Fig. 4.

Compromised proliferation of trophoblast cells missing Cnr1. (A) BrdU incorporation results show that Cnr1^−/− TS cells in the EPC proliferate at a much slower rate compared with WT TS cells, whereas Faah^−/− TS cells show less reduction in proliferation. Em, embryo; EPC, ectoplacental cone. (Scale bar, 200 μm.) (B) RT-PCR analysis coupled with Southern blotting shows that Cnr1, but not Cnr2, is expressed in WT TS cells. RNA samples from brain (Br) and spleen (Sp) were used as positive controls for Cnr1 and Cnr2, respectively. TS, trophoblast stem cells. (C) Proliferation of Cnr1^−/−/Cnr2^−/− and Faah^−/− TS cells is much slower than WT TS cells in vitro (n = 3). (D) Treatment with mAEA (7 nM) increases WT TS cell proliferation in vitro, and this effect is suppressed by a CNR1-specific inhibitor, SR141716 (n = 3; unpaired t test, *P < 0.05).