A reduced protein diet induces stearoyl-CoA desaturase protein expression in pig muscle but not in subcutaneous adipose tissue: relationship with intramuscular lipid formation

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The present study investigated whether enrichment of the pig maternal diet with n-3 polyunsaturated fatty acids (PUFA) affects the fatty-acid composition of female piglets via enhancing of expression of the lipogenic enzymes D5-desaturase (D5d) and D6-desaturase (D6d). The sows (50% Landrace 3 50% Large White) were fed a control diet or one of the experimental diets starting at day 45 in gestation. The experimental diets were supplemented either with linseed oil or fish oil, whereas the control diet contained palm oil. Expression of D5d and D6d, and fatty-acid composition was determined by Western blotting and gas-liquid chromatography, respectively, in muscle, subcutaneous adipose tissue and liver. The highest D5d protein expression was observed in the piglets' muscle, followed by subcutaneous adipose tissue, with the lowest level in the liver. Expression of D6d in the piglets' tissues followed an opposite pattern, and was highest in the liver, followed by subcutaneous adipose tissue, with the lowest level in muscle. Supplementation of the maternal diet with fish oil or linseed oil increased the level of n-3 PUFA of the piglets in a tissue-specific manner. The response of D6d and D5d protein expression in female piglets, with average birth weight 2.4 kg, to the dietary manipulation was also tissue-specific. It is suggested that the increase in n-3 PUFA content in the progeny was related, at least partially, to the activation of D6d and D5d expression.

Section: -Desaturasementioning

confidence: 92%

Section: Isolation Of Microsomesmentioning

confidence: 99%

Effect of supplementation of the maternal diet with fish oil or linseed oil on fatty-acid composition and expression of Δ5- and Δ6-desaturase in tissues of female piglets

Missotten

Smet

Raes

et al. 2009

Self Cite

“…The most successful nutritional strategy in non-ruminants to dissociate fat accumulation in muscle to that in other parts of the body has been obtained with subtle protein-deficient diets (Gondret and Lebret, 2002;Doran et al, 2006;D'Souza et al, 2008 in pigs). The basis of these strategies was to restrict muscle development, but the mechanisms involved in the observed increase in IMF content remain elusive.…”

Section: Manipulating Dietary Protein Energy and Micronutrientsmentioning

confidence: 99%

“…The basis of these strategies was to restrict muscle development, but the mechanisms involved in the observed increase in IMF content remain elusive. One of the possible explanations could be that lower dietary protein levels stimulate the expression of SCD1, which catalyses the cellular biosynthesis of monounsaturated fatty acids (Doran et al, 2006). Indeed, oleic and palmitoleic fatty acids, as the main products of SCD, are the main monounsaturated fatty acids in fat depots and membrane phospholipids, and a different pattern of SCD gene isoforms may exist between muscle and subcutaneous fat tissues.…”

Section: Manipulating Dietary Protein Energy and Micronutrientsmentioning

confidence: 99%

Intramuscular fat content in meat-producing animals: development, genetic and nutritional control, and identification of putative markers

Hocquette

Gondret

Baéza³

et al. 2010

654

447

Intramuscular fat (IMF) content plays a key role in various quality traits of meat. IMF content varies between species, between breeds and between muscle types in the same breed. Other factors are involved in the variation of IMF content in animals, including gender, age and feeding. Variability in IMF content is mainly linked to the number and size of intramuscular adipocytes. The accretion rate of IMF depends on the muscle growth rate. For instance, animals having a high muscularity with a high glycolytic activity display a reduced development of IMF. This suggests that muscle cells and adipocytes interplay during growth. In addition, early events that influence adipogenesis inside the muscle (i.e proliferation and differentiation of adipose cells, the connective structure embedding adipocytes) might be involved in interindividual differences in IMF content. Increasing muscularity will also dilute the final fat content of muscle. At the metabolic level, IMF content results from the balance between uptake, synthesis and degradation of triacylglycerols, which involve many metabolic pathways in both adipocytes and myofibres. Various experiments revealed an association between IMF level and the muscle content in adipocyte-type fatty acid-binding protein, the activities of oxidative enzymes, or the delta-6-desaturase level; however, other studies failed to confirm such relationships. This might be due to the importance of fatty acid fluxes that is likely to be responsible for variability in IMF content during the postnatal period rather than the control of one single pathway. This is evident in the muscle of most fish species in which triacylglycerol synthesis is almost zero. Genetic approaches for increasing IMF have been focused on live animal ultrasound to derive estimated breeding values. More recently, efforts have concentrated on discovering DNA markers that change the distribution of fat in the body (i.e. towards IMF at the expense of the carcass fatness). Thanks to the exhaustive nature of genomics (transcriptomics and proteomics), our knowledge on fat accumulation in muscles is now being underpinned. Metabolic specificities of intramuscular adipocytes have also been demonstrated, as compared to other depots. Nutritional manipulation of IMF independently from body fat depots has proved to be more difficult to achieve than genetic strategies to have lipid deposition dependent of adipose tissue location. In addition, the biological mechanisms that explain the variability of IMF content differ between genetic and nutritional factors. The nutritional regulation of IMF also differs between ruminants, monogastrics and fish due to their digestive and nutritional particularities.

“…Recently, it has been suggested that a reduction in dietary protein impacts pig's fat partitioning, with an increase in IMF and a minor effect on the amount of subcutaneous adipose tissue (SAT) Doran et al, 2006). Reducing the proportion of protein relative to energy in the diet consistently increases fat deposition, especially at the intramuscular level, because excess energy is diverted to fat deposition (Lebret et al, 2001;Wood et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

Contrasting cellularity on fat deposition in the subcutaneous adipose tissue and longissimus lumborum muscle from lean and fat pigs under dietary protein reduction

Lopes

Costa

et al. 2014

The production of pork with high amounts of intramuscular fat (IMF) without an increase in subcutaneous fat is highly desirable for the pig industry and consumers. Herein, we question the impact of dietary protein reduction (18% v. 13%) on fat deposition in the subcutaneous adipose tissue (SAT) and longissimus lumborum (LL) muscle using genetically diverse pigs for body fatness (lean v. fat). A clear effect of genotype was observed on plasma insulin (P = 0.004) and leptin (P < 0.001), as well as on backfat thickness (P < 0.001), with the fat pigs having higher values. Accordingly, IMF was higher in the fat pigs, when compared with their lean counterparts (P = 0.003), which was supported by enlarged adipocytes (P < 0.001). The area of lipid droplets within the LL fibres (P = 0.039) and extramyocellular lipids number (P = 0.017) were increased in pigs fed reduced protein diets, regardless of genotype, which is consistent with higher levels of plasma triacylglycerols (P = 0.002). The gene-expression pattern of lipogenic factors in the SAT was distinct from the LL muscle. In the SAT, PPARG expression was similar among genotypes (P > 0.05), whereas in the LL muscle it was higher in the lean pigs (P = 0.023), especially when fed on low protein diet (P = 0.057). The CEBPA and FABP4 mRNA levels were increased in the SAT of fat pigs (P < 0.001), without changes in the LL muscle (P > 0.05). The influence of diet on FABP4 expression in the SAT was dependent on pig's genetic background (P = 0.005). In conclusion, fat deposition was clearly influenced by genotype and, to a lesser extent, by dietary protein level, the SAT being more sensitive than the LL muscle. One can speculate that the pathways involved in lipid metabolism are downregulated in intramuscular adipocytes when compared with SAT fat cells. This result might be a direct consequence of the relatively low proportion of adipocytes found in the LL muscle.