Expression Of Obestatin And GHRL Mrna In The Gastrointestinal Tract Of Piglets At Different Stages

Obestatin, as a kind of Ghrelin associated peptide, is generated by GHRL gene. Obestatin and Ghrelin are derived from prepropeptide by posttranslational processing, which is translated by GHRL gene. Obestatin, with a molecular mass of2516.3Da, is composited by23-amino acid, which is from76-98of GHRL. Amino acid sequence of Obestatin has high conservatism. Obestatin bioactivity is based on the amidation of its C-terminal. The expression of Obestatin is confirmed in the gastrointestinal tract, pancreas, testicular interstitial cells, hypothalamus and pituitary. Obestatin can combine together with GPR39, and can suppress orexia, decrease food intake and body-weight gain, inhibite jejunal contraction and gastric emptying. In addition, Obestatin can also suppress water drinking, protect myocardial cells, regulate insulin resistance, promote sleeping, improve learning,memory abilities and so on. Interestingly, although Obestatin and Ghrelin derived from the same gene, mRNA and the same precursor polypeptide, their biological function are diametrically opposite. Thus, Obestatin is considered as the biological antagonists of Ghrelin. Therefore, the discovery of Obestatin can help to understand the roles which post-translational modification plays on regulations of gene expression.Obestatin can play biological function on the mechanism of energy homeostasis and the controlling of body mass. Besides, piglet stage is the most important part in the pig farming, as the most active metabolism and fastest growth development. So far, there are few studies about Obestatin on pigs’digestive system, and no relevant literature about the difference between gastrointestinal tract tissues yet. Therefore, we determined the concentration of Obestatin and the expression of GHRL mRNA in the gastrointestinal tract of piglets at different stages. We aimed to explore the regulation of the expressions of Obestatin and GHRL mRNA, to provide experimental basis for deeper research on the Obestatin function, and to provide reference basis for further study on Obestatin.1day old (newly born),15days old (breastfeeding),30days old (weaned) and45days old (nursery) piglets were selected and sacrificed, then gastric parts:fundus, antrum and intestinal parts:duodenum, jejunum and colon were excised. Part of these tissues was used to determine the contents of Obestatin. BC A Protein Assay Kit was performed after the extraction of total proteins from tissues. By using this Kit, concentration of total proteins from tissues were determined and diluted by PBS buffer to2.000mg/mL. ELISA was performed to determine the contents of Obestatin in gastrointestinal tract of piglets at different stages after dilutions of total proteins. Another part of tissues were used to extract the total RNA. Then Q-PCR was performed to determine the expression of GHRL mRNA in gastrointestinal tract of piglets at different stages after reverse transcription. SPSS Statistics17.0was utilized for data analysis.The results analysis showed that:1. It could be clearly found that the concentration of Obestatin in all gastrointestinal tract tissues of piglets showed a same tendency:significantly decreased at day15(p<0.05) when compared with day1, then revealed progressive increase from day30to day45.2. There’s no significant difference between gastrointestinal tract tissues of piglets at all stages.3. In gastric fundus, the expression of GHRL mRNA decreased at15days, then progressive increased at30and45days; In gastric antrum, it revealed progressive increased; while in intestinal parts, it showed the same tendency:increased firstly, then decreased.4. GHRL mRNA expression levels of piglets in gastric tissues were significantly higher than intestinal tissues.Conclusion:Expressions levels of Obestatin in gastrointestinal tract were different between piglets at different stages. Expression of GHRL mRNA in gastrointestinal tract of piglets at different stages showed spatial and temporal specificity, and its expression in gastric tissues was significantly higher than the intestinal tissue. The expressions of Obestatin and GHRL mRNA didn’t showed space and time synchronization.