UCP1 is present in porcine adipose tissue and is responsive to postnatal leptin

Abstract

Intrauterine growth restriction (IUGR) may be accompanied by inadequate thermoregulation, especially in piglets that are not considered to possess any brown adipose tissue (BAT) and are thus entirely dependent on shivering thermogenesis in order to maintain body temperature after birth. Leptin can stimulate heat production by promoting non-shivering thermogenesis in BAT, but whether this response occurs in piglets is unknown. Newborn female piglets that were characterised as showing IUGR (mean birth weight of approximately 0.98 kg) were therefore administered injections of either saline or leptin once a day for the first 5 days of neonatal life. The dose of leptin was 0.5 mg/kg, which is sufficient to increase plasma leptin by approximately tenfold and on the day of birth induced a rapid increase in body temperature to values similar to those of normal-sized 'control' piglets (mean birth weight of w1.47 kg). Perirenal adipose tissue was then sampled from all offspring at 21 days of age and the presence of the BAT-specific uncoupling protein 1 (UCP1) was determined by immunohistochemistry and immunoblotting. UCP1 was clearly detectable in all samples analysed and its abundance was significantly reduced in the IUGR piglets that had received saline compared with controls, but was raised to the same amount as in controls in those IUGR females given leptin. There were no differences in gene expression between primary markers of brown and white adipose tissues between groups. In conclusion, piglets possess BAT that when stimulated exogenously by leptin can promote increased body temperature. IntroductionBrown adipose tissue (BAT) is essential for effective adaptation to cold exposure of the extra-uterine environment in precocial species such as sheep in which there is rapid activation of BAT around the time of birth (Clarke et al. 1997). In pigs, however, it has long been considered that BAT is not present (Trayhurn et al. 1989) and the newborn is Journal of Endocrinology Thematic ResearchA MOSTYN and others UCP1 and leptin in porcine 223:1 M31-M38http://joe.endocrinology-journals.org Ñ 2014 Society for Endocrinology DOI: 10.1530/JOE-14-0155Printed in Great BritainPublished by Bioscientifica Ltd.primarily dependent on shivering thermogenesis in muscle in order to prevent hypothermia at birth (Symonds & Lomax 1992). This due to an open reading frame on the BAT-specific uncoupling protein 1 (UCP1) gene in the porcine species meaning that UCP1 is not expressed (Berg et al. 2006). However, it has more recently been suggested that BAT is present in young piglets because of the different morphological appearances of adipocytes within perirenal adipose tissue in 2-week-old females (Attig et al. 2008). However, this remains to be confirmed by direct measurements of UCP1. Moreover, our understanding of BAT has now been transformed as a consequence of the discovery of beige adipocytes that express UCP1 at approximately 10% of the amount observed in classical BAT , Wu et al. 2013, but whether comparable depots are be pr...

The Placenta, Maternal Diet and Adipose Tissue Development in the Newborn

“…It is possible that all fat laid down in the fetus for a majority of large mammalian species is primarily brown adipose tissue that is characterized as possessing the unique mitochondrial uncoupling protein (UCP1) [10] . The one exception being the litter-bearing pig although brown fat has been found within an isolated depot [15] . When activated through the unmasking of GDP-binding sites the free flow of protons across the mitochondria enables the rapid production of heat with the need for the production of ATP as required in mitochondria of all other tissues or organs [16] .…”

When pigs fly, UCP1 makes heat

“…A paper published in Volume 223, October 2014 of the Journal of Endocrinology shows positive effects of leptin administration on body temperature in juvenile pigs and claims the presence of uncoupling protein 1 (UCP1) [19] . Given that UCP1 is involved in thermoregulation and body mass regulation, its presence is important for domestic animal and human translational research.…”

Brown Adipose Tissue and Browning Agents: Irisin and FGF21 in the Development of Obesity in Children and Adolescents

“…A large number of endocrine factors have a potential to activate BAT in newborns including: catecholamines , thyroid hormones (Heasman et al 2000), cortisol (Clarke et al 1998), leptin (Mostyn et al , 2014, and prolactin (Pearce et al 2005). The release of these factors declines over the first few weeks of life thermogenesis from shivering to nonshivering mode as a dominant response to cold exposure (Symonds et al 1989;Bispham et al 2002).…”