Serum n‐3 Tetracosapentaenoic Acid and Tetracosahexaenoic Acid Increase Following Higher Dietary α‐Linolenic Acid but not Docosahexaenoic Acid

Abstract

n-3 Tetracosapentaenoic acid (24:5n-3, TPAn-3) and tetracosahexaenoic acid (24:6n-3, THA) are believed to be important intermediates to docosahexaenoic acid (DHA, 22:6n-3) synthesis. The purpose of this study is to report for the first time serum concentrations of TPAn-3 and THA and their response to changing dietary α-linolenic acid (18:3n-3, ALA) and DHA. The responses will then be used in an attempt to predict the location of these fatty acids in relation to DHA in the biosynthetic pathway. Male Long Evans rats (n = 6 per group) were fed either a low (0.1% of total fatty acids), medium (3%) or high (10%) ALA diet with no added DHA, or a low (0%), medium (0.2%) or high (2%) DHA diet with a background of 2% ALA for 8 weeks post-weaning. Serum n-3 and n-6 polyunsaturated fatty acid (PUFA) concentrations (nmol/mL ± SEM) were determined by gas chromatography-mass spectrometry. Serum THA increases from low (0.3 ± 0.1) to medium (5.8 ± 0.7) but not from medium to high (4.6 ± 0.9) dietary ALA, while serum TPAn-3 increases with increasing dietary ALA from 0.09 ± 0.04 to 0.70 ± 0.09 to 1.23 ± 0.14 nmol/mL. Following DHA feeding, neither TPAn-3 or THA change across all dietary DHA intake levels. Serum TPAn-3 demonstrates a similar response to dietary DHA. In conclusion, this is the first study to demonstrate that increases in dietary ALA but not DHA increase serum TPAn-3 and THA in rats, suggesting that both fatty acids are precursors to DHA in the biosynthetic pathway.

Fatty acid amide hydrolase (FAAH) regulates hypercapnia/ischemia‐induced increases in n‐acylethanolamines in mouse brain

“…; Metherel et al . ). Upon removal from heat, the reagent mixture was evaporated under nitrogen, dissolved in 100 μL of hexane, and stored in GC vials until analysis by GC‐MS.…”

“…; Metherel et al . ). The fatty acid PFB esters were injected via an Agilent 7693 auto‐sampler into a DB‐FFAP 30 m × 0.25 mm i.d.…”

“…After drying the plate at 21°C, the individual bands were visualized under ultraviolet light, after lightly spraying with 8-anilino-1-naphthalene sulfonic acid in methanol (0.1% by volume) (Wang and Gustafson 1992;Song et al 2010;Hopperton et al 2014). Bands containing free fatty acids were scraped into test tubes and extracted as previously described (Metherel et al 2017). The dried total lipid extracts were then dissolved in 100 lL of (1 : 10 : 1000, by volume) pentafluorobenzyl bromide: diisopropylamine: acetonitrile and heated at 60°C for 15 min to form the fatty acid pentafluorobenzyl (PFB) esters as previously described (Pawlosky et al 1992;Metherel et al 2017).…”

“…Bands containing free fatty acids were scraped into test tubes and extracted as previously described (Metherel et al 2017). The dried total lipid extracts were then dissolved in 100 lL of (1 : 10 : 1000, by volume) pentafluorobenzyl bromide: diisopropylamine: acetonitrile and heated at 60°C for 15 min to form the fatty acid pentafluorobenzyl (PFB) esters as previously described (Pawlosky et al 1992;Metherel et al 2017). Upon removal from heat, the reagent mixture was evaporated under nitrogen, dissolved in 100 lL of hexane, and stored in GC vials until analysis by GC-MS.…”

“…Fatty acid PFB esters were analyzed on a Agilent 5977A quadrupole mass spectrometer coupled to an Agilent 7890B gas chromatograph (Agilent Technologies, Mississauga, ON, USA) in negative chemical ionization mode, as described previously (Pawlosky et al 1992;Metherel et al 2017). The fatty acid PFB esters were injected via an Agilent 7693 auto-sampler into a DB-FFAP 30 m 9 0.25 mm i.d.…”