the gut synthesis of OEA. Another oil high in oleic acid, but not as readily available as a food-grade oil, is argan oil. Argan oil is better known for its use in cosmetics However, one can find this highly beneficial oil in food quality on the internet in bottled form as well as in gel cap form.


If you start spreading the word about the health benefits of argan oil I would appreciate you mentioning that you heard it from Dr. Michael W. King, and NOT Dr. Oz!!!

Tuesday, August 6, 2013

MATERNAL DIABETES ALTERS EPIGENOME OF HER EGGS WHICH AFFECTS THE RESULTING EMBRYO

I have posted several times here about the consequences of a mothers dietary intake and weight status on the future health of her unborn child. There are numerous reports in the literature that clearly point to the fact that if a mother consumes a diet in excess of her caloric needs, her unborn child will have a significantly altered pattern of neurotransmitter expression related to the control of appetite and feeding behavior. In other word,s the child/children of an overweight/obese mother will have a strong innate desire to consume a diet of excess caloric need, will have a significant increase in the likelihood of becoming obese, and suffer the consequences of that inappropriate diet such as type 2 diabetes, hypertension, and cardiovascular disease. This very fact is resulting in an uncontrolled explosion in the obese population in the US and other industrialized nations who consume a typical "Western-style" diet particularly among adolescent children. 

A new report just published in the journal, Biology of Reproduction, presents further evidence linking maternal diabetes and epigenetic alterations in offspring due to changed in the expression of imprinted genes in oocytes (eggs).

Maternal Diabetes Causes Alterations of DNA Methylation Statuses of Some Imprinted Genes in Murine Oocytes

bit.ly/19DzUtb

This study examined the effects/consequences of maternal diabetes on the methylation status of several imprinted genes during embryonic development in laboratory mice. Imprinted genes are a class of genes whose expression pattern is dictated by the parental origin and this expression pattern is controlled by the methylation status of the imprinted gene, or in some cases to the alelle-specific state of histone methylation or acetylation. The first imprinted gene identified was the insulin-like growth factor 2 (IGF-2) gene. At least 80 genes are known to be imprinted in the human genome. Defects in the proper expression of numerous imprinted loci result in potentially devastating disorders.

You can read more about some of the most common imprinting diseases in the Diseases Associated with Genomic Imprinting page on themedicalbiochemistrypage.org

Many previous studies demonstrated that oocytes exposed to diabetic conditions during folliculogenesis exhibit negative effects related to maturation and developmental potential. Mitochondrial function, glucose metabolism pathways, and communications between cumulus cells and the oocyte are all changed in follicles of maternal diabetic mice.

In non-imprinted regions of the chromosomes, the parental epigenetic marks are erased in the germ cells only to be newly established in a parental-specific manner. Once the parental-specific epigenetic marks are established, they are maintained following fertilization. In contrast, imprinted genes exhibit what are referred to as differentially methylated regions (DMRs) and these DMRs escape the genome-wide demethylation that takes place during the earliest cleavage events of embryonic development. In addition, these DMRs escape the global de novo methylation that normally occurs when the embryo undergoes implantation. Two distinct types of DMRs have been found: those that are formed following fertilization and those that are formed in the germ cells and maintained throughout development. The latter DMRs are associated with chromosomal regions termed imprinting control centers, ICRs. Therefore, defects in the proper regulation of these DMRs can lead to profound consequences for the offspring resulting from fertilization of epigenetically altered oocytes and/or sperm.

This study examined the effects of maternal diabetes on the methylation status of two maternal genes Peg3 (a zinc-finger transcription factor originally identified as "paternally expressed gene 3") and Snrpn (small nuclear ribonucleoprotein polypeptide N). What this research discovered is that maternal diabetes altered the methylation status of Peg3 in a time-dependent manner. In othre words the changes become more pronounced the longer the female was diabetic. However, in this study the methylation status of Peg3 was not altered in the oocytes of female offspring.


So there is a bad-news good-news side to this research. The bad-news is that maternal diabetes has a negative effect on oocyte maturation and epigenetic status which results in negative consequences to oocyte maturation which can, in turn, result in negative developmental outcomes for offspring but the good-news is that the study did not find that the altered maternal oocyte epigenome was "transferred" to the female offspring oocyte epigenome.