The developmental patterns of GHr gene expression in gastric tissue of Erhualian and large white pigs

Pituitary growth hormone (GH) is essential for postnatal growth in animal, it regulates numerous cellular functions by direct effect on it's receptor (GHr) in many different tissues. And it is believed that the abundance of GHr in different tissue determines the tissue sensitivity to GH. However, the regulation of GH on porcine stomach development is still unknown. So, in present experiment single tube semi quantitative RT PCR was applied to investigate the developmental patterns of gastric GHr mRNA expression in Large White and Erhualian Boars, and the Classic 18S internal standards (Ambion Inc.USA) was used. Pigs were sampled at birth,and 3, 20, 30, 45, 90, 120, 180 days of age respectively, meanwhile the bodyweight and gastric weight were recorded. The results indicated that the expression of gastric GHr mRNA was high at birth, followed by a significantly decrease ( P 0.05) at 3 days of age (D3) in both breeds. In Erhualian boars, GHr mRNA expression reached a peak at D45, then remarkablely declined till D90 ( P 0.05), and kept constant thereafter. In Large White boars, however, the expression of GHr mRNA reached a peak at D90 and remained pleateau afterwards. From birth to D30, the GHr mRNA expression was higher in Erhualian than that in Large White, the significant strain difference were founded at D20 ( P 0.05). But from D30 to D180, the higher expression was found in Large white,the significant strain difference was especially at D90 ( P 0.05). Significant positive correlation was found between the expression of GHr mRNA and the ratio of gastric weight to bodyweight from birth to D180 ( r =0.54, P 0.05). The results suggest that, (1) GHr mRNA in porcine stomach is expressed according a strain specific development pattern; (2) GH directly acts at the gastric tissue and regulates it's growth. The relationship between GH and the development of gastric function is to be elucidated.