Biochemistry and physiology of n‐3 fatty acids

Abstract

Considering the n-3 fatty acids to be partial agonists relative to n-6 fatty acids helps consolidate into a unified interpretation the many diverse reports and controversies on the actions of these two types of essential fatty acids. Some research reports illustrate the similarities between these two types and some emphasize the differences, leaving readers to evaluate the status of n-3 fatty acids from a viewpoint that is conceptually similar to regarding a glass of water as half empty or half full. Both n-3 and n-6 types of fatty acids must be obtained through the diet because they are not synthesized de novo by vertebrates. Both types can support important physiological and developmental processes, can form eicosanoids (prostaglandins, leukotrienes, lipoxins, etc.), can be esterified to and hydrolyzed from tissue glycerolipids, and can be metabolically elongated and desaturated to a variety of highly unsaturated fatty acids. However, some nonesterified n-6 acids are vigorously converted to potent n-6 eicosanoids that exert intense agonist actions at eicosanoid receptors, whereas the n-3 acids less vigorously form n-3 eicosanoids that often produce less intense (partial) actions. Because both types owe their presence in vertebrate tissues to dietary intake, important physiological consequences follow the inadvertent selection of different average daily dietary supplies of these two types of polyunsaturated fatty acids.

α-Linolenic acid content of adipose breast tissue: a host determinant of the risk of early metastasis in breast cancer

“…In experimental animal models of mammary carcinogenesis, high n-6 PUFA diets stimulate mammary tumour growth and development as well as metastases (Carroll, 1986;Erickson & Hubbard, 1990), while long-chain n-3 PUFA (Adams et al, 1990;Cave, 1991) or 18:3,, 3 enrichment of the diet (Tinsley et al, 1981;Kamano et al, 1989;Fritsche & Johnston, 1990;Hirose et al, 1990) inhibits tumour growth. Therefore, in the rat, the effects of dietary long-chain n-3 PUFAs seem to oppose the stimulation of tumour growth induced by n-6 essential fatty acids (Lands, 1992), and 18:3,3 appears also to bear inhibitory properties.…”

Relationship between fat cell size and number and fatty acid composition in adipose tissue from different fat depots in overweight/obese humans

“…24 Part of these effects are related to changes in plasma membrane fatty acid composition 25 and eicosanoid biosynthesis. 26,27 On the other hand, n-3 PUFAs suppress fatty acid synthesis, 28 increase oxidation of fatty acids 28 and reduce triacylglycerol synthesis. 29 In general the n-3 fatty acids, particularly Fat cell data and fatty acid composition in obesity M Garaulet et al eicosapentaenoic (20:5n-3) and the docosahexaenoic (22:6 n-3) acids, are closely associated with the expression of the genes encoding lipogenic (FAS, LPL) enzymes, lipolytic (HSL), glyceroneogenic (PEPCK) enzymes, the transcription factor (C/EBPa) and leptin.…”

Decreased Glutamate/Glutamine Levels May Mediate Cytidine’s Efficacy in Treating Bipolar Depression: A Longitudinal Proton Magnetic Resonance Spectroscopy Study

“…Biochemical alterations in the structure and function of neuronal membranes can affect the intracellular and extracellular processes and synaptic neurotransmission, all of which may be involved in the pathophysiology of mood disorders (Carlezon et al, 2005;Lands, 1992;Nomura et al, 2001;Pacheco and Jope, 1996). Pyrimidines have also shown antidepressant-like effects in animal studies (Carlezon et al, 2002(Carlezon et al, , 2005, which may stem from the alteration of cerebral neurotransmission (Carlezon et al, 2002;Martinet et al, 1978Martinet et al, , 1979.…”