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

Effects of catechol estrogen methyl ethers on lipid metabolism in prepubertal rats

Thirty-five day old ovariectomised rats were given daily subcutaneous injections (0.05-5.0 micrograms/100 gm body weight) of estradiol (E2) 2-methoxyestradiol (2-ME2) or 4-methoxyestradiol (4-ME2) for six days. At the end of the last injection, the animals were sacrificed and serum lipoproteins were analysed. It was observed that cholesterol decreased significantly in normal fed animals who received E2 and 4-ME2, while no effect was seen in cholesterol fed animals. In the E2 treated group there was a decrease in esterified and free cholesterol, while in the 4-ME2 group only esterified cholesterol decreased. High density lipoproteins were significantly elevated in the E2 treated group. However, there was an increase in very low density lipoproteins and a decrease in low density lipoproteins in 2-ME2 and 4-ME2 treated groups. These results suggest that catechol estrogens may play an important role in the lipoprotein metabolism and atherosclerotic diseases, and the mechanism of action may differ from that of estradiol.

Estrogen regulation of yolk and non-yolk protein synthesis in the avian liver. An immunocytochemical study

The effects of acute and chronic estrogen treatment on two egg yolk proteins, vitellogenin and apoVLDL-II, and two non-yolk proteins, ovalbumin and apoA-I, were studied by immunocytochemical techniques. Three groups of cockerels received either no treatment, or a single injection of diethylstilbestrol (DES, 2.5 mg) (acute stimulation) 24 h before killing, or 14 daily injections of 2.5 mg DES (chronic stimulation) before killing. The animals were killed at 4 weeks of age and their livers examined with respect to the distribution of the four different proteins by the indirect immunoperoxidase method. Vitellogenin was undetectable in the untreated cockerel liver. A single injection of DES resulted in the appearance of the protein in approximately 10%-15% of the hepatocytes. Chronic DES stimulation increased the number of positive cells to about 20%. In contrast, apoVLDL-II was present in 1%-2% of the hepatocytes in untreated animals. It was detected in an increased proportion (20%-25%) of cells after a single dose of DES. After chronic estrogen treatment, there was a very marked increase in the number of positive cells (less than 90%). Ovalbumin was undetectable in untreated cockerel liver, while apoA-I was detected in an extremely low proportion of cells (0.005%-0.01%). Neither ovalbumin nor apoA-I distribution seemed to be affected by a single dose of DES. However, chronic DES treatment resulted in the appearance of ovalbumin-containing cells (approximately 0.02%) and a marked increase in the number of cells containing apoA-I (10%-15%).

The specific binding of estradiol to the nuclear matrix

Recent studies on the eukaryotic nucleus have described the presence of a structural component termed the nuclear matrix, that appears to be involved in nucleic acid synthesis. This study will present evidence that the nuclear matrix of both the rat uterus and chick liver contains specific, high affinity, saturable estradiol binding sites.