Oestrone, oestradiol and oestriol glucosiduronates and sulphates in human puerperal plasma and milk

Oestrogens and progesterone in human milk and their effects on infant health outcomes: A narrative review

Human milk (HM) is a complex biological system that contains a wide range of bioactive components including oestrogens and progesterone. Whilst maternal oestrogens and progesterone concentrations drop rapidly after birth, they remain detectable in HM across lactation. Phytoestrogens and mycoestrogens, which are produced by plants and fungi, are also present in HM and can interact with oestrogen receptors to interfere with normal hormone functions. Despite the potential impact of HM oestrogens and progesterone on the infant, limited research has addressed their impact on the growth and health of breastfed infants. Furthermore, it is important to comprehensively understand the factors that contribute to these hormone levels in HM, in order to establish effective intervention strategies. In this review, we have summarized the concentrations of naturally occurring oestrogens and progesterone in HM from both endogenous and exogenous sources and discussed both maternal factors impacting HM levels and relationships with infant growth.

Role of sensory, social, and hormonal signals from the mother on the development of offspring

For mammals, sensory, social, and hormonal experience early in life is essential for the continuity of the infant's development. These experiences come from the mother through maternal care, and have enduring effects on the physiology and behavior of the adult organism. Disturbing the mother-offspring interaction by maternal deprivation (neglect) or exposure to adverse events as chronic stress, maltreatment, or sexual abuse has negative effects on the mental, psychological, physiological, and behavioral health. Indeed, these kinds of negative experiences can be the source of some neuropsychiatric diseases as depression, anxiety, impulsive aggression, and antisocial behavior. The purpose of this chapter is to review the most relevant evidence that supports the participation of cues from the mother and/or littermates during the postnatal preweaning period for the development of nervous system of the offspring. These findings come from the most frequently utilized experimental paradigms used in animal models, such as natural variations in maternal behavior, handling, partial maternal deprivation, and total maternal deprivation and artificial rearing. Through the use of these experimental procedures, it is possible to positively (handling paradigm), or negatively (maternal deprivation paradigms), affect the offspring's development. Finally, this chapter reviews the importance of the hormones that pups ingest through the maternal milk during early lactation on the development of several physiological systems, including the immune, endocrine systems, as well as on the adult behavior of the offspring.

Inhibitory effect of 5β-pregnane-3α,20β-diol on transcriptional activity and enzyme activity of human bilirubin UDP-glucuronosyltransferase

Prolonged unconjugated hyperbilirubinemia in infants associated with breast milk feeding is a common pediatric problem known as breast milk jaundice (BMJ). A polymorphic mutation (G71R) of bilirubin UDP-glucuronosyltransferase (UGT1A1) is a known cause of BMJ on the infantile side, but the responsible components of breast milk are not currently known. We analyzed the inhibitory effect of 5β-pregnane-3α,20β-diol (pregnanediol) on transcriptional activity and enzyme activity of UGT1A1. To this end, we constructed two types of expression vectors. One type comprised vectors including the upstream enhancer-promoter sequence of UGT1A1 for WT and variant type (-3279T>G with A(TA)7TAA), used in studying transcriptional regulation. The other type comprised vectors including cDNA of UGT1A1 for WT and the G71R variant, used in studying enzyme activity. In an in vitro expression study, pregnanediol did not affect the transcriptional activity of UGT1A1 enhancer-promoter complex of WT and variant type, even with coexistence of transcriptional factors such as constitutive androstane receptor or pregnane X receptor. In contrast, in the presence of 100 μM pregnanediol, bilirubin glucuronidation of G71R-UGT1A1 was reduced to 51% of WT. We suggest that pregnanediol is a cause of breast milk jaundice in carriers of G71R.

Determination of naturally occurring oestrogens and androgens in retail samples of milk and eggs

The occurrence of the main steroid hormones (oestrone, 17alpha-oestradiol, 17beta-oestradiol, 17alpha-testosterone, 17beta-testosterone, dehydroepiandrosterone, 4-androstenedione), especially in milk and eggs, was investigated. An analytical method based on GC-MS/MS was developed for steroid measurement at an ultra-trace level in food products. The limits of detection for oestrogens were about 5 and 30 ng kg(-1) in milk and eggs, respectively. For androgens, the limits of detection were around 10 and 50 ng kg(-1) in milk and eggs, respectively. The method was applied to milk and egg samples collected in a French supermarket. In milk, oestrone was found at levels between 100 and 300 ng l(-1), while 17beta-oestradiol levels were estimated to be near 20 ng l(-1). 17alpha-testosterone was found to be from 50 ng l(-1) in skimmed milk to 85 ng l(-1) in whole milk. In egg samples, oestrone and 17beta-oestradiol were found at 1.5 and 0.9 microg kg(-1), respectively, while 17alpha-oestradiol was found to be in lower concentrations (i.e. around 0.55 microg kg(-1)). Regarding androgens, 17alpha- and 17beta-testosterone were estimated at 1.9 and 1.3 microg kg(-1), respectively. These results represent a first attempt to estimate the food exposure to steroid hormones. In the future, the collection of additional data should permit the comparison between this exogenous dietary intake and the daily endogenous production in pre-pubertal children as a basis of risk assessment regarding endocrine disruption linked to these molecules for this critical population.

Insulin-like growth factors (IGFs), IGF binding proteins, and other endocrine factors in milk: role in the newborn

The role of colostrum and milk in the neonate has been chiefly recognized as a comprehensive nutrient foodstuff. In addition, the provision of colostrum-the first milk-for early immune capacity has been well documented for several species. Colostrum is additionally a rich and concentrated source of various factors that demonstrate biological activity in vitro. Three hypotheses have been proposed for the phenotypic function of these secreted bioactive components: (1) only mammary disposal, (2) mammary cell regulation, and (3) neonatal function [gastrointestinal tract (GIT) or systemic]. Traditionally, it was assumed that the development of the GIT is preprogrammed and not influenced by events occurring in the intestinal lumen. However, a large volume of research has demonstrated that colostrum (or milk-borne) bioactive components can basically contribute to the regulation of GIT growth and differentiation, while their role in postnatal development at physiological concentrations has remained elusive. Much of our current understanding is derived from cell culture and laboratory animals, but experimentation with agriculturally important species is taking place. This chapter provides an overview of work conducted primarily in neonatal calves and secondarily in other species on the effects on neonates of selected peptide endocrine factors (hormones, growth factors, in part cytokines) in colostrum. The primary focus will be on insulin-like growth factors (IGFs) and IGF binding proteins (IGFBPs) and other bioactive peptides, but new interest and concern about steroids (especially estrogens) in milk are considered as well.

Naturally occurring estrogens in processed milk and in raw milk (from gestated cows)

The occurrence of the steroid hormones estrone (E1), 17alpha-estradiol (alphaE2), 17beta-estradiol (betaE2), and estriol (E3) in processed bovine milk with different fat contents and in raw milk from (non)gestated cows was investigated. Following liquid extraction, optional enzymatical deconjugation, C18 solid-phase extraction, and derivatization, estrogens were analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Free and deconjugated E1 (6.2-1266 ng/L) was the major estrogen followed by alphaE2 (7.2-322 ng/L) and betaE2 (5.6-51 ng/L), whereas E3 was detected regularly at the detection limit of 10 ng/L. The lowest and highest concentrations were determined in raw milk from nonpregnant and from cows in the third trimester of gestation, respectively. The estrogen concentration in processed milk coincides with that of raw milk between first and second trimesters, reflecting the contribution of lactating pregnant cows to the final consumable product. The daily intake of total investigated estrogens through milk is 372 ng, which is dramatically more than currently recognized.

Systemic distribution of steroid sulfatase and estrogen sulfotransferase in human adult and fetal tissues

Estrogens play a key role in various target tissues. Enzymes involved in the biosynthesis and metabolism of these sex steroids also regulate estrogenic actions in these tissues. Estrone sulfate (E1S) is a major circulating plasma estrogen that is converted into the biologically active estrogen, estrone (E1), by steroid sulfatase (STS). E1 is also sulfated and reverted into E1S by estrogen sulfotransferase (EST). These two enzymes have recently been shown to play important roles in the in situ estrogen actions of various sex steroid-dependent human tumors. However, the distribution of STS and EST in normal adult and fetal human tissues remains largely unknown. Therefore, in this study, in addition to examining the tissue distribution of both STS and EST mRNA in human adult and fetal tissues using RT followed by quantitative PCR, we studied the activity of these enzymes using (3)H-labeled E1/E1S as substrates in the homogenates of various human adult tissues. We also examined the localization of STS and EST protein in human adult and fetal tissues using immunohistochemistry, and that of EST mRNA in the adult kidney using laser dissection microscopy and PCR. STS mRNA, enzyme activity, and immunoreactivity were either absent or detected at very low levels in all adult and fetal tissues examined in this study. EST mRNA expression, however, was detected in all of the tissues examined, except for adult spleen and pancreas. EST enzyme activities were consistent with those of mRNA expression in the great majority of the tissues examined. Marked EST immunoreactivity was detected in hepatocytes, adrenal gland (adult, zona fasciculate to the reticularis; fetus, fetal zone), and epithelial cells of the gastrointestinal tract, smooth muscle cells of the tunica media in aorta, Leydig cells of the testis, and syncytiotrophoblast of the placenta. Patterns of EST immunolocalization were similar between adult and fetal human tissues, but EST immunoreactivity was detected in the urinary tubules of adult kidney, whereas in the fetal kidney, it was localized in the interstitial cells surrounding the urinary tubules. In the adult kidney, the presence of EST mRNA was also confirmed in the cells of urinary tubules using laser dissection microscopy and RT-PCR. Although the number of human tissues available for examination in this study was limited, our results suggest that between the enzymes involved in estrogen activation or inactivation, EST and not STS is the more widely expressed enzyme in various peripheral tissues in humans. We speculate that EST may play an important role in protecting peripheral tissues from possible excessive estrogenic effects.

Isoflavones, soy-based infant formulas, and relevance to endocrine function

For more than 60 years, soy-based infant formulas have been fed to millions of infants worldwide and studied in controlled clinical research. These products provide essential nutrients required for normal growth and development. The safety of isoflavones in soy-based products, including infant formulas, has been questioned recently owing to reports of possible endocrine effects in animals and in cultured cells. The literature offers no evidence of endocrine effects in humans from infant consumption of modern soy-based formulas. Growth is normal and no changes in the timing of puberty or in fertility rates have been reported in humans who consumed soy formulas as infants. Consequently, soy-based infant formulas continue to be a safe, nutritionally complete feeding option for most infants.

Relationships of peri-partum, plasma concentrations of progesterone, oestrogens and 13,14-dihydro-15-ketoprostaglandin F2alpha in heifers and of anatomical measurements of dam and calf with difficulty of calving in early-bred Hereford x Friesian heifers

Plasma concentrations of progesterone, oestradiol-17beta, oestrone, oestrone sulphate and PGFM have been measured daily during the first peri-partum period of 45 Hereford x Friesian heifers bred at 11 months of age. Anatomical measurements of dam and calf were also recorded. Twelve of the calvings were scored easy, 33 difficult. Each of five models (fitted by linear logistic regression) relating difficulty of calving to the hormonal and anatomical measurements, predicts with at least 94% accuracy the calving score (easy or difficult) among the calvings. The models predict that increases of progesterone concentration on the day before calving, of oestrone sulphate concentration on the day after calving and of heifer heart girth decrease the odds of difficult calving, whereas increases of heifer body length and of calf head circumference increase the odds of difficult calving.

Lower serum oestrogen concentrations associated with faster intestinal transit

Increased fibre intake has been shown to reduce serum oestrogen concentrations. We hypothesized that fibre exerts this effect by decreasing the time available for reabsorption of oestrogens in the colon. We tested this in volunteers by measuring changes in serum oestrogen levels in response to manipulation of intestinal transit times with senna and loperamide, then comparing the results with changes caused by wheat bran. Forty healthy premenopausal volunteers were placed at random into one of three groups. The first group took senna for two menstrual cycles then, after a washout period, took wheat bran, again for two menstrual cycles. The second group did the reverse. The third group took loperamide for two menstrual cycles. At the beginning and end of each intervention a 4-day dietary record was kept and whole-gut transit time was measured; stools were taken for measurement of pH and beta-glucuronidase activity and blood for measurement of oestrone and oestradiol and their non-protein-bound fractions and of oestrone sulphate. Senna and loperamide caused the intended alterations in intestinal transit, whereas on wheat bran supplements there was a trend towards faster transit. Serum oestrone sulphate fell with wheat bran (mean intake 19.8 g day(-1)) and with senna; total- and non-protein-bound oestrone fell with senna. No significant changes in serum oestrogens were seen with loperamide. No significant changes were seen in faecal beta-glucuronidase activity. Stool pH changed only with senna, in which case it fell. In conclusion, speeding up intestinal transit can lower serum oestrogen concentrations.

Comparison of the effects of oral and transdermal oestradiol administration on oestrogen metabolism, protein synthesis, gonadotrophin release, bone turnover and climacteric symptoms in postmenopausal women

We compared the effect of administering oestradiol via the transdermal or oral routes in six and eight postmenopausal women respectively. Although both treatments achieved similar plasma levels of oestradiol, oral administration led to much greater increases in plasma levels of oestrone and the sulphates and glucuronides of oestradiol, oestrone and oestriol than transdermal treatment (P less than 0.001). Both treatments reduced plasma FSH; from 42 +/- 10 (SE) IU/l to 30 +/- 2 IU/l with oral and from 46 +/- 7 IU/l to 28 +/- 6 IU/l with transdermal treatment. Urine calcium excretion fell from 0.41 +/- 0.06 (molar ratio to creatinine) to 0.17 +/- 0.02 with oral and from 0.25 +/- 0.06 to 0.13 +/- 0.02 with transdermal treatment. Patients' symptoms were improved by both treatments. These changes were related to the plasma oestradiol concentration but not to that of oestrone. Oral, but not transdermal, treatment stimulated hepatic protein synthesis as shown by increased plasma levels of both vitamin-D-binding globulin and sex-hormone-binding globulin. We conclude that although both oral and transdermal oestradiol reduce postmenopausal bone loss, gonadotrophin secretion and symptoms, oral treatment also leads to hepatic stimulation and extensive metabolism of oestradiol, both of which may increase side-effects without conferring additional benefit.

Influence of pregnancy and lactation on serum and breast fluid estrogen levels: implications for breast cancer risk

We investigated estrogen (estrone and estradiol) levels in serum and in nipple aspirates of breast fluid in relation to reproductive and menopausal characteristics in 104 normal women. In general, breast fluid and serum estrogen levels were not correlated and breast fluid estrogen levels were approximately 5 to 45 times higher than serum levels. Serum estrogen levels were lower in post-menopausal than in pre-menopausal women. In contrast, breast fluid estrogen levels were approximately the same in pre- and post-menopausal women. Breast fluid estrogen mean levels were lower in pre-menopausal parous women than in nulligravidous or nulliparous women whereas serum estrogen levels did not differ in these 3 groups. Breast fluid estrogen levels were positively correlated with months since last birth or since last breast-feeding. Estrogen levels were low in nipple aspirates of breast milk but gradually increased in breast fluid of non-lactating women over a period of several years after cessation of lactation. Serum estrogen levels did not increase with months since last breast-feeding. We were unable to evaluate the post-partum effect of pregnancy without lactation due to the small numbers of these subjects. The high concentrations of estrogen in breast fluid and the absence of a relationship to serum estrogen levels may explain why prior serum studies have failed to link variations in serum estrogens with breast cancer risk. The prolonged low levels of breast fluid estrogens following full-term birth and lactation may, in part, provide a mechanism by which parity reduces breast cancer risk.

Saliva oestriol, oestradiol, oestrone and progesterone levels in pregnancy: spontaneous labour at term is preceded by a rise in the saliva oestriol:progesterone ratio

Saliva steroid levels reflect the unbound unconjugated (free, biologically active) plasma hormone levels. Saliva oestriol (E3), oestradiol (E2), oestrone (E1) and progesterone levels were estimated by radioimmunoassay in saliva samples obtained twice a week from 18 weeks gestation until 38 days before delivery and then daily until the spontaneous onset of labour at term from 20 normal pregnant women. The overall percentage increases in the median concentrations of E3, E2, E1 and progesterone were 718, 370, 80 and 214%, respectively, in the last 20 weeks and 149, 82, 24 and 41%, respectively, in the last 6 weeks of pregnancy. The median E3:progesterone ratio rose slowly from 0.65 at 20 weeks before delivery to 1.0 at 5 weeks before delivery and then rapidly to 1.65 one day before the spontaneous onset of labour. There was an increase in the E3:progesterone ratio from less than 1 to greater than 1 before labour in every subject.

beta-Glucuronidase levels in patients with fibrocystic breast disease

Certain enzymes in tissues and body fluids may, through reversal of the detoxification process, influence the composition and availability of steroid hormones, toxins, and carcinogens. The ubiquitous enzyme beta-glucuronidase, which hydrolyzes glucuronide conjugates, thereby reversing one of the main detoxification and excretion pathways, was found to vary in concentration in different cysts over a 300-fold range. The distribution was a continuum, devoid of discrete sub-populations. Evidence obtained on selected cyst fluids of high and low beta-glucuronidase activities indicated that the level of the enzyme significantly influenced the ratio of unconjugated: glucuronidated estradiol. The patients with fibrocystic breast disease fell into 2 distinct subpopulations on the basis of their serum beta-glucuronidase activity. In one group the activity was near normal, while in the second group the average serum beta-glucuronidase activity was 3-fold higher than in the women who did not have benign breast disease.

Identification and quantitation of free and conjugated steroids in milk from lactating women

A method for analysis of metabolic profiles of free and conjugated steroids in milk has been developed. Milk is diluted with aqueous triethylamine sulphate and liquid-solid extraction is achieved on a Sep-Pak C18 cartridge at 60-64 degrees C. Steroids are purified by chromatography on small columns of Lipidex 5000 and sulphohydroxypropyl Sephadex LH-20 [H+] prior to separation into neutral and phenolic compounds, glucuronide, mono- and disulphate conjugate groups on the lipophilic strong anion exchanger triethylaminohydroxypropyl Sephadex LH-20 (TEAP-LH-20). Conjugated steroids are released by enzymatic or solvolytic procedures and separated into a neutral and a phenolic fraction on TEAP-LH-20. The O-methyloxime and trimethylsilyl ether derivatives of the steroids are analyzed by capillary column gas chromatography-mass spectrometry. Fifty steroids were identified in milk collected from women a few days after delivery. Quantitatively about 80% were present as sulphates, 15% as glucuronides and only 5% were unconjugated steroids. The steroid pattern was similar to that in late pregnancy plasma with pregnanolone, pregnanediol and pregnanetriol isomers and dehydroepiandrosterone being predominant. About 10% of the steroid content consisted of estrogens. The total concentration of steroids 2 days after delivery was 20-116 ng/ml, i.e. about 1-5% of the concentration was about 10 ng/ml 1 month after delivery. In one milk sample, collected 2 days after delivery, the steroid concentration (3.6 micrograms/ml) was similar to that in plasma.

Hormones in milk

Protein hormones (especially prolactin) and steroid hormones (gestagens, estrogens, corticoids, and androgens) can be detected by bioassay and radioimmunoassay in milk in a variety of species. In addition, milk contains vitamin D and beta-casomorphins (opiate-like peptides). It has been assumed that most of the hormones are transferred into milk by diffusion. However, evidence is available for active mechanisms like those for progesterone in goats and prolactin in cows. Most of the hormone profiles in milk are similar to the ones in blood plasma. Hormone concentrations in milk seem to be a good estimate of the average hormone content in plasma, especially for the measurement of longer-lasting secretory activities like progesterone and estrogen release during the estrous cycle or seasonal changes of prolactin in ruminants. Determination of progesterone and estrone sulfate in milk serves as a diagnostic tool in fertility control, especially in cows. Enzyme immunoassay kits are available for this monitoring purpose. Exogenously administered hormones are also transferred into milk. Residue studies have shown that the dilution is so great that it may be assumed that there is no potential risk for the consumer.

Metabolism of 4-hydroxyandrost-4-ene-3,17-dione by rat hepatocytes

4-[14C]HAD was rapidly metabolized (99% after 5 min) by hepatocytes from phenobarbital-treated rats. An array of phase I metabolites was formed, variously involving one and two reductions, hydroxylation, hydration and hydroxylation plus one or two reductions. Some of the metabolites were identified by synthesis and others tentatively by mass spectrometry. After 10 min, approximately 30% of the original radioactivity was present in HAD glucuronide and, after 15 min, approximately 60% was present in the total glucuronide fraction which contained several components. Only one of the phase I metabolites (2-hydroxy-HAD) exhibited significant aromatase inhibitory activity (45% of that of HAD).

A double antibody radioimmunoassay for free and conjugated estradiol-17 beta in cow's milk

A radioimmunoassay for free estradiol-17 beta, conjugated estradiol-17 beta or total (free + conjugated) estradiol-17 beta in defatted milk of cows is described. Conjugated estradiol-17 beta was hydrolyzed by enzymes of Helix pomatia juice. Estrogens were extracted with dichloromethane; no other purification step was required before radioimmunoassay because of the high specificity of the antiserum. Immunoprecipitation was used to separate bound and free estradiol-17 beta. Concentrations measured were corrected for procedural losses on a per sample basis. The assays were shown to be accurate and specific. The sensitivity was 1.3pg/ml for the assay of free estradiol-17 beta (5ml of milk extracted) and 2.9pg/ml for conjugated or total estradiol-17 beta (2 ml of milk hydrolyzed and extracted). Estrogens were measured in the milk of cyclic cows and in cows stimulated with pregnant mare serum gonadotropin (PMSG). A preovulatory increase was clearly observed. Wether or not the ovary was stimulated by PMSG, concentrations of estrogens were higher and the relative increase during the preovulatory peak was greater for conjugated estradiol-17 beta than for the free form. The assay of conjugated or total estradiol-17 beta in defatted milk should be a practical method for assessing preovulatory growth of follicles in cows.