The diurnal variation of plasma oestrone (E1), oestradiol (E2), oestriol (E3), progesterone (P), cortisol (F) and dehydroepiandrosterone sulphate (DHAS) and saliva E1, E2, E3, P and F was investigated in matched plasma, and saliva samples were obtained hourly from 08.00 to 24.00 h and at 04.00, 07.00 and 08.00 h from nine pregnant women (3 at 30, 3 at 34 and 3 at 38 weeks gestation). A diurnal variation in plasma and saliva cortisol levels was found in all subjects and in plasma DHAS in 8 out of 9 subjects. No consistent diurnal variation was found at any gestation in any of the other hormones in plasma or saliva. There was a significant correlation between saliva E3 and P levels at 30 weeks gestation but no other consistent correlations between hormone levels were found at any gestation.

The clinical and biochemical effects of combined treatment with the two aromatase inhibitors aminoglutethimide and 4-hydroxyandrostenedione were evaluated in 10 patients suffering from advanced breast cancer. All patients had become resistant to treatment with one of the drugs before having combined treatment. Seven patients progressing on 4-hydroxyandrostenedione who had aminoglutethimide added to their treatment and achieved a further suppression of plasma oestradiol by a mean of 40.0% (p < 0.05). Plasma oestrone was suppressed by a mean of 40.6% (p < 0.025) and plasma oestrone sulphate was suppressed by a mean of 63.6% (p < 0.025). Two of the patients, neither of whom had responded to 4-hydroxyandrostenedione alone, experienced objective tumour regression when aminoglutethimide was given in concert. Three patients progressing on aminoglutethimide who had 4-hydroxyandrostenedione added showed no further suppression of their plasma oestrogen levels, and no tumour regression was observed. These findings suggest a dose-response relationship between plasma oestrogen suppression at low postmenopausal levels and objective tumour response in breast cancer.

17Beta-hydroxysteroid dehydrogenase Type 1 (17beta-HSD1) has a pivotal role in regulating the synthesis of oestradiol (E2) within breast tumours. In whole body studies in postmenopausal women with breast cancer the conversion of oestrone (E1) to E2 (4.4+/-1.1%) was much lower than the inactivation of E2 to E1 (17.3+/-5.0%). In contrast, an examination of in vivo oestrogen metabolism within breast tumours revealed that whereas little metabolism of E2 occurred, E1 was converted to E2 to a much greater extent in malignant (48+/-14%) than in normal (19+/-6%) breast tissue. Findings from these studies originally suggested that oestrogen metabolism within breast tumours may differ from the mainly oxidative direction found in most other body tissues and that the activity of 17beta-HSD1 might be regulated by tumour-derived factors. Several growth factors (e.g. IGF-I, IGF-II) and cytokines (e.g. IL-6, TNFalpha) have now been identified which can markedly stimulate the activity of 17beta-HSD1 and such a mechanism may account for the high concentrations of E2 found in most breast tumours. Cells of the immune system, which can infiltrate breast tumours, are thought to be a major source of the growth factors and cytokines which can modulate 17beta-HSD1 activity. Given the central role that 17beta-HSD1 has in regulating breast tumour E2 concentrations the development of potent inhibitors of this enzyme has recently attracted considerable attention. Our initial studies in this area explored the use of derivatives of E1 as inhibitors, with 2-ethyl- and 2-methoxy E1 being found to inhibit 17beta-HSD1 activity in T-47D breast cancer cells by 96+/-2 and 91+/-1% respectively at 10 microM, but with a lack of specificity. Using the E1 scaffold a number of potent, selective 17beta-HSD1 inhibitors have now been identified including E1- and 2-ethyl-E1 containing a side chain with a m-pyridylmethylamidomethyl functionality extending from the 16beta position of the steroid nucleus. At 10 microM these compounds both inhibited 17beta-HSD1 activity by >90%, however some inhibition of 17beta-HSD2 activity was exhibited by the E1 derivative (25%) but not the 2-ethyl analogue. It is now apparent that 17beta-HSD1 activity contributes to the high E2 concentrations found in most breast tumours. The identification of potent, selective novel 17beta-HSD1 inhibitors will allow their efficacy to be tested in in vitro and in vivo studies.

Carcinogens, such as benzo[a]pyrene (B[a]P), allow cells to evade G(1) arrest (the stealth property), thus increasing the chance that DNA damage will ultimately result in transformation. In this study we have investigated the effects of B[a]P in MCF-7 cells incubated in the presence or absence of oestrogens (beta-oestradiol, oestrone or oestriol). The cytokinesis block micronucleus assay was used to examine cells for chromosomal damage. Micronuclei were scored in 500 binucleate cells per treatment. Increased micronucleus formation (3-fold) occurred following 24 h treatment with 10(-6) M B[a]P alone. Following co-treatment with either 10(-9) M beta-oestradiol, 10(-8) M oestrone or 10(-8) M oestriol, 2- to 3-fold increases in micronuclei were observed with 10(-8) M B[a]P. When MCF-7 cells were pre-incubated for 96 h with 10(-9) M beta-oestradiol, 10(-8) M oestrone or 10(-8) M oestriol prior to the addition of B[a]P for 24 h, up to a 5-fold enhanced sensitivity to micronucleus formation was observed with beta-oestradiol and oestrone, while oestriol appeared to reduce levels of micronucleus formation. B[a]P-induced decreases in cell proliferation (per cent binucleate cells) and plating efficiency were reversed by all three oestrogens. Analysis of cell cycle distributions revealed that treatment with oestrogens or B[a]P alone did not induce marked effects on cell cycle distributions. However, in combination oestrogen and B[a]P induced increases in G(0)/G(1), decreases in S phase and increases in G(2)/M. This work suggests that whilst oestrogens appear to enhance carcinogen-induced DNA damage, they also appear, paradoxically, to trigger mechanisms that facilitate clonogenic survival, which may be relevant to breast cancer initiation.

Uptake and local formation of oestrone (E1) were studied in vivo by a double isotopic technique in normal and malignant breast tissues from 24 postmenopausal women with breast cancer. Active uptake of radio-labelled E1 beyond plasma was found both in normal and malignant tissue, the effect being significantly greater in non-malignant compared with cancer tissue. The presence of local E1 formation was also demonstrated in most samples. Both uptake and synthesis positively correlated with total amount of radioactive E1 found in the tissues. Uptake appeared to make a greater contribution to E1 levels within the breast than in situ synthesis, although there were marked variations between specimens from different patients and the relative proportion of synthesis to uptake was higher in tumour compared with non-malignant tissue. These results demonstrate quantitative differences in the different compartments by which postmenopausal breasts obtain oestrogen and highlight variations between individual breasts. This may be important in optimising oestrogen deprivation therapy for postmenopausal patients with hormone-dependent cancers.

Plasma and urinary oestrogens were measured in nine breast cancer patients (eight postmenopausal women and one man) before and during treatment with the aromatase inhibitor 4-hydroxyandrostenedione. Urinary oestrogens were measured by using a highly specific GC-MS method. Plasma levels of oestrone, oestradiol and oestrone sulphate were suppressed by 66.6% (+/- 3.6%), 57.7% (+/- 5.1%) and 51.8% (+/- 6.4%) respectively (P < 0.005 for all). Twenty-four hour urinary excretion of total oestrogens, oestradiol, oestriol, 2-hydroxyoestrone, 16 alpha-hydroxyoestrone and the minor metabolites 16 beta- and 15 alpha-hydroxyoestrone were all suppressed by mean values ranging from 60% to 82%, (oestradiol: P < 0.025, otherwise P < 0.005). There were no significant changes in the ratios between the different plasma oestrogens. The finding of sustained plasma and urinary oestrogens at 20-40% compared to their control levels indirectly support a hypothesis of alternative oestrogen sources in postmenopausal breast cancer patients on treatment with 4-hydroxyandrostenedione.

1. A study of 150 middle-aged male industrial employees has shown significant positive correlations between plasma levels of high-density-lipoprotein (HDL) cholesterol and both serum testosterone and alcohol intake, and significant negative correlations between HDL cholesterol and both serum thyroxine and obesity. These associations persist when examined by multiple linear regression, indicating their independence. 2. Significant positive correlations are also shown between plasma triglyceride levels and both obesity and serum thyrotropic hormone (TSH) levels. 3. There are no evident relationships between serum oestrone or oestradiol and either HDL cholesterol or triglyceride levels, nor between any of the hormones and either total or low-density-lipoprotein (LDL) cholesterol. 4. Because of the potential importance in relation to coronary heart disease prevention, further studies are needed to try and understand the mechanisms of the associations between HDL cholesterol and obesity, alcohol intake and thyroid and sex hormone levels.

The plasma protein distribution of oestradiol (E2) and oestrone (E1) during transdermal E2 administration (100 micrograms/24 hr) was studied in 12 post-menopausal women. The E2 and E1 levels observed were 43-83 pg/ml and 37-73 pg/ml, respectively. The levels of the free, albumin-bound and sex-hormone-binding globulin (SHBG) bound fractions were in the ranges 1.4-1.9%, 60-65% and 35-45%, respectively, in the case of E2, and 2.8-3.0%, 80-89% and 15-20%, respectively, in that of E1. The SHBG levels also remained unaltered. It was concluded that transdermal administration of E2 at the dosage employed produces a physiological plasma protein distribution of E2 and E1 and does not affect liver protein production.

Ten feral mares free-roaming in Maryland, USA, were inoculated with porcine zonae pellucidae (PZP) protein before the breeding season for three consecutive years (1988-90). Ovarian function was monitored for 51 days during the peak of the breeding season after the third annual PZP inoculation, in seven of these mares and in four untreated control mares, by means of urinary oestrone conjugates and nonspecific progesterone metabolites. None of the ten inoculated mares became pregnant in 1990, compared with 55% of 20 control mares, which included two of the four monitored for ovarian function. Three of the untreated mares demonstrated apparent normal ovarian activity, characterized by preovulatory oestrogen peaks, concurrent progesterone nadirs at ovulation, breeding activity, and luteal-phase progesterone increases after ovulation. Two of the seven monitored PZP-treated mares demonstrated ovulatory cycles that did not result in conception. One was pregnant as a result of conception in 1989 and demonstrated a normal, late-gestation, endocrine profile. The remaining four PZP-treated mares revealed no evidence of ovulation, and urinary oestrogen concentrations were significantly depressed. The experiments indicated that (i) a third consecutive annual PZP booster inoculation is greater than 90% effective in preventing pregnancies in mares and (ii) three consecutive years of PZP treatment may interfere with normal ovarian function as shown by markedly depressed oestrogen secretion.

The results of daily determination of the levels of gonadotrophins, oestradiol, oestrone, progesterone, aldosterone, dehydroepiandrosterone, androstenedione, testosterone, and aetiocholanolone in the serum of 6 normal, ovulating women are reported and discussed. A pre-ovulatory aldosterone peak and rising values in the luteal phase of the cycle were found. Androstenedione, testosterone, and aetiocholanolone levels were significantly elevated from 3 days before until 3 days after ovulation. Since the mean androstenedione/aetiocholanolone ratio in the individual cycles in this period was similar to the ratio found during the rest of the cycle, we think it unlikely that aetiocholanolone is produced by the ovaries. No correlation was found between the aetiocholanolone patterns and the basal body temperature. In a case of conception followed for 20 days after ovulation, the steroid patterns remained unchanged until the presumed day of implantation, after which the aldosterone, androstenedione, testosterone, and aetiocholanolone levels started to rise. The mean androstenedione/aetiocholanolone ratio during the 10 days after implantation did not differ from the values obtained in the foregoing periods, so direct aetiocholanolone production by the ovaries after implantation seems unlikely.

Steroid hormone concentrations in plasma have been measured in blood samples taken from conscious sows with ear vein catheters. In late pregnancy, the plasma progesterone concentration ranged from 6 to 12 ng/ml and it decreased in all animals before the onset of parturition. Total unconjugated oestrogens increased to high values of up to about 3 ng/ml in late pregnancy and then declined after the onset of parturition. Oestrone was the predominant unconjugated oestrogen measured. Plasma corticosteroid (mainly cortisol) concentration was about 33 ng/ml and showed no consistent change at the time of parturition. During lactational anoestrum the plasma concentration of progesterone and total unconjugated oestrogens was very low, while that of corticosteroids was 21 ng/ml. When the piglets were weaned at 26-31 days, sows came into oestrus 4-12 days later, and this was preceded, or accompanied by, an increase in plasma oestrogens. In the luteal phase, plasma progesterone concentrations rose to 20-35 ng/ml. A sow whose piglets were removed at birth, showed signs of oestrus (vulval enlargement and a lordosis response), but a lack of receptivity to the boar associated with no detectable changes in the plasma oestrogen concentration; however, ovulation probably occurred since plasma progesterone values increased in a manner comparable to that found after the formation of normal corpora lutea in other sows. After a second non-receptive cycle, the sow was mated and became pregnant at the third post-weaning oestrus. At parturition the concentration of progesterone and total unconjugated oestrogens was greater in placental venous plasma than in maternal jugular plasma, which indicates placental synthesis of these hormones. A greater concentration of plasma corticosteroids in foetal blood than in placental venous or maternal jugular plasma suggests foetal synthesis in late pregnancy.

Adult sheep which has been castrated either before or after puberty were treated with a variety of steroids. The administration of testosterone propionate, oestrone, oestradiol-17 beta or diethylstilboestrol to animals castrated before puberty caused them to mount oestrous ewes. Oestradiol-17 alpha was less effective than these hormones in this regard, whilst oestriol, hexoestrol and 5 alpha-dihydrotestosterone were ineffective. The response to oestradiol-17 beta was not altered by the concurrent administration of dexamethasone to block the pituitary-adrenal axis which suggests that oestradiol-17 beta was not exerting its effect indirectly by causing the release of adrenal steroids. When 5 alpha-dihydrotestosterone was administered in conjunction with oestradiol-17 beta intromission and ejaculation were observed in addition to mounting behaviour. When rams were castrated as adults their mating behaviour slowly declined over the course of 2 years. After this time, mounting behaviour was rapidly restored by the administration of oestradiol-17 beta but not by 5 alpha-dihydrotestosterone. These results are consistent with the hypothesis that oestrogens are the ultimate agents responsible for promoting mating behaviour in male animals and hence aromatizable androgens, such as testosterone, are effective whereas non-aromatizable androgens, such as 5 alpha-dihydrotestosterone, are not.

To determine the role of sex hormones and sodium intake in hypertension seen in postmenopausal woman, 12 women (aged 50 to 59 years) in whom blood pressure increased for the first time to above 150/90 mmHg after cessation of menstruation were examined in comparison with 7 age-matched postmenopausal normotensive women (118 +/- 2/62 +/- 3 mmHg). All subjects were admitted to the hospital and their sodium intake was maintained at 204 (normal), 306 (high), and 51 (low) mmol/day for 5 days each. In each period, body weight, blood pressure, heart rate, serum levels of sex hormones and vasoactive hormones, and urinary excretions of sodium, kallikrein and dopamine were determined. The plasma levels of prolactin, progesterone, oestrone, and oestradiol in the hypertensive women were all significantly lower than those in the normotensive women in all study periods. With a change in sodium intake from high to low, blood pressure in 8 out of 12 hypertensive patients decreased by more than 10% from 160 +/- 2/100 +/- 2 mmHg to 144 +/- 2/87 +/- 2 mmHg, while in the normotensive women, only 1 out of 7 patients responded to this change in sodium intake. The changes in sodium intake did not alter the plasma levels of sex hormones in the hypertensive and normotensive subjects. Among the hypertensive patients, three had a history of pregnancy-induced hypertension, while none of the normotensive subjects had such a history. The results of the present study suggest that decreases in sex hormones and increased sensitivity to sodium are important factors in the genesis of postmenopausal hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)

BACKGROUND

Hormone replacement therapy is associated with both reflux symptoms and oesophagitis. During pregnancy, elevated sex hormones are thought to contribute to the high prevalence of reflux symptoms. Increased female sex hormone levels may thus contribute to the aetiology of gastro-oesophageal reflux disease (GORD).

OBJECTIVE

To determine if female sex hormone levels are associated with symptomatic acid reflux.

METHODS

Women with GORD symptoms undergoing oesophageal pH monitoring were prospectively recruited. 'Cases' and 'controls' were defined by normal and excess total acid exposure on pH monitoring and were age-matched and BMI-matched. Case and control groups were further stratified into premenopausal and postmenopausal groups. Demographic data were collected, body morphological parameters were measured and oestradiol, oestrone, progesterone and sex hormone-binding globulin were measured.

RESULTS

One hundred and twenty-one women [mean age 52 (SD 11.6) years] were recruited and 104 [mean age 51 (SD 11.6) years] were matched for age and BMI. Increasing BMI, as expected, correlated with increasing acid exposure [premenopausal (r=0.404, P=0.02), postmenopausal (r=0.401, P=0.01)]. Increasing BMI also correlated with sex hormone levels [premenopausal oestradiol (r=0.52, P=0.004), postmenopausal oestrone (r=0.364, P=0.01)]. In premenopausal women, sex hormone binding globulin (r=-0.27, P=0.05) and testosterone (r=0.29, P=0.05) correlated with increasing acid exposure, but oestradiol fell just short of significance (r=0.26, P=0.06). However, on matching for BMI, no association between sex hormones and increased acid exposure on pH monitoring was found on multivariate logistic regression analysis.

CONCLUSIONS

Female sex hormone levels do not appear to contribute to GORD, once adjustment is made for the influence of increasing BMI.

The regulation of angiogenesis in the ovarian follicle and corpus luteum is unclear. Steroids are produced at very high concentrations in these tissues and we therefore examined the effect of steroids on angiogenesis in vitro. Explants of rat aorta were embedded in collagen gel and cultured in serum-free medium. Capillary-like microvessels were produced from the explants and microvessel number and length were measured in the presence and absence of steroids. At a concentration of 10 micrograms/ml, cortisol, progesterone, 17 alpha-hydroxyprogesterone and medroxyprogesterone acetate produced degeneration of microvessels after 7 days of steroid treatment (P < 0.01). Androstenedione and tetrahydro-S-(11-deoxytetrahydrocortisol) (tetrahydro S) produced degeneration at a slower rate: androstenedione inhibited microvessel growth after 11 days (P < 0.01) and tetrahydro S after 14 days (P < 0.05). Oestriol had no effect on microvessels; oestrone had a slow degenerative effect with significant inhibition seen after 14 days (P < 0.01). Oestradiol-17 beta at a concentration of 10 micrograms/ml completely inhibited microvessel growth from the explant cultures (P < 0.01) while at 1 microgram/ml it caused degenerative effects on growing microvessels. The effects of oestradiol and cortisol were reversible on removal of steroid-containing medium and replacement with 10% serum. We conclude that oestradiol may modulate angiogenesis in tissues in which the steroid concentration is high.

Young female rats of 160-180 g were implanted with osmotic minipumps releasing 3.0 micromol/day per kg of oleoyl-oestrone in liposomes (Merlin-2) into the bloodstream for up to 14 days. Merlin-2 induced a loss of appetite in the first days, later recovered, and a decrease in body weight of 7%, which contrasts with the 15% increase in controls during the 2-week period. Neither plasma glucose nor urea was affected by treatment, but liver glycogen increased by 50% in 14 days. Insulin decreased slightly with Merlin-2 treatment. Plasma corticotropin (ACTH) and corticosterone showed a transient increase by day 6 of treatment. The expression of the ob gene in adipose tissue fell during the period studied to practically nil on day 14; circulating leptin levels decreased more than 70% from day 1 to day 14. Oestrone levels increased from 0.3 nM (controls) to a maintained 40-60 nM level for the rest of the experiment. Oleoyl-oestrone levels first increased 4-fold, to decrease again to the initial levels on day 10, increasing later to 100-fold on day 14. The three phases observed in food intake, weight loss and oleoyl-oestrone levels match fairly well, which supports the direct involvement of oleoyl-oestrone in body-weight control. However, the control of oleoyl-oestrone levels seems to be mediated in part by corticosterone. The practical disappearance of leptin synthesis coincides with the massive accumulation of oleoyl-oestrone in plasma. The results presented suggest the involvement of oleoyl-oestrone in the main mechanisms of control of body weight and its regulation by glucocorticoids and leptin.

OBJECTIVE

The origin of oestrogens in men is only partly understood. From infusion studies with radioactively labelled hormones, we know that oestradiol (E2) and oestrone (E1) are either directly secreted by the testes and adrenal glands or peripherally produced from testicular or adrenal androgens.

METHODS

We determined E2, E1, androstenedione, testosterone and dehydroepiandroster-one sulphate (DHEAS) in 292 elderly men and 367 postmenopausal women. We considered post-menopausal women as men without testes, assuming that the postmenopausal ovary is not endocrinologically active and that the testes do not contribute to circulating levels of DHEAS. Subjects were stratified by DHEAS levels to adjust for differences in DHEAS levels between sexes. For men and women separately, mean levels of E2, E1, androstenedione and testosterone were calculated per DHEAS stratum. The relative direct and indirect contributions of the testes to steroid levels in men were calculated by the formula [(C(m) - C(f))/C(m)] x 100%, in which C(m) and C(f) represent the mean concentrations of the steroid in men and women respectively.

RESULTS

The relative contributions (%) of the testes to hormone levels per DHEAS stratum (<2, 2-4, 4-6 and >6 micromol/l) respectively were, for E2, 72%, 60%, 52% and 44%; for E1, 54%, 47%, 35% and 34%; for androstenedione, 14%, 4%, 12% and 0%; and, for testosterone, 88%, 88%, 87% and 83%.

CONCLUSIONS

We conclude that in elderly men dependent on DHEAS levels, 44-72% of E2 and 34-54% of E1 originate directly or indirectly from the testes.

The possible existence of correlations between bone mineral content (BMC), age and serum levels of steroid hormones was investigated. It was found that dehydroepiandrosterone sulphate (DHEA-S), oestradiol (E2) and delta-4-androstenedione (A) were correlated with BMC, whereas oestrone (E1) and testosterone (T) were not. Partial correlations after adjustment for age were significant (P less than 0.05) only between E2 and DHEA-S and BMC at the L2-L4 lumbar site (BMC-1) and between DHEA-S (P less than 0.01) and BMC at the midradius site (BMC-r). Stepwise multiple regression analysis showed that, apart from age, E2 was the only factor to fit (P less than 0.05) into the mathematical model with BMC-1 as the dependent variable, while DHEA-S was the only factor to fit (P less than 0.01) with BMC-r as the dependent variable. These data suggest that different hormonal influences are related to BMC at different sites, namely E2 to lumbar trabecular bone (L2-L4) and DHEA-S to cortical bone (midradius).

1. Reconstitution of UDP-glucuronyltransferase preparations with phosphataidylcholine liposomes facilitated the purification of testosterone UDP-glucuronyltransferase. 2. Transferase activity towards testosterone co-purifies with that towards 4-nitrophenol. 3. UDP-glucuronyltransferase activity towards oestrone was separated from that towards testosterone. 4. These results suggest that testosterone and 4-nitrophenol may be glucuronidated by a different form of UDP-glucuronyltransferase from the one glucuronidating oestrone.

Silicone vaginal rings for the continuous release of 17 beta-oestradiol (E2) with 2 constant in vitro release rates were used for the treatment of symptoms of urogenital atrophy in 2 groups of postmenopausal women. The very low dose of 7 micrograms/24 h was found to alleviate atrophic symptoms effectively and to induce significant maturation of vaginal and urethral epithelium. After a brief initial peak, the serum levels of E2 over 3 mth of treatment remained close to the detection limit. The 'undetectable' E2 release pattern was reflected only in increased levels of oestrone sulphate. There was no evidence of a systemic metabolic response and patient acceptance of the method was excellent. Continuous low-dose release of E2 via vaginal rings consequently offers an alternative means of administering local oestrogen therapy which may be particularly suitable for geriatric patients.

Oestrogen-containing vaginal rings of various designs have been utilised in hormone replacement therapy. In contrast to the traditional 'homogeneous' design, rings designed with a steroid-containing core and outer polymer sheath provide a diffusion-controlled release rate which enables the delivery of low doses of drug. The aim of this investigation was to evaluate in vitro oestradiol release from a 'core' designed vaginal ring (Estring) and furthermore, to establish the in vivo concentration-time course of oestradiol, oestrone and total oestrone (unconjugated plus conjugated) in consecutive applications of such an oestradiol-containing vaginal ring in postmenopausal women. Results indicate that the controlled release design of Estring produces stable, low systemic plasma concentrations of oestradiol and has an extended time period of release.

To determine whether or not the weight (and fat) loss induced by oleoyl-oestrone treatment results only as a consequence of decreased food intake, we compared treated animals with a pair-fed model. To this end, Wistar female rats received daily oral gavages of 10 mumol/kg per d oleoyl-oestrone in sunflower oil, or vehicle alone for 10 or 20 d. A second group of rats received the gavage of sunflower oil and the same amount of food ingested as the oleoyl-oestrone-treated animals (pair-fed group). Rats treated with oleoyl-oestrone maintained glucidic metabolism homeostasis despite a marked decrease in adipose tissue weight (P<0.001). Pair-fed rats exhibited a different pattern, comparable to short-term starvation, with greatly decreased glycogen stores (P<0.0001). The most significant effects were detected in the 10 d period groups. Oleoyl-oestrone affected the activity of the ponderostat system not only by decreasing appetite but also by modifying energy partition: treated animals maintained their glucose and energy homeostasis despite decreased food intake and the massive depletion of lipid stores.

Pulmonary artery thrombosis and an anti-ethinyl-oestradiol monoclonal IgGlambda were found to be associated in a 36-year-old woman (Mrs MAI.) who took an oral contraceptive containing 50 mug ethinyl-oestradiol and 500 mug nor-ethisterone daily. After appropriate purification including methods by which the IgG was separated of bound circulating hormones, its binding activity was demonstrated by several methods: passive haemagglutination of oestradiol-benzoate sensitized red blood cells; gel filtration on Sephadex G-25; ultracentrifugation and equilibrium dialysis. IgGlambda MAI bound ethinyl oestradiol (Ka=2-7 X 10(1) M-1) and also 17-beta-oestradiol, with a lower affinity (Ka=0-4 X 10(7) M-1). The valency for these two hormones was near 2. Ethinyl-oestradiol bound to the IgG was displaced by ethinyl-oestradiol itself and in decreasing order of potency by 17-beta-oestradiol, progesterone, oestriol, and testosterone. Oestrone and hydrocortisone had no effect. Although the localization of the binding sites of this IgGlambda was not studied, it is likely that they were the antibody sites of the molecule and, according to immunochemical criteria, it may be classified as a monoclonal anti-ethinyl-oestradiol antibody. It is felt that its association with the pulmonary thrombosis and the oral contraceptive may be significant. This supports the hypothesis of an immunological mechanism for the unexplained thrombotic risk of oral contraceptives.