Effects of estrogen on very low density lipoproteins (VLDL) synthesis in avian liver slices in vitro: Lack of correlation with nuclear estrogen receptors

Abstract

Very low density lipoproteins (VLDL) synthesis in liver slices maintained in organ culture was stimulated by the administration of estradiol-17β (E 2) in vitro. However, the effects of the hormone were inconsistent and in only 25% of our experiments was significant stimulation observed. To study whether the failure of induction was due to the complete disappearance of estrogen receptor in the liver slices in vitro, we have measured the level of nuclear estrogen receptors. Irrespective of whether induction of VLDL synthesis was observed, estrogen receptor was consistently demonstrated in the liver slices maintained in culture, with an apparent k D , of 6 × 10 −9 M. These findings suggest that the failure of consistent induction of VLDL synthesis in liver slices in vitro by estrogen is due to defects in hormone action subsequent to the nuclear binding of the hormone.