Biliary excretion and enterohepatic circulation of estrone and estriol in rodents

Aa, Sandberg; Ry, Kirdani; Back, Nathan; Weyman, P; Wr, Slaunwhite

doi:10.1152/ajplegacy.1967.213.5.1138

Cited by 52 publications

(20 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…An enterohepatic circulation of lignans occurs; they are absorbed from the intestine, transferred to the liver and conjugated, excreted in bile and reabsorbed mainly as conjugates. Their physiological behaviour resembles cholesterol [1720],bile acids [21] bile pigments [22],oestrogens [23,24],vitamin Blz [25] andfolicacid [26,27],compounds which also have an enterohepatic circulation.…”

Section: Discussionmentioning

confidence: 99%

The excretion of lignans in rats — evidence for an intestinal bacterial source for this new group of compounds

Axelson

Setchell²

1981

FEBS Letters

249

106

View full text Add to dashboard Cite

Section: Discussionmentioning

confidence: 99%

The excretion of lignans in rats — evidence for an intestinal bacterial source for this new group of compounds

Axelson

Setchell²

1981

FEBS Letters

249

106

View full text Add to dashboard Cite

“…Sandberg et al (1967) after administration of oestrone to intact rabbits re¬ covered 69 % of the dose in the urine and 16% in the faeces; in animals with a bile fistula 17% was recovered in the bile and the amount in the urine (36 %) was reduced, suggesting a substantial enterohepatic circulation. After administration of large doses of oestradiol to rabbits, Collins et al (1967) re¬ covered about 80 % in the urine over a period of 20 days.…”

Section: E Metabolism Of Oestrogens In Rabbitsmentioning

confidence: 98%

Metabolism of Synthetic Steroids by Animals and Man

Fotherby

1974

Acta Endocrinologica

View full text Add to dashboard Cite

The metabolism of naturally occurring oestrogens in humans is outlined and compared with that in other species and with the metabolism of synthetic oestrogens. There is a close similarity in humans between the metabolism of the naturally occurring oestrogens and that of ethynyl \x=req-\ oestradiol with the exception that the latter is less extensively metabolised than the former. With the exception of the baboon, the metabolism of oestrone and oestradiol appears to differ significantly in other species from that of the human. Our knowledge of the metabolism of oestrone and oestradiol and the synthetic oestrogens in the baboon is still meagre and much more information is required before one can ascertain to what extent metabolism in this species can serve as a model for that in humans.Little information is available concerning the metabolism of synthetic progestogens in species other than man and rabbits. There are many similarities between these two species both in the metabolism of progesterone and of synthetic progestogens related both to 19-nortestosterone and to 17\g=a\-hydroxyprogesterone. Insufficient information is available to know how far these similarities extend.Little is known about the in vitro metabolism of either the synthetic oestrogens or synthetic progestogens. Such information as is available does not suggest that in vitro metabolic studies, with their well-known limitations, are likely to be helpful. In vivo metabolism of oestrogensThe metabolism in humans of the naturally occurring oestrogens is briefly outlined to aid comparison with that in other species and also with the meta¬ bolism of synthetic oestrogens.A. Metabolism of oestrone and oestradiol in humans The major pathways for the metabolism of oestrogens are outlined in Fig. 1.Oestrone and oestradiol are interconvertible by 17/3-hydroxysteroid oxidoreductase, the dehydrogenation of oestradiol to oestrone being more rapid than the reduction of oestrone to oestradiol so that the equilibrium between oestrone and oestradiol favours oestrone. Although a 17a-hydroxysteroid oxidoreductase is present in man (Breuer 8c Schott 1966), 17a-oestradiol is not an important metabolite but it is important in some species. One of the main metabolic pathways for oestrone is 16a-hydroxylation leading to 16a-hydroxyoestrone and oestriol. Some of the oestriol produced is oxidized to 16-oxo-oestradiol which can undergo reduction to 16/?-hydroxyoestradiol (16-e/«oestriol). The second major pathway appears to be hydroxylation at C-2 with the formation of 2-hydroxyoestrone which is readily converted to 2-methoxyoestrone by an 0-methyl transferase. Demethylation of 2-methoxyoestrogens occurs to only a slight extent. It seems likely that oestrone sulphate rather than oestrone is the precursor for the hydroxylated metabolites found in urine (Fishman 8c Hellman 1973). Hydroxylation may also occur at C-6. Oestradiol -17 a Ha^/V^" HC 2-Hydroxyoestrone 16a-Hydroxyoestrone lóB-Hydroxyoestrone * OH O Me O HO OH -OH 2-Methoxyoestrone Oestriol Fig. 1.Metabolism of oestrog...

show abstract

“…Several in vivo studies in the same species suggested that little other than glucuronides were to be found in urine ( 5 , 6 ) or bile (5). Guinea pig liver perfusion experiments (7) failed to detect additional types of conjugates.…”

Section: Introductionmentioning

confidence: 99%

In vitro and in vivo studies on the metabolism of estrogens and their sulfates in guinea pigs

Hobkirk¹,

Freeman²,

Harvey³

et al. 1977

Can. J. Biochem.

View full text Add to dashboard Cite

Labelled estradiol-17 beta(E2) or estrone (E1), when incubated with guinea pig liver slices, is metabolized by two main pathways. Part of each substrate is converted to estrone-3-glucuronide and estradiol-3-glucuronide. A further part of each is metabolized to estradiol-3-sulfate (E23S) and estrone-3-sulfate (E13S), which are interconverted. The latter conjugate appears to be the substrate for a 16 alpha-hydroxylase forming 16 alpha-hydroxyestrone-3-sulfate (16 alpha OHE13S). This, in turn, is further sulfurylated to yield 16 alpha-hydroxyestrone-3, 16-disulfate, accompanied by estriol-3,16-disulfate. A relatively small amount of tentatively indentified '6-hydroxyestrone disulfate accompanies these other two diconjugates. The guinea pig liver system suggests itself as a useful and relatively simple model for further study of 16 alpha-hydroxylation of E13S. The use of the latter as a natural subd E23S are present in liver, kidney, blood, gallbladder bile, intestine, uterus, and placenta after injection of labelled E2 into mature male and female guinea pigs. Some evidence has been obtained for the disulfate fraction (above) in liver and bile after injection of labelled E1.

show abstract

Biliary excretion and enterohepatic circulation of estrone and estriol in rodents

Cited by 52 publications

References 0 publications

The excretion of lignans in rats — evidence for an intestinal bacterial source for this new group of compounds

The excretion of lignans in rats — evidence for an intestinal bacterial source for this new group of compounds

Metabolism of Synthetic Steroids by Animals and Man

In vitro and in vivo studies on the metabolism of estrogens and their sulfates in guinea pigs

Contact Info

Product

Resources

About