Inaugural ASAS–CAAV Asia Pacif ic Rim Conference Abstracts

T286 Effect of dexamethasone on lipid deposition andperilipin expression in primary cultured adipocytes of pigs. X. Zhang,J. Liang, and X. Yang*, Nanjing Agricultural University, Nanjing, Jiangsu,China.We investigated the effects of dexamethasone on lipid storage and geneexpression of perilipin, as well as its potential regulation mechanism. Stromalvascularcells were separated from subcutaneous adipose tissue of weanedpiglets. Cells were cultured to 80% confluence followed by treatments with10 -6 M dexamethasone with or without GR antagonist RU486. An MTTassay was performed to assess cell viability. Red oil was used to detect fatdroplet deposition state, and real-time quantitative PCR was used to analyzegene expression. The results showed there was no effect of dexamethasone orRU486 on the cell viability. Triglyceride content in cultured adipocytes wassignificantly increased after dexamethasone treatment for 48 h compared withcontrol group, and this effect could be blocked by RU486. Dexamethasonecould significantly up-regulate gene expression of perilipin and PPAR butdown-regulate C/EBP- mRNA expression. Yet GR mRNA expression in thedexamethasone-treated group did not change significantly compared with thecontrol group. Taken together, it can be concluded that glucocorticoids increasetriglyceride content though up-regulating expression of perilipin, and PPARmaybe involved in this effect.Key Words: dexamethasone, adipocyte, pigT287 The novel estrogen receptor, G protein-coupledreceptor 30, mediates the proliferative effect induced by 17β-estradiolon chicken primordial germ cells. C. Ge*, M. Yu, W. Zeng, and C. Zhang,College of Animal Sciences, Zhejiang University, Hangzhou 310029, China.Many studies have indicated that estrogens have an important role in theregulation of animal reproduction. However, it remains unclear whetherestrogens are capable of directly activating the signaling pathways in fetal germcells. Estrogens are synthesized by the enzyme aromatase and classically act bybinding to estrogen receptors (ER)-α and ERβ. Knockout mice for both receptorisoforms have normal reproductive tracts at birth, suggesting the existence ofan estrogen-binding receptor that may compensate for the lack of ER. Recently,many studies have identified a transmembrane estrogen-binding protein, the Gprotein-coupled receptor 30 (GPR30), which is able to mediate estrogen action.In the present study, The effect of 17β-estradiol (E2) on chicken primordialgerm cells (cPGC) and the involvement of GPR30 were investigated. Using thecPGC culture system, we demonstrated that cPGC express GPR30; however,ERα and ERβ were not detected. Treatment with (1 to 100 nM) E2 significantlyincreased the area and number of cPGC colonies in a time- and dose-dependentmanner. The E2 also activated protein kinase B (PKB, usually termed Akt), aprocess that was inhibited by AG1478 (EGFR inhibitor) or LY294002 (PI3Kinhibitor). In addition, the phosphorylation of β-catenin was observed afterE2 treatment, which was significantly blocked by pretreatment with AG1478,LY294002 or KP372-1(Akt inhibitor), and was enhanced by GSK3 inhibitorBIO. Furthermore, we found that E2-induced cell proliferation was significantlyattenuated by AG1478, LY294002, and KP372-1 but was accelerated by BIO orGPR30 agonist G-1. In conclusion, E2 stimulated proliferation of chicken PGCvia GPR30, Akt/β-catenin signaling cascades. These observations suggest thatE2/GPR30 signaling pathway may play an important role in regulating germcell development in the chicken embryonic gonads.Key Words: 17β-estradiol, G protein-coupled receptor 30, chicken primordialgerm cell82