Poor prenatal nutrition, acting through epigenetic processes, induces persistent changes in offspring phenotype. We investigated the effect of maternal fat intake on polyunsaturated fatty acid (PUFA) status and on the epigenetic regulation of Fads2, encoding Δ6 desaturase (rate limiting in PUFA synthesis), in the adult offspring. Rats (n=6 per dietary group) were fed either 3.5% (w/w), 7% (w/w) or 21% (w/w) butter or fish oil (FO) from 14 days preconception until weaning. Offspring (n=6 males and females per dietary group) were fed 4% (w/w) soybean oil until postnatal day 77. 20:4n-6 and 22:6n-3 levels were lower in liver phosphatidylcholine (PC) and phosphatidylethanolamine and plasma PC (all P<.0001) in offspring of dams fed 21% than 3.5% or 7% fat regardless of type. Hepatic Fads2 expression related inversely to maternal dietary fat. Fads2 messenger RNA expression correlated negatively with methylation of CpGs at −623, −394, −84 and −76 bases relative to the transcription start site (all P<.005). Methylation of these CpGs was higher in offspring of dams fed 21% than 3.5% or 7% fat; FO higher than butter. Feeding adult female rats 7% fat reduced 20:4n-6 status in liver PC and Fads2 expression and increased methylation of CpGs −623, −394, −84 and −76 that reversed in animals switched from 7% to 4% fat diets. These findings suggest that fat exposure during development induces persistent changes, while adults exhibit a transient response, in hepatic PUFA status in offspring through epigenetic regulation of Fads2. Thus, epigenetic regulation of Fads2 may contribute to short- and long-term regulation of PUFA synthesis.

In a model of chronic hind limb ischaemia, we examined whether impaired muscle blood flow, particularly during exercise, is partly due to modification of the reactivity of skeletal muscle resistance vessels by prolonged low blood flow. Two or 5 weeks after unilateral iliac artery ligation, terminal (A4) and preterminal (A3) arterioles of extensor digitorum longus muscle were viewed by intravital microscopy using epi-illumination, and diameter changes to topical application of endothelium-dependent (bradykinin, acetylcholine) and endothelium-independent (adenosine, sodium nitroprusside and noradrenaline) agonists measured. Chronic ischaemia had no effect on resting diameters of A3 or A4 vessels. Two weeks after ligation, dilation to bradykinin was attenuated by 75% for A3 and 50% for A4 arterioles (p < 0.01 vs. control) and responses to acetylcholine were reversed from dilation to constriction (A3: control diameter change +29%, 2-week-ligated –17%; A4: control 18%, 2-week-ligated –13%). Five weeks after ligation, these effects were still apparent and, additionally, dilation to adenosine and sodium nitroprusside and constriction to noradrenaline were reduced. Thus, impaired dilation, most likely due to endothelial dysfunction, is an early manifestation of altered reactivity in the microcirculation of chronically ischaemic muscles, with functional impairment of vascular smooth muscle as a later consequence. These changes occurred despite modest improvements in muscle blood flow and perfusion pressure over the same time. These changes will act to the detriment of blood flow in contracting muscles and could limit the outcome of interventions to restore flow such as angioplasty or surgical bypass.

Nutrition during development affects risk of future cardiovascular disease. Relatively little is known about whether the amount and type of fat in the maternal diet affect vascular function in the offspring. To investigate this, pregnant and lactating rats were fed either 7%(w/w) or 21%(w/w) fat enriched in either18:2n-6, trans fatty acids, saturated fatty acids, or fish oil. Their offspring were fed 4%(w/w) soybean oil from weaning until day 77. Type and amount of maternal dietary fat altered acetylcholine (ACh)-mediated vaso-relaxation in offspring aortae and mesenteric arteries, contingent on sex. Amount, but not type, of maternal dietary fat altered phenylephrine (Pe)-induced vasoconstriction in these arteries. Maternal 21% fat diet decreased 20:4n-6 concentration in offspring aortae. We investigated the role of Δ6 and Δ5 desaturases, showing that their inhibition in aortae and mesenteric arteries reduced vasoconstriction, but not vaso-relaxation, and the synthesis of specific pro-constriction eicosanoids. Removal of the aortic endothelium did not alter the effect of inhibition of Δ6 and Δ5 desaturases on Pe-mediated vasoconstriction. Thus arterial smooth muscle 20:4n-6 biosynthesis de novo appears to be important for Pe-mediated vasoconstriction. Next we studied genes encoding these desaturases, finding that maternal 21% fat reduced Fads2 mRNA expression and increased Fads1 in offspring aortae, indicating dysregulation of 20:4n-6 biosynthesis. Methylation at CpG −394 bp 5′ to the Fads2 transcription start site predicted its expression. This locus was hypermethylated in offspring of dams fed 21% fat. Pe treatment of aortae for 10 minutes increased Fads2, but not Fads1, mRNA expression (76%; P<0.05). This suggests that Fads2 may be an immediate early gene in the response of aortae to Pe. Thus both amount and type of maternal dietary fat induce altered regulation of vascular tone in offspring though differential effects on vaso-relaxation, and persistent changes in vasoconstriction via epigenetic processes controlling arterial polyunsaturated fatty acid biosynthesis.

Nitric oxide release from CPO-27 MOFs and the resulting coronary artery relaxation response are tuned by isomorphous substitution of Ni into the MOF framework.