Progesterone receptors regulate gallbladder motility

The increased incidence of gallstones in multiparous women may be related to hormonal effects on the gallbladder and its contractility. The occurrence of estrogen and progesterone receptors were studied in the gallbladders of three groups of female guinea pigs (normals, oophorectomized, and oophorectomized treated with estrogen + progesterone for 14 days). Gallbladder contractile response in vivo to cholecystokinin (CCK) was related to the presence of these receptors. The gallbladders from normal females showed low progesterone and estrogen binding activity (4.9 ± 2.0 and 2.4 ± 0.8 fmoles/mg cytosol protein). Oophorectomized females had no detectable progesterone or estrogen receptors, but after treating oophorectomized females for 14 days with estrogen + progesterone, gallbladder concentrations of progesterone receptors increased significantly to 14.7 ± 5.9 fmoles/mg and estrogen binding activity was minimally detectable at 1.4 ± 0.8 fmoles/mg. The gallbladder contractile response to CCK was inversely related to the concentration of progesterone receptors in the gallbladder wall. These data suggest that the gallbladder contains progesterone receptors which are susceptible to circulating hormonal conditions and which have a regulatory effect on gallbladder contractility.