The research studied mice fed a life-long diet imbalanced in omega-3 and omega-6 fatty acids, finding that in omega-3 difficient mice certain receptors in the central nervous system – which play a strategic role in neurotransmission – suffer a complete loss of function. The researchers said that this neuronal dysfunction was accompanied by depressive behaviours among the malnourished mice.
The researchers said that the new study provides the first biological components of an explanation for the observed correlation between omega-3 poor diets, which are very widespread in the industrialized world, and mood disorders such as depression.
“Given the epidemiological and clinical data linking omega-3 PUFAs [polyunsaturated fatty acids] deficiency and mood disorders, we hypothesized that lifelong malnutrition may influence synaptic functions in brain areas controlling mood.,” said the researchers, led by Olivier Manzoni and Sophie Layé, from the Université de la Méditerranée and University of Bordeaux respectively.
Omega-3 & mood
According to the research, around 30 percent of all pregnancies in the U.S are carried by obese women. The authors said however that the functional, long-term, consequences of maternal malnutrition on the brains and behavior of their children remain “mostly unknown.”
“Lipid molecules are the building blocks of the CNS. In contrast with other tissues, the CNS and retina are enriched in PUFAs: arachidonic acid and docosahexaenoic acid (DHA) …These long chain PUFAs are indispensable to the normal development and function of the CNS,” said Manzoni and Layé.
They said that linoleic acid (the precursor of arachidonic acid) and alpha-linolenic acid (the precursor of DHA) are known as essential lipids because the body cannot synthesize them from new. Therefore, it is suggested that a balanced diet containing appropriate amounts of these precursors is necessary to maintain sufficient brain levels of long chain PUFAs.
Despite their high-caloric contents, western diets are generally low in essential nutrients. Manzoni and Layé said that as such a western diet is “notorious for their low levels of omega-3 and high levels of omega-6 PUFAs.”
Low levels of omega-3 fatty acids have long been implicated in many illnesses; in particular omega-3 has been consistently linked to effects on mood disorders.
Recently NutraIngredients reported that research being performed by the US Army in Iraq may help to boost service personnel’s mood and reduce the incidence of suicide in the forces by supplementing soldiers’ diets with omega-3 to improve their mental health and stress resilience.
However, Manzoni and Layé said that the underlying synaptic alterations that may be implicated in such mood alterations are unknown.
They said that obesity and poor diet is associated with psychological morbidity, including major depression, but the underlying mechanisms are poorly understood.
In the new study the researchers used a specific diet to mimic lifelong omega-3/omega-6 imbalance of essential PUFAs in mice.
The research reported that reducing omega-3 levels markedly reduced the synaptic and behavioral functions of the cannabinoid CB1R receptor.
In the omega-3–deficient mice, the researchers found that pre-synaptic cannabinoid CB1 receptors were uncoupled from their effector proteins, and observed that a dietary-induced reduction of CB1R functions in mood-controlling structures was associated with impaired emotional behavior.
The authors said that reducing omega-3 levels in mice markedly reduced the function of the most abundant G protein–coupled receptor of the CNS – the cannabinoid CB1R receptor.
“By linking diet to altered synaptic functions of CB1R in relevant brain areas, our data provide the first synaptic substrate for the impairment of emotional behavior, including depression, associated with the low levels of omega-3 PUFAs that are frequently observed in western diets,” said Manzoni and Layé.
“These findings identify a plausible synaptic substrate for the behavioral alterations caused by the omega-3 PUFAs deficiency that is often observed in western diets,” they added.
The full study from Nature Neuroscience can be found by clicking here.
Source: Nature Neuroscience
Published online ahead of print, doi: 10.1038/nn.2736
“Nutritional omega-3 deficiency abolishes endocannabinoid-mediated neuronal functions”
Authors: M. Lafourcade, T. Larrieu, S. Mato, A. Duffaud, M. Sepers, I. Matias, et al