Three dairy heifers (A, B and C) were induced to parturition with two prostaglandin (PG) F(2alpha) injections on day 268 and 269 of pregnancy. Signs of approaching parturition were carefully observed. The following parameters were registered: degrees of calving difficulty, date and time of parturition, calf's birth weight and calf's sex. Body temperature was measured and blood samples were taken every 3 h 3 days before the first PGF(2alpha) injection until 3 days after parturition. The plasma concentrations of the PGF(2alpha) metabolite, progesterone, cortisol, oestrone sulphate and pregnancy associated glycoproteins (PAGs) were analysed. Heifers A, B and C delivered 48, 51 and 57 h after the first PGF(2alpha) injection, respectively. Heifer A delivered without any signs of calving difficulty, whereas, the parturition was considered to be slight and moderate difficulty occurred in the delivery of heifers B and C, respectively. The calf of heifer C, without any abnormal gross-evidences, was stillborn. All animals had retained foetal membranes. A slight increase of the PGF(2alpha) metabolite at the time of parturition was found only in heifer C, whereas the levels dramatically increased in all animals 15-24 h after parturition. At the same time, progesterone levels decreased within 3 h after the first PGF(2alpha) injection (P < 0.05) and reached 0.8, 2.7 and 12.4 nmol/l at the time of parturition in heifers A, B and C, respectively. High release of cortisol at the time of parturition was seen in heifer C. Rising levels of oestrone sulphate around the time of parturition were recorded in all heifers, whereas, increasing levels of PAGs were recorded only in heifer A. In conclusion, the patterns of the PGF(2alpha) metabolite, cortisol, progesterone and PAGs were changed in the cases of calving difficulty and stillbirth after PGF(2alpha)-induction of parturition. However, the relationship between oestrone sulphate and PAGs and the status of foetal well being prior to parturition require further elucidation.

The expression of drug metabolizing cytochrome P4502A (CYP2A) is highly gender-dependent in minipigs with the highest activity in females. In other species, orthologs of CYP2A have been shown to be under the regulation of nuclear receptor constitutive androstane receptor, whereas little is known about regulation in pigs. To investigate the effect of sex hormones on porcine cytochrome P450 CYP2A and CYP3A expression was assessed in liver samples taken before and after castration of sexually mature minipig boars. Removal of the primary androgen source resulted in significant increases of CYP2A mRNA, protein and enzyme activity levels. Likewise, expression of CYP3A was increased, although to a lesser extent. To examine the involvement of constitutive androstane receptor in the regulation of CYP2A, primary porcine hepatocytes were exposed to modulators of murine constitutive androstane receptor and human constitutive androstane receptor activity. The CYP2A activity was significantly increased by exposure to phenobarbital, an indirect activator of constitutive androstane receptor, and the human constitutive androstane receptor-ligand CITCO. In contrast, no effect was seen following exposure to the potent murine constitutive androstane receptor-ligand TCPOBOP and the hormonal murine constitutive androstane receptor-ligands androstenol and oestrone. Thus, the results support that 1) porcine CYP2A is reversibly inhibited by androgens on a transcriptional basis in vivo; 2) the induction profile of CYP2A in vitro shares similarity with that of human constitutive androstane receptor-regulated CYPs, indicating an involvement of a porcine constitutive androstane receptor in the regulation of CYP2A.

Many hormones are involved in the regulation of male reproductive functions, controlling sexual behavior, and influencing sexual arousal, the onset of erection and ejaculation, and the post-ejaculatory detumescence. The aims of this study were to analyze the plasma concentrations of 15-ketodihydro-PGF(2α) (PGFM), LH, testosterone (T), oestrone sulphate (OS), and cortisol (C) in relation to sexual stimulation and to evaluate the possible correlations among circulating hormones and between hormones and semen characteristics in the donkey stallion. Thirteen sexually experienced Martina Franca jackass of proven fertility were enrolled and semen was collected through an artificial vagina. Plasma samples were collected at 12, 9, 6 and 3 min before oestrous jenny exposure, at the first erection in the mating arena in the presence of an oestrous jenny, during ejaculation, at dismounting, 3, 6, 9 and 12 min after ejaculation in box, and then every 10 min during the following 50 min. PGFM showed an increasing trend with significant differences between the pre-ejaculatory and post-ejaculatory period, suggesting a role of this hormone in the control of ejaculation. LH showed a significantly higher concentration at ejaculation compared to last samples, while T showed significantly higher levels at erection, ejaculation and dismounting, probably for its influence on these processes and on sexual behavior. Finally, OS did not show any difference in the period of observation, while C presented a significant increase only 22 minutes after erection. The only hormonal correlation found was a positive one between LH and T at erection and dismounting, while T and OS were positively correlated with total and progressive motility, respectively.

Steroid hormone concentrations have been measured in the peripheral plasma of 3 Barbary sheep over 3 breeding seasons. During pregnancy mean progesterone values rose initially and after a small decline between Days 30 and 50, increased again and remained between 17 and 28 nmol/l until the last 2 days of pregnancy. Oestradiol-17 beta reached a peak of about 300 pmol/l during mid-pregnancy, increasing to over 400 pmol/l in the last 5 days of pregnancy. Oestrone sulphate began to increase in concentration from about Day 40 of pregnancy and reached a peak of about 19 nmol/l by Day 120. Following a slight decrease from Day 130, there was a further rise in values just before parturition. Values for these steroids in the Barbary sheep studied were between those expected for domestic sheep and goats.

Ovaries were obtained from sows immediately after slaughter and were morphologically assigned to different stages of the ovarian cycle. Follicular fluid contained in the predominating follicles was analysed for ten steroid hormones by a multiple, simultaneous radioimmunoassay technique. The steroids measured were pregnenolone, progesterone, 20 alpha-dihydroprogesterone, 17 alpha-hydroxyprogesterone, androstenedione, 5 alpha-dihydrotestosterone, dehydroepiandrosterone, testosterone, oestrone and oestradiol-17 beta. The concentrations of the steroids remained relatively low during the luteal stages until the mid-follicular stage when ovaries contained predominantly small to medium-sized (less than 5.0 mm in diam.) follicles. With the exception of 5 alpha-dihydrotestosterone concentrations, which remained low regardless of the size of the follicles or the stage of the cycle, the concentrations of all the steroids were significantly elevated in the transition from the mid- to late follicular stage, a period when the ovaries contained mainly large (6-10 mm diam.) follicles. Follicles at the ovulatory stage exhibited a profound decline in the concentrations of androgens and oestrogens. In contrast, the magnitude of decline in the levels of 3 progestagens, i.e. pregnenolone, progesterone and 17 alpha-hydroxyprogesterone, was much less than that for androgens and oestrogens, while the concentration of 20 alpha-dihydroprogesterone was actually elevated in the ovulatory follicles. The present results agree with those of earlier studies which measured fewer steroids in follicles obtained by repeated and sequential laparotomies of sows during spontaneous cycles. In contrast, these hormone results differ from those using the PMSG/hCG-stimulated ovary, suggesting that such ovaries may not be a completely valid model for ovarian steroid hormone metabolism in the normally cycling sow.

Commercial ELISA kits for the determination of steroid hormones in milk and blood of domestic animals have been used by veterinary surgeons in practice as a method of pregnancy diagnosis in cattle, horses and pigs. In goats, the complex metabolism of steroid hormones in the mammary gland has made the test unsatisfactory. In five non-pregnant Saanen does, milk and blood samples were taken daily through a complete oestrous cycle, and the concentrations of progesterone measured by ELISA. A wide variation in the pattern of progesterone concentration was recorded. In seven non-pregnant and early pregnant does (less than 35 days) the mean concentration of oestrogens in milk was 0.5 ng/ml. Pregnancy in 88 does was subsequently predicted, based upon a concentration of oestrone sulphate in milk over 0.5 mg/ml, and was approximately 80 per cent accurate for determination of both pregnancy and non-pregnancy when compared with actual kidding data. Reasons are given for these errors.

A total of 54 Holstein-Friesian cows (13 primiparous and 41 multiparous) was used to study maternal plasma oestrone sulphate (E1S) during pregnancy and its relationship to birth weight and viability of calves and time required for placental expulsion after calving. Plasma samples were obtained from the tail vein of cows once every month from days 90 to 180, every 2 weeks from days 181 to 270, and every day from day 270 of gestation to parturition. The E1S concentrations were measured by radioimmunoassay, and birth weight, placental measurements, neonatal viability and the period from calving to placental expulsion were recorded. E1S concentrations were correlated positively (0.71>> or = r>> or = 0.32, P < 0.05 or P < 0.01) with calf birth weight and weights of cotyledons, intercotyledonary membranes and total placenta from days 210 of gestation to 1 day prepartum. Calf birth weight was correlated positively (p < 0.01) with the weight of the cotyledons (r = 0.87), intercotyledonary membranes (r = 0.78) and total placenta (r = 0.88). In addition, E1S concentrations were positively correlated (0.63>> or = r>> or = 0.28, P < 0.05 or P < 0.01) with the neonatal viability after day 195 of pregnancy, and were negatively correlated (-0.29>> or = r>> or = -0.55, P < 0.05 or P < 0.01) with the intervals from parturition to placental expulsion after 225 days of pregnancy. The results suggest that variation among dams for circulating E1S levels during late pregnancy may be caused by variation of placental development and ability for oestrogen production and conjugation, and they may influence fetal growth, neonatal viability and retained placenta.

BACKGROUND

Prolonged sitting and lower levels of physical activity have been associated with increased levels of parent oestrogens (oestrone and oestradiol), the key hormones in female cancers, in postmenopausal women. However, it is unknown whether sitting and physical activity are associated with circulating oestrogen metabolite levels.

METHODS

Among 1804 postmenopausal women enrolled in the Women's Health Initiative Observational Study, 15 serum oestrogens/oestrogen metabolites were quantified using liquid chromatography-tandem mass spectrometry. Physical activity and sitting were self-reported via questionnaire. Using baseline, cross-sectional data, geometric means (GM) of oestrogens/oestrogen metabolites (pmol l-1) were estimated using inverse probability weighted linear regression, adjusting for potential confounders and stratified on menopausal hormone therapy (MHT) use.

RESULTS

Longer time spent sitting (⩾10 vs ⩽5h per day) was associated with higher levels of unconjugated oestrone, independent of moderate- to vigorous-intensity physical activity and body mass index, among both never/former (GM=70.6 vs 57.7) and current MHT users (GM=242 vs 179) (P-trend ⩽0.03). Among never/former MHT users, sitting (⩾10 vs ⩽5h per day) was positively associated with 2-methoxyestradiol (GM=16.4 vs 14.4) and 4-methoxyestradiol (GM=2.36 vs 1.98) (P-trend ⩽0.04), independent of parent oestrogens. Inverse associations between moderate- to vigorous-intensity physical activity (⩾15 vs 0 metabolic equivalent task-hours per week) and parent oestrogens were found as expected. After adjustment for parent oestrogens, physical activity was not associated with oestrogen metabolites.

CONCLUSIONS

Our data suggest that prolonged sitting and lower moderate- to vigorous-intensity physical activity are associated with higher levels of postmenopausal oestrogens/oestrogen metabolites, the oestrogen metabolism patterns that have previously been associated with higher endometrial and breast cancer risk.

In polycystic ovary syndrome (PCOS), increased luteinizing hormone (LH) pulse frequency has been attributed to either the hypothalamic gonadotrophin-releasing hormone (GnRH) pulse generator or ovarian oestrogen feedback. To address this issue, a detailed examination of pulsatile LH secretion was undertaken during recovery from GnRH agonist (GnRHa) suppression. Each of six women with PCOS and six normal ovulatory women received daily GnRHa treatment for 14 weeks. Frequent blood samples were collected and assayed for gonadotrophins, androgens and oestrogens before, during and up to 4 weeks after treatment. Women with PCOS had higher basal LH pulse frequency and amplitude and increased serum concentrations of LH, androstenedione, testosterone and oestrone than controls. After 3 months of GnRHa treatment, all these parameters were suppressed with no differences observed between the two groups. One week after cessation of GnRHa, LH pulse frequency promptly returned to pre-treatment range with no between-group differences noted, whereas LH pulse amplitude, serum gonadotrophins and ovarian steroids remained maximally suppressed and equivalent in the two groups. Subsequent LH pulse frequency remained constant while LH pulse amplitude and circulating concentrations gradually increased in parallel with a return of serum oestrogen to pre-treatment values. Despite comparable resumption of LH secretion in the two groups, corresponding androgen concentrations in women with PCOS were greater than those of normal ovulatory women. Thus, the immediate restoration of LH pulse frequency after discontinuing GnRHa treatment is largely independent of ovarian oestrogen production and reflects primacy of the GnRH pulse generator in determining basal LH pulse frequency. Equivalent LH pulse frequency rates in the two groups during the recovery period do not suggest an intrinsic hypothalamic-pituitary hyperactivity in PCOS.

The porcine myometrium possesses steroidogenic activity. LH and FSH are hypothesised to regulate the myometrial production of androstenedione (A4), testosterone (T), oestrone (E1) and 17β-oestradiol (E2). In this study, we used myometrium collected from cycling (n=15) and pregnant (n=15) pigs on Days 10-11, 12-13 and 15-16 of the oestrous cycle or pregnancy to determine: (1) the abundance of LH and FSH receptor (LH/choriogonadotrophin receptor (CGR) and FSHR) mRNA and protein; (2) activity of 17β-hydroxysteroid dehydrogenase 1 (17βHSD1); and (3) A4, T, E1 and E2 release in response to LH and FSH treatment, used at doses 10 or 100ng mL-1 for 6h. In results, the myometrium possesses LH/CGR and FSHR with minor alterations in their expression in the course of the oestrous cycle or early pregnancy. 17βHSD1 activity was the highest on Days 12-13 of the oestrous cycle and the lowest on Days 15-16 of the oestrus cycle and pregnancy, when compared to the other studied days of the oestrous cycle or pregnancy. The LH and FSH treatment increased A4 release on Days 12-13 of the oestrous cycle, and E1 and E2 release on Days 15-16 of the oestrous cycle. Moreover, on Days 12-13 E2 release was increased in response to FSH treatment (100ng mL-1) in cycling pigs and in response to LH (100ng mL-1) in pregnant pigs. In conclusion, the myometrium of pregnant and non-pregnant pigs expresses LH/CGR and FSHR and has 17βHSD1 activity. In addition, the amount of A4, E1, and E2 release from the myometrium is altered in response to LH and FSH, especially in cycling pigs. LH and FSH appear to be important regulators of myometrial oestrogen release in pigs mostly during luteolysis.

The aim of this prospective cohort study was to determine the time-course in androgen and semen parameters in men after weight loss associated with bariatric surgery. Six men aged 18-40 years, meeting National Institutes of Health bariatric surgery guidelines, were followed between 2005 and 2008. Study visits took place at baseline, then 1, 3, 6 and 12 months after surgery. All men underwent Roux-en-y gastric bypass (RYGB). At each visit, biometric, questionnaire, serum, and urinary specimens and seman analysis were collected. Urinary integrated total testosterone levels increased significantly (P < 0.0001) by 3 months after surgery, and remained elevated throughout the study. Circulating testosterone levels were also higher at 1 and 6 months after surgery, compared with baseline. Serum sex hormone-binding globulin levels were significantly elevated at all time points after surgery (P < 0.01 to P = 0.02). After RYGB surgery, no significant changes occurred in urinary oestrogen metabolites (oestrone 3-glucuronide), serum oestradiol levels, serial semen parameters or male sexual function by questionnaire. A threshold of weight loss is necessary to improve male reproductive function by reversing male hypogonadism, manifested as increased testosterone levels. Further serial semen analyses showed normal ranges for most parameters despite massive weight loss.

The evolution of primate sexual swellings and their influence on mating strategies have captivated the interest of biologists for over a century. Across the primate order, variability in the timing of ovulation with respect to females' sexual swelling patterns differs greatly. Since sexual swellings typically function as signals of female fecundity, the temporal relation between ovulation and sexual swellings can impact the ability of males to pinpoint ovulation and thereby affect male mating strategies. Here, we used endocrine parameters to detect ovulation and examined the temporal relation between the maximum swelling phase (MSP) and ovulation in wild female bonobos (Pan paniscus). Data were collected at the Luikotale field site, Democratic Republic of Congo, spanning 36 months. Observational data from 13 females were used to characterise female swelling cycles (N = 70). Furthermore, we measured urinary oestrone and pregnanediol using liquid chromatography-tandem mass spectrometry, and used pregnanediol to determine the timing of ovulation in 34 cycles (N = 9 females).

We found that the duration of females' MSP was highly variable, ranging from 1 to 31 days. Timing of ovulation varied considerably in relation to the onset of the MSP, resulting in a very low day-specific probability of ovulation and fecundity across female cycles. Ovulation occurred during the MSP in only 52.9 % of the analysed swelling cycles, and females showed regular sexual swelling patterns in N = 8 swelling cycles where ovulation did not occur. These findings reveal that sexual swellings of bonobos are less reliable indicators of ovulation compared to other species of primates.

Female bonobos show unusual variability in the duration of the MSP and in the timing of ovulation relative to the sexual swelling signal. These data are important for understanding the evolution of sexual signals, how they influence male and female mating strategies, and how decoupling visual signals of fecundity from the periovulatory period may affect intersexual conflict. By prolonging the period during which males would need to mate guard females to ascertain paternity, the temporal variability of this signal may constrain mate-guarding efforts by male bonobos.

Blood samples were taken at weekly intervals during the last 2 months of pregnancy from a mature (7-year-old) harbour seal which had conceived and was kept in captivity. The concentrations of oestrone, oestrone sulphate, progesterone and glucocorticoids were determined by radioassays. The plasma levels of unconjugated oestrone were slightly greater than those of oestrone sulphate. Total oestrone declined steadily over the last month from a peak of 2.3 ng/ml at 30 days before parturition. Plasma progesterone concentrations rose to 61 ng/ml at 2 weeks before parturition and fell to about half that value by 2 days before birth of a normal male pup. Plasma glucocorticosteroids reached a peak of 164 ng/ml, also at 2 weeks, but showed only a slight decline thereafter. A higher value (392 ng/ml) was recorded 5 days after parturition.

This study describes the age-related variation in boar taint compounds, skatole and androstenone, and testosterone, oestradiol-17 beta (E17 beta), oestrone sulphate (ES), dehydroepiandrosterone sulphate (DHEAS), triiodothyronine (T(3)) and insulin-like growth factor-1 (IGF-1) in six boars. Three pairs of littermates of crossbred entire male pigs (from three Yorkshire x Duroc dams and one Hampshire sire) were included. Blood samples were taken at the age of 9-15 weeks and thereafter at weekly intervals from the age of 20-32 weeks. Plasma concentrations of skatole, androstenone, testosterone, E17 beta, ES, DHEAS, T(3) and IGF-1 were measured. We found that skatole levels in boars increased at the age around puberty after an increase in the levels of testicular steroids. Levels of skatole were not associated with the levels of sex steroids, T(3) and IGF-1. However, the increased level of testicular steroids is probably the underlying factor needed for high skatole levels to occur although the specific mechanism leading to increased skatole levels remains unknown.

A method for the extraction of oestrone and equilin from the plasma of the pregnant mare is described, and the levels obtained for eighty-two samples from fourteen Welsh Mountain Ponies at different stages of pregnancy are recorded. Oestrone (fifteen samples) and equilin (three samples) were not found before Day 120. From Day 120 to 240, oestrone levels exceeded 100 ng/ml and then declined to parturition. The high concentrations of oestrone in mid-pregnancy were associated with gradually increasing concentrations of equilin which tended to plateau after Day 180 at just under 100 ng/ml and declined significantly only in the last month of pregnancy. Evidence is presented that both oestrone and equilin occur in peripheral plasma largely as sulphates.

Intracellular oestrogen metabolism has been investigated in endometrial tissue from postmenopausal women receiving oestrogen therapy either alone or in combination with a progestogen. During oestrogen therapy alone, there was a 3.2 fold predominance of oestradiol over oestrone within the endometrial cell nucleus and the mean nuclear oestrogen receptor content was 1.40 pmol/mg DNA. The addition of norethisterone decreased the nuclear oestradiol/oestrone ratio to 1.4:1 by lowering the oestradiol mass. A concurrent reduction in the mean level of the nuclear oestrogen receptor to 0.58 pmol/mg DNA indicated a decrease in oestrogenic stimulation. The activity of oestradiol-17 beta dehydrogenase was significantly increased. There was a plasma excess of oestrone over oestradiol during oestrogen therapy alone and oestrone/oestradiol ratio was not significantly altered following norethisterone administration. The ability of the endometrium to incorporate oestradiol selectively into the nucleus is discussed in relation to the risk of endometrial hyperplasia with unopposed oestrogen therapy. The profound biochemical changes induced by norethisterone help elucidate mechanisms whereby progestogens lower oestrogenic potency and thereby protect the endometrium against excessive stimulation.

Segments of individual blastocysts collected on Days 10, 12, 14 and 16 were examined microscopically to observe yolk-sac development and treated immunocytochemically to localize oestrogens in specific membranes. Mesoderm was present beneath the embryonic disc of ovoid blastocysts on Day 12. The mesoderm spread beyond 1 cm from the disc on Day 14, producing a splanchnic yolk-sac membrane extending across the blastocoelomic cavity, but no mesodermal cells had yet reached 5 cm. By Day 16, proliferation of mesoderm and development of the yolk sac had progressed beyond 20 cm from the disc in most of the specimens examined. Incubation of ultrathin sections with sheep antiserum to oestrone or oestradiol-17 beta followed by rabbit anti-ovine IgG-gold complex and subsequent counting of gold particles retained over the tissues gave a weakly positive reaction for oestrone in trophectodermal cells on Day 10. The most intense reaction for oestradiol-17 beta was also present in the trophectoderm and yolk-sac endoderm on Days 12, 14 and 16.

The effect of danazol in a dose of 600 mg a day was studied in 20 women with moderate or severe endometriosis. The clinical effect was found to be excellent and repeat laparoscopy after about 6 months treatment revealed a marked regression in all patients with only small residual foci of endometriosis in two of them. The side effects were few. The metabolic studies revealed a significant increase in serum aspartate aminotransferase (AST), serum alanine aminotransferase (ALT), serum potassium, serum albumin and serum creatinine, but a significant decrease in serum gamma glutamyl transpeptidase (GT). Serum sodium showed no alteration. A longitudinal study of basal plasma luteinizing hormone (LH) and follicle-stimulating hormone (FSH) and their responses to 25 microgram gonadotrophic releasing hormone (GnRH) i.v. as well as basal plasma levels of oestradiol, oestrone, progesterone and prolactin was performed. During treatment with danazol (600 mg a day) basal levels of LH, FSH, oestradiol, oestrone and progesterone were low but did not differ from the levels found in the early follicular phase of the menstrual cycle. On the other hand the pituitary response to GnRH was significantly greater for both LH and FSH than observed during the early follicular phase. These conflicting results are discussed. It seems that danazol inhibits the pituitary secretion of biologically active LH and FSH and this action is responsible for the decreased ovarian steroid secretion. Whether the atrophy of the uterine and ectopic endometrium is an effect of the reduced oestradiol levels or is a direct effect of danazol on endometrial oestrogen receptors, or a combination of both modes of action, is not clear.

Ovarian and peripheral plasma levels of oestrone (E1), oestradiol (E2), androstenedione (A) and testosterone (T) were assayed in 58 post-menopausal women who underwent hysterectomy and oophorectomy (35 for endometrial carcinoma and 23 for benign gynaecological diseases). No significant difference between the two groups was seen when they were matched for percentage of ideal weight. However, significant differences were found between the ovarian and peripheral levels of the four steroids investigated. To facilitate analysis of the data, 40 of these women were classified into three groups (1, 2 and 3) according to degree of stromal hyperplasia of the ovary. Group 1 comprised those with atrophic ovaries, group 2 those with slight stromal hyperplasia and group 3 those with moderate or marked stromal hyperplasia. Ovarian levels of A and T were significantly higher than peripheral levels in all three groups, but the ovarian/peripheral oestrogen differences were significant only in groups 1 and 2. The ovarian steroid levels in group 3 were significantly higher than those in groups 1 and 2 in the cases of E1 (P less than 0.01), E2 (P less than 0.001) and A (P less than 0.001), but not in that of T. It was concluded that ovaries showing marked stromal hyperplasia can produce significant amounts not only of androgens but also of E2, and hence that any evaluation of the hormonal pattern in post-menopausal women must also take into account the microscopic characteristics of the ovary.

Immunoreactive urinary oestrogen conjugates were assessed in daily urine samples (approximately 5 samples/week) collected from 8 Przewalski's mares maintained under semi-free-ranging pasture conditions. The relative percentage contributions of immunoreactive urinary oestrogens during different reproductive stages (oestrus, luteal phase, early, mid- and late gestation) were determined using high-pressure liquid chromatography. In general, conjugated forms of oestrone (oestrone sulphate and oestrone glucuronide) were the major excreted immunoreactive oestrogens in nonpregnant and pregnant Przewalski's mares. Variations in urinary oestrogen conjugates indicated that the onset of oestrous cyclicity coincided with increasing daylengths, and the non-conception oestrous cycle was 24.1 +/- 0.7 days (n = 17) in duration. Most copulations (29/35, 82.9%) were observed between Day -4 and Day +1 from the preovulatory oestrogen conjugates peak (Day 0). Based on known copulation dates, the mean gestation length was 48.6 +/- 0.4 weeks (range 47.3-50.3 weeks). During pregnancy, urinary excretion of oestrogen conjugates increased approximately 300-fold over levels in non-pregnant mares, reaching peak concentrations by Week +24 (51% of gestation). These results demonstrate that longitudinal reproductive events, including oestrous cyclicity and pregnancy, can be monitored precisely by evaluating urinary oestrogen conjugates in samples from Przewalski's mares maintained under semi-free-ranging conditions.

Two groups of postmenopausal women were seen at monthly intervals during a 6-month trial of cyclic therapy with conjugated equine oestrogens ('Premarin'). the seven women in the first group were taking premarin alone and the six women in the second group were taking premarin plus a progestagen, norethisterone acetate. On each visit, serum unconjugated oestrogens were measured by radioimmunoassay. Mean concentrations for the first group were 393 (+/- 203, SD) pmol/l for 17 beta-oestradiol, 599 (+/- 180) pmol/l for oestrone, and 6840 (+/- 5130) pmol/l for equilin. Corresponding levels for the second group were 342 (+/- 112) pmol/l, 564 (+/- 279) pmol/l, and 8840 (+/- 4020) pmol/l. 3 months after completion of therapy, the oestrone and 17 beta-oestradiol concentrations had returned to pre-treatment levels in both groups, but equilin was detected in 3 out of 3 women in the first group at a mean level of 532 (+/- 267) pmol/l and in 2 out of 4 women in the second group at 1170 (+/- 870) pmol/l. In view of the prolonged presence of equilin and the possible association between treatment with conjugated equine oestrogens and endometrial cancer, it is suggested that equilin-containing compounds should not be given for more than 12 months.

Twenty-four hour profiles of circulating prolactin have been documented in eight boys with simple delayed puberty, eleven with gynaecomastia, three of whom were retested following its spontaneous resolution, and two normal adult men. Mean 24 h prolactin levels in four boys with delayed puberty and ten with gynaecomastia exceeded the mean levels for the two adult men. A sleep-associated rise in prolactin levels occurred at all stages of puberty irrespective of the presence or absence of gynaecomastia, and in some subjects peaks also occurred during the daytime. Boys with gynaecomastia had higher 24 h means levels of prolactin (P less than 0.05), higher daytime levels (P less than 0.05) and higher sleep-associated levels (P less than 0.05) than did control subjects. These were not related to the degree or duration of the gynaecomastia, but 24 h mean levels of prolactin and oestradiol were positively correlated. In one subject who had had transient galactorrhoea, high levels of circulating prolactin, oestrone and oestradiol fell following spontaneous resolution of the gynaecomastia. We believe that oestrogen: androgen imbalance during the daytime is the major cause of pubertal gynaecomastia, with hyperprolacinaemia (which may cause galactorrhoea) sometimes occurring as a response to relative hyperoestrogenaemia.