Peripheral Testosterone Concentrations Research Articles

Influence of electroejaculation on peripheral blood concentrations of corticosteroids, progesterone, LH, and testosterone in bulls.

Temporal relationships among serum concentrations of corticosteroids (CS), luteinizing hormone (LH), progesterone (P), and testosterone (T) were examined in ten bulls exposed to the stress of electroejaculation (EE). Concentrations of CS and P increased concomitantly among bulls to peak levels by 15 min post-EE and then declined to pre-EE levels between 2 and 4 hr after EE. Total number of LH and T peaks decreased from 24 and 18, respectively, during the 12-hr pre-EE period to 11 and 14 during the 12-h post-EE period. Mean concentration of LH decreased after EE until 4 hr post-EE when episodic LH secretion resumed and concentrations of CS and P had declined to pre-EE levels. Similarly, mean concentration of T declined after EE and then increased 6-8 hr post-EE in response to resumption of LH secretion. The temporal associations of elevated concentrations of CS and P with basal LH and T before EE, absence of T response to endogenous LH peaks, and the temporary absence of episodic LH and T peaks after EE, suggest that endogenous adrenal steroids may modulate secretion of T in the bull.

Effect of Anesthetics on Testosterone Production in Rats

Changes in testicular vein and peripheral testosterone concentrations in mature rats were monitored during anesthesia with six different agents. Samples taken 2–3 minutes after initial disturbance of the resting animal yielded mean testicular vein testosterone levels of 59–247 ng/ml plasma in nine separate groups of rats. Sustained anesthesia under halothane, enflurane, pentobarbital, ether, urethan, or ketamine/promazine resulted in a decline in testicular vein testosterone to 10–60 ng/ml by the third hour. Luteinizing hormone levels, measured under enflurane anesthesia, also fell significantly by 1 and 2 hours after administration of anesthesia, although follicle‐stimulating hormone remained constant. Testes of the enflurane‐anesthetized rat were still able to respond to gonadotropins, but withdrawal of the anesthetic did not reverse the downward trend in testosterone. No changes in testicular blood flow were detected during anesthesia, although flow under urethan anesthesia was consistently slower than with other agents. The first 90 minutes of urethan anesthesia were characterized by severe fluctuations in testicular vein testosterone. Halothane, enflurane, and pentobarbital resulted in a larger ratio of peripheral to testicular vein testosterone compared with ether or rapid sampling, suggesting a reduction in turnover rate under these three agents. Conclusions were that different anesthetic agents can distort hormone levels and endocrine function of the testes in various ways, and that the production rate of testosterone by rat testes is higher than has been previously suggested.

Effects of Estrogens on the Testosterone Levels of peripheral and Spermatic Vein Blood in Patients With Prostatic Cancer

The mean testosterone levels of peripheral and spermatic vein blood in 16 patients with prostatic cancer who did not have estrogen therapy were 418.2 plus or minus 30.8ng./dl. (mean plus or minus standard error) and 39.7 plus or minus 5.6 μg./dl., respectively. There were 13 patients with prostatic cancer who received estrogen therapy with daily doses of 30mg. hexesterol or 300mg. diethylstilbestrol diphosphate and who had decisive decreases of testosterone levels in peripheral (90.1 plus or minus 23.2ng./dl.) and spermatic vein blood (3.3 plus or minus 1.2 μg./dl.).The rate of reduction of testosterone by estrogen therapy was one-tenth in the spermatic vein blood, while that in the peripheral blood was one-fifth. These data indicate that continuation of oral estrogens of these doses is sufficient to suppress the testicular androgens.On the other hand, the spermatic testosterone concentration was about 40 times higher than the peripheral testosterone concentration in patients receiving estrogen treatment. This result suggests that testosterone still is secreted from the testes under large therapeutic doses of estrogens.

Temporal relationships among peripheral blood concentrations of corticosteroids, luteinizing hormone and testosterone in bulls

Interrelationships among peripheral blood concentrations of corticosteroids (CS), luteinizing hormone (LH) and testosterone (T) were evaluated over a 24-hr period in four Angus bulls (18 months of age and 450 kg in body weight). Concentrations of LH and T were determined by radioimmunoassay and concentrations of CS by competitive protein binding assay of blood samples collected via jugular cannula at hourly intervals for 24 consecutive hr. A positive temporal relationship was observed between LH and T as significant positive correlations were obtained between concentrations of LH at one hour and concentrations of T at the subsequent hour in 3 of 4 bulls. Although LH peaks preceded T peaks by 1 hr, variation in this temporal relationship was observed as LH peaks occurred which were not accompanied by T peaks in some bulls. LH peaks were usually preceded by basal or declining concentrations of CS and prolonged elevations in concentrations of CS were often coincident with basal concentrations of LH and T. Negative correlations were obtained between concentrations of CS at one hour and concentrations of LH and T at the subsequent hour. These data describe the positive regulatory role of LH in testicular T production in the bull and suggest that alterations in endogenous concentrations of CS may influence peripheral concentrations of LH and T in the bull.

Influence of bromocriptine on plasma levels of prolactin and steroid hormones in the 20th week of pregnancy.

The influence of bromocriptine, a prolactin antagonist, on maternal plasma and amniotic fluid prolactin (PRL) was investigated in two pregnancies at the 20th week with medical indication for abortion. Voluntary consensus of the patients was obtained. Blood sample determinations demonstrated that bromocriptine inhibits the secretion of PRL both in plasma and amniotic fluid. Since no changes were observed in peripheral maternal steroid concentrations of dehydroepiandrosterone, dehydroepiandrosterone-sulfate, delta 4-androstene-3, 17-dione, testosterone, estradiol, estriol, and cortisol, it is concluded that PRL does not seem to affect maternal and fetal adrenal cortex as supposed in amenorrhoic patients with hyperprolactinemia.

Preoperative localization of virilizing tumors by selective venous sampling

Two postmenopausal patients with virilization had preoperative localization of ovarian tumors by selective blood sampling from both ovarian and adrenal veins and assay of hormone levels. In the first patient, the peripheral concentrations of testosterone (T), androstenedione, and estrone were 936, 1,508, and 73 pg. per milliliter, respectively, levels which are above the ranges found in normal postmenopausal women. The catheterization study showed an increase in the left ovarian vein of all hormones except cortisol. It was predicted that a tumor was present in the left ovary. At operation a 7 by 4 mm. lipid cell tumor was found. In the peripheral blood of the second patient, the T level (4,518 pg. per milliliter) was markedly elevated and the estradiol concentration (73 pg. per milliliter) was increased. At retrograde catheterization the concentration of T in the right ovarian vein was markedly elevated at 120,400 pg. per milliliter. At operation a hilus cell tumor of the right ovary was found. These two cases represent the third and fourth consecutive androgen-secreting tumors from this institution that have been localized by selective ovarian and adrenal vein catheterization and sampling.

Adrenal and gonadal steroids in girls during sexual maturation.

SUMMARYThe peripheral venous plasma concentrations of gonadotrophins (LH and FSH), prolactin (Prl), cortisol, dehydroepiandrosterone (DHA), dehydroepiandrosterone‐sulphate (DHA‐S), pregnenolone (Δ5P), progesterone (P), 17‐hydroxyprogesterone (17P), androstenedione (A), testosterone (T), dihydrotestosterone (DHT) and oestradiol (E2) were measured in girls at different stages of sexual development (from P1 to P4–5 according to Tanner, 1962). Both gonadotrophins increase progressively during sexual maturation, to reach the highest concentrations in P4–5. However, the FSH values were significantly lower in these P4–5 pre‐menarchal girls than those found in adult women in the early follicular phase. No significant changes were found in plasma Prl, cortisol and 17P levels during pubertal development; in contrast, plasma concentrations of DHA tripled from P1 to P4–5, reaching adult levels. A progressive rise was also found in DHA‐S plasma levels. A significant, but less evident increase was found in Δ5P and P plasma concentrations, from group P1 to P4–5. A, T and DHT levels rose progressively and significantly from P1–2 to the end of sexual maturation. In the case of E2, only a moderate increase was found during pubertal development.All these data indicate that during pubertal development, there is a progressive reduction in the sensitivity towards oestrogen of the hypothalamic centres controlling gonadotrophin secretion.Prl does not seem to be involved in human sexual maturation, while important changes have been found in adrenal androgens. The constant levels of 17P and cortisol, in comparison with the behaviour of DHA, DHA‐S, T and A, seem to indicate that during this period of life, the adrenal gland is stimulated by unknown factors other than ACTH, acting on the adrenal androgen‐producing cells and responsible for the reported rises in plasma adrenal androgens.

Testicular LH binding in the hamster: modification by photoperiod and prolactin.

Suppression of testicular weight and activity induced in the hamster by light deprivation can be partially reversed by treatment with prolactin (PRL). The present study investigates the possibility that the stimulatory effect of PRL in this preparation may be mediated through increased LH binding. Hamsters exposed to 5 h light per day for two months to induce gonadal atrophy were injected daily for 2 1/2 weeks with saline, 250 mug PRLP, 20 MUG LH+150 mug FSH, or PRL+LH+FSH. Short light control animals exhibited significantly less LH binding than controls on 14 h of light per day. Treatment with LH+FSH had no effect on LH binding while PRL alone or in combination with LH+FSH increased binding to levels greater than the long light controls. Peripheral testosterone concentrations reflected the level of LH binding. Scatchard analysis indicates that the decreased binding in the short-day animals is due to reduced LH receptor numbers and that PRL treatment elevates receptor levels thereby increasing LH binding. These results suggest that the mechanism by which PRL stimulates testicular function in hamsters with regressed gonads is through increased binding of endogenously produced LH.

Influence of sex, testicular development and liver function on the bioavailability of oral testosterone

The bioavailability of orally administered testosterone was investigated in normal and hypogonadal men, prepubertal boys, normal women, and in patients with fatty liver, liver cirrhosis and surgical portocaval shunts. Peripheral testosterone concentrations remained unchanged in normal men and men with fatty liver, whereas a steep increase was observed in all other groups. The greatest increase was seen in patients with compensated liver cirrhosis and with portocaval shunts. The steep increase of peripheral testosterone in boys, women and hypogonadal men is attributed to their having a lower activity of androgen-metabolizing liver enzymes than normal men. The increase in patients with cirrhosis is most likely caused by intra- and extra-hepatic portocaval shunts.

Testicular LH Binding in the Hamster: Modification by Photoperiod and Prolactin1

Suppression of testicular weight and activity induced in the hamster by light deprivation can be partially reversed by treatment with prolactin (PRL). The present study investigates the possibility that the stimulatory effect of PRL in this preparation may be mediated through increased LH binding. on LH binding while PRL alone or in combination with LH+FSH increased binding to levels greater than the long light controls. Peripheral testosterone concentrations reflected the level of LH binding. Hamsters exposed to 5 h light per day for two months to induce gonadal atrophy were injected daily for 2 1/2 weeks with saline, 250 µg PRL, 20 µg LH+150 µg FSH, or PRL+LH+FSH. Short light control animals exhibited significantly less LH binding than controls on Ik h of light per day. Treatment with LH+FSH had no effect on LH binding while PRL alone or in combination with LH+FSH increased binding to levels greater than the long light controls. Peripheral testosterone concentrations reflected the level of LH binding. Scatchard analysis indicates that the decreased binding in the shortday animals is due to reduced LH receptor numbers and that PRL treatment elevates receptor levels thereby increasing LH binding. These results suggest that the mechanism by which PRL stimulates testicular function in hamsters with regressed gonads is through increased binding of endogenously produced LH.

Effects of gonadotropins on androgen levels in rete testis fluid of the ram.

Effects of gonadotropins on androgen levels in rete testis fluid (RTF) of the ram were investigated. Injection of 750 IU human chorionic gonadotropin (HCG) or 1 mg luteinizing hormone (LH) caused an increase in the concentration of both RTF androgens. The elevation of androgen levels in RTF was smaller, occurred later and persisted for a longer period of time than did the increase in peripheral testosterone concentration. There was a significant negative correlation an .05) between pretreatment levels of testosterone and the LH- or HCG-induced elevation in plasma and RTF androgen levels. Injections of 5 or 10 mg follicle stimulating hormone was ineffective in altering the androgen levels in RTF ata indicate that gonadotropins can cause acute changes in the androgen levels in seminiferous tubules and suggest that the androgen levels in seminiferous tubules and suggest that the androgen concentrations in the is much more stable than that in the peripheral plasma.

The effects of dexamethasone on plasma free androgens during the normal menstrual cycle

In order to evaluate the ovarian and adrenal contribution to peripheral plasma concentrations of total testosterone (TTe), indexes of the plasma concentrations of free testosterone (FTeI), free 17β-hydroxysteroid androgens (FHSI), and testosterone-binding globulin (TeBG) during the menstrual cycle, women were examined during three normal cycles and three other cycles under dexamethasone (0.5 mg., four times a day) suppression. All study cycles were apparently ovulatory. The mean TTe and FTeI during the midcycle period were significantly higher than during the early follicular (P < 0.05) and the midluteal periods (P < 0.01 and P < 0.001, respectively). During the menstrual cycles under dexamethasone suppression only the difference in TTe and FTeI between the midcycle (37 ± 12.4 (S.D.) ng. per 100 ml. and 10.5 ± 4.0 (S.D.), respectively) and the midluteal (26.0 ± 10.1 (S.D.) ng. per 100 ml. and 7.2 ± 3.2 (S.D.), respectively) periods was significant statistically (P < 0.05). No significant differences in the mean levels of FHSI and TeBG between three periods within the cycle were noted in either the control or the dexamethasone-treated cycle. When each phase was compared, the mean levels of TTe, FTeI, and FHSI were significantly lower in the dexamethasone-treated cycles than in the normal cycles. The data suggest that the level of TeBG is not perceptibly affected by physiologic fluctuation of estrogen levels during the menstrual cycle, and the FHSI levels are stable throughout the ovulatory cycle. Decrease in levels of TTe, FTeI, and FHSI during dexamethasone suppression seems to be due to reduction of androgen production as TeBG, a major determinant of the metabolic clearance rate of androgens, was not affected by dexamethasone.

ANDROGEN LEVELS IN THE PLASMA AND PROSTATIC TISSUES OF PATIENTS WITH BENIGN HYPERTROPHY AND CARCINOMA OF THE PROSTATE

Specific radioimmunoassays for testosterone, dihydrotestosterone (DHT) and androstenedione were carried out to measure the concentrations of the three hormones in the plasma and prostatic tissue of ten patients with benign prostatic hypertrophy (BPH) and ten patients with carcinoma of the prostate. The results indicate that there are no significant differences between the peripheral plasma concentrations of testosterone, DHT and androstenedione in BPH [19.7 +/- 2.6, 2.6 +/- 0.9 AND 5.5 +/- 1.7 (S.E.M.) nmol/l respectively] and in carcinoma [16.9 +/- 2.8, 2.4 +/- 0.5, 4.4 +/- 1.1 nmol/l respectively], (in all cases P greater than 0.1). In contrast, the prostate tissue rations DHT: testosterone (3.59 +/- 0.55 for BPH and 0.66 +/- 0.09 for carcinoma) and androstenedione: testosterone (2.83 +/- 0.38 for BPH and 1.07 +/- 0.16 for carcinoma) are significantly less in carcinoma than in benign hypertrophy ( in all cases P less than 0.01). The accumulation of testosterone in the carcinoma, relative to values found in BPH tissue is, therefore, not associated with changes in the concentrations of androgens in the plasma pool but may be related to local factors and metabolic changes within the prostate.

Testerone concentrations in the peripheral plasma of adrogenized female rats and in the estrous cycle of normal female rats.

Previous in vitro data have suggested that the ovaries of androgen sterilized female rats (ASFR) have the capacity to incorporate more labeled precursors into androgens than ovaries from normal rats. In order to test the biosynthetic capacity of the ASFR ovary in vivo, the following experiments were carried out. Blood was collected from 120-day-old intact, castrated or adrenalectomized ASFR. In addition, blood was collected from diestrous, estrous, proestrous, adrenalectomized proestrous and castrated female rats. The plasma was assayed for testosterone by a radioimmunologic system which did not require chromatography. The plasma testosterone concentration in ASFR was lower than that found in proestrous and diestrous females, similar to that found in estrous females, and higher than that found in castrated females. The proestrous females had significantly higher peripheral testosterone concentrations than either estrous or diestrous females. Furthermore, the testosterone concentration in the peripheral bl...

Effect of gonadotrophins on the secretion of oestradiol- and testosterone by the rat testis.

SUMMARY Concentrations of oestradiol-17β and testosterone were estimated in peripheral venous plasma and testicular venous plasma of adult male rats before and after administration of human chorionic gonadotrophin (HCG) or follicle-stimulating hormone (FSH). The concentration of oestradiol-17β in peripheral plasma, as measured with a radioimmunological technique, was 2·0 ± 0·9 (s.d.) pg/ml (n = 12). Peripheral testosterone concentrations were 2·4 ± 1·8 (s.d.) ng/ml (n = 21). Concentrations of oestradiol-17β and testosterone in testicular venous plasma were significantly higher than those in peripheral plasma. After intravenous administration of HCG (100 i.u.), oestradiol-17β and testosterone concentrations in testicular venous plasma increased significantly. After prolonged s.c. administration of HCG (5 days) the concentration of oestradiol-17β in testicular venous plasma did not change significantly, although the concentration of testosterone increased more than ten times. Intravenous administration of HCG after 5 days of pretreatment with HCG caused a significant increase in oestradiol-17β concentrations in testicular venous plasma. The increase in testosterone concentration was not significant under these conditions. Intravenous administration of FSH did not change oestradiol-17β or testosterone concentrations in testicular venous plasma.

Studies of androgens in patients with congenital adrenal hyperplasia.

ABSTRACT Six patients with the simple vitalizing form of congenital adrenal hyperplasia, 4 patients with the salt-losing form of the disease, and 1 patient with a partial 3β-hydroxysteroid dehydrogenase defect have been studied. In all patients with the simple and salt-losing form of the disease, peripheral plasma concentrations of testosterone (T) and particularly of androstenedione (Δ) were elevated. Plasma concentrations of dehydroepiandrosterone (D) and its sulfate (DS) were elevated in some of these patients. In 2 non-salt-losing patients, blood production of T and Δ was determined by the constant infusion technique. The blood production rate of Δ was very high. The blood production of T was also elevated for the age and sex of the 2 patients and approximately 50% of it arose from peripheral interconversion of Δ to T. There was a marked disagreement between blood and urinary production of T. The discrepancy could be accounted for by the contribution of the blood production of Δ to urinary T glucuroni...

Studies of androgens in patients with adrenocortical tumors.

ABSTRACT Seven patients with adrenal tumors have been studied. Two of them showed signs of feminization, 4 demonstrated only symptoms of masculinization, and 1 had a nonfunctional tumor. Peripheral and adrenal vein plasma concentrations of testosterone (T), androstenedione (Δ), dehydroepiandrosterone (D), its sulfate (DS) and glucuronide (DG) conjugates, androsterone sulfate (AS) and glucuronide (AG), and etiocholanolone sulfate (ES) and glucuronide (EG) were determined. Adrenal secretion of T, Δ, D and DS was established on the basis of differences in steroid concentrations in peripheral and adrenal vein blood. None of the other androgen conjugates (AS, AG, ES and EG) were found to be secreted by the adrenal tumors. When considering the age and sex of the patients, the concentrations in peripheral vein plasma of T, Δ, D and DS were increased in all subjects studied except for a normal level of T and D in 1 of the 2 patients with symptoms of feminization. Fractionation of urinary steroids in 3 patients wi...

Studies of androgens in the syndrome of male pseudohermaphroditism with testicular feminization.

Eleven patients with the syndrome of male pseudohermaphroditism with testicular feminization have been studied. Peripheral and spermatic vein plasma concentrations of testosterone (T), androstenedione (Δ), dehydroepiandrosterone (D), its sulfate and glucuronide conjugates, androsterone sulfate and glucuronide, and etiocholanolone glucuronide were determined in 5 patients. Testicular secretion of T, Δ and D was established in all the patients on the basis of peripiheral-spermatic vein differences in concentration. None of the conjugates was found to be present in greater concentration in spermatic vein blood than in peripheral vein blood. In one patient, a constant infusion of 14C-T and 3H-Δ was administered. Metabolic clearance rate and blood interconversion of T and Δ were determined and found to be similar to those of normal subjects. Blood production rates of T and Δ were 11.6 and 2.9 mg/24 hr, respectively. No significant discrepancy was found between urinary and blood production rate of T. Urinary T production rate and urinary T glucuronide excretion were found to be in the male range in 3 patients after puberty but were much lower in a prepubertal patient and in another studied 7 yr after gonadectomy. Two patients who received synthetic androgens decreased their plasma and urinary testosterone levels in a way no different from that of normal controls. A specific biological effect of androgens was therefore demonstrated in patients with testicular feminization who, otherwise, have been reported to be unresponsive to androgens.