Effects of Female Sex Hormones and Pregnancy on Gallbladder Prostaglandin Synthesis

To investigate whether female sex hormones and pregnancy induce increased gallbladder synthesis of prostaglandin I₂ (PGI₂) and prostaglandin E (PGE), we used an in vitro incubation chamber to quantitate the effects of progesterone, estrogen, pregnancy, and pregnancy plus a 2%-cholesterol diet on mucosal and serosal PGI₂ and PGE production by the rabbit gallbladder. Neither the female sex hormones nor pregnancy alone caused a significant increase in PGI₂ or PGE synthesis. The gallbladders of cholesterol-fed, pregnant rabbits demonstrated significant increases only in serosal synthesis of PGI₂. This increased production was equivalent to that noted for gallbladders from nonpregnant rabbits fed a high-cholesterol diet. There were no increases in mucosal synthesis of PGE or of PGI₂. Thus, neither elevated levels of progesterone or estrogen nor pregnancy is directly responsible for the increased PGI₂ activity in the female gallbladder; conversely, this effect seems to be mediated by the increased biliary concentrations of cholesterol.