Fatty Acids Affect Behavior and Mood

Summary
A recent study in France examined the effect of incorporating correct levels of polyunsaturated fatty acids (PUFAs) in the diet to treat behavioral issues. PUFAs are important components of the central nervous system and should be included in the diet since they are not manufactured by the body. Though the lack of PUFAs has been associated with certain neuropsychiatric illnesses, how this occurs has not been discovered. This research project found that mood disturbances are correlated with disruption of the endocannabinoid (eCB) signaling system, a group of receptors that control some physiological processes including mood and appetite. Also, malfunctions in the “accumbens” and “prefrontal cortex” (PFC) regions of the brain have been found to cause depression and troubled emotional tendencies.

Introduction
The n-6 and n-3 varieties of PUFAs are essential nutrients and their source is diet-dependent since mammals cannot synthesize them. Modern Western diets not only are high in calories and low in nutrient value, but they also have high n-6 and low n-3 levels, leading to an imbalance of PUFA ratios. While this is related to chronic conditions like obesity and resultant disorders, it also leads to dysfunction of some areas of the brain that control mood. The researchers intended to discover the exact mechanism by which n-3 fatty acid supplementation exerts changes in the brain, and by extension how long-term or lifelong deprivation of these fatty acids affects the mood and behavior in mammals.

Methodology

  • The design simulated a lifetime of PUFA imbalance in the diet of mice.
  • The animals were allowed to mate.
  • Pregnant female mice were either fed n-3 rich diets or n-3 deficient diets throughout pregnancy and lactation. The young mice were given similar diets after weaning.
  • The young mice underwent behavioral tests and their brain tissue samples were subjected to several tests followed by statistical analysis.

Results

  • The eCB receptors affecting mood, appetite and pain in the “prefrontal cortex” and “accumbens” areas of the brain was worn out in mice fed with the n-3–deficient diet.
  • Behavioral tests recorded higher immobility, decreased swimming time, less sociability and higher displays of anxiety in the n-3–deficient mice.
  • Insufficient n-3 levels seemed to reduce the action of the cannabinoid receptor in the mice, which led to behavioral changes.

Shortcomings/next steps
The levels of eCB circulating in the brain were not estimated in the current study and these could have contributed to changes in receptor binding in the early stages. Further elaborate studies are necessary to understand whether n-3 PUFA-inadequate diets are responsible for disturbed behavior, specifically their role in depression.

Conclusion
These experiments showed clearly that permanent disruption in n-3/n-6 PUFA ratio in the diet could directly affect the emotional centers of the brain by altering the lipid biochemistry. From the findings, it can be understood that certain receptors are desensitized with the lack in n-3 PUFAs. This, in turn, leads to the poor signal conduction at synaptic junctions. This effect has been observed specifically in the prefrontal cortex and the accumbens, two regions of the brain known to be mapped to emotion, behavioral patterns and mood imbalances. Future studies should work to evaluate whether dietary supplements of n-3 PUFAs could target these specific receptors to counter negative tendencies in mood and behavior.

For More Information:
Nutritional omega-3 deficiency abolishes endocannabinoid-mediated neuronal functions
Publication Journal: Nature Neuroscience, January 2011
By Mathieu Lafourcade; Thomas Larrieu; Physiopathology of Synaptic Plasticity Group, Bordeaux Cedex, France; and Nutrition and Integrative Neurobiology, Bordeaux Cedex, France; and the University of Bordeaux, France

*FYI Living Lab Reports Are Summaries of the Original Research.


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