Lipogenic enzyme activities in different adipose depots of Pirenaican and Holstein bulls and heifers taking into account adipocyte size

Abstract

The effects of sex, genotype, and adipose depot on lipogenic enzyme activity have been investigated in Holstein and Pirenaican bulls and heifers, taking into account differences in adipocyte size. Fifteen Pirenaican bulls and 15 heifers and 15 Holstein bulls and 13 heifers were fattened until slaughter (12 to 13 mo old and 450 to 500 kg of body weight). During the fattening period, animals had ad libitum access to commercial concentrates and straw. The 10th rib was dissected to determine the fat content. Adipocyte size and activities of the following lipogenic enzymes were determined: glycerol 3-phosphate dehydrogenase, fatty acid synthase, nicotinamide adenine dinucleotide phosphate (NADP)-malate dehydrogenase, glucose 6-phosphate dehydrogenase, and NADP-isocitrate dehydrogenase, in the omental, perirenal, subcutaneous, and intermuscular adipose depots, respectively. Because adipocyte mean cell volume varied with sex, breed, and depot, regression analyses of log(e) activity per cell and log(e) cell volume were used to compare activities per unit volume. Sex, breed and depot had no effect (P > 0.05) on the gradients of regressions, which did not differ significantly from 1. Thus, activity per unit volume did not vary with cell size. Consequently, sex, breed, and depot effects on the regression analyses were equivalent to effects on activity per unit volume. Females had greater amounts of fat in the 10th rib (P < 0.001), larger adipocytes (P < 0.001) and, in general, greater (P < 0.05) lipogenic activity per cell, even when adjusted for cell size, than males. These findings suggest that differences in adiposity between sexes are mainly due to females having a greater capacity for lipid synthesis, and hence, hypertrophy, than males. When adjusted for differences in carcass weight, Holsteins had larger adipocytes than Pirenaicans. The abdominal depots, omental and perirenal, had a greater adipocyte size (P < 0.001) and, in general, greater lipogenic enzyme activities per cell (P < 0.05) than the subcutaneous and intermuscular carcass depots. However, when activity per cell was adjusted for cell size, subcutaneous depots had greater fatty acid synthae, glucose 6-phosphate dehydrogenase, and NADP-malate dehydrogenase activities than omental and perirenal, indicating that other factors such as nutrient supply may restrict hypertrophy of carcass adipocytes.

Adipocyte cellularity in different adipose depots in bulls of seven Spanish breeds slaughtered at two body weights

“…The degree of lipid accumulation was intermediate in the Pirenaica and Parda Alpina breeds, which, together with the Asturiana and Rubia Gallega breeds, are raised principally in northern Spain (Casasú s et al, 2002). A comparison of Pirenaica bulls and Holstein bulls, deemed to be an early-maturing breed, showed that the latter exhibited a higher degree of lipid accumulation than the former (Eguinoa et al, 2003). Mendizabal et al (1999) reported results similar to the findings reported here in bulls of these same seven breeds at an intermediate weight at slaughter of 470 kg BW.…”

Ontogenesis of muscle and adipose tissues and their interactions in ruminants and other species

“…Sixteen-month-old steers and heifers have leanto-fat ratios 20% and 45% lower than bulls (Gettys et al, 1988). This may partly result from the greater amount of fat, larger adipocytes and in general greater lipogenic activities in females than in males, both in meat and dairy breeds, compared at similar adiposity (Eguinoa et al, 2003).…”

“…In several studies comparing pure or crossbred Pirenaican, Limousin, Holstein, Wagyu, Santa Gertrudis, Angus, and Japanese Black growing cattle it was repeatedly observed that the leaner breeds had lower adipocyte size in carcass and muscular WAT (Miller et al, 1991;May et al, 1994;Eguinoa et al, 2003), concomitant with lower gene expression of C/EBPs (Yamada et al, 2009) and PPARg (Bonnet et al, 2007), lipogenic activities (Hood and Allen, 1973;Miller et al, 1991;Eguinoa et al, 2003;Bonnet et al, 2007), leptin gene expression (Chilliard et al, 2005;Bonnet et al, 2007), and higher resistin (Komatsu et al, 2005) when slaughtered at similar age. However, when growing animals were slaughtered at different ages, but similar carcass adiposities, no differences between breeds persisted for gene expression of C/EBPs (Xu et al, 2009;Yamada et al, 2009), lipogenic activities (Chakrabarty and Romans, 1972;Eguinoa et al, 2003) or leptin gene expression (Chilliard et al, 2005). This shows that the lower adiposity repeatedly observed in lean genotypes partly results from a delay in adipocyte hypertrophy relative to fatter genotypes, and thus to their lower maturity at any given age or weight.…”

Foetal bovine intermuscular adipose tissue exhibits histological and metabolic features of brown and white adipocytes during the last third of pregnancy

“…The activities of FAS and G6PDH, which are involved in de novo lipogenesis, and G3PDH, which is involved in glycerol phosphate synthesis, strongly decreased from 180 dpc onwards when expressed per million adipocytes or from 210 dpc onwards when expressed per milligram of proteins. Difficulties encountered in establishing a satisfactory and meaningful baseline expression of enzyme activities in AT have been repeatedly reported (Bonnet et al, 2000;Eguinoa et al, 2003;Bonnet et al, 2004). Expressing results on a cellular or protein basis was shown to be more relevant because of its better relation to total activity in the studied AT sites (Hood and Allen, 1973).…”