The effect of prostaglandin (PG) on proliferation of chicken theca externa cells from prehierarchical small yellow follicles (SYF) was evaluated and involved signaling pathways as well as mRNA expression of cAMP response element binding protein (CREB1), cyclins (CCND1 and CCNE1) and cyclin-dependent kinases (CDKs) were investigated. Results showed that PGE(1) (1-100 ng/ml) manifested a similar proliferating effect as LH on theca externa cells, and this stimulating effect was restrained by the prostaglandin receptor antagonist SC19220 at 10(-7) to 10(-5)M. Moreover, prostaglandin synthase inhibitor indomethacin (10(-7) to 10(-5)M) suppressed LH-induced increase in the cell number. In addition, PGE(1)-stimulated cell proliferation was also predominantly hindered by H(89) (PKA inhibitor) instead of H(7) (PKC inhibitor). Meanwhile, BrdU incorporation experiment displayed similar changes with the cell number. Furthermore, H(89), SC19220 and indomethacin abolished the PGE(1)-stimulated increase in the expression of CREB1, CCND1/CDK6 and CCNE1/CDK2 mRNAs, indicating that cAMP/PKA/CREB1 signaling cascade was involved in PGE(1)-stimulated DNA synthesis. In conclusion, PG could promote proliferation of theca externa cells from prehierarchical follicles through changes in cyclin D1/CDK6, cyclin E1/CDK2 and CREB1 mRNA expression via cAMP/PKA and CREB1 signaling cascade. These results suggest that PG may promote development of chicken prehierarchical follicles and is related to dominant follicle selection in laying hens.