Estrogens In Blood Research Articles

Effects of Hemicastration or hCG‐treatment on Steroids in Testicular Vein and Jugular Vein Blood of Stallions

The relationships among testicular vein and jugular vein concentrations of androgens and estrogens were studied in anesthetized stallions. Blood was sampled from a vein on the surface of the testis and simultaneously from an artery on the surface of the testis and from the jugular vein. Concentrations of total 17β‐hydroxy‐androgens and total estrogens were measured for all samples and testosterone, dihydrotestosterone, 3α‐andostanediol, 3β‐androstanediol, and 5‐androstenediol were quantified In selected samples. Following halothane anesthesia and hemicastration of 19 stallions, the testosterone concentration in jugular blood dropped over 3 hours but returned to normal within two days. Although jugular levels of total 17β‐hydroxy‐androgens were normal (∼1.4 ng/ml) 12 days after hemicastration, the concentration of total 17β‐hydroxy‐androgens in testicular vein blood was sixfold greater (P < 0.01) than it had been at hemlcastratlon (368 vs 62 nglml). The ratio of testosterone to 5α‐reduced‐androgens was similar in testicular vein blood from the first and second testes. Apparently, the clearance rate for testosterone had changed from ∼2.4 I/minI stallion to ∼6.2 1/min/stallion in 12 days. Concentrations of total estrogens in testicular vein blood were similar for the first and second testes (27, 400 pg/ml) as compared with the values for jugular vein and testicular artery blood (63 and 293 pg/mI, respectively). Clearance rate of estrogens (∼23.3 1/mm in Intact stallions) apparently decreased by 50%. Although anesthesia plus hemicastration may have altered blood flow to the remaining testis, a change in blood flow could not account for the concurrent increase in testosterone and decrease in estrogen clearance rates. Injection of 1500 IU of hCG markedly increased (P < 0.01) the concentration of total 17β‐hydroxy‐androgens in testicular vein blood 1 hour later, but the concentration of total estrogens was unaltered 1 or 2 hours after treatment. We concluded that the concentrations of total 17β‐hydroxy‐androgens and total estrogens in jugular blood bear little relationship to their concentrations a few minutes earlier in venous blood draining the testis.

Maternal steroid changes after fetal death until delivery of the dead sheep fetus.

Progesterone, estrone, and estradiol have been determined during late pregnancy and at parturition in the maternal plasma of sheep bearing live and dead fetuses. Mean concentrations of the steroids at days 125--130 after mating were lower after fetal death, although the differences were not significant. The mean interval between fetal death and delivery was 11.8 +/- 5.8 (0.01 +/- 0.01 ng/mL) on the day of delivery. There was no preparturient rise in maternal estrogen levels in animals with dead fetuses. The ratios of progesterone:estradiol and progesterone:estrone fell from 130 and 140 to 2.9 and 1.2, respectively, during the 5 days prior to delivery due entirely to the fall in progesterone. In normal animals the ratios of progesterone:estradiol and progesterone:estrone decreased from 186.1 and 81.7 at 5 days before parturition to 9.4 and 2.0 on the day of birth. This was attributable partly to a fall in progesterone but largely to the preparturient rise in estrone and estradiol. We conclude that some placental steroid output continues after fetal death in the sheep but that deliveries of both dead and live fetuses are associated with an abrupt change in the ratio of progesterone:estrogens in maternal blood.

Episodic fluctuation of total estrogens in peripheral blood of bulls: effects of estradiol-17 beta on LH and testosterone secretion.

Fluctuations in peripheral concentrations of total unconjugated estrogens (F) and the response of luteinizing hormone (LH), testosterone (T), and total glucocorticoids (CC) to administration of exogenous estradiol-17#{216}(E2 ) were studied in the male bovine in two experiments. In Experiment 1 hourly blood samples were collected via jugular cannula from four puberal Angus bulls during 24 h preinfusion, 12 h infusion and 12 h postinfusion periods. Episodic fluctuations in peripheral concentrations of E, LII, T, and CC were observed during the 24 h preinfusion period; however, the only significant temporal relationship observed was between concentrations of LH at 1 h and concentrations of T at the subsequent hour (LAG- LH-T-CORR, r = 0.42). Infusion of E2 at the rate of 41.7 mg/h resulted in acute increases in circulating concentrations and areas beneath hormone profile curves for LH, T, and CC. During the postinfusion period, both LH and T areas were less than areas calculated for similar times during the preinfusion period. In contrast, GC areas were greater (P<0.10) during the postinfusion period than at similar times prior to infusion. Based on results of the first experiment, Experiment 2 was designed to compare the effects of E2 infusion on circulating levels of Lii, T, and CC between eight control and seven E2 -treated bulls. Blood samples were collected every 30 mm for a 6 h preinfusion period after which E2 or propylene glycol was continuously infused for 6 h at a rate of 16.7 mg/h. Samples were also collected for a maximum of 6 h postinfusion. Significant acute increases in circulating concentrations and areas of LH and T were observed in five of seven E2 -treated bulls. There were no changes in hormone levels of control bulls during infusion. Both LH and T areas were not significantly different between F2 -treated and control bulls during the postinfusion period. Infusion of F2 did not influence levels of circulating CC and areas of CC. These results demonstrate that E can be included with LH, T, and CC as hormones whose peripheral concentrations fluctuate in an episodic manner. Also, administration of pharmacological levels of E2 can result in an acute increase in levels of circulating LH and T.

Corticosteroid-binding globulin and estrogens in maternal and cord blood

Corticosteroid-binding globulin (CBG) is produced by the liver in small concentrations and binds steroids with high affinity. Its concentration in the blood is sensitive to endogenous or exogenous estrogens in a dose-response manner and serves as a biological assay for estrogens. CBG concentrations were measured in sera collected from maternal and umbilical vein blood during labor and delivery and at elective cesarean section and correlated with endogenous estradiol and estriol concentrations. CBG and estradiol concentrations of maternal blood were significantly exceeded those of maternal serum. A highly significant increase in cord blood estriol concentration was found following vaginal delivery compared to elective cesarean section, indicating an increase in adrenal activity due to the stress of labor. CBG levels correlated directly with maternal estradiol but not estriol cencentrations. Cord blood CBG concentration varied little despite a wide range of estrogen concentrations. The physiologic significance of CBG concentrations in maternal and fetal blood is discussed.

Seasonal changes in the concentration of estrogens and testosterone in the plasma of the stallion

A blood sample was taken from each of 15 stallions at monthly intervals for 14 consecutive months. Plasma concentrations of estrogens and testosterone were measured by radioimmunoassay methods. Estrogens in peripheral blood were present in much higher amounts than testosterone and were principally in a water-soluble, solvolyzable form (> 98%). The major component in the solvolyzed extracts behaved chromatographically as estrone. The mean plasma level (± S.E.) of estrogens averaged across months was 52.9 ± 4.5 ng ml −1. Individual stallions showed considerable month-to-month variation; for example, single monthly samples ranged from 29.5 to 160.6 ng ml −1 for the stallion with the highest single value. The highest mean monthly concentration was 69 ± ng ml −1 in May, and plasma levels were < 40 ng ml −1 during November and December. For the 11 Thoroughbred stallions in the study, the mean concentrations of estrogens were 73 ± 5.8 ng ml −1 for May to July and 45 ± 4.1 ng ml −1 for November to January ( P > 0.001). The mean monthly concentrations (± S.E.) of testosterone ranged from 0.22 ± 0.05 to 0.90 ± 0.14 ng ml −1, and individual samples ranged from < 0.02 to 2.8 ng ml −1 of plasma. While the highest mean level of testosterone was seen in September, there was a significant difference ( P < 0.01) between the values in the breeding season (May–July, 0.73 ± 0.07 ng ml −1) and the non-breeding season (November–January, 0.38 ± 0.08 ng ml −1). No marked seasonal changes were observed, however, in testosterone levels in several stallions. It was concluded that plasma estrogen levels may provide a more sensitive index of endocrine function of the testes in the stallion.

Homologies of Structure and Function in Mammalian Testes and Ovaries

In mammalian testes and ovaries, gametogenic and steroidogenic compartments interact in producing gametes and secreting sex steroid hormones. Components of these compartments share a number of structural and functional homologies. In the gametogenic compartments, Sertoli cells in testicular tubules and granulosa cells in ovarian follicles form diffusion barriers between germ cells and substances in blood and lymph, secrete luminal fluid and synthesize proteins and steroid hormones. However, steroid hormone concentrations in spermatic and ovarian veins represent the secretory activities of steroidogenic compartments.Interstitial cells in testes and ovaries synthesize and secrete androgens but whether they are the major source of estrogens in ovarian venous blood remains controversial. There are data which suggest that androgens and estrogens, acting on Sertoli cells and granulosa cells, mediate the role of gonadotrophins in induction and maintenance of gametogenesis in testis and ovary. Collectively, the numerous homologies of structure and function provide evidence for conservation and adaptation of mechanisms in mammalian gonads.

Induction of ovulation.

Ovulation has been induced by clomiphene citrate and human gonadotropins in infertile women. Clomiphene should be the first choice in anovulatory women with active ovaries as indicated by basic levels of estrogens in blood or urine, in women with post-pill amenorrhea even if their ovaries are quiescent and in women with functional abnormalities of the hypothalamus or pituitary. Human gonadotrophins should be used as a second alternative when clomiphene fails. It should also be used as a first choice in women with primary amenorrhea and quiescent ovaries and in women with gross anatomical changes in the pituitary or hypothalamus. If no result is obtained after two courses of gonadotropic therapy, further treatment should be reconsidered and the infertile couple reinvestigated.

Endocrine function of the postmenopausal ovary: concentration of androgens and estrogens in ovarian and peripheral vein blood.

ABSTRACT The concentrations of testosterone, androstenedione, 17β-estradiol, and estrone were measured in peripheral and ovarian vein sera obtained at the time of surgery from 10 postmenopausal women undergoing bilateral oophorectomy. A higher ovarian than peripheral vein concentration was found for all hormones studied. The differences between ovarian and peripheral vein concentrations were 15-fold for testosterone (3033 ± 1046 pg/ml vs 198 ± 27 pg/ml, p <0.01); 4-fold for androstenedione (3455 ± 1330 pg/ml vs 754 ± 174 pg/ml, NS) and 2-fold for both 17β-estradiol (31.1 ± 6.3 pg/ml vs 14.6 ± 2.9 pg/ml, p < 0.05); and estrone (71.5 ± 13.3 pg/ml vs 30.3 ± 3.4 pg/ml, p < 0.05). It is concluded that the postmenopausal ovary continues to secrete a large amount of testosterone and a moderate amount of androstenedione. The small magnitude of the peripheral and ovarian vein estrogen differences could account for only minimal ovarian estrogen secretion.

The Value of Plasma Estrogen Estimations in the Maragement of Preganancy

Considerable experience has been gained on the application of plasma estrogen assays in the management of pregnancy. A review of this experience takes into consideration theoretical aspects, background provided by urinary estrogen assay, methods for measuring estrogens in blood, normal plasma estrogen values and variations, effects of pregnancy complications on these values, comparison of plasma and urinary estrogen in determining fetal risk, and the value of blood estrogen assays during labor.

Radioimmunoassay for estrogens in maternal blood in late pregnancy: Values for normal and complicated pregnancy

A previously described radioimmunoassay which measures free estrogens and estriol-16-glucuronide but not 3-sulfoconjugated estrogens was applied to maternal plasma in normal and complicated pregnancy. The results were compared to those reported in the literature for total estriol. The concentration of immunoreactive estriol, i.e., the estrogens measured by this assay, increases with gestational age more rapidly than total estriol. Following delivery, the clearance of immunoreactive estriol is faster than that of total estriol. The concentration of immunoreactive estriol in blood declined in some cases of complicated pregnancy and was undetectable in women with a hydatidiform mole, an anencephalic fetus, and a dead fetus.

Measurement of steroid hormones using intracellular receptor proteins

The high affinity saturable estrogen receptor of the uterus has been successfully employed by a number of groups to assay individual estrogens in blood. Such measurements have elucidated alterations occurring during the normal menstrual cycle, during normal and abnormal pregnancy, during the estrus cycle of a variety of mammals, in a few abnormal menstrual cycles, and in normal men. A few studies possible associated with estrogen excess in men were also reported.

Plasma estrogens in postmenopausal women

The concentration of plasma estrone and estradiol was measured in different groups of postmenopausal women; including physiologic menopause, castration menopause, and those who in addition to menopause had diabetes, hypertension, or cardiac disease. The mean values for estrone were 41 pg. per milliliter and for estradiol 13 pg. per milliliter. There was no statistical difference in the levels of plasma estrogen in all groups of postmenopausal women studied. In 3 individuals, studies of estrogens in ovarian vein blood suggested a nonovarian origin of estrogen.

Interaction between regions of the hypothalamus regulating hypophyseal gonadotropic function in female rats.

1. Wide frontal section through the hypothalamus at the level of the suprachiasmatic nuclei leads to permanent estrus. 2. Deafferentation of the basal hypothalamus from the preoptic region leads to accumulation of LH in the hypophysis and to an increase in estrogen secretion. The LH content in the hypophysis is at the estrus level, while the content of estrogens in ovarian venous blood is at the proestrus level of intact rats. 3. Deafferentation lowers the sensitivity of these hypothalamic regions to estrogen. 4. Ovulation does not take place under these experimental conditions.

Use of enzyme hydrolysis in the rapid analysis of blood estrogens

A procedure for rapid enzymic hydrolysis of conjugated estrogens in blood employing a mixed glucuronidase-sulfatase enzyme preparation is described and examples of the results obtained with typical blood samples are presented. The method is no more difficult nor time-consuming than hot acid hydrolysis.