Brain PUFA Concentrations Are Differentially Affected by Interactions of Diet, Sex, Brain Regions, and Phospholipid Pools in Mice

Abstract

Background: PUFAs play vital roles in the development, maintenance, and functioning of circuitries that regulate reward and social behaviors. Therefore, modulations in PUFA concentrations of these brain regions may disrupt reward and social circuitries contributing to mood disorders, developmental disabilities, and addictions. Though much is known about regional and phospholipid-pool-specific PUFA concentrations, less is known about the effects of dietary interventions that concurrently lowers n-6 PUFA and supplements n-3 PUFA, on brain PUFA concentrations. There is even less knowledge on the effects of sex on brain PUFA concentrations.

Objective: This study aimed to comprehensively examine the interaction effects of diet (D), sex (S), brain regions (BR), and phospholipid pools (PL) on brain PUFA concentrations.

Methods: Male and female C57BL/6J mice were fed 1 of 4 custom-designed diets varying in linoleic acid (LNA) (8 en% or 1 en%) and eicosapentaenoic acid/docosahexaenoic acid (EPA/DHA) (0.4 en% or 0 en%) concentrations from in utero to 15 weeks old. At 15 weeks old, the prefrontal cortex, dorsal striatum, and cerebellum were collected. Fatty acids of 5 major PL were quantified by GC-flame ionization detection. Repeated measures ANOVA was used to test for differences among the groups for D, S, BR, and PL.

Results: No significant 4-way interactions on PUFA concentrations. DHA, predominant n-3 PUFA, concentrations were dependent on significant D × BR × PL interactions. DHA concentration was not affected by sex. Arachidonic acid (ARA; predominant n-6 PUFA) concentrations were not dependent on 3-way interactions. However, significant 2-way D × PL, BR × PL, and D × Sinteractions affected ARA concentrations. Brain fatty acid concentrations were differentially affected by various combinations of D, S, BR, and PL interactions.

Conclusion: Though DHA concentrations are not affected by sex, ARA concentrations are affected by interactions of the 4 variables examined. This study provides comprehensive references in the investigation of complex interactions between factors that affect brain PUFA concentrations in mice.

Keywords: ARA; DHA; brain; fatty acid concentration; sex difference.

FIGURE 1

Brain arachidonic acid concentrations of mice fed diets varying in dietary LNA (8 en% or 1 en%) and EPA/DHA (0.4 en% or 0 en%) concentrations. (A) Diet by phospholipid pool interaction; (B) brain region by PL interaction; (C) D by sex interaction. Bars are estimated marginal mean ± SE. Sample size: 8LNA = 27, 1LNA = 30, 8LED = 33, 1LED = 30; PFC = 39–37, STR = 39–40, CB = 40. Bars without common letters denote significantly different groups (a >b >c, P < 0.05 by the Sidak multiple comparison test). ARA, arachidonic acid; 8LNA, 8 en% LNA, 0 en% EPA/DHA diet; 1LNA, 1 en% LNA, 0 en% EPA/DHA diet; 8LED, 8 en% LNA, 0.4 en% EPA/DHA; 1LED, 1 en% LNA, 0.4 en% EPA/DHA; BR, brain region; CB, cerebellum; CerPCho, ceramide phosphocholine (sphingomyelin); ChoGpl, choline glycerophospholipids; D, diet; EtnGpl, ethanolamine glycerophospholipids; LNA, linoleic acid; PFC, prefrontal cortex; PL, phospholipid pool; PtdIns, phosphatidylinositol; PtdSer, phosphatidylserine; S, sex; STR, dorsal striatum.

FIGURE 2

Brain α-linolenic acid concentrations of mice fed diets varying in dietary LNA (8 en% or 1 en%) and EPA/DHA (0.4 en% or 0 en%) concentrations that had significant brain region by phospholipid pool interaction. Bars are estimated marginal mean ± SE. Sample size: PFC = 39–37, STR = 39–40, CB = 40. Bars without common letters denote significantly different groups (a >b >c, P < 0.05 by the Sidak multiple comparison test). ALA, α-linolenic acid; BR, brain region; CB, cerebellum; CerPCho, ceramide phosphocholine (sphingomyelin); ChoGpl, choline glycerophospholipids; EtnGpl, ethanolamine glycerophospholipids; LNA, linoleic acid; PFC, prefrontal cortex; PL, phospholipid pool; PtdIns, phosphatidylinositol; PtdSer, phosphatidylserine; STR, dorsal striatum.

FIGURE 3

Brain palmitic acid and stearic acid concentrations of mice fed diets varying in dietary LNA (8 en% or 1 en%) and EPA/DHA (0.4 en% or 0 en%) concentrations. (A) Diet by phospholipid pool interaction on PA concentrations; (B) BR by PL interaction on PA concentrations; (C) D by PL interaction on SA concentrations; (D) BR by PL interaction on SA concentrations; (E) D by sex (S) interaction on SA concentrations. Bars are estimated marginal mean ± SE. Sample size: 8LNA = 27, 1LNA = 30, 8LED = 33, 1LED = 30; PFC = 39–37, STR = 39–40, CB = 40. Bars without common letters denote significantly different groups (a >b >c, P < 0.05 by the Sidak multiple comparison test). 8LNA, 8 en% LNA, 0 en% EPA/DHA diet; 1LNA, 1 en% LNA, 0 en% EPA/DHA diet; 8LED, 8 en% LNA, 0.4 en% EPA/DHA; 1LED, 1 en% LNA, 0.4 en% EPA/DHA; BR, brain region; CB, cerebellum; CerPCho, ceramide phosphocholine (sphingomyelin); ChoGpl, choline glycerophospholipids; D, diet; EtnGpl, ethanolamine glycerophospholipids; LNA, linoleic acid; PA, palmitic acid; PFC, prefrontal cortex; PL, phospholipid pool; PtdIns, phosphatidylinositol; PtdSer, phosphatidylserine; SA, stearic acid; STR, dorsal striatum.