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PubMed1991

Comparison of the effects of high dose testosterone and 19-nortestosterone to a replacement dose of testosterone on strength and body composition in normal men.

We examined the extent to which supraphysiological doses of androgen can modify body composition and strength in normally virilized men. In doubly blind tests, 30 healthy young men received testosterone enanthate (TE) or 19-nortestosterone decanoate (ND), at 100 mg/wk or 300 mg/wk for 6 weeks. The TE-100 mg/wk group served as replacement dose comparison, maintaining pretreatment serum testosterone levels, while keeping all subjects blinded to treatment, particularly through reduction in testicular volumes. Isokinetic strength measurements were made for the biceps brachii and quadriceps femoris muscle groups before treatment and 2-3 days after the 6th injection. Small improvements were noted in all groups but the changes were highly variable; a trend to greater and more consistent strength gain occurred in the TE-300 mg/wk group. There was no change in weight for TE-100 mg/wk but an average gain of 3 kg in each of the other groups. No changes in 4 skinfold thicknesses or in estimated percent body fat were observed. Of 15 circumferences, significant increases were observed only for men receiving TE-300 mg/wk (shoulders) and ND-300 mg/wk (shoulders and chest). The data suggest that high dose androgens increase body mass and may increase strength in normal men but, except for a consistent weight gain with greater than replacement doses, the detectable changes were highly variable and relatively small, especially in comparison to the significant alterations which were observed for other markers of androgen action.

Adult↗

PubMed1995

Lack of estrogenic potential of progesterone- or 19-nor-progesterone-derived progestins as opposed to testosterone or 19-nor-testosterone derivatives on endometrial Ishikawa cells.

Estrogen receptors of human endometrial cancer Ishikawa cells were found to be present in moderate amounts (160-200 fmol/mg protein), and to specifically bind moxestrol (R2858) with a very high affinity characterized by a Kd around 60 pM, when measured under equilibrium conditions. The binding specificity respected a decreasing order as follows: estradiol (E2: 100%) > 4-hydroxy-tamoxifen (4OHTAM: 52.7%) > estriol (E3: 5.7%) > estrone (E1: 2.1%) > TAM (0.2%). The induction of alkaline phosphatase activity (APase) used as an estrogen-specific response, confirmed the intrinsic estrogenicity of progestins derived from 19-nor-testosterone (19NT): norethindrone (NOR), norethynodrel and levonorgestrel, at concentrations ranging from 10(-8) to 10(-6) M. The effect of NOR was partially blocked by the antiestrogen 4OHTAM, which was also partially agonistic in this model, but neither by the antiprogestin mifepristone (RU486) nor by the aromatase inhibitor aminoglutethimide. A simulatory effect was also detected at 10(-7) or 10(-6) M with ethindrone, the testosterone- (T) derived progestin homologous to NOR, and with both androgenic parent-compounds, i.e. T and 19NT themselves. In contrast, progesterone (P) derivatives like medroxyprogesterone acetate (MPA) and chlormadinone acetate (CMA) remained totally inactive, as well as 19-nor-progesterone (19NP) itself or its progestagenic derivatives: ORG 2058 and nomegestrol acetate (NOM). Structure-activity relationships deduced from these studies suggest that it is not the absence of the 19-methyl group which can account for the estrogenic potential of the so-called "19-norprogestins", but rather their steroid structure derived from T in a broad sense (including the 19NT derivatives), as opposed to the non-estrogenic therapeutic progestins derived from P like MPA or CMA, or from 19NP like NOM.

Adenocarcinoma↗

PubMed1983

In vivo patterns of circulating testosterone following castration and intramuscular testosterone propionate injections of adult male rats.

In vivo patterns of circulating testosterone (T) were investigated in castrated and in intact male rats following a single intramuscular injection of 1mg testosterone propionate (TP). In addition, the in vivo clearance pattern of T was investigated following castration. The injection of TP into intact rats resulted in a rapid, statistically significant increase in circulating T which lasted for 12h and returned to normal by 24h post-injection. Circulating T decreased to nondetectable levels by 6h following orchiectomy. Injection of TP into castrated rats caused a rapid increase in circulating T which reached highest levels 60 min after administration. The concentrations of T in TP-treated orchiectomized rats remained elevated for 12h with a gradual decline which persisted for the experimental period of 6 days post-injection and provided moderate maintenance of sex accessory organ weights. TP injections increased circulating T levels in both groups of rats, but the magnitude of elevation was greater in intact animals where the normal T diurnal variations were disturbed. The elevation in circulating T persisted longer in the castrate-TP-treated animals than in intact animals, suggesting a difference in clearance, distribution and metabolism of T in orchiectomized rats.

Animals↗

PubMed2001

The testosterone metabolite and neurosteroid 3alpha-androstanediol may mediate the effects of testosterone on conditioned place preference.

Testosterone (T) and pregnane neurosteroids can enhance conditioned place preference (CPP). The present experiment examined CPP produced by T and its androgenic metabolite dihydrotestosterone (DHT) and 3alpha-Androstanediol (3alpha-diol; an androstane neurosteroid). Administration of 3alpha-diol (>DHT>T) to intact male Long-Evans rats, 1.0 mg daily for six days, 30 min prior to exposure to the non-preferred side of the CPP chamber significantly increased preference for the non-preferred side of the chamber compared to that seen in home cage controls. Levels of circulating 3alpha-diol were increased significantly in 3alpha-diol>DHT>T-administered rats, compared to rats that had vehicle administered or androgen-administration discontinued. Androgen administration decreased seminal vesicle weight and intrahypothalamic androgen receptor (AR) binding compared to that seen in rats that had vehicle administered or androgen-administration discontinued. Testosterone, DHT, and 3alpha-diol decreased GABA-stimulated chloride influx in cortical synaptoneurosomes, and muscimol binding in the hippocampus compared to that seen in rats with vehicle administered or that had androgen-administration discontinued. These data indicate that administration of 3alpha-diol is more effective at enhancing CPP and increasing circulating 3alpha-diol levels than is DHT or T administration, and that all of the androgen regimens employed decreased peripheral and hypothalamic androgen receptor binding and cortical and hippocampal GABA(A) receptor function. Hence, whether the effects of 3 alpha-diol on CPP are mediated by differential actions at ARs or GABA(A) receptors in particular brain regions needs to be determined.

Androgens↗

PubMed1985

Determination of plasma testosterone by mass fragmentography using [3,4-13C]testosterone as an internal standard.

The combination of glass capillary gas chromatography--mass spectrometry is especially suitable for the recognition of compounds. The use of [3,4-13C]testosterone as internal standard, mass fragmentography and isotope ratio measurement have been applied to the quantitative determination of testosterone in plasma. This paper describes the method, using tert.-butyldimethylsilylmethoxime and di-heptafluorobutyrate derivatives. The calibration graph in isotopic dilution is examined. The results obtained are compared with the results obtained by radioimmunoassay. The sensitivity of the method is judged from the lower limit of detection: 4.5 pg. The precision, and inter- and intra-assay are calculated.

Dehydroepiandrosterone↗

PubMed1997

In vitro production of testosterone and plasma levels of luteinising hormone, testosterone and cortisol in male rats treated with heptachlor.

Male rats were divided into six groups of five rats each. Rats were injected subcutaneously with different concentrations of heptachlor for 2 weeks. Heptachlor at all doses significantly suppressed plasma testosterone levels (P < 0.05). Plasma luteinizing hormone (LH) (P < 0.01) and cortisol (P < 0.02) levels were significantly elevated in heptachlor-treated rats as compared to corn oil-treated controls. LH and testosterone levels showed strong correlation (r = 0.69, P < 0.05). The testes in rats treated with 25 mg/kg body weight of heptachlor showed some pathological changes. We conclude that heptachlor causes adverse effects on several male reproductive parameters in rats.

Animals↗

PubMed1991

[Contraception with cyclic administration of buserelin and gestagens: increase in testosterone and free testosterone serum concentration].

During contraception with the LH-RH analogue buserelin, some women developed mild androgenic symptoms. Therefore, we investigated in 10 women various hormonal serum parameters during one cycle of treatment with daily 300 micrograms buserelin intranasally (day 1-22) and 5 mg medroxyprogesterone acetate (MPA) orally (day 16-22), and, after a washout cycle, during another cycle of treatment with daily 300 micrograms buserelin intranasally (day 1-15) and 5 mg norethisterone acetate (NETA) orally (day 16-22). The serum parameters were investigated on day 1, 15 and 21 during the 4 hours after administration of the drugs. During the treatment, LH release was significantly reduced, whereby additional MPA had no effect whatsoever, while NETA profoundly suppressed LH. During treatment with buserelin and MPA, the average oestradiol levels remained unaltered, but were significantly suppressed by 65% during intake of NETA. Contrary to 17 alpha-hydroxyprogesterone, which did not change, serum testosterone was significantly increased by 30% when buserelin was given with or without MPA, while NETA had no effect. During both regimens, the serum concentrations of SHBG were reduced by 15 to 25%, and those of free testosterone were increased by 30 to 50%. These alterations in hormonal parameters may have contributed to the development of seborrhoeic symptoms and acne of the facial skin which were observed in 6 of the 10 women treated with intranasal buserelin for contraception.

Administration, Intranasal↗

PubMed1978

Serum estradiol, testosterone and dihydrotestosterone in male monkeys treated with testosterone propionate.

Serum estradiol (E2), testosterone (T) and dihydrotestosterone (DHT) were measured in juvenile (pre-pubertal) male rhesus monkeys injected with either 8 mg or 80 mg of testosterone propionate (TP). After one week, the three steroids were elevated and remained essentially unchanged for the duration of the study. There was little difference in serum E2 or DHT when comparing the two groups of steroid-treated monkeys. In contrast, T levels were consistently greater in the animals given the high dosage of TP.

Animals↗

PubMed1976

Enzyme immunoassay of testosterone using the testosterone-glucoamylase complex.

A highly sensitive, reproducible method was established for enzyme-coupled immunoassay of testosterone, involving coupling of testosterone to glucoamylase [EC 3.2.1.3] with a water-soluble coupling reagen carbodimide. No enzyme activity was lost during this coupling procedure. The sensitivity of the method was comparable to that of competitive protein binding assay.

Carbodiimides↗

PubMed1989

cDNA-directed expression of rat testosterone 7 alpha-hydroxylase using the modified vaccinia virus, T7-RNA-polymerase system and evidence for 6 alpha-hydroxylation and delta 6-testosterone formation.

The modified vaccinia virus, T7-RNA-polymerase cDNA-expression system was used to express rat cytochrome P-450a. Various parameters such as host-cell type and density, and duration of infection were tested to optimize the level of expression of cytochrome P-450a enzyme activity. Cytochrome P-450a expressed from the cDNA sequence was exclusively incorporated into the membrane-containing portions of the cell lysates, as expected from its normal association in the liver endoplasmic reticulum. The enzyme displayed a carbon-monoxide-reduced-cytochrome-P-450a difference spectrum with a Soret maximum of 450 nm. Activity measurements revealed that cytochrome P-450a produced three metabolites of testosterone; 7 alpha-hydroxytestosterone and 6 alpha-hydroxytestosterone and delta 6-testosterone at a ratio of about 38:1:1. Under the appropriate conditions, the vaccinia-virus, T7-RNA-polymerase system produces high levels of a single form of cytochrome P-450 in cells that are virtually devoid of endogenous cytochrome P-450. Analysis of the cytochrome P-450 in its natural membrane-bound state, as opposed to artificial-lipid reconstitution studies of purified enzymes, allows accurate and confident measurements of substrate specificities.

Animals↗

PubMedDate not supplied

Basal and LHRH-stimulated gonadotropin levels and the circadian rhythm of testosterone and the effect of exogenous testosterone thereon.

In seven eugonadal men, aged 20-26 years, a fall in plasma and saliva testosterone (T) levels between 8.00 and 16.00 h of the day was observed, but plasma oestradiol-17 beta levels did not show a significant variation. These findings substantiate the existence of a circadian rhythm in T levels. Concurrent with the decrease of T levels over the day, a small but significant rise in basal LH, but not in LHRH-stimulated LH levels were observed. Then the fall of plasma and saliva T levels over the day was prevented by the administration of 80 mg testosterone undecanoate (Andriol, Organon) by mouth at 8.00 h. A rise in plasma T and even more in saliva T levels was measured, which persisted till at least 16.00 h. At this hour basal LH, but not LHRH-stimulated LH levels appeared to be slightly, though significantly depressed. From our data we conclude that fluctuations of T levels of the magnitude of 25% around the baseline values, affect slightly basal LH levels, but not LHRH-stimulated LH levels.

Adult↗

PubMed2003

Contribution of lymphatically transported testosterone undecanoate to the systemic exposure of testosterone after oral administration of two andriol formulations in conscious lymph duct-cannulated dogs.

Orally administered testosterone (T) is ineffective in the treatment of male androgen deficiency syndromes due to extensive presystemic first-pass metabolism. In contrast, the lipophilic long-chain ester testosterone undecanoate (TU) exhibits androgenic activity that has been attributed to formation of T via systemic hydrolysis of lymphatically transported TU. However, there are no definitive data regarding the oral bioavailability of TU or the extent to which lymphatically transported TU contributes to the systemic availability of T after oral TU administration. This report describes the application of stable isotope methodology in a thoracic lymph duct-cannulated dog model to study the oral bioavailability and lymphatic transport of TU after postprandial administration. When administered as either Andriol or Andriol Testocaps, the mean (+/-S.E., n = 4) absolute bioavailability of TU was 3.25 +/- 0.48 and 2.88 +/- 0.88%, respectively, and lymphatically transported TU accounted for between 91.5 and 99.7% of the systemically available ester. Model-independent pharmacokinetic analysis indicated that 83.6 +/- 1.6 and 84.1 +/- 8.2% of the systemically available T, resulting from Andriol or Andriol Testocaps, respectively, was due to systemic hydrolysis of lymphatically transported TU. These data demonstrate that intestinal lymphatic transport of TU produces increased systemic exposure of T by avoiding the extensive first-pass effect responsible for the inactivation of T after oral administration.

Absorption↗

PubMed1980

Short-term response of testosterone, dihydrotestosterone, 5 alpha-androstane-3 beta, 17 beta-diol, testosterone-glucosiduronate and estradiol-17 beta as measured in the spermatic vein of human male subjects after infusion of gonadotropins.

In 8 male subjects with normal testicular function, blood was drawn from the left spermatic vein and from the right cubital vein before and during an infusion of 4,000 IU human chorionic gonadotropin (hCG) (preceded by a bolus of 1,000 IU) or of 500 IU hCG plus human menopausal gonadotropin (hMG), respectively, within 30 min. Testosterone levels in the spermatic vein blood increased rapidly up to 518 or 215%, respectively. An increase of estradiol-17 beta and of 5 alpha-dihydrotestosterone concentrations in spermatic vein blood was observed only in 1 and 2 subjects, respectively. It was shown that the human testicle releases also 5 alpha-androstane-3 alpha, 17 beta-diol and testosterone-glucosiduronate. Both steroids did not respond to the short-term infusion of gonadotropins. The same holds true for all five steroids measured in peripheral vein blood.

Adult↗

PubMed1988

Age-related changes in plasma dehydroepiandrosterone sulphate, cortisol, testosterone and free testosterone circadian rhythms in adult men.

The circadian rhythms of serum luteinizing hormone, follicle-stimulating hormone, testosterone (T), free testosterone (fT), sex hormone-binding globulin (SHBG), oestradiol, cortisol and dehydroepiandrosterone sulphate (DHA-s) have been investigated in 5 normal male adults and 6 elderly men. Circadian rhythms were detected statistically significant (p less than 0.05) by population mean cosinor analysis, for T, fT, cortisol and DHA-s in the young group. In the elderly population, serum cortisol showed a clear circadian rhythm, although with some phase modification, whereas DHA-s secretion lost its circadian rhythmicity. This demonstrates that ageing differently affects the two major adrenal functions, glucocorticoid and androgenic; further, the data suggest that an independent adrenal androgen-regulating system could be selectively impaired in the older subjects. In the elderly group the loss of T circadian rhythm was confirmed, but a statistically significant circadian rhythm of fT was recorded. It was characterized by a marked phase advance and not related with the SHBG modifications found in elderly men. This finding leads us to reconsider the role of fT, which appears more sensitive than total T, in studying circadian rhythm of gonadal androgen secretion.

Adult↗

PubMed2004

New testosterone buccal system (Striant) delivers physiological testosterone levels: pharmacokinetics study in hypogonadal men.

A new mucoadhesive testosterone buccal system (Striant), 30 mg testosterone (T), was applied twice daily in 82 hypogonadal men for 3 months. Serum T, free T, and 5alpha-dihydrotestosterone were measured during this period. T pharmacokinetics were determined from the data obtained during a 24-h sampling at wk 12. Physiological mean serum T concentrations were steady and consistently maintained. The mean percentage of time over a 24-h period that total serum T concentrations were above the lower limit of adult male range was 80.1%. During treatment, mean serum 5alpha-dihydrotestosterone, free T, and estradiol concentrations paralleled serum T. T pharmacokinetics were not significantly affected by body mass index, age, food or beverage, gum abnormalities, or medications known to cause dry mouth. Gum-related adverse events occurred in 16.3% of subjects. Except for three subjects, the gum adverse effects occurred early during treatment, did not cause interruption of treatment, and resolved rapidly and completely. The T buccal system is a novel T formulation that offers a safe, effective, and convenient alternative to existing formulations for physiological T replacement therapy in hypogonadal men.

Adult↗

PubMed2005

Low-dose human chorionic gonadotropin maintains intratesticular testosterone in normal men with testosterone-induced gonadotropin suppression.

In previous studies of testicular biopsy tissue from healthy men, intratesticular testosterone (ITT) has been shown to be much higher than serum testosterone (T), suggesting that high ITT is needed relative to serum T for normal spermatogenesis in men. However, the quantitative relationship between ITT and spermatogenesis is not known. To begin to address this issue experimentally, we determined the dose-response relationship between human chorionic gonadotropin (hCG) and ITT to ascertain the minimum dose needed to maintain ITT in the normal range. Twenty-nine men with normal reproductive physiology were randomized to receive 200 mg T enanthate weekly in combination with either saline placebo or 125, 250, or 500 IU hCG every other day for 3 wk. ITT was assessed in testicular fluid obtained by percutaneous fine needle aspiration at baseline and at the end of treatment. Baseline serum T (14.1 nmol/liter) was 1.2% of ITT (1174 nmol/liter). LH and FSH were profoundly suppressed to 5% and 3% of baseline, respectively, and ITT was suppressed by 94% (1234 to 72 nmol/liter) in the T enanthate/placebo group. ITT increased linearly with increasing hCG dose (P < 0.001). Posttreatment ITT was 25% less than baseline in the 125 IU hCG group, 7% less than baseline in the 250 IU hCG group, and 26% greater than baseline in the 500 IU hCG group. These results demonstrate that relatively low dose hCG maintains ITT within the normal range in healthy men with gonadotropin suppression. Extensions of this study will allow determination of the ITT concentration threshold required to maintain spermatogenesis in man.

Adolescent↗

PubMed2004

Intramuscular testosterone undecanoate: pharmacokinetic aspects of a novel testosterone formulation during long-term treatment of men with hypogonadism.

In an open-label, randomized, prospective trial, we investigated pharmacokinetics and several efficacy and safety parameters of a novel, long-acting testosterone (T) undecanoate (TU) formulation in 40 hypogonadal men (serum testosterone concentrations < 5 nmol/liter). For the first 30 wk (comparative study), the patients were randomly assigned to receive either 10 x 250 mg T enanthate (TE) im every 3 wk (n = 20) or 3 x 1000 mg TU im every 6 wk (loading dose) followed by 1 x 1000 mg after an additional 9 wk (n = 20). In a follow-up study, observation continued in those patients who completed the comparative part and opted for TU treatment (8 x 1000 mg TU every 12 wk in former TU patients and 2 x 1000 mg TU every 8 wk plus 6 x 1000 mg every 12 wk in former TE patients) for an additional 20-21 months. Here we report only the pharmacokinetic aspects of the new TU formulation for the first approximately 2.5 yr of treatment. At baseline, serum T concentrations did not significantly differ between the two study groups. In the TE group, mean trough levels of serum T were always less than 10 nmol/liter before the next injection, whereas in the TU group, mean trough levels of serum T were 14.1 +/- 4.5 nmol/liter after the first two doses (6-wk intervals) and 16.3 +/- 5.7 nmol/liter after the 9-wk interval at wk 30. The mean serum levels of dihydrotestosterone and estradiol also increased in parallel to the serum T pattern and remained within the normal range. In the follow-up study, the former TU patients (n = 20) received eight TU injections at 12-wk intervals, and the TE patients (n = 16) switched to TU and initially received two TU injections at 8-wk intervals (loading) and continued with six TU injections at 12-wk intervals (maintenance). This regimen resulted in stable mean serum trough levels of T (ranging from 14.9 +/- 5.2 to 16.5 +/- 8.0 nmol/liter) and estradiol (ranging from 98.5 +/- 45.2 to 80.4 +/- 14.4 pmol/liter). The present study has shown that 1000 mg TU injected into male patients with hypogonadism at 12-wk intervals is well tolerated and leads to T levels within normal ranges, using four instead of 17 or more TE injections per year. An initial loading dose of either 3 x 1000 mg TU every 6 wk at the beginning of hormone substitution or 2 x 1000 mg TU every 8 wk after switching from the short-acting TE to TU were found to be a adequate dosing regimens for starting of treatment with the long-acting TU preparation.

Adolescent↗

PubMed1975

Daytime titers of testosterone, LH, estrone, estradiol, and testosterone-binding protein: acute effects of LH and LH-releasing hormone in men.

Four normal 18-20 yr-old men were studied on 3 occasions, from 0830 h to 1500 h. The baseline for each study consisted of 3 or 4 measurements of the respective hormone obtained between 0830 and 0900 h. In the control studies mean testosterone (T) fell by 43% (P less than 0.01) during the final 30 min. The fall was gradual throughout the day and was significant by 1100 h (P less than 0.05). Administration of LH and LH-releasing hormone (LHRH) at 0900 h resulted in 9-fold (5 min) and 3-fold (30 min) higher concentrations of LH respectively. LH declined more slowly after LHRH. Titers of T rose to the 0830-0900 h mean 130 min after LH but were never significantly elevated; the occurrence of a significant drop in mean T was delayed for 70 min. After LHRH there was a nonsignificant 24% increase of the mean T followed by a slow decline; however, T did not fall significantly below the mean baseline level. In contrast, in 2 of the 4 subjects LHRH resulted in rises in T levels (P less than 0.05) above the basal titers. Testosterone-binding globulin (TeBG) mean titers showed no diurnal rhythm in the control studies. There were statistically significant elevations of mean TeBG 150 min after LH and 340 to 370 min after LHRH, as well as sustained increases during the final 30 to 210 min of 1 or 2 individuals in each group. The reason for these increases in TeBG is not presently known. Estrogen analyses performed in all studies on 2 of the subjects revealed: 1) afternoon titers of estrone were lower than baseline in all 6 studies, 2) there was no diurnal rhythm for estradiol in control studies, and 3) estradiol increased during the final 2.5 to 3 h after LHRH (P less than 0.01), but after LH it was not altered in 1 man and was lower in the other.

Adolescent↗