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PubMed1997

Treatment of hypogonadal adolescent boys with long acting subcutaneous testosterone pellets.

AIMS: Long acting subcutaneous testosterone pellets are of proved efficacy for the treatment of hypogonadal men, but have not been reported as a treatment modality in adolescent boys. Pharmacodynamic studies of subcutaneous testosterone release have shown prolonged normalisation of testosterone levels for at least four months. Administration of a long acting, safe, effective, and convenient form of treatment is desirable when life-long treatment is indicated. PATIENTS AND METHODS: Eighteen boys (aged 13.9-17.5 years at the start of treatment)-seven with primary hypogonadism, nine with secondary hypogonadism, and two boys being treated with testosterone for tall stature--were given testosterone pellets (8-10 mg/kg) every six months for 18 months. Height, weight, pubertal status, and psychosocial parameters were assessed and follicle stimulating hormone, luteinising hormone, testosterone, prolactin, and lipids were measured at 0, 1, 3, 6, 12, and 18 months. Bone age was measured at 0 and 12 months. RESULTS: In all boys growth velocity continued appropriately for bone age. Puberty continued to progress in all boys and in two boys the amount of virilisation exceeded that seen with previous treatment with intramuscular testosterone. After testosterone administration, follicle stimulating hormone and luteinising hormone suppressed incompletely in the boys with primary hypogonadism. Serum testosterone ranged from 4.3 to 26.7 nmol/l at three months to less than 10 nmol/l at six months after implantation. Prolactin and lipid levels were normal throughout the study. By report, there was an improvement in mood and emotional wellbeing. No pellet extrusions occurred in a total of 156 pellet insertions. CONCLUSIONS: All boys preferred this mode of testosterone administration to intramuscular injections. Long acting subcutaneous testosterone pellets are safe, efficacious, well tolerated, and convenient, and result in normal physical growth and improved psychological outlook in adolescent hypogonadal boys.

Adolescent↗

PubMed2002

Testosterone increases neurotoxicity of glutamate in vitro and ischemia-reperfusion injury in an animal model.

Increasing evidence has demonstrated striking sex differences in the outcome of neurological injury. Whereas estrogens contribute to these differences by attenuating neurotoxicity and ischemia-reperfusion injury, the effects of testosterone are unclear. The present study was undertaken to determine the effects of testosterone on neuronal injury in both a cell-culture model and a rodent ischemia-reperfusion model. Glutamate-induced HT-22 cell-death model was used to evaluate the effects of testosterone on cell survival. Testosterone was shown to significantly increase the toxicity of glutamate at a 10 microM concentration, whereas 17beta-estradiol significantly attenuated the toxicity at the same concentration. In a rodent stroke model, ischemia-reperfusion injury was induced by temporal middle cerebral artery occlusion (MCAO) for 1 h and reperfusion for 24 h. To avoid the stress-related testosterone reduction, male rats were castrated and testosterone was replaced by testosterone pellet implantation. Testosterone pellets were removed at 1, 2, 4, or 6 h before MCAO to determine the duration of acute testosterone depletion effects on infarct volume. Ischemic lesion volume was significantly decreased from 239.6 +/- 25.9 mm(3) in control to 122.5 +/- 28.6 mm(3) when testosterone pellets were removed at 6 h before MCAO. Reduction of lesion volume was associated with amelioration of the hyperemia during reperfusion. Our in vitro and in vivo studies suggest that sex differences in response to brain injury are partly due to the consequence of damaging effects of testosterone.

Animals↗

PubMed2003

Testosterone gel supplementation for men with refractory depression: a randomized, placebo-controlled trial.

OBJECTIVE: Testosterone supplementation may produce antidepressant effects in men, but until recently it has required cumbersome parenteral administration. In an 8-week randomized, placebo-controlled trial, the authors administered a testosterone transdermal gel to men aged 30-65 who had refractory depression and low or borderline testosterone levels. METHOD: Of 56 men screened, 24 (42.9%) displayed morning serum total testosterone levels of 350 ng/dl or less (normal range=270-1070). Of these men, 23 entered the study. One responded to an initial 1-week single-blind placebo period, and 22 were subsequently randomly assigned: 12 to 1% testosterone gel, 10 g/day, and 10 to identical-appearing placebo. Each subject continued his existing antidepressant regimen. Ten subjects receiving testosterone and nine receiving placebo completed the 8-week trial. RESULTS: The groups were closely matched on baseline demographic and psychiatric measures. Subjects receiving testosterone gel had significantly greater improvement in scores on the Hamilton Depression Rating Scale than subjects receiving placebo. These changes were noted on both the vegetative and affective subscales of the Hamilton Depression Rating Scale. A significant difference was also found on the Clinical Global Impression severity scale but not the Beck Depression Inventory. One subject assigned to testosterone reported increased difficulty with urination, suggesting an exacerbation of benign prostatic hyperplasia; no other subject reported adverse events apparently attributable to testosterone. CONCLUSIONS: These preliminary findings suggest that testosterone gel may produce antidepressant effects in the large and probably underrecognized population of depressed men with low testosterone levels.

Adult↗

PubMed2005

Androgen conversion in osteoarthritis and rheumatoid arthritis synoviocytes--androstenedione and testosterone inhibit estrogen formation and favor production of more potent 5alpha-reduced androgens.

In synovial cells of patients with osteoarthritis (OA) and rheumatoid arthritis (RA), conversion products of major anti-inflammatory androgens are as yet unknown but may be proinflammatory. Therefore, therapy with androgens in RA could be a problem. This study was carried out in order to compare conversion products of androgens in RA and OA synoviocytes. In 26 OA and 24 RA patients, androgen conversion in synovial cells was investigated using radiolabeled substrates and analysis by thin-layer chromatography and HPLC. Aromatase expression was studied by immunohistochemistry. Dehydroepiandrosterone (DHEA) was converted into androstenediol, androstenedione (ASD), 16alphaOH-DHEA, 7alphaOH-DHEA, testosterone, estrone (E1), estradiol (E2), estriol (E3), and 16alphaOH-testosterone (similar in OA and RA). Surprisingly, levels of E2, E3, and 16alpha-hydroxylated steroids were as high as levels of testosterone. In RA and OA, 5alpha-dihydrotestosterone increased conversion of DHEA into testosterone but not into estrogens. The second androgen, ASD, was converted into 5alpha-dihydro-ASD, testosterone, and negligible amounts of E1, E2, E3, or 16alphaOH-testosterone. 5alpha-dihydro-ASD levels were higher in RA than OA. The third androgen, testosterone, was converted into ASD, 5alpha-dihydro-ASD, 5alpha-dihydrotestosterone, and negligible quantities of E1 and E2. 5alpha-dihydrotestosterone was higher in RA than OA. ASD and testosterone nearly completely blocked aromatization of androgens. In addition, density of aromatase-positive cells and concentration of released E2, E3, and free testosterone from superfused synovial tissue was similar in RA and OA but estrogens were markedly higher than free testosterone. In conclusion, ASD and testosterone might be favorable anti-inflammatory compounds because they decrease aromatization and increase anti-inflammatory 5alpha-reduced androgens. In contrast, DHEA did not block aromatization but yielded high levels of estrogens and proproliferative 16alpha-hydroxylated steroids. Androgens were differentially converted to pro- and anti-inflammatory steroid hormones via diverse pathways.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗

PubMed1983

Intraovarian localization of luteinizing hormone/human chorionic gonadotropin stimulation of testosterone and estradiol synthesis in the pregnant rat.

The objective of this investigation was to determine whether LH acts directly on luteal cells to stimulate testosterone and estradiol synthesis or whether it stimulates follicular and/or interstitial production of androgen and thus provides androgen substrate for luteal cell production of estradiol. Pregnant rats were injected with 1.5 IU human CG (hCG) twice daily sc between days 12 and 14. On day 14, blood was obtained from both the jugular and ovarian vein. Corpora lutea (CL), follicles, and interstitium were isolated and incubated at 37 C for 4 h. Estradiol, testosterone, and progesterone levels were measured in the peripheral circulation, ovarian vein plasma, tissues, and medium. After hCG treatment, no ovulation occurred, rats remained pregnant, and progesterone levels in the serum and in the ovarian vein plasma remained unchanged. In contrast, estradiol and testosterone levels in the ovarian vein increased from 0.7 +/- 0.1 and 0.6 +/- 3.4 ng/ml, respectively, in vehicle-treated rats to 12.5 +/- 3.5 and 4.8 +/- 1.4 ng/ml in hCG-treated animals. In vivo treatment with hCG dramatically increased the in vitro capacity of luteal cells to synthesize de novo both testosterone and estradiol but had no stimulatory effect on progesterone synthesis. Testosterone synthesis by CL increased from 21 +/- 4 to 255 +/- 114 pg/CL whereas estradiol synthesis rose from 30 +/- 7 to 4481 +/- 641 pg/CL. hCG also increased follicular synthesis of both estradiol and testosterone. The interstitium responded to the hCG challenge with a 50-fold increase in testosterone synthesis but with no change in estradiol production. To determine whether hCG rapidly stimulates ovarian production of testosterone, both in vivo and in vitro approaches were used. In the in vitro experiments, CL follicles, or interstitium obtained from day 14 pregnant rats were incubated with or without 3 IU hCG. In the in vivo experiments, day 14 pregnant rats were injected with 3 IU hCG iv and were bled from the jugular and ovarian veins 0.5 and 2 h later. No increase in testosterone and estradiol production was observed after a short challenge with hCG. In summary, this study demonstrates that in the pregnant rat a sustained increase in serum hCG activity stimulates ovarian secretion of both testosterone and estradiol. We conclude that LH can act to induce the synthesis and/or activation of enzyme(s) involved in the conversion of progesterone to androgen in luteal tissue. The results also demonstrate that LH stimulates the synthesis of androgens but not of estradiol in interstitial tissue and confirms the finding that LH stimulates follicular production of both testosterone and estradiol.

Animals↗

PubMed1984

Inhibition of luteinizing hormone (LH)-releasing hormone-induced secretion of LH in rat anterior pituitary cell culture by testosterone without conversion to 5 alpha-dihydrotestosterone.

The role of 5 alpha-reduction of testosterone in the inhibition of LH secretion was investigated in rat anterior pituitary cell cultures. Pituitary cells were preincubated with testosterone or dihydrotestosterone (17 beta-hydroxy-5 alpha-androstan-3-one) for 17 h and then with LHRH for an additional 4 h. Dihydrotestosterone was 6-fold more potent than testosterone in the inhibition of LHRH-induced LH release. Basal LH secretion was not affected by either androgen. The inhibition curves of testosterone and dihydrotestosterone were not shifted by the presence of the 5 alpha-reductase inhibitors 17 beta-N,N-diethylcarbamoyl-4-methyl-4-aza-5 alpha-androstan-3-one (4-MA) and 17 beta-N,N-diisopropylcarbamoyl-4-aza-androstan-3-one (DIPA). Neither 4-MA nor DIPA alone had an effect on either basal or LHRH-induced LH release. When pituitary cells were incubated with [3H]testosterone for 17 h, the radioactivities were found to be unmetabolized testosterone (66.9 +/- 2.4%), dihydrotestosterone (13.3 +/- 0.5%), androstenedione (15.9 +/- 1.3%), 5 alpha-androstane-3,17-dione (2.8 +/- 0.3%), and 3 alpha (beta), 17 beta-androstanediol (less than 1%). In the presence of 4-MA or DIPA, 5 alpha-reduction of testosterone was completely inhibited; androstenedione was the only metabolite. Androstenedione was only 12% as potent as testosterone in the inhibition of LHRH stimulation of LH release, and conversion of [3H]androstenedione to testosterone and dihydrotestosterone did occur in these cells. When [3H]dihydrotestosterone was incubated with pituitary cells, the radioactivities were dihydrotestosterone (64.4 +/- 0%), 5 alpha-androstanedione (19.3 +/- 1%), 3 alpha (beta), 17 beta-androstanediol (7.7 +/- 1.7%), and unknown polar metabolites. 4-MA and DIPA had no effect on the metabolism of dihydrotestosterone. These results indicate that both testosterone and dihydrotestosterone inhibit LHRH-induced LH release and that this activity of testosterone does not depend on its 5 alpha-reduction.

5-alpha Reductase Inhibitors↗

PubMed2004

Blood testosterone threshold for androgen deficiency symptoms.

There are few systematic studies of the relationship between blood testosterone concentrations and the symptoms of overt androgen deficiency. Because most testosterone preparations are relatively short-term, the rapid changes in blood testosterone concentrations they cause make it difficult to define any testosterone threshold. By contrast, subdermal testosterone implants provide stable blood testosterone concentrations over days to weeks, while gradually declining to baseline over 5-7 months. Hence, this provides an opportunity to define a blood testosterone threshold for androgen deficiency symptoms by observing androgen-deficient men as their familiar androgen deficiency symptoms return as testosterone pellets slowly dissolve. Among 52 androgen-deficient men who underwent 260 implantations over 5 yr, at the time of return of androgen deficiency symptoms the blood total and free testosterone concentrations were highly reproducible within individuals (F = 0.8, P = 0.49 and F = 1.4, 0.24, respectively) but varied markedly between men (F = 167 and F = 138, both P < 0.001), indicating that each person had a consistent testosterone threshold for androgen deficiency symptoms that differed markedly between individuals. The most reported symptoms of androgen deficiency were lack of energy, lack of motivation, and reduced libido. The symptomatic threshold was significantly lower in men with secondary hypogonadism compared with men with primary or mixed hypogonadism (total, 9.7 +/- 0.5 nmol/liter vs. 11.7 +/- 0.4 nmol/liter and 10.2 +/- 0.3 nmol/liter, P = 0.006; free, 146 +/- 10 pmol/liter vs. 165 +/- 6 pmol/liter and 211 +/- 18 pmol/liter, P = 0.002) but was not affected by the underlying cause of hypogonadism or by specific symptoms of any severity. Despite a wide range in individual thresholds for androgen deficiency symptoms, the mean blood testosterone threshold corresponded to the lower end of the eugonadal reference range for young men. The implications of these observations for the development of more specific quality-of-life measures, as well as for other potential androgen deficiency states such as chronic diseases and aging, remain to be determined.

Adult↗

PubMed2004

Testosterone administration in women with anorexia nervosa.

Anorexia nervosa (AN) is complicated by severe bone loss, cognitive function deficits, and a high prevalence of major depression. We hypothesized that bone formation would increase and depressive symptoms and spatial cognition would improve with short-term physiological testosterone administration. We randomized 33 women with AN and relative testosterone deficiency to transdermal testosterone (Intrinsa, Procter and Gamble Pharmaceuticals, Cincinnati, OH), 150 mug, 300 mug, or placebo, for 3 wk. At baseline, free testosterone correlated with L4 bone density (r = 0.51, P < 0.001), body mass index (r = 0.39, P = 0.02), depressive symptoms (r = -0.44, P = 0.02), and spatial cognition (r = 0.45, P = 0.04). C-terminal propeptide of type 1 collagen levels were higher during testosterone administration than placebo (P = 0.03). The change in propeptide of type 1 collagen correlated with change in free testosterone over 3 wk (r = 0.50, P = 0.02). Osteocalcin and bone-specific alkaline phosphatase did not change. Depressed patients receiving testosterone improved from severely depressed to moderately depressed; the placebo group was unchanged (P = 0.02). Spatial cognition improved in the testosterone group, compared with placebo (P = 0.0015). Therefore, short-term low-dose testosterone may improve depressive symptoms and spatial cognition in women with AN. Low-dose testosterone may also prevent decreased bone formation in AN, but because testosterone did not affect all markers of bone formation studied, further data are needed.

Administration, Cutaneous↗

PubMed2005

Independent and combined effects of testosterone and growth hormone on extracellular water in hypopituitary men.

CONTEXT: Symptoms of fluid retention in GH-deficient patients during GH replacement are greater in men than in women, suggesting that testosterone may augment or estradiol may attenuate the antinatriuretic actions of GH. The mechanisms underlying the sodium-retaining effects of GH are poorly understood. AIM: The aim of this study was to investigate the effects of GH and testosterone, alone and in combination, on extracellular water (ECW) and the hormonal mechanisms involved. DESIGN: Two separate, open-label, randomized, two-period, crossover studies were performed; the first compared the effects of GH alone with those of GH and testosterone, and the second compared the effects of testosterone alone with those of GH and testosterone. PARTICIPANTS: Twelve hypopituitary men with GH deficiency and hypogonadism were studied. INTERVENTION: During the weeks of intervention, GH (0.5 mg/d) and testosterone enanthate (250 mg) were administered by im injection. OUTCOME MEASURES: The outcome measures were ECW, IGF-I, plasma renin activity (PRA), aldosterone (Aldo), and atrial natriuretic peptide (ANP). RESULTS: GH treatment significantly increased (P < 0.05) both IGF-I and ECW, and these changes were enhanced by cotreatment with testosterone (P = 0.07 for both). PRA, Aldo, and ANP levels did not change. Testosterone treatment alone did not change the IGF-I concentration, whereas cotreatment with GH induced a marked increase. Testosterone alone increased (P < 0.05) ECW, and the effect was augmented (P < 0.01) by cotreatment with GH. Although PRA and ANP did not change, plasma Aldo decreased after single and combined treatments. CONCLUSION: GH and testosterone exerted independent and additive effects on ECW. The mechanisms of fluid retention for both hormones are likely to be exerted on the renal tubules. This is the first direct evidence that testosterone increases ECW.

Adult↗

PubMed2000

Effects of hypogonadism and testosterone administration on depression indices in HIV-infected men.

Hypogonadism is prevalent among human immunodeficiency virus-infected men, in whom significantly reduced quality of life and mood disturbances have been reported. Previous studies have not investigated the relationship between depression score and gonadal function among such patients. We first compared depression scores in hypogonadal (n = 52) and eugonadal (n = 10) patients with acquired immunodeficiency syndrome (AIDS) wasting, matched for weight and disease status, and then investigated the effects of testosterone administration on depression score in a randomized, double-blind, placebo-controlled study among the group of hypogonadal men with AIDS wasting. The primary end point in all comparisons was the Beck Depression Inventory. Hypogonadal patients demonstrated significantly increased scores on the Beck inventory compared with eugonadal-, age-, weight-, and disease status-matched subjects (15.5+/-1.1 vs. 10.6+/-1.4 mean +/- SEM, P = 0.02). Among the combined hypogonadal and eugonadal subjects, a significant inverse correlation was seen between the Beck score and both free (r = 0.41, P<0.01) and total serum testosterone levels (r = -0.43, P<0.001). The relationship between the Beck score and testosterone levels remained highly significant, controlling for weight, viral load, CD4 count, and antidepressant use (P<0.01 for free testosterone, P<0.001 for total testosterone). Furthermore, when subjects were divided into two groups, based on a Beck score greater than 18 or less than or equal to 18, serum total and free testosterone levels were significantly lower in the subjects with a Beck score greater than 18, whereas there were no differences in weight, viral load, CD4 count, or Karnofsky status. End of study data were available in 39 patients who completed the randomized, placebo-controlled study. Beck score decreased significantly only in the subjects receiving testosterone (-5.8+/-1.3, P< 0.001), but not in subjects randomized to placebo (-2.7+/-1.3, P> 0.05). In a regression analysis, the change in Beck score was related significantly to change in weight (P<0.01). These data demonstrate increased depression score in association with hypogonadism in men with AIDS wasting, independent of weight, virologic status, and other disease factors. In such patients, administration of testosterone results in a significant improvement in depression inventory score. This effect may be a direct effect of testosterone or related to positive effects of testosterone on weight and/or other anthropometric indices. Additional studies are needed to assess the effects of testosterone on clinical depression indices in human immunodeficiency virus-infected patients.

Acquired Immunodeficiency Syndrome↗

PubMed2001

Disruption of the joint synchrony of luteinizing hormone, testosterone, and androstenedione secretion in adolescents with polycystic ovarian syndrome.

The present study explores the postulate that the polycystic ovarian syndrome (PCOS) is marked by failure of physiological feedforward and feedback signaling between pituitary LH and ovarian androgens. To this end, we appraised the 3-fold simultaneous overnight release of LH (assayed by high precision immunofluorometry), testosterone (RIA), and androstenedione (RIA) in 12 an- or oligoovulatory adolescents with PCOS (mean +/- SEM age, 16.4 +/- 0.47 yr) and 10 eumenorrheic girls (age, 16.5 +/- 0.45 yr). Gynecological (postmenarchal) ages (years) were also comparable at 4.8 +/- 0.39 (PCOS) and 4.0 +/- 3.6 (control; P = NS). Body mass index and fasting serum insulin and estradiol concentrations were indistinguishable in the two study cohorts. Mean overnight serum concentrations of LH (assayed by both immunofluorometry and Leydig cell bioassay), testosterone, androstenedione, and 17alpha-hydroxyprogesterone were each elevated significantly in patients with PCOS (all P </= 0.027). The bivariate cross-approximate entropy (cross-ApEn) statistic was used as a sensitive barometer of altered within-axis feedback. This scale-invariant metric is designed to quantitate the joint synchrony of putatively linked (neurohormone) time series in a lag-independent pattern-sensitive manner. Here, we applied cross-ApEn to the coupled release of LH and testosterone, LH and androstenedione, and testosterone and androstenedione. Statistical comparisons of the two adolescent study cohorts unveiled consistently elevated cross-ApEn in patients with PCOS, denoting disruption of the pairwise synchrony of LH and testosterone (P = 0.0055), LH and androstenedione (P = 0.0076), and testosterone and androstenedione (P = 0.014) secretion. As an analytically distinct technique to monitor coordinate hormone release, we also applied cross-correlation analysis with variable lag. This appraisal revealed that adolescents with PCOS further exhibit 1) loss of rapid feedforward coupling between LH and testosterone output, 2) erosion of the time-lagged positive linkages between LH and androstenedione secretion, and 3) attenuation of the coordinate relationship between testosterone and androstenedione release. In summary, based on complementary, but independent, statistical tools, the present two-variable analyses unmask vivid deterioration of the joint synchrony of LH-testosterone, LH-androstenedione, and testosterone-androstenedione secretion in adolescents with PCOS. The multiplicity of the bihormonal coupling defects points to impaired feedforward and feedback signaling interfaces among the hypothalamus, pituitary gland, and ovary. Disruption of interandrogen synchrony also identifies pathophysiological dissociation of testosterone and androstenedione cosecretion. Whether presumptive failure of integrative hypothalamo-pituitary-gonadal control emerges prepubertally in girls at risk for PCOS or persists in adults with PCOS is not known.

Adolescent↗

PubMed1990

Testosterone decreases ornithine decarboxylase messenger RNA levels in primary cultures of rat Sertoli cells.

We have previously reported that testosterone decreased ornithine decarboxylase (ODC) activity in primary cultures of rat Sertoli cells. In this report we examined the mechanism of this reduction. In cells pretreated with testosterone (5 x 10(-7) M) for 48 h before the start of the experiment ODC activity was decreased, on the average, 43% at all time points examined. ODC mRNA levels were also decreased an overall 33%. The testosterone-mediated decrease in ODC activity was first seen 8 h after the addition of testosterone to the cells. Testosterone had no significant affect on the levels of actin or transferrin mRNA. The effect of testosterone was androgen specific. Neither ODC activity nor mRNA was affected by the nonandrogenic steroids progesterone or cortisol. These results suggest that testosterone decreases ODC mRNA in Sertoli cells either through an inhibition of transcription or through a decrease in message stability. Testosterone does not appear to affect ODC mRNA translation, since the percent decreases in ODC activity and mRNA in response to testosterone were essentially equivalent. Regulation of Sertoli cell ODC expression by testosterone may reflect one mechanism by which Sertoli cell function is integrated with surrounding cell types. The Sertoli cell, unlike any other cell, secretes putrescine, the product of ODC catalysis of ornithine. We suggest that the modulation of ODC by testosterone and, hence, the amount of putrescine secreted by the Sertoli cell may be significant in the process of spermatogenesis.

Animals↗

PubMed2004

Plasma testosterone levels in Alzheimer and Parkinson diseases.

BACKGROUND: Testosterone deficiency, a treatable condition commonly seen in aging men, has been linked to Parkinson disease (PD) and Alzheimer disease (AD). In normal subjects, low testosterone levels are associated with cognitive and neuropsychiatric symptoms, yet the relationship between testosterone levels and cognitive function in PD and AD remains unclear. OBJECTIVE: To examine the relationship of testosterone levels to age and cognitive function in PD and AD. METHODS: Plasma testosterone levels were determined in men enrolled in a clinical registry of subjects with PD and AD, and neuropsychological testing was performed on subjects who consented. Testosterone levels in men with PD were compared with those in men with AD. In both groups, the relationship between testosterone levels and neuropsychological test scores was analyzed, adjusting for age and education. RESULTS: Linear regression analysis revealed that testosterone levels decreased with age in male PD patients (p < 0.03) and male AD patients (p < 0.07). The rate of decline was similar for the two groups. In PD patients, lower testosterone levels were associated with poorer performance on Trails B Seconds (p < 0.02). CONCLUSIONS: There is a similar age-related decline in plasma testosterone levels in men with either PD or AD. Previously described associations between low testosterone levels and frontal lobe dysfunction in normal aged men, together with these results, suggest that the hormonal deficiency may act as a "second hit" to impair cognitive function in neurodegenerative disease.

Adult↗

PubMed1976

[Sexually differentiated metabolism of testosterone in liver slices of mouse, and its alteration by a mutation in the X-chromosome that results in testicular feminization].

1. Sexual differentiation of the metabolism of testosterone in liver slices of normally developed, sexually mature mice: Sexual differentiation in the mouse, unlike that in the rat, shows a high degree of uniformity: Where the formation of metabolites with the composition C19O2 is markedly greater in one sex, then this is invariably the male. The formation of C19O3 steroids and 4-androstene-3,17-dione, and the turnover of testosterone show no marked sexual differences, although the sum of the C19O2-type delta4-hydrogenation products of testosterone is significantly greater in the male. This apparent discrepancy is explained by the fact that the sum of the delta4-hydrogenation products represents no more than 10% of testosterone turnover. Thus, sexual differences in the formation of individual delta4-hydrogenation products are not apparent from a consideration of the overall turnover of testosterone. 2. Sexual differentiation of testosterone metabolism studied in genetically male litter mates, carrying the X-chromosome-bound mutation and showing testicular feminization (Tfm): The Tfm mutation (genotype XTfm Blo/Y; Blo = coat colour gene Blotchy) results in a feminization of testosterone metabolism. Where the level of testosterone metabolites is significantly higher in the normal male than in the normal female, the Tfm mutation shows a level that is significantly lower than in the normal male, and which, in most cases, is the same as that in the normal female. The concentration of three metabolites (3alpha- and 3beta-hydroxy-5beta-androstan-17-one, and 5beta-androstane-3,17-dione), which do not show sex-based differences, were significantly increased in the Tfm mutation. The Tfm mutation therefore effects the formation of all ring A hydrogenation products of type C19O2 (with the single exception of 5bets-androstane-3alpha,17beta-diol). It does more than simply equalize sexual differences by feminization. It has no effect on the hydroxylation of testosterone, or on its 17beta-dehydrogenation to 4-androstene-3,17-dione. The consequences of the Tfm mutation for the liver are irreversible: The formation of 5alpha-androstane-3,17-dione, which is a representative parameter for the sexual differentiation of testosterone metabolism, is not influenced by the injection of testosterone (15 mg i.p. 6 days before investigation).

Androgen-Insensitivity Syndrome↗

PubMed1990

Pharmacokinetics and pharmacodynamics of testosterone enanthate and dihydrotestosterone enanthate in non-human primates.

The pharmacokinetics and pharmacodynamics of testosterone enanthate and dihydrotestosterone-enanthate were compared in orchidectomized cynomolgus monkeys (Macaca fascicularis) and in intact GnRH agonist-suppressed rhesus monkeys (Macaca mulatta). Following a single im injection of 32.8 mg testosterone enanthate or 32.7 mg dihydrotestosterone-enanthate, i.e. 23.6 mg of pure steroid, in the orchidectomized cynomolgus monkeys, serum testosterone and dihydrotestosterone levels rose to 400 and 800% of baseline, respectively, within 24 h. Androgen levels remained in that range for 3-5 days followed by a continuous decline until baseline values were attained after 4-5 weeks. The areas under the testosterone- and dihydrotestosterone-curves did not differ significantly 2290 +/- 340 (dihydrotestosterone-enanthate) vs 2920 +/- 485 (testosterone-enanthate) suggesting that similar amounts of steroid had been released from the respective ester preparation. Mean half-life estimates of the terminal elimination phase were 4 and 7 days for testosterone-enanthate and dihydrotestosterone-enanthate, respectively. In a second experiment rhesus monkeys received, at 4-weekly intervals, sc implantation of a biodegradable polylactic:polyglycolide rod loaded with the GnRH agonist buserelin. The last injection was given during week 20. GnRH agonist treatment suppressed serum bioactive LH, testosterone and dihydrotestosterone levels, testicular size, sperm production, and seminal carnitine content. The ejaculatory response to electrostimulation and the masturbatory behaviour were abolished. Testosterone or dihydrotestosterone injections at the same doses as above were given in week 10, 14, 17 and 20 of GnRH agonist treatment. Serum testosterone and dihydrotestosterone levels were stimulated 9- and 4-fold, respectively. Mean half-life estimates for testosterone-enanthate and dihydrotestosterone were 5 and 7 days, respectively. Both ester preparations completely restored the ejaculatory response, ejaculate size, masturbatory behaviour, and seminal carnitine levels. In conclusion, androgen substitution with dihydrotestosterone-enanthate, in equivalent doses, is as effective as testosterone-enanthate in restoring reproductive functions in hypogonadal monkeys.

Androgens↗

PubMed1992

Testosterone-induced suppression of self-healing Plasmodium chabaudi malaria: an effect not mediated by androgen receptors?

This study investigates whether androgen receptors (AR) mediate the suppressive effect of testosterone on self-healing Plasmodium chabaudi malaria. Our data show the following. (1) Female and castrated male mice of the inbred strain C57BL/10 self-heal and survive infections when challenged with 10(6) P. chabaudi-parasitized erythrocytes. However, self-healing is prevented when circulating testosterone levels are high as in intact males or in females and castrated males pretreated with 0.9 mg testosterone twice a week for 3 weeks. (2) The lethal outcome of P. chabaudi in intact males is not affected by different doses of AR blockers such as cyproterone acetate, cyproterone, flutamide and nilutamide when applied at least 3 weeks before infection and during infection. Also, these AR blockers do not impair the testosterone-induced lethal outcome of infections in testosterone-treated females and castrated males. (3) Tfm mice possessing mutant non-functional ARs and normal 'male' testosterone levels succumb to infection with P. chabaudi. However, the corresponding wild-type mice possessing functioning ARs are able to resist P. chabaudi infections at low circulating testosterone levels. (4) In contrast to testosterone, testosterone metabolites such as 5 alpha-dihydrotestosterone, 5 beta-dihydrotestosterone, androsterone and 1-dehydrotestosterone cannot suppress self-healing in castrated male B10 mice. Our data suggest that testosterone suppresses the development of protective immunity against P. chabaudi malaria, and that this immunosuppressive effect of testosterone is not primarily mediated by the classical AR response.

Animals↗

PubMed1999

Seasonal changes in the negative feedback regulation of the secretion of the gonadotrophins by testosterone and inhibin in rams.

Three experiments were conducted with castrated Romney Marsh rams (wethers) to investigate the ability of testosterone and inhibin to suppress the secretion of LH and FSH during the breeding and the non-breeding seasons. In Experiment 1, wethers (n=5/group) were treated every 12 h for 7 days with oil or 16 mg testosterone propionate (i.m.) and were then given two i.v. injections either of vehicle or of 0.64 microg/kg human recombinant inhibin A (hr-inhibin) 6 h apart. Blood samples were collected for 4 h before inhibin or vehicle treatment and for 6 h afterwards for the assay of LH and FSH. In Experiments 2 and 3 wethers underwent hypothalamo-pituitary disconnection (HPD) and were given 125 ng GnRH i.v. every 2 h. In Experiment 2, HPD wethers (n=3/group) were injected (i.m.) every 12 h with oil or testosterone and blood samples were collected over 9 h before treatment and 7 days after treatment. In Experiment 3, HPD (n=5/group) wethers were treated with vehicle or hr-inhibin, as in Experiment 1, after treatment with oil, or 4, 8 or 16 mg testosterone twice daily for 7 days. Blood samples were collected over 4 h before treatment with vehicle or hr-inhibin and for 6 h afterwards. Treatment of wethers with testosterone (Experiment 1) resulted in a significant decrease in the plasma concentrations of LH and number of LH pulses per hour but the magnitude of these reductions did not differ between seasons. Testosterone treatment had no effect on LH secretion in GnRH-pulsed HPD wethers in either season and treatment with hr-inhibin did not affect LH secretion in wethers or HPD wethers in any instance. Plasma concentrations of FSH were significantly (P<0.05) reduced following treatment with testosterone alone during the breeding season but not during the non-breeding season. FSH levels were reduced to a greater extent by treatment with hr-inhibin but this effect was not influenced by season. During the non-breeding season, the effect of hr-inhibin to suppress FSH secretion was enhanced in the presence of testosterone. These experiments demonstrate that the negative feedback actions of testosterone on the secretion of LH in this breed of rams occurs at the hypothalamic level and is not influenced by season. In contrast, both testosterone and inhibin act on the pituitary gland to suppress the secretion of FSH and these responses are affected by season. Testosterone and inhibin synergize at the pituitary to regulate FSH secretion during the non-breeding season but not during the breeding season.

Analysis of Variance↗

PubMed2004

Testosterone-dependent variations in plasma and intrapituitary corticosteroid binding globulin and stress hypothalamic-pituitary-adrenal activity in the male rat.

Hypothalamic-pituitary-adrenal (HPA) activity is governed by glucocorticoid negative feedback and the magnitude of this signal is determined, in part, by variations in plasma corticosteroid-binding globulin (CBG) capacity. Here, in gonadectomized male rats we examine the extent to which different testosterone replacement levels impact on CBG and HPA function. Compared with gonadectomized rats with low testosterone replacement ( approximately 2 ng/ml), plasma adrenocorticotropin and beta-endorphin/beta-lipotropin responses to restraint stress were reduced in gonadectomized rats with high testosterone replacement ( approximately 5 ng/ml). Plasma CBG levels also varied negatively as a function of testosterone concentration. Moreover, glucocorticoid receptor binding in the liver was elevated by higher testosterone replacement, suggesting that testosterone acts to enhance glucocorticoid suppression of CBG synthesis. Since pituitary intracellular CBG (or transcortin) is derived from plasma, this prompted us to examine whether transcortin binding was similarly responsive to different testosterone replacement levels. Transcortin binding was lower in gonadectomized rats with high plasma testosterone replacement ( approximately 7 ng/ml) than in gonadectomized rats with low testosterone replacement ( approximately 2 ng/ml). This testosterone-dependent decrease in pituitary transcortin was associated, in vitro, with an enhanced nuclear uptake of corticosterone. These findings indicate that the inhibitory effects of testosterone on corticotrope responses to stress may be linked to decrements in plasma and intrapituitary CBG. This could permit greater access of corticosterone to its receptors and enhance glucocorticoid feedback regulation of ACTH release and/or proopiomelanocortin processing.

Adrenocorticotropic Hormone↗