Rats given linseed oil in microemulsion forms enriches the brain synaptic membrane with docosahexaenoic acid and enhances the neurotransmitter levels in the brain

Abstract

Long chain n-3 fatty acids such as docosahexaenoic acid (DHA) are essential for the normal functioning of the brain. The vegetarian sections of the population get only alpha-linolenic acid (ALA) through their diet as a source of n-3 fatty acids. Hence, in this group of the population, the ALAs need to be converted to DHA through the action of the desaturase and the elongase enzymes. However, the conversion of the ALA to the DHA is very minimal (<2%) in mammals. Our recent studies have shown that the conversion of the ALA to the DHA can be enhanced significantly when given in the microemulsion forms. This work was undertaken to study the feasibility of enriching the synaptic membranes of rat brain with the DHA by providing the microemulsions of linseed oil (LSO) containing ALA. The rats were fed LSO as microemulsions in whey protein or in lipoid for 60 days through gavage. The rats given LSO microemulsions in lipoid showed higher levels of the DHA in the brain synaptic membrane when compared to rats given LSO without emulsion formation. This decreased the n-6/n-3 fatty acid ratio of the brain synaptic membrane. This also increased the membrane fluidity, Na⁺-K⁺ ATPase activity, and acetylcholine esterase activity in the synaptic membranes. Furthermore, Ca²⁺-Mg²⁺ ATPase activity, monoamine oxidase A and monoamine oxidase B activity was lowered in the rats given LSO in the microemulsion form. The dopamine and the serotonin levels in the brain were increased in the rats given LSO in the microemulsion form with lipoid as compared to those given LSO without the preemulsion formation. This study indicates that the LSO microemulsions in the lipoid can enhance the synaptic membrane DHA levels and influence the functions associated with the brain in a beneficial manner.

Keywords:

• Linseed oil microemulsion
• Lipoid
• Brain synaptic membrane
• Alpha-linolenic acid
• Docosahexaenoic acid

Acknowledgment

The authors thank Ram Rajasekharan, Director of the Central Food Technological Research Institute, Mysore, for his encouragement and support for this work. D. Sugasini acknowledges the grant of a Senior Research Fellowship by the Indian Council of Medical Research, New Delhi, India. The authors also thank Sridevi Annapurna Singh for help in the membrane fluidity measurements and Poorna Chandra Rao for help in the neurotransmitter analysis.