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Title: Impact of runting on adipokine gene expression in neonatal pig adipose tissue

Author
item Ramsay, Timothy
item Stoll, Margo
item Caperna, Thomas

Submitted to: Comparative Biochemistry and Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/13/2008
Publication Date: 2/1/2010
Citation: Ramsay, T.G., Stoll, M.J., Caperna, T.J. 2010. Adipokine gene transcription level in adipose tissue of runt piglets. Comparative Biochemistry and Physiology. 155(2):97-105.

Interpretive Summary: Recent studies have demonstrated that adipose tissue produces a number of cytokines, hormones and growth factors that can impact health and metabolism. These various proteins have now been grouped and are described by the name “adipokines”. These adipokines have been examined for their potential roles in humans and rodents metabolic and physiological responses to stress. A few initial studies have shown some of these adipokines are produced in swine adipose tissue. One model for stress in the pig is the small for gestational age pig, called the “runt” pig. These are pigs born at less than 1 kg birth weight, relative to normal littermate weights of 1.4 to 1.6 kg. The present study was designed to examine the change in expression of a variety of adipokines in response to the stress affecting the runt pig, relative to the normal sized littermate. This is the first study to characterize the expression of adipokines in the small for gestational age for any species during the neonatal period, a critical time for the development of adipose tissue and for the survival of the baby pig. Adipokines that were examined included leptin, adiponectin, interleukin 1ß (IL1ß), IL6, IL8, IL10, IL15, tumor necrosis factor a, haptoglobin, macrophage migration inhibitory factor, monocyte chemotactic protein 1 and vascular endothelial growth factor. The adipose tissue from neonatal pigs at the ages of 1, 7, and 21 days of age were collected and extracted for RNA content. The RNA was then used for real-time PCR to assess the relative expression of these genes during neonatal development of the adipose tissue. The development of gene expression for each adipokine varied depending upon cell type of origin, the adipose tissue location and the type of adipokine. This study provides critical information for further research to determine if these adipokine genes respond to stressors(environmental, immunological or nutritional) and what impact they might have on neonatal survival.

Technical Abstract: This study examined the effects of runting on adipokines in neonatal adipose tissue. Pigs were selected as runts (R) by birth weight < 1 kg and compared to littermates (C) of mean litter weight. Subcutaneous (SQ) and perirenal (PR) adipose tissues were collected at d1 (n = 5), d7 (n = 7) or d21 (n = 9) of age and total RNA extracted. Real-time PCR was used to quantify mRNA abundance for: leptin, adiponectin, interleukin 1ß (IL-1ß), IL-6, IL-8, IL-10, IL-15, tumor necrosis factor a, haptoglobin, macrophage migration inhibitory factor (MIF), monocyte chemotactic protein 1, vascular endothelial growth factor and cyclophilin. Runt pigs were smaller than C at all ages (P < 0.05). Leptin and adiponectin mRNA abundance were lower, while IL-1ß, IL-6, IL-10 and MIF mRNA abundance were higher in the SQ of R at d1 (P < 0.05). Leptin, IL-6, IL-10, haptoglobin and MIF gene expression were higher PR from R than C at d7 (P< 0.05) and MIF expression was elevated by 30 fold in PR of R at d21(P < 0.001). Thus, stressors placed upon the neonatal runt produce different responses in adipokine gene expression by PR and SQ than in the normal sized littermate.