Mostyn Alison, Sebert Sylvain, Litten Jennie C, Perkins Katharine S, Laws John, Symonds Michael E, Clarke Lynne
Institute of Clinical Research, Centre for Reproduction and Early Life, University Hospital, Nottingham NG7 2UH, UK.
J Endocrinol. 2006 Sep;190(3):631-9. doi: 10.1677/joe.1.06731.
Neonatal mortality is greater in commercial porcine genotypes, compared with the ancient Meishan breed that rapidly lay down adipose tissue; this may be related to hormones, such as triiodothyronine (T(3)) or leptin. Leptin is present in maternal milk; however, the extent to which this supply provides the neonate with leptin is unknown, but may play a role in growth and development. We investigated whether thyroid hormones and leptin concentrations in maternal milk differed between genotypes; and whether this influenced piglet concentrations or expression of genes involved in adipose tissue regulation. Eight Meishan and six commercial sows were entered into the study and milk samples from the day of parturition to day 4 postpartum was taken daily. The median birth weight piglet in each litter had a daily venous blood sample taken and was euthanised on day 4. Gene expressions of IGF-I, IGF-binding protein 3 (IGFBP-3), peroxisome proliferators activated receptor (PPAR)gamma and glucocorticoid receptor (GR) were measured in adipose tissue using real-time PCR. T(3) was increased in Meishan milk, but not in piglet plasma. Milk thyroxine was similar between breeds but commercial piglet levels were significantly higher. Leptin was higher in commercial sow milk throughout the study. Milk leptin was strongly correlated to plasma leptin during the first postnatal days and also to organ and body weight in Meishan piglets that also had significantly higher expression of GR, but not IGF-I, IGFBP-3 or PPARgamma. In conclusion, we have found a significant disparity in the provision of thyroid hormones in Meishan and commercial sow's milk. These changes are not always translated to plasma concentrations of hormone in the piglet. Leptin appears to have a stronger role in growth and development in the Meishan genotype compared with commercial; along with the increased GR expression, this may also represent a potential mechanism behind the rapid accumulation of adipose tissue in Meishan piglets.
与能迅速沉积脂肪组织的古老梅山猪品种相比，商业猪基因型的新生儿死亡率更高；这可能与三碘甲状腺原氨酸（T(3)）或瘦素等激素有关。瘦素存在于母乳中；然而，这种供应能为新生儿提供多少瘦素尚不清楚，但可能在生长发育中发挥作用。我们研究了不同基因型母猪乳汁中甲状腺激素和瘦素浓度是否存在差异；以及这是否会影响仔猪体内脂肪组织调节相关基因的浓度或表达。八头梅山母猪和六头商业母猪参与了本研究，每天采集分娩当天至产后第4天的乳汁样本。每窝中出生体重中位数的仔猪每天采集静脉血样，并在第4天实施安乐死。使用实时PCR测定脂肪组织中胰岛素样生长因子-I（IGF-I）、胰岛素样生长因子结合蛋白3（IGFBP-3）、过氧化物酶体增殖物激活受体（PPAR）γ和糖皮质激素受体（GR）的基因表达。梅山猪乳汁中的T(3)增加，但仔猪血浆中未增加。不同品种间乳汁甲状腺素相似，但商业猪品种仔猪的水平显著更高。在整个研究过程中，商业母猪乳汁中的瘦素更高。产后头几天，乳汁瘦素与血浆瘦素密切相关，也与梅山仔猪的器官和体重密切相关，梅山仔猪的GR表达也显著更高，但IGF-I、IGFBP-3或PPARγ并非如此。总之，我们发现梅山母猪和商业母猪乳汁中甲状腺激素的供应存在显著差异。这些变化并不总是转化为仔猪血浆中的激素浓度。与商业猪基因型相比，瘦素在梅山猪基因型的生长发育中似乎发挥着更强的作用；随着GR表达的增加，这也可能是梅山仔猪脂肪组织快速积累背后的潜在机制。
