Hormonal abnormalities in obesity

We have found a number of interesting hormonal abnormalities in obese men and women: 1) Obese women have normal levels of estrone, total estradiol, and total testosterone, but as a consequence of their subnormal levels of SHBG, their levels of free estradiol and free testosterone are significantly elevated. 2) Massive weight loss in obese women (to still elevated weight) results in normalization of the previously elevated free estradiol and free testosterone. 3) Obese women have normal plasma DHEA levels, but a significant, age-invariant decrease of the plasma DHEA/T ratio, which could be due to increased tissue activity of 3 beta-hydroxysteroid dehydrogenase. 4) Massive weight loss produces an age-dependent effect on DHEA levels in obese women: the levels increase to supranormal values in women around age 20, with diminishing increases at higher premenopausal ages and no increase at all at perimenopausal age. 5) Obese men have elevated levels of estrone and both free and total estradiol, and subnormal levels of free and total testosterone and of FSH; all these abnormalities are proportional to the degree of obesity. They also have relatively subnormal LH levels, i.e. normal in the face of hypotestosteronemia. The combination of these findings represents a state of mild hypogonadotropic hypogonadism (HHG), which we believe to be induced by the hyperestrogenemia. 6) Normalization of the estrogen levels of obese men, by suppression of adrenocortical secretion of aromatase substrates or by inhibition of aromatase, tends to normalize the HHG. 7) Massive weight loss in obese men normalizes their HHG without any decrease in plasma estrogen levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Cyclic AMP and the reverse transformation reaction

Traditional methods for cancer treatment have been aimed at killing the cancer cells. Unfortunately this approach all too often is accompanied by harmful killing of normal cells. The present paper describes an experimental program in our laboratory in which cancer cells are treated so as to revert to normal cell behavior. This process, which we have named reverse transformation, appears to offer considerable hope in the treatment of a large number of malignancies.

The effect of supraphysiologic doses of testosterone on fasting total homocysteine levels in normal men

Elevated total homocysteine (tHcy) levels are associated with increased risk for atherosclerotic cardiovascular disease. tHcy levels are higher in men than in women, and estrogen replacement therapy may reduce tHcy levels in postmenopausal women. The effect of androgenic hormones on tHcy levels in men has not been examined. The present study determined the effect of supraphysiologic doses of testosterone, with or without its aromatization to estradiol, on fasting tHcy levels in 14 normal male weightlifters aged 19-42 years. Subjects received testosterone-enanthate (200 mg/week intramuscularly), the aromatase inhibitor, testolactone (1 g/day orally), or both drugs together in a crossover design. Each treatment lasted 3 weeks and each treatment was separated by a 4-week washout. Both testosterone regimens increased serum testosterone levels, whereas estradiol increased only during testosterone alone. Mean tHcy levels were not significantly altered when testosterone was given alone or together with testolactone. Testolactone did not significantly influence tHcy levels. We conclude that short-term, high-dose testosterone administration does not affect fasting tHcy levels in normal men.

Effect of aromatase inhibitor, TZA-2209, on the prostate of androstenedione-treated castrated dogs: changes in prostate volume and histopathological findings

To determine whether the inhibition of estrogen-related effect in the prostate would be of value in the management of benign prostate hyperplasia (BPH), we examined the effect of TZA-2209, a new steroidal aromatase inhibitor, on the prostate in three of six castrated beagles that received 75 mg/week androstenedione. The three other animals served as controls. Sequential measurements of prostate volume by transrectal ultrasonography showed that the volume in TZA-treated dogs was significantly decreased compared with that in the controls. Prostatic aromatase activity was suppressed by TZA administration. Histopathologically, the stromal component was increased and glands were atrophied by androstenedione treatment. TZA administration increased the volume of the glands. Immunohistochemical detection of estramustine-binding protein showed more positive staining of the protein in the glands that were increased in volume by TZA administration. We concluded that the aromatase inhibitor effectively antagonized the estrogen-related stromal changes, however, this action was accompanied by stimulation of the glandular component due to the accumulation of androgens, the substrate of the aromatase. In the light of these findings, we suggest the simultaneous treatment for the androgen-glandular component route in the prostate is necessary for the effective management of BPH.

Physiological levels of estradiol stimulate plasma high density lipoprotein2 cholesterol levels in normal men

Premenopausal women have a lower risk of coronary artery disease than men or postmenopausal women; estrogens are thought to contribute to this lower risk. Administration of exogenous estrogen to post-menopausal women increases plasma high density lipoprotein (HDL) cholesterol and may reduce mortality from coronary disease in users. Although many investigations have examined the roles of estrogen in the regulation of lipoproteins in women, little attention has been directed to estrogen regulation of lipids in men. We designed a paradigm to study the role of physiological levels of estradiol (E2) on plasma lipoproteins in healthy men. We used a GnRH antagonist, Nal-Glu, to suppress endogenous steroid hormones in healthy men. We then administered testosterone (T) enanthate (100 mg, im, weekly) to restore T levels to the baseline range, and we administered an aromatase inhibitor, testolactone (Teslac), to prevent the normal conversion of T to E2, thereby producing a selective estrogen deficiency state in normal young men. As controls, we administered Nal-Glu and T along with placebo Teslac to a separate group of men; a third group of men received all placebo medications. We found that in men who received Nal-Glu plus T plus Teslac, E2 levels were profoundly suppressed during treatment, whereas T levels remained in the baseline range. Plasma HDL cholesterol, particularly, the HDL2 fraction, decreased significantly in response to the low serum E2 level. Plasma apoprotein-AI levels also decreased significantly. Plasma LDL and triglyceride levels did not change. All hormone and lipoprotein parameters returned to baseline within 4 weeks after treatment ended. In men who received Nal-Glu plus T, plasma HDL and apoprotein-AI decreased, but these decreases did not achieve statistical significance. Only a small decrease in HDL2 cholesterol was seen in these men. There were no hormonal or lipid changes in the placebo group. We conclude that in men, physiological levels of E2 are important in maintaining plasma levels of HDL cholesterol, especially the HDL2 fraction. These observations suggest that estrogen, in the amount normally produced in men, may offer some degree of protection against cardiovascular disease in males, as they do in women.

The effect of testosterone aromatization on high-density lipoprotein cholesterol level and postheparin lipolytic activity

Stanozolol, an oral 17 alpha-alkylated androgen, increases hepatic triglyceride lipase activity (HTGLA) and decreases high-density lipoprotein cholesterol (HDL-C) levels, whereas intramuscular testosterone has comparatively little effect. In the present study, we tested the hypothesis that aromatization of androgen to estrogen blunts the lipid and lipase effects of exogenous testosterone. Fourteen male weightlifters received testosterone enanthate (200 mg/wk intramuscularly), the aromatase inhibitor testolactone (250 mg four times per day), or both drugs together in a randomized cross-over design. Serum testosterone level increased during all three drug treatments, whereas estradiol level increased only with testosterone alone (+47%, P < .05), demonstrating that testolactone effectively inhibited testosterone aromatization. Testosterone decreased HDL-C(-16%, P < .05), HDL2-C(-23%, NS), and apoprotein (apo) A-I (-12%, P < .05) levels, effects that were consistently but not significantly greater with simultaneous testosterone and testolactone administration (HDL-C, -20%; HDL2-C, -30%; apo A-I, -15%; P < .05 for all). In contrast, both testosterone regimens decreased HDL3-C levels by 13% (P < .05 for both). HTGLA increased 21% during testosterone treatment and 38% during combined testosterone and testolactone treatment (P < .01 for both). Lipoprotein lipase activity (LPLA) increased only during combined testosterone and testolactone treatment (+31%, P < .01), suggesting that estrogen production may counteract the effects of testosterone on LPLA. Testolactone alone had little effect on any lipid, lipoprotein, apoprotein, or lipase concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

Familial adrenal feminization probably due to increased steroid aromatization

5/10 members of a North African family (father, 2 male and 2 female siblings) had gynaecomastia, early growth and short final stature. The 8-year-old propositus had advanced bone age, facial acne, gynaecomastia, pubic hair and prepubertal testicular volume. Basal oestrone (E1) was elevated (670 pmol/l) and increased with adrenocorticotropic hormone (ACTH; 826 pmol/l). After human chorionic gonadotropin stimulation testosterone (T) responded normally whereas E1 and oestradiol (E2) remained unchanged. ACTH-dependent adrenal feminization was confirmed by a transient reduction of breast tissue following dexamethasone or cypropterone acetate treatment. Testolactone increased T/E2 (from 5.6 to 20.3) and A/E1 (from 3.4 to 31.4) ratios and temporarily reduced the breast tissue. In conclusion, this is a familial type of adrenal feminization with increased adrenal androgen aromatization. This is the first time that male-to-male and male-to-female transmission has been reported.

Sex steroid control of gonadotropin secretion in the human male. I. Effects of testosterone administration in normal and gonadotropin-releasing hormone-deficient men

The precise sites of action of the negative feed-back effects of gonadal steroids in men remain unclear. To determine whether testosterone (T) administration can suppress gonadotropin secretion directly at the level of the pituitary, the pituitary responses to physiological doses of GnRH were assessed in six men with complete GnRH deficiency, whose pituitary-gonadal function had been normalized with long term pulsatile GnRH delivery, before and during a 4-day continuous T infusion (15 mg/day). Their responses were compared with the effects of identical T infusions on spontaneous gonadotropin secretion and the response to a 100-micrograms GnRH bolus in six normal men. Both groups were monitored with 15 h of frequent blood sampling before and during the last day of the T infusion. In the GnRH-deficient men, the first three GnRH doses were identical and were chosen to produce LH pulses with amplitudes in the midphysiological range of our normal men (i.e. a physiological dose), while the last four doses spanned 1.5 log orders (7.5, 25, 75, and 250 ng/kg). The 250 ng/kg dose was always administered last because it is known to be pharmacological. In the GnRH-deficient men, mean LH (P less than 0.02) and FSH (P less than 0.01) levels as well as LH pulse amplitude (P less than 0.05) decreased significantly during T infusion, demonstrating a direct pituitary-suppressive effect of T and/or its metabolites. Mean LH levels were suppressed to a greater extent in the normal than in the GnRH-deficient men (58 +/- 15% vs. 28 +/- 7%; P less than 0.05). In addition, LH frequency decreased significantly (P less than 0.01) during T administration in the normal men. These latter two findings suggest that T administration also suppresses hypothalamic GnRH release. T was unable to suppress gonadotropin secretion in one GnRH-deficient and one normal man. In both groups, the suppressive effect of T administration was present only in response to physiological doses of GnRH. Because the pituitary- and hypothalamus-suppressive effects of T could be mediated by its aromatization to estrogens, five GnRH-deficient and five normal men underwent identical T infusions with concomitant administration of the aromatase inhibitor testolactone (TL; 500 mg, orally, every 6 h). As an additional control, four GnRH-deficient and four normal men received TL alone. TL administration completely prevented the effect of T administration to suppress gonadotropin secretion in both the normal and GnRH-deficient men, and mean LH levels increased significantly in both the GnRH-deficient (P less than 0.01) and the normal (P less than 0.001) men who received TL alone. The increase in mean LH levels was greater (P less than 0.01) in the normal men who received TL alone than in the normal men who received T plus TL, thus revealing a direct effect of androgens in normal men. Measurements of T and estradiol production rates in three men demonstrated that TL effectively blocked aromatization.(ABSTRACT TRUNCATED AT 400 WORDS)

Altered testicular hormone production in infertile patients with idiopathic oligoasthenospermia

We studied the kinetics of testicular response to human chorionic gonadotropin (hCG) in oligoasthenospermic and asthenospermic patients (OAZ-AZ). The responses of testosterone (T), androstenedione (A), 17 OH-progesterone (17OHP), and estradiol (E2) were evaluated in 60 OAZ-AZ patients and compared to those of 10 normal men. The responses of T, A, and 17OHP to hCG in the control group displayed a biphasic pattern with an initial peak at 4 hours and a second peak after 24 hours. The E2 response showed a single peak between 24 and 48 hours after hCG administration. OAZ-AZ patients had two types of T responses: group 1 (n = 40) had no first peak and group 2 (n = 20) had a normal response pattern. The response of A was similar to that of T, and the E2 response was normal in both groups. There were three types of 17OHP responses in group 1 (low, high, or normal); however, the 17OHP response was normal in group 2. Treatment of group 1 with aromatase inhibitors (aminoglutethimide or testolactone) induced an improvement of the acute T response only in patients with high or normal 17OHP response to hCG, whereas no effects were observed in patients with low 17OHP response. In group 2, the aromatase inhibitors induced no changes in the T response. These results demonstrate that in some OAZ-AZ patients (group 1, blunted T response) testicular hormone production is altered. They also suggest the presence of two enzyme blocks: one at the 17,20 desmolase level, mediated by E2, and another at early biosynthetic steps, not mediated by E2.

[Therapeutic efficacy of testolactone (aromatase inhibitor) to oligozoospermia with high estradiol/testosterone ratio]

To our knowledge, the action of estradiol which is produced from testosterone by aromatase on human spermatogenesis has not been fully clarified. In oligozoospermia, with high values of E2/T ratio, it is considered that the role of estradiol is suppressive to spermatogenesis. In this study, alteration of spermatogenesis was evaluated when serum estradiol levels were decreased by suppression of aromatase activity. Nine male infertile patients were treated with testolactone (Teslac: 1.0 g/day, for 3 months), one of the aromatase inhibitors. Four of them had an increase in sperm count (more than 10 x 10(6)/ml relative to base line). In endocrinological findings, serum estradiol levels and E2/free T ratio were significantly decreased after treatment. Serum free testosterone levels were significantly increased in all cases, presumably from decreased sex hormone binding globulin (SHBG) levels. These findings suggested the effectiveness of the administrated aromatase inhibitor. In particular four patients whose sperm counts were improved after testolactone treatment had high values of basal serum estradiol levels and E2/free T ratio before treatment, and these values were normalized after treatment. In conclusion we suggest that an aromatase inhibitor may be effective to male infertile patients with high serum estradiol levels.

High-density lipoprotein cholesterol is not decreased if an aromatizable androgen is administered

We examined the influence of aromatization of testosterone on serum high-density lipoprotein cholesterol (HDL-C) and postheparin plasma hepatic triglyceride lipase activity (HTLA) in men. Eighteen healthy lean nonsmokers (ages, 20 to 33) were administered androgens in a weekly total dose of 280 mg for 12 weeks in one of three groups: testosterone enanthate (TE) (280 mg/wk intramuscularly [IM]); TE (280 mg/wk IM) + testolactone (TL) (250 mg orally [PO] four times daily); or methyltestosterone (MeT) (20 mg PO twice daily). Serum testosterone achieved steady state levels by 4 weeks with greater than 40 nmol/L (TE and TE + TL) and less than 15 nmol/L (MeT) while 17b-estradiol (E2) rose to greater than 250 pmol/L (TE) or remained below 70 pmol/L (TE + TL and MeT). LH fell to less than 5 U/L (TE and TE + TL) but remained unchanged with MeT. By 4 weeks, HDL-C had decreased significantly from 1.20 +/- 0.13 to 0.77 +/- 0.13 mmol/L (MeT), from 1.18 +/- 0.15 to 0.89 +/- 0.13 mmol/L (TE TL), and demonstrated no decrease in the TE group across the time course of the study. These changes were preceded by mean increases in HTLA of 102% (MeT) and 55% (TE + TL) over baseline, and no significant change with TE. The changes in HDL-C and HTLA returned to baseline within 2 weeks of steroid cessation. There were no changes in total cholesterol, triglycerides, or insulin in any group but, in the MeT group, apo AI levels decreased and low-density lipoprotein cholesterol (LDL-C) increased.(ABSTRACT TRUNCATED AT 250 WORDS)

An in vitro method to determine the selective inhibition of estrogen biosynthesis by aromatase inhibitors

Potency and selectivity of aromatase inhibition are parameters which ultimately influence the therapeutic efficacy of aromatase inhibitors. This report describes an in vitro model which allows an assessment of the selectivity with which aromatase inhibitors inhibit estrogen biosynthesis. Estrogen production was stimulated by incubating adult female hamster ovarian tissue with ovine LH. The production rates of estrogens (E), testosterone (T) and progesterone (P) were determined using radioimmunoassays to measure the amount of these steroids released into the incubation medium over a 4-hour incubation period. The selectivity of aromatase inhibition was assessed by determining the IC50S with which each inhibitor inhibited the production of E (end product), T (immediate precursor of E) and P (early precursor of E). Selectivity was studied for each of the 4 aromatase inhibitors, CGS 16949A (a new non-steroidal compound), 4-OH-androstenedione, aminoglutethimide and testolactone. CGS 16949A was the most potent of the four, followed by 4-OH-androstenedione, aminoglutethimide and testolactone. As far as selectivity was concerned, both CGS 16949A and 4-OH-androstenedione selectively inhibited aromatase judging from the IC50s for E and P production (CGS 16949A: IC50 for E & P = 0.03 & 160 microM, resp.; 4-OH-androstenedione: IC50 for E & P = 0.88 & greater than or equal to 330 microM, resp.). Aminoglutethimide was the least selective inhibitor of aromatase (IC50 for E & P = 13 & 60 microM, resp.). For testolactone, the least potent of the four (IC50 for E = 130 microM), no conclusive data were obtained concerning the selectivity of aromatase inhibition. Thus a simple, effective and reproducible method is described for assessing the selectivity with which aromatase inhibitors inhibit aromatase.

Treatment of men with idiopathic oligozoospermic infertility using the aromatase inhibitor, testolactone. Results of a double-blinded, randomized, placebo-controlled trial with crossover

The hypothesis that increased estradiol production may be the cause of impaired spermatogenesis in infertile men with idiopathic oligozoospermia was tested by administering the aromatase inhibitor, testolactone, and by assessing its effects on sperm output and fertility. Our study was a randomized, placebo-controlled double-blind crossover trial. Subjects (n = 25) with infertility due to unexplained oligozoospermia were given testolactone (2 g/day) or placebo for 8 months followed by crossover to the other treatment for an additional 8 months. Total estradiol and testosterone levels during testolactone exposure did not change from basal and placebo values. However, sex hormone-binding globulin binding capacity consistently decreased (30%, p less than 0.01) and free testosterone levels increased (36%, p less than 0.01). Free estradiol values increased but not significantly. Additionally, LH and FSH serum levels increased by 15% and 20%, respectively (p less than 0.05), and 17 alpha-hydroxyprogesterone values increased by 90% (p less than 0.05) during drug administration. Sperm output and semen quality remained unchanged during either testolactone or placebo treatment, and no pregnancies occurred during the 16-month study. These data suggest that chronic administration of testolactone at this dose fails to maintain aromatase inhibition despite depression of 17,20-desmolase activity with elevated 17 alpha-hydroxyprogesterone and depressed SHBG binding capacity with elevation of free testosterone. Testolactone is not efficacious in the treatment of idiopathic oligozoospermic infertility.

Enhancement of the hypertensinogenic action of 19-hydroxyandrostenedione by aromatase inhibitor, delta 1-testololactone

To evaluate the enhancing effects of 1,2-dehydrotestololactone (delta 1-testololactone) on the hypertensinogenic action of 19-hydroxyandrostenedione (19-OH-A-dione), 1 mg 19-OH-A-dione, 10 mg delta 1-testololactone, or a combination of 1 mg 19-OH-A-dione and 10 mg delta 1-testololactone was injected into intact rats drinking water once a week for 4 weeks. The blood pressure of control rats and rats given 19-OH-A-dione, delta 1-testololactone, and a combination of 19-OH-A-dione and delta 1-testololactone in the fourth week was 130 +/- 2 (SE), 140 +/- 2, 128 +/- 6, and 152 +/- 5 mmHg, respectively. The blood pressure of rats given 19-OH-A-dione and a combination of 19-OH-A-dione and delta 1-testololactone was significantly higher than that of control rats. In addition, the blood pressure of rats given a combination of 19-OH-A-dione and delta 1-testololactone was significantly higher than that of rats given 19-OH-A-dione alone. As delta 1-testololactone itself did not show any hypertensinogenic action, it is considered to enhance the hypertensinogenic action of 19-OH-A-dione. Although plasma 19-OH-A-dione concentrations of control rats and rats given delta 1-testololactone were lower than the sensitivity of RIA, those of rats given 19-OH-A-dione and a combination of 19-OH-A-dione and delta 1-testololactone were 116 +/- 3 and 222 +/- 37 pg/ml, respectively. Plasma 19-OH-A-dione concentrations of rats given a combination of 19-OH-A-dione and delta 1-testololactone were significantly higher than those of rats given 19-OH-A-dione alone. Therefore, delta 1-testololactone is considered to enhance the action of 19-OH-A-dione by increasing plasma concentrations of 19-OH-A-dione. As delta 1-testololactone is an aromatase inhibitor, the inhibition of the conversion of circulating 19-OH-A-dione to estrogens in peripheral tissues might be the cause of the elevation of plasma 19-OH-A-dione concentrations. These results indicate that aromatose inhibitors enhance the hypertensinogenic action of 19-OH-A-dione by decreasing the degradation of 19-OH-A-dione.

[The inhibitory effect of miconazole on aromatase activity for androstenedione in human placental and ovarian preparations]

The inhibitory effects of miconazole, an antimycotic agent, on aromatase activity for androstenedione in human placenta (105,000 X g pellet fraction) and ovary (800 X g supernatant fraction) were investigated. Various concentrations (0.1-100 microM) of miconazole, aminoglutethimide or delta 1-testololactone were added to the human placental preparation (1 mg protein) and then the mixture was incubated with [1 beta-3 H]-androstenedione (300 pmol) and NADPH (0.5 mg), at 37 degrees C for 30 minutes in air. The reaction was stopped by 10%-trichloroacetic acid (0.8 ml) and the mixture was extracted with chloroform (3 ml). The residual aqueous phase was subjected to Amberlite XAD-II resin-charcoal column chromatography. The amount of 3H2O obtained was regarded as aromatase activity for androstenedione. The effects of miconazole on aromatase activity in human ovarian preparation was also investigated. Aromatase activity in human placenta was suppressed concentration-dependently by miconazole. The inhibition of aromatase activity by miconazole was significantly higher than that by aminoglutethimide and delta 1-testololactone. The I50 values for the inhibition of aromatase activity by miconazole, aminoglutethimide and delta 1-testololactone were 0.60 microM, 15 microM and 34 microM, respectively. The apparent Km value for androstenedione was 320 nM and the apparent Ki value was 120 nM in this assay. The inhibition of aromatase by miconazole in human ovary was also significantly higher than that by aminoglutethimide (I50 value for miconazole = 0.98 microM; I50 value for delta 1-testololactone = 15 microM). These results indicate that miconazole suppresses aromatase activity for androstenedione reversibly in human placenta and ovaries in vitro.

Cell-type-specific responses of RT4 neural cell lines to dibutyryl-cAMP: branch determination versus maturation

This report describes the induction of cell-type-specific maturation, by dibutyryl-cAMP and testololactone, of neuronal and glial properties in a family of cell lines derived from a rat peripheral neurotumor, RT4. This maturation allows further understanding of the process of determination because of the close lineage relationship between the cell types of the RT4 family. The RT4 family is characterized by the spontaneous conversion of one of the cell types, RT4-AC (stem-cell type), to any of three derivative cell types, RT4-B, RT4-D, or RT4-E, with a frequency of about 10(-5). The RT4-AC cells express some properties characteristic of both neuronal and glial cells. Of these neural properties expressed by RT4-AC cells, only the neuronal properties are expressed by the RT4-B and RT4-E cells, and only the glial properties are expressed by the RT4-D cells. This in vitro cell-type conversion of RT4-AC to three derivative cell types is a branch point for the coordinate regulation of several properties and seems to resemble determination in vivo. In our standard culture conditions, several other neuronal and glial properties are not expressed by these cell types. However, addition of dibutyryl-cAMP induces expression of additional properties, in a cell-type-specific manner: formation of long cellular processes in the RT4-B8 and RT4-E5 cell lines and expression of high-affinity uptake of gamma-aminobutyric acid, by a glial-cell-specific mechanism, in the RT4-D6-2 cell line. These new properties are maximally expressed 2-3 days after addition of dibutyryl-cAMP. This indicates that conversion of RT4-AC to the derivative cell types is also a branch point for the regulation of cell-type-specific properties whose expression is responsive to cAMP. Thus, the potential for maturation in response to increased cAMP is a property that segregates in a cell-type-specific manner and is activated at the determinational level in this system.

Effect of aromatase inhibitors on the histology of the cycling rat ovary

Two aromatase inhibitors, 4-hydroxyandrostenedione (4-OHA) and testololactone (Teslac), were tested to determine their effects on folliculogenesis, particularly ovarian histologic alterations, in the cycling rat. Adult, female Sprague-Dawley rats were treated with continuous infusion of both inhibitors at concentrations of 10(-8), 10(-4), and 10(-2) M for 30 days. The effect of the inhibitors on cultured granulosa cells harvested on proestrus was determined in vitro. The in vivo administration of each inhibitor induced significant reduction in ovarian-vein estradiol levels. Estradiol synthesis in cultured granulosa cells was inhibited by both aromatase inhibitors in a dose-dependent fashion. These observations indicate that 4-OHA and Teslac significantly inhibit basal estradiol synthesis in vivo and in vitro. This effect on estrogen synthesis was not reflected in alteration of the ovarian histology in the cycling rat.

Metabolism of androgens in human benign prostatic hyperplasia: aromatase and its inhibition

As an extension of our studies on androgen metabolism in epithelium and stroma of human benign prostatic hyperplasia (BPH) tissue our attempts to demonstrate the presence of aromatase are described. Additionally, the question is raised whether the aromatase inhibitor 17 alpha-oxa-D-homoandrosta-1.4-diene-3.17-dione (testolactone) might also act by inhibition of 17 beta-hydroxysteroid dehydrogenase (17 beta-HSDH). In vitro metabolism and inhibition were analyzed by TLC. The main results were: (1) Two aromatase assays (estrone formation and tritium release) were tested with placenta microsomes. Identical results were obtained (Km = 43 +/- 7 nmol/l n = 5; Vmax = 100 resulted in recovery of the aromatase activity added. (3) In BPH tissue alone, formation of estrone from androstenedione could not be detected (less than 7 x 10(-17) mol/min per mg protein, n = 8). (4) 4-Hydroxyandrostenedione inhibited placental aromatase (Ki = 37 nmol/l) distinctly better than 17 beta-HSDH from human BPH (Ki = 18 mumol/l), whereas the Ki values for testolactone (3.7 and 29 mumol/l, respectively) were more similar. It is concluded that aromatization of androgens is not an important pathway in BPH tissue. An alternative mode of action of testolactone by inhibition of 17 beta-HSDH is discussed.

Enzymatic control of estrogen production in human breast cancer: relative significance of aromatase versus sulfatase pathways

One-third of the cases of breast cancer in postmenopausal women are hormone-dependent and the lesions regress upon treatment with antiestrogens or inhibition of estrogen biosynthesis. In these patients, estrogens are synthesized in extraglandular tissues from adrenal precursors and re-enter plasma to produce estrone levels of 52 +/- 6.5 pg/ml (mean +/- SEM) and estradiol concentrations of 13.1 +/- 0.7 pg/ml. However, the fact that the levels of estrogen in breast tumor tissue are an order of magnitude higher than plasma levels suggested the possibility of in situ estrogen production. To address this possibility, we measured several enzymes involved in estradiol biosynthesis in human tumors. Forty-eight of 61 tumors contained aromatase (estrogen synthetase) activity ranging from 5-80 pg/gm protein per hour. By comparison, the levels of estrone sulfatase were 10(6) higher, ranging from 0.8-125 micrograms/gm protein per hour. Because the sulfatase enzyme was of lower affinity (i.e., Km = 27 microM) than that of aromatase (i.e., 0.027 microM), the amount of estrogen formed under conditions of similar substrate concentrations was compared and found to be 10-fold higher via the sulfatase enzyme. In 41 additional tumors, the 17 beta-hydroxysteroid dehydrogenase enzyme, catalyzing the conversion of estrone to estradiol, was uniformly present. To test the biologic relevance of the estrone sulfate to estrone to estradiol pathway, estrogen-dependent nitrosomethylurea rat mammary tumors were grown in soft agar in the presence of estrone sulfate. Concentrations of estrone sulfate of 10(-6) microM significantly (p less than 0.01) stimulated colony formation in this system in which 75.5-98.6% of estrone sulfate was converted to estrone and 0.2 to 6% to estradiol. These data support the hypothesis that mammary carcinomas can synthesize estradiol in situ from circulating estrogen precursor and that local conversion is biologically important. On the basis of comparative data, the estrone sulfate to estrone to estradiol pathway is quantitatively more important than that involving androstenedione to estrone to estradiol.

Effect of chronic aromatase inhibition by delta 1-testolactone on pituitary-gonadal function in oligozoospermic men

Aromatase inhibition by delta 1-testolactone (Teslac, 500 mg twice daily) for 6 months in 9 patients with idiopathic oligozoospermia lowered the levels of serum estradiol (E2) and thereby sex hormone binding globulin (SHBG) (rS = +0.40, p less than 0.025) to values -35 and -25%, respectively, below the pretreatment values (P less than 0.001 and less than 0.005). The E2 decrease was accompanied by a temporary increase (+50%) in the levels of follicle stimulating hormone (FSH), not of luteinizing hormone (LH), and of 17 alpha-hydroxyprogesterone (17 alpha-OHP), but less of testosterone (T) (+30%), which led to a transient rise in the 17 alpha-OHP/T ratio. The T/E2 ratio and "free T" index (T/SHBG) almost doubled until the end of the treatment period. During delta 1-testolactone treatment the mean sperm density gradually rose from 8.1 +/- 1.3 (SEM) before to 21.3 +/- 6.7 X 10(6)/ml after 6 months (P less than 0.01), whereas the total sperm count almost threefold increased (P less than 0.05). Sperm concentrations exceeding 20 X 10(6)/ml were achieved in 4 of the 9 patients. Two of these patients' wives became pregnant. Although the data point to a pivotal role of estrogens in the pathogenesis of the spermatogenic lesion in some patients with idiopathic oligozoospermia, the lack of a beneficial effect of estrogen lowering in others points to a multicausal nature of the disease entity.

Aromatase inhibition by delta 1-testolactone does not relieve the gonadotropin-induced late steroidogenic block in normal men

Aromatase inhibition by delta 1-testolactone [(17 oxa-D-homo 1,4 androstanediene-3,17 dione) 500 mg twice daily for 10 days] in nine normal men lowered circulating estradiol (E2) levels by about 25%, enhanced the secretion of FSH, 17-hydroxyprogesterone (17-OHP), and to a lesser degree testosterone (T), but did not affect serum LH levels. Despite E2 lowering there was greater accumulation of 17-OHP than of T after 7 days of treatment, suggesting 17,20-lyase inhibition. Unexpectedly, administration of delta 1-testolactone almost halved the T response to hCG (Pregnyl, 1500 IU), but did not affect the 17-OHP response. Thus, E2 lowering by testolactone aggravated the hCG-induced 17,20-lyase block present before testolactone administration. Although the present data might suggest that estrogens do not play a role in the genesis of the hCG-induced late steroidogenic block, the results suggest that testolactone per se, in addition to its reported antiestrogenic action, inhibits 17,20 lyase.

Effect of aromatase inhibition by delta 1-testolactone on basal and luteinizing hormone-releasing hormone-stimulated pituitary and gonadal hormonal function in oligospermic men

Aromatase inhibition by delta 1-testolactone (TL), 500 mg twice daily for 4 weeks, in nine patients with idiopathic oligospermia lowered circulating estradiol (E2) levels by about 30%, enhanced the secretion of follicle-stimulating hormone (+ 30%), 17-hydroxyprogesterone (17-OHP) (+ 40%), and testosterone (T) (+ 30%), but did not affect serum luteinizing hormone levels. Despite E2 lowering, there was an accumulation of 17-OHP over T, suggesting 17, 20-lyase inhibition. Unexpectedly, administration of TL almost completely deleted the T response to continuous luteinizing hormone-releasing hormone infusion present before TL therapy, despite similar gonadotropin release. Because the 17-OHP response to the luteinizing hormone-releasing hormone infusion was even higher during therapy, the 17,20-lyase lesion seemed aggravated despite substantial reduction of E2 levels. Although the present data suggest that estrogens play a less dominant role in the origin of the late steroidogenetic lesion than previously assumed, the suggestion also arises that TL per se, in addition to its antiestrogenic action, exerts an inhibiting effect on the 17,20-lyase locus, which may obscure the beneficial effect of reducing E2.

Short-term effects of testolactone on human testicular steroid production and on the response to human chorionic gonadotropin

Testicular responsiveness to a single dose of human chorionic gonadotropin was studied in five normal men before and during short-term treatment with an aromatization inhibitor, testolactone (TL). TL alone resulted in significant increases in the serum concentrations of progesterone, 17-hydroxyprogesterone, 17-hydroxypregnenolone, dehydroepiandrosterone, androstenedione, and the sulfate conjugates of pregnenolone, 17-hydroxypregnenolone and testosterone (T). Concentrations of 5-androstene-3 beta, 17 beta-diol and T remained unchanged, and those of estradiol (E2) decreased. TL had no major influence on serum luteinizing hormone, follicle-stimulating hormone, prolactin, or sex-hormone-binding globulin concentrations. During TL administration, human chorionic gonadotropin stimulation led to a significantly decreased E2 response, but the T response was unchanged. Alleviation of an inhibitory influence of E2 on the steroidogenic enzymes, especially 17,20-desmolase, was probably the reason behind the increased synthesis of several T precursors. In addition, TL appeared to have an inhibitory influence on the 17 beta-reduction of T precursors. TL resulted in increased serum concentrations of some steroid sulfates, but the mechanism of this effect remains unclear.

Estrogens in the feedback regulation of gonadotropin secretion in men: effects of administration of estrogen to agonadal subjects and the antiestrogen tamoxifen and the aromatase inhibitor delta'-testolactone to eugonadal subjects

To elucidate the specific role of estrogens in the feedback regulation of gonadotropin secretion in men, basal and LRH-stimulated gonadotropin levels were studied in: Six agonadal subjects Six agonadal subjects continuously treated with 50 micrograms ethinylestradiol Six eugonadal subjects, treated with the aromatase inhibitor delta'-testolactone, which induced a reduction of estrogen levels, independently of testosterone. Further, to determine whether estrogens exert differential effects in time on LH and FSH secretion, the anti-estrogen tamoxifen was administered to: Six eugonadal subjects for two weeks and Six eugonadal subjects for six weeks. It was found that estrogens have a strong suppressive effect on both LH and FSH secretion. However, changes in estrogen levels and blocking of estrogen receptors are followed more rapidly by FSH than LH. Estrogens affect LRH-induced LH release more than basal LH levels; basal and LRH-stimulated FSH are approximately equally influenced. Basal and LRH-induced LH secretion are known to be more dependent upon previous LRH stimulation than FSH secretion. Since FSH followed changes of estrogens more rapidly than LH did, we postulate that the negative feedback action of estrogens on: LH secretion is predominantly exerted at the level of the hypothalamus, through inhibition of LRH secretion FSH secretion predominantly at the level of the pituitary through a direct action on the gonadotroph.

Additive effects of aminoglutethimide, testololactone, and 4-hydroxyandrostenedione as inhibitors of aromatase

In vitro p450 spectral data suggested that combinations of aromatase inhibitors might produce enhanced biologic effects. If correct, two clinically available aromatase inhibitors, aminoglutethimide (AG) and testololactone (TL) could potentially be given together at lower than usual dosage with reduction of patient side effects and preservation of aromatase inhibition. Using a [3H]water aromatase assay and a placental microsomal system, AG and TL were tested individually and in combination over their respective dose response ranges. Additive effects of these two compounds were observed. Another inhibitor, 4-hydroxyandrostenedione, given with AG produced similar additive inhibition. These data provide a basis for a future trial of AG and TL in combination in patients with breast carcinoma.

Prolactin secretion in the human male is increased by endogenous oestrogens and decreased by exogenous/endogenous androgens

There is evidence that prolactin may be involved in testicular steroidogenesis, and we have therefore investigated whether there is feedback regulation of androgens/oestrogens on prolactin secretion in the human male. To assess this we have measured basal and TRH-stimulated prolactin levels in: Six eugonadal men before and after 2 weeks' administration of the aromatase inhibitor delta'-testolactone, which led to a fall in oestradiol levels with unchanged levels of testosterone. In these patients, prolactin levels decreased. Six eugonadal subjects before and after 6 weeks' administration of dihydrotestosterone undecanoate. In these subjects, prolactin levels decreased. Six agonadal subjects, tested after 12 weeks' treatment with dihydrotestosterone undecanoate and compared to: Six agonadal subjects who received no sex steroid treatment. Again, it was found that dihydrotestosterone treatment decreased prolactin levels in patients from Group C. Six eugonadal subjects were also studied before and after 6 weeks' administration of the androgen receptor antagonist, spironolactone, and this treatment increased Prl secretion. It is concluded that in the human male, endogenous oestrogens increase prolactin secretion whilst exogenous/endogenous androgens decrease prolactin secretion.

The effect of delta 1-testolactone on serum testosterone and estradiol in the adult male rat

delta 1-Testolactone, an androgen derivative without intrinsic hormonal action, is known to block the aromatization of androgens to estrogens. This study was designed to assess its effect upon serum testosterone (T) and estradiol (E2) in the adult male rat. By itself, testolactone (TL) did not affect T/E2 levels in the dosages utilized. Daily injections of human chorionic gonadotropin (hCG) for 15 days caused a tenfold rise in serum T, although there was no increase in serum E2. When given along with hCG, TL did not alter the Leydig cell response. However, pretreatment of animals with TL increased the testicular response to hCG over that of saline-treated animals. Studies were also carried out to delineate the sources of estrogen in the adult male rat. These experiments demonstrate that (1) the majority of E2 is not testicular in origin but is derived from the adrenal; (2) the conversion of androgen precursors to E2 in the rat is not affected by TL; and (3) in spite of no demonstrable inhibition of E2 production, TL causes an increased Leydig cell responsiveness to hCG.

Biological significance of aromatase activity in human breast tumors

Human breast carcinomas contain aromatase, the enzyme necessary for the conversion of androgens to estrogens. If present in sufficient amounts, aromatase could catalyze the synthesis of estrogens from plasma steroid precursors and produce high breast cancer tissue concentrations. To determine the biological importance of tumor aromatase, we validated a specific and highly sensitive 3H-labeled water release assay for aromatase and used this to quantitate the amount of estrogen synthesized in vitro in breast tumors. As proof of assay validity, the [3H] water release assay detected 22.7 +/- 0.09 (+/- SEM) pmol/g . h estrogen formed vs. 24.7 pmol/g . h with the direct product isolation assay. Of 61 human breast tumors studied, 48 contained measurable aromatase activity, ranging from 5-70.5 pmol estrone formed/g . h. Three aromatase inhibitors (aminoglutethimide, testololactone, and 4-hydroxyandrostenedione) blocked this activity at concentrations similar to those affecting aromatase activity in other tissues. If biologically important, the estrogen formed locally from aromatase would be expected to stimulate production of the progesterone receptor. Under these circumstances, a positive correlation of progesterone receptor and local estrogen production should be found. In contrast, no significant correlation between aromatase activity and progesterone receptor level was observed (r = -0.27; P = NS). In addition, no correlation between estrogen receptor content and aromatase activity was detected. Finally, the amount of aromatase activity present in most tumors was insufficient to produce biologically meaningful saturation of estrogen receptors. These observations suggested that aromatase, while present in the majority of breast cancer tissues, may only be biologically important in those few tumors with very high aromatase activity.

Hydrotestolactone lowers serum oestradiol and PRL levels in normal men: evidence of a role of oestradiol in prl secretion

The effect on serum PRL levels of lowering serum oestradiol (E2) concentration by short-term administration of an aromatase activity inhibitor, hydrotestolactone (HT), was studied in six healthy male subjects. After HT administration serum E2 levels decreased from 68 +/- 5.8 to 26 +/- 2.5 pmol/l (mean +/- SE, P less than 0.05). These E2 changes were accompanied by a significant decrease in mean 2-h PRL levels from 11.2 +/- 2.1 to 6.5 +/- 1.6 ng/ml mean +/- SE, P less than 0.05). The evaluation of individual percentage change from basal concentrations showed a varying decrease in all subjects. These findings suggest that under physiological conditions E2 may be one of the factors which control blood PRL concentrations in men.

Comparative studies of aromatase inhibitors in cultured human breast cancer cells

The presence of aromatase activity, estrogen receptors, and estrogenic responsiveness in MCF-7 human breast cancer cells has allowed this cell line to be used as a unique in vitro system for investigating the biological activities of potentially therapeutic aromatase inhibitors. We now report the results of studies which have examined the cytotoxicity, antiaromatase, and intrinsic estrogenic activities of aminoglutethimide, 1,2-dehydrotestolactone (testolactone), dihydrotestosterone, 4-hydroxy-4-androstene-3,17-dione, and 10-propargylestr-4-ene-3,17-dione within MCF-7 monolayer cultures. Cell viability was determined by trypan blue exclusion, and aromatase activity was assessed by quantifying the amounts of [3H]estradiol formed from [3H]testosterone. Estrogenic activity was assessed by examining the ability of each inhibitor to increase cytoplasmic progesterone receptor and deplete cytoplasmic estrogen receptor concentrations in these cells during a 5-day incubation period. Cytoplasmic progesterone and estrogen receptors were measured by the single-saturating-dose technique using [17 alpha-methyl-3H]-17 alpha, 21-dimethyl-19-norpregna-4,9-diene-3,20-dione and [3H]estradiol as the labeled ligands for each assay, respectively. The results showed that all of these compounds were noncytotoxic aromatase inhibitors in MCF-7 cells but that these agents demonstrated marked differences in inhibitory potency (10-propargylestr-4-ene-3,17-dione greater than 4-hydroxy-4-androstene-3,17-dione much greater than dihydrotestosterone much greater than testolactone = aminoglutethimide). The incubation of cells with 4-hydroxy-4-androstene-3,17-dione resulted in cytoplasmic progesterone and estrogen receptor responses that were similar in magnitude to those observed in other cultures incubated with equimolar concentrations of estradiol. None of the other four agents demonstrated estrogenic activity in this system. However, we have previously observed that dihydrotestosterone has substantial antiestrogenic action in this system. Taken together, these results indicate that some aromatase inhibitors may influence the hormonal regulation of human breast cancer cells by more than one mechanism.

A new hypothesis based on suicide substrate inhibitor studies for the mechanism of action of aromatase

Recently, it was discovered that 4-hydroxy-4-androstene-3,17-dione, 4-androstene-3,6,17-trione, and 1,4,6-androstatriene-3,17-dione, compounds previously reported to be competitive inhibitors of aromatase, cause a time-dependent loss of aromatase activity in human placental microsomes. We report here that 1,4-androstadiene 3,17-dione (Ki 0.32 microM; kinact 0.91 X 10(-3)/sec) and testolactone (Ki 35 microM; kinact 0.36 X 10(-3)/sec) also cause a similar loss of aromatase activity. The mechanism which explains the unexpected loss of activity caused by these five inhibitors is neither established nor apparent from current theories of the enzyme mechanism of action of aromatase. We propose an inactivation mechanism based on a new hypothesis for estrogen biosynthesis in which the third enzyme oxidation carried out by aromatase results in the formation of an enzyme-bound intermediate. This intermediate is released as an aromatized product via a facile elimination reaction which simultaneously regenerates the unaltered active enzyme. Various structural modifications made in these five inhibitors are hypothesized to redirect this elimination reaction so that the steroid intermediate remains covalently attached to the enzyme instead of being released as an aromatized product.

Estrogen synthesis in human breast tumor and its inhibition by testololactone and bromoandrostenedione

A total of 53 tumors have been examined for estrogen synthesis from androstenedione and assayed for estradiol receptors. It was found that of the 40 tumors that metabolized androstenedione to estrogens, 17 tumors were estradiol receptor negative and 23 tumors were estradiol receptor positive. Of the 13 tumors that did not synthesize estrogens, 7 tumors were receptor negative and 6 tumors were receptor positive. No correlation was found between the ability of the tumor to synthesize estrogens and the presence or absence of estradiol receptors. The inhibition of aromatase enzyme in human breast tumors by delta 1-testololactone, testololactone, and 6 alpha- and 6 beta-bromoandrostenedione was investigated. Estrone and estradiol synthesis from androstenedione was reduced in five tumor incubations by the presence of 0.2 mM delta 1-testololactone and testololactone, 6 alpha- and 6 beta-bromoandrostenedione (2.0 microM) were also shown to block estrogen synthesis in 5 tumors. Furthermore, Lineweaver-Burk plots revealed that all four compounds were competitive inhibitors of androstenedione aromatization. An apparent Km of the aromatase enzyme for androstenedione of 0.08 microM and a Vmax of 23 pmol of estrone synthesized per g tumor per hr were determined for one human breast tumor specimen. The use of an aromatase inhibitor such as delta 1-testololactone in the treatment of breast cancer should be reconsidered. Data from one patient with advanced cancer of the breast, responding to previous oophorectomy and adrenalectomy and treated with large doses of delta 1-testololactone, are presented to illustrate the significance of successful treatment by scientific approaches.

In vivo effects of delta 1-testololactone on peripheral aromatization

To evaluate the in vivo effect of delta 1-testololactone on peripheral aromatization, studies were performed on seven postmenopausal women with metastatic breast cancer. Analysis of variance indicated that there were significant increases of circulating androstenedione (p less than 0.05) and estradiol (p less than 0.001) during administration of different doses of testololactone. Androstenedione levels were increased with all doses of testololactone tested (50, 100, 250, and 500 mg every 6 hr for 14 days each), while estradiol rose with only the 250- and 500-mg dosages. With administration, there was a significant decrease of estrone (p less than 0.001) with the mean level falling from 26 +/- 3 (S.E.) to 11 +/- 2 pg/ml. The addition of adrenal suppression (dexamethasone, 1 mg nightly at 11 p.m.) significantly lowered androstenedione (p less than 0.05) but had no effect on estrone or estradiol levels. Long-term therapy (up to 6 months) with the 250-mg dosage showed continual suppression of estrone with no escape being observed. Studies to determine the reason for the increase of estradiol with testololactone suggested cross-reactivity of the antibody with in vivo metabolites of the drug. However, these possible metabolites did not bind to uterine cytosol estrogen receptors. The decrease in estrone with testololactone administration presumably explains its antitumor properties.

The antiandrogenic effects of delta 1-testolactone (Teslac) in vivo in rats and in vitro in human cultured fibroblasts, rat mammary carcinoma cells, and rat prostate cytosol

The antiandrogenic properties of delta 1-testolactone (17 alpha-oxa-D-homo-1,4-androstane-3,17-dione; Teslac) were investigated in vivo and in vitro. Teslac (75 mg/day for 7 days) inhibited the rise in ventral prostate weight induced by testosterone (T) (P less than 0.001), dihydrotestosterone (DHT) (P less than 0.05), and a combination of T plus 17 beta-estradiol (E2) (P less than 0.01) in immature castrate rats. Similar effects were seen on the seminal vesicles after T and T plus E2 (P less than 0.001). Teslac also decreased prostate and seminal vesicle weights in intact immature rats. The effects of Teslac were dose and time dependent. Teslac did not change the concentration of serum T or DHT. However, Teslac inhibited DHT binding to the androgen receptor (Ki = 2.5 +/- 0.8 X 10(-7) M) in cytosol of the rat prostate. Teslac also inhibited DHT binding to the androgen receptor in cultured human prepuce fibroblasts and cultured rat mammary tumor cells (Ki = 1.9 +/- 0.3 X 10(-5) M). The results indicate that Teslac, in addition to its antiaromatase activity, is an antiandrogen by virtue of its interaction with the androgen receptor.

Rapid endocrine effects of tamoxifen and testolactone in prostatic carcinoma patients

The short-term (6-day) endocrine effects of tamoxifen and testolactone were investigated in men with prostatic carcinoma. Tamoxifen treatment (20 mg/day) did not affect the gonadotropin levels, but it temporarily increased prolactin, induced sex hormone-binding globulin production, and suppressed peripheral serum progesterone, 17-hydroxyprogesterone, androstenedione, testosterone, and 5 alpha-dihydrotestosterone concentrations. These changes were attributed to the estrogenic properties of tamoxifen, since no changes in peripheral serum estradiol concentrations were observed. Testolactone (1000 mg/day) decreased peripheral estradiol concentrations by 50% and increased the concentrations of the neutral steroids measured. The increases in serum FSH and LH were very small. This study corroborates the early estrogen-like action of tamoxifen, and the experiment with testolactone further suggests that endogenous estradiol has physiological functions in man, regulating gonadotropin and androgen production.

Direct evidence in men for a role of endogenous oestrogens on gonadotrophin release

In six healthy subjects serum oestradiol was selectively decreased by administering an aromatase activity inhibitor, hydrotestolactone (HT). After HT administration serum oestradiol (Oe2) decreased from 18.7 +/- 2.3 (SEM) to 6.7 +/- 0.6 pg/ml whereas testosterone (T) and dihydrotestosterone (DHT) blood levels were not modified. These oestradiol changes were associated with a significant increase in serum LH and FSH concentrations (P less than 0.001). The administration of tamoxifen, an oestrogen antagonist, to 5 subjects caused a sharp increase in LH and FSH levels (P less than 0.001). Oe2 was unchanged after the treatment with tamoxifen, whereas T levels were significantly higher. The sum of these data suggests that oestradiol under physiological conditions plays a specific role in the feedback mechanism of gonadotrophin release.

[3H-thymidine incorporation under endocrine influence and hormone receptor content of human mammary carcinoma (author's transl)]

The effect of medroxyprogesterone acetate, oestradiol-17 beta and testolactone on 3H-thymidine incorporation in human mammary carcinoma was studied in vitro. 54% of the tumours reacted to medroxyprogesterone, while testolactone and oestradiol-17 beta changed 3H-thymidine incorporation in 45.1 and 41.3%, respectively. Both inhibition and the in vivo undesirable stimulation of 3H-thymidine incorporation was observed. No relation could be established between oestrogen receptor content and reaction of the mammary carcinoma to oestradiol-17 beta. On the other hand, the gestagen receptor content and the reaction of the mammary carcinoma to medroxyprogesterone acetate correlated significantly (P < 0.001). This underlines the increasing significance of the gestagen receptor in the selective endocrine treatment of mammary carcinoma.

Influence of some antineoplastic agents on genetic exchange in Bacillus subtilis

The influence of three categories of anti-cancer agents on competence development and on the binding of homologous DNA to cells have been studied in the Bacillus subtilis transformation system. Treatment of cells developing competence with testolactone resulted in a slight enhancement of transforamtion at high doses (50 and 100 micrograms/ml) of the drug, but this process was inhibited at 25 micrograms/ml. DNA binding was unaffected by this drug. DNA-interacting agents (daunomycin, prospidine, peptichemio and mithramycin) usually inhibited DNA-mediated transformation in a higher extent than DNA binding. Antimetabolites of DNA synthesis were also tested: dacarbazine did not greatly inhibit the binding and expression of donor DNA. 5-Fluorouracil appeared to slightly enhance transformation at low levels 1 microgram/ml), although it was inhibited at higher doses.

Evidence that testosterone can suppress pituitary gonadotropin secretion independently of peripheral aromatization

Testosterone (T) was given to normal men with and without the concomitant administration of the aromatase inhibitor, delta 1-testolactone (Teslac), to examine the role of peripheral aromatization of T in gonadotropin regulation. When T was administered alone by continuous iv infusion (15 mg/day for 4 days), serum T increased 3-fold (P less than 0.01) and estradiol (E) increased by 50% (P less than 0.01). These changes were associated with a 50% decrease in serum LH and FSH concentrations (P less than 0.01). When T was infused into men taking Teslac (2000 mg/day), serum T levels doubled (P less than 0.01), but E levels did not change (13.4 +/- 1.5 vs. 13.5 +/- 1.0 pg/ml; P = NS). This pattern of plasma steroids, increased T and unchanged E, was also associated with significantly decreased serum LH and FSH concentrations (14.5 +/- 0.4 vs. 8.0 + 0.4 mIU/ml and 9.9 +/- 2.5 vs. 5.8 +/- 0.1 mIU/ml, respectively; P less than 0.01). These data support the hypothesis that T or one of its metabolites can modulate LH and FSH secretion independently of peripheral aromatization to E.

The role of butyrate in the reverse transformation reaction in mammalian cells

The reverse transformation reaction of Chinese hamster ovary cells from compact, epithelial-like, randomly growing, heavily knobbed, lectin reactive cells into stretched, tighly adherent, smooth-surfaced, lectin resistant, fibroblast-like cells normally elicited by dibutyryl cAMP can be produced to its complete extent by N6-monobutyryl cAMP or 8-bromo-cAMP, O2'-monobutyryl cAMP is ineffective as is cAMP itself in the absence of an inhibitor of phosphodiesterase activity. In the presence of a phosphodiesterase inhibitor, cAMP is fully effective. These results indicate that the role of the butyryl groups of dibutyryl cAMP and, especially, the N6-butyryl, in the reverse transformation reaction is protection of the cAMP analogue from degradation. Butyrate at concentrations of about 1 mM does produce a response which to some extent mimics that of cAMP analogues. The cells, however, fail to assume a fibroblastic-like shape, but rather become flattened. The butyrate effect is much slower and less readily reversible than that evoked by cAMP analogues. Butyrate produces an approximately 2-fold increase in intracellular cAMP levels. These results are consistent with the hypothesis that butyrate effects, in part, are mediated by AMP.

Antagonism by dibutyryl adenosine cyclic 3',5'-monophosphate and testololactone of concanavalin A capping

Exposure of CHO-K1 cells in vitro to dibutyryl adenosine cyclic 3',5'-monophosphate (DBcAMP) plus testololactone produces a rapid, reversible antagonism of ligand-induced collection of initially dispersed concanavalin A (Con A) binding sites into a caplike mass. Morphologically, as Con A capping occurs, the cells become less spread and then round completely. With prolonged Con A exposure, cells cultured in either the absence or the presence of DBcAMP plus testololactone cap and round. Capping is blocked by cold treatment and respiratory inhibitors. Colcemid at concentrations greater than 1 muM promotes both Con A capping and cell rounding. Cytochalasin B at similar concentrations inhibits both capping and cell rounding. Treatment of cells with Con A has little effect on intracellular cAMP concentration. Possible mechanisms by which cAMP may modulate the movement of Con A binding sites are discussed.