Influence of genotype on the differential ontogeny of uncoupling protein 2 and 3 in subcutaneous adipose tissue and muscle in neonatal pigs

Abstract

The present study aimed to determine whether porcine genotype and/or postnatal age influenced mRNA abundance or protein expression of uncoupling protein (UCP)2 or 3 in subcutaneous adipose tissue (AT) and skeletal muscle (SM) and the extent to which these differences are associated with breed-specific discordance in endocrine and metabolic profiles. Piglets from commercial and Meishan litters were ranked according to birth weight. Tissue samples were obtained from the three median piglets from each litter on either day 0, 4, 7, 14 or 21 of neonatal life. UCP2 protein abundance in AT was similar between genotypes on the first day of life, but it was elevated at all subsequent postnatal ages (P<0·05) in AT of Meishan piglets. In contrast, UCP2 mRNA abundance was lower in Meishans up to 14 days of age. UCP2 mRNA expression was not correlated with protein abundance in either breed at any age. UCP3 mRNA in AT was similar between breeds up to day 7; thereafter, expression was higher (general linear model, P<0·05) in Meishan piglets. Conversely, UCP3 mRNA expression in SM was higher in commercial piglets after day 7. Colonic temperature remained lower in Meishan than commercial piglets throughout the study; this was most obvious in the immediate post-partum period when Meishan piglets had lower (P<0·05) plasma triiodothyronine. In conclusion, we have demonstrated that porcine genotype influences the expression and abundance of UCP2 and 3, an influence which may, in part, be due to the distinctive endocrine profiles associated with each genotype.

Influence of porcine genotype on the abundance of thyroid hormones and leptin in sow milk and its impact on growth, metabolism and expression of key adipose tissue genes in offspring

“…Interestingly, the differences observed in plasma T 3 between Meishan and commercial piglets on day 0 in a previous study (Mostyn et al 2004) were not apparent. A potential reason for this disparity was that the maternal diet was different in the present study.…”

“…Milk was manually sampled from each sow and immediately frozen at K20 8C. On days 0 and 4, morphometric measurements, including head circumference and crown to rump length (CRL), were made along with the measurement of total body electrical conductivity (TOBEC) as described previously (Mostyn et al 2004). This is a non-invasive technique designed to estimate fatfree mass and thereby indirectly measures body fat in live animals (Bellinger & Williams 1993).…”

“…Meishan sows are obese and produce milk with a higher fat content than commercial sows (Alston-Mills et al 2000), which may be one factor responsible for the apparent resistance to hypoglycaemia and hypothermia observed in their piglets. Our recent studies have established that there is a significant disparity in the expression of the mitochondrial uncoupling proteins (UCP)2 and 3 in adipose tissue and skeletal muscle between these breeds, as well as significantly higher plasma triiodothyronine (T 3 ) in the commercial breed on the first day of life, but this does not appear to improve their ability to thermoregulate (Mostyn et al 2004).…”

Porcine models for the metabolic syndrome, digestive and bone disorders: a general overview

“…However, physiological studies have shown that porcine genotype must be taken into consideration when selecting an appropriate model because despite the minipig being smaller, it possesses more fat (0.117 to 0.158 kg fat for a 1.25 kg 5-day old neonatal piglet, (Sheng et al, 1988)) compared with modern domestic breeds (0.03 kg fat for a 1.5 kg 1 day old neonatal piglet, Shields et al, 1983)) and exhibits altered uncoupling protein (UCP) expression and endocrine profile at birth compared with modern domestic breeds of pigs (Knol et al, 2002;Mostyn et al, 2004Mostyn et al, , 2006. Compromised UCP abundance in adipose tissue may contribute to excess fat deposition in later life resulting in obesity, hence providing a natural model for obesity (Dyson et al, 2006).…”

“…However, an air of caution must be taken if using these porcine growth curves as data were collected only for a specific domestic breed combination (i.e. Large White X Landrace), reared under standard commercial conditions, not experimental conditions; it is known that growth and development varies between porcine genotypes (Mostyn et al, 2004) and also under different management regimes (Kusec et al, 2007).…”