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In obese subjects, the loss of fat mass during energy restriction is often accompanied by a loss of muscle mass. The hypothesis that n-3 PUFA, which modulate protein homoeostasis via effects on insulin sensitivity, could contribute to maintain muscle mass during energy restriction was tested in rats fed a high-fat diet (4 weeks) rich in 18 : 1 n-9 (oleic acid, OLE-R), 18 : 3 n-3 (α-linolenic acid, ALA-R) or n-3 long-chain (LC-R) fatty acid and then energy restricted (8 weeks). A control group (OLE-ad libitum (AL)) was maintained with AL diet throughout the study. Rats were killed 10 min after an i.v. insulin injection. All energy-restricted rats lost weight and fat mass, but only the OLE-R group showed a significant muscle loss. The Gastrocnemius muscle was enriched with ALA in the ALA-R group and with LC-PUFA in the ALA-R and LC-R groups. The proteolytic ubiquitin–proteasome system was differentially affected by energy restriction, with MAFbx and muscle ring finger-1 mRNA levels being decreased in the LC-R group (−30 and −20 %, respectively). RAC-α serine/threonine-protein kinase and insulin receptor substrate 1 phosphorylation levels increased in the LC-R group (+70 %), together with insulin receptor mRNA (+50 %). The ALA-R group showed the same overall activation pattern as the LC-R group, although to a lesser extent. In conclusion, dietary n-3 PUFA prevent the loss of muscle mass associated with energy restriction, probably by an improvement in the insulin-signalling pathway activation, in relation to enrichment of plasma membranes in n-3 LC-PUFA. [ABSTRACT FROM PUBLISHER]

Linseed oil, being rich in 18 : 3n-3, represents an alternative source of n-3 PUFA in the maternal diet. However, little is known about the effect of this oil on the long chain n-3 PUFA composition of offspring, which are required for normal growth and maturation of numerous organs. The main objective of the experiment was therefore to investigate fatty acid composition of tissues from sows at the end of gestation and from piglets during the first week of postnatal life in response to maternal dietary linseed oil intake. Sows received either a lard (LAR)-based diet or a linseed oil (LSO)-based diet during gestation and lactation. Fatty acid composition was evaluated in sow plasma, placenta and milk, and in different tissues of piglets on days 0, 3, 7, 21 and 32. The LSO diet increased the proportions of n-3 PUFA and especially 22 : 6n-3 in the placenta. The carcass of LSO piglets at birth contained greater proportions of 20 : 5n-3, 22 : 5n-3 and 22 : 6n-3. The LSO sow milk exhibited greater proportions of 18 : 3n-3 compared with the LAR sow milk. The piglets suckling LSO sows had greater proportions of 18 : 3n-3, 20 : 5n-3 and 22 : 5n-3 in plasma and carcass. The proportions of 22 : 5n-3 and 22 : 6n-3 were greater in the brain of LSO piglets than in that of LAR piglets during the suckling period. In conclusion, LSO in the maternal diet during gestation and lactation increases 22 : 6n-3 concentrations in the placenta and in the foetus carcass, and it maintains 22 : 6n-3 concentrations in the brain during the first week of postnatal life. [ABSTRACT FROM PUBLISHER]

Gender and dietary fatty acids are involved in the regulation of lipid metabolism, disturbances of which can lead to pathologies such as metabolic syndrome or CVD. Possible interactions between these factors were investigated in male and female hamsters fed diets rich in either saturated fatty acids (???butter??? diet) or in ??-linolenic acid (???linseed oil??? diet). Gender effect predominated over the diet effect on cholesterol (CH) metabolism; compared to males, females exhibited lower concentrations of plasma total CH (???20%, P<0??001), LDL-CH (???40%, P<0??001) and HDL-CH (???16%, P<0??001), together with higher LDL receptor (+40%) and lower HDL receptor (???60%) hepatic content. Triacylglycerol (TG) metabolism was affected by diet above all: compared to animals fed the ???butter??? diet, those fed the ???linseed oil??? diet exhibited lower plasma (???23%, P=0??046) and liver TG (???20%, P=0??026) concentration which may result from both an increased ??-oxidation (P<0??001), without any change in PPAR?? mRNA, and a decreased hepatic lipogenesis (P=0??023), without increased sterol response element binding protein 1c (SREBP1c) mRNA. The response to diet was much more pronounced in males than in females, without gender effect on the transcription level of PPAR?? and SREBP1c. Finally, the ???linseed oil??? diet decreased the insulin resistance index (???80%, P<0??001) with a more marked effect in males, in relation to their higher hepatic PPAR?? expression (+90%, P=0??012). In conclusion, in our model, the response of either TG or CH to dietary fatty acids is modulated differently by gender. The possible relevance of these interactions to dietary practice should be taken into account in man. [ABSTRACT FROM PUBLISHER]

Predicting aspects of pork quality becomes increasingly important from both a nutritional and a technological point of view. Little information is, however, available concerning the quantitative relation between nutrient intake and fatty acid (FA) deposition at the whole-animal level. In this study, eight blocks of five littermate barrows were used in a comparative slaughter trial. At 24 kg body weight (BW), one pig from each litter was slaughtered to determine the initial FA composition. The other littermates were assigned to one of four feeding levels (ranging from 70 % to 100 % of intake ad libitum) and were given a diet containing 0??36 g/kg lipid and 0??22 g/kg FA. The temperature for each block was maintained at either 23 or 30??C. At 65 kg, the pigs were slaughtered and the body lipid and FA composition was determined. Seventy per cent of the digested n-6 FA and 50 % of the n-3 FA were deposited. The average composition of de novo synthesised FA corresponded to 1??7, 30??3, 2??4, 19??7 and 45??9 % for 14: , 16: , 16: 1, 18: and 18: 1 FA, respectively. At 23??C and for feeding ad libitum, 33 % of 16: FA was deposited, 1??7 % shortened to 14: , 63 % elongated to 18: and 2??8 % unsaturated to 16: 1. Twenty-eight per cent of 18: FA was deposited and 72 % unsaturated to 18: 1. At 30??C, 18: FA desaturation was reduced by 3??5 %. Feed intake and temperature independently affected the elongation of 16: FA. A reduction in feed intake increased the elongation rate, whereas the increase in temperature reduced the elongation rate. [ABSTRACT FROM PUBLISHER]