Search results for "TESTOSTERONE"
showing 10 items of 420 documents
Characterization of cryopreserved rat liver parenchymal cells by metabolism of diagnostic substrates and activities of related enzymes
1992
The metabolism of testosterone and benzo(a)pyrene (BaP) which is mediated by diverse enzymes was determined in cryopreserved rat liver parenchymal cells and compared with that found in freshly isolated cells. In addition, the activities of single xenobiotic-metabolizing enzymes were measured by using specific substrates. The cytochrome P450 (P450)-mediated total metabolic conversion of testosterone was reduced to 55% in cryopreserved cells. The metabolite profile, i.e. the formation of single metabolites compared with total metabolic conversion, was however unchanged when compared with freshly isolated cells. A concomitant reduction in the activities of the involved P450 isoenzymes can ther…
Inducing properties of rifampicin and rifabutin for selected enzyme activities of the cytochrome P-450 and UDP-glucuronosyltransferase superfamilies …
1996
Important species differences have been reported concerning the induction properties of rifampicin towards enzymes of the P-450 superfamily. Mice, rabbits and humans are far more responsive than rats and guinea pigs. In the present study a strong induction of cytochrome P-450 3A-dependent enzyme activities was observed in female rat liver microsomes after high dose treatment (> or = 250 mg/kg/day for 9 days) with rifampicin, resulting in an up to 30-fold enhanced hydroxylation rate of testosterone in the 2 beta-, 6 beta- and 15 beta-position in vitro. Other cytochrome P-450 isozyme-selective reactions were not, or only marginally, affected. A steep increase in cytochrome P-450 3A activity o…
Differential influence of peripheral and systemic sex steroids on skeletal muscle quality in pre- and postmenopausal women
2011
Aging is associated with gradual decline of skeletal muscle strength and mass often leading to diminished muscle quality. This phenomenon is known as sarcopenia and affects about 30% of the over 60-year-old population. Androgens act as anabolic agents regulating muscle mass and improving muscle performance. The role of female sex steroids as well as the ability of skeletal muscle tissue to locally produce sex steroids has been less extensively studied. We show that despite the extensive systemic deficit of sex steroid hormones in postmenopausal compared to premenopausal women, the hormone content of skeletal muscle does not follow the same trend. In contrast to the systemic levels, muscle t…
Nandrolone decanoate interferes on testosterone biosynthesis and alters blood-testis barrier.
2018
Nandrolone decanoate (ND) is a synthetic testosterone analogue considered one of the most commonly abused anabolic androgenic steroids by adolescents and athletes. ND is alleged to promote an increase in muscle mass and improves both physical appearance and sporting performance, but ND abuse is often associated with serious adverse effects, interfering with the endocrine system and the reproductive system. In a previous study, we demonstrated that ND treatment of Leydig cells interferes with the biosynthesis of testosterone in a dose increase-dependent fashion (1). As a consequence of the results obtained in vitro, in this study an animal model was utilized to better understand the side eff…
Nocturnal hormone profiles in patients with schizophrenia treated with olanzapine.
2005
Summary Nocturnal hormone profiles were measured in patients with schizophrenia with predominantly negative symptoms both under drug-free baseline conditions and after subchronic administration of the atypical antipsychotic olanzapine, with the aim of characterizing its pharmacological properties on the neuroendocrine level. The following hormones were studied in the sleep laboratory under polysomnographic control: adrenocorticotrophic hormone, cortisol, growth hormone (GH), prolactin, testosterone, and melatonin. Blood samples were taken at regular time intervals over the night, and serum concentrations of the hormones were determined. Ten patients completed the study, two of them were exc…
Endocrine and Clinical Evaluation of 107 Patients With Advanced Prostatic Carcinoma Under Long-Term Pernasal Buserelin or Intramuscular Decapeptyl De…
1988
Three major assumptions emerged from these clinical and endocrine long-term studies. First, buserelin, given pernasally in the conventional doses, and Decapeptyl microcapsules administered intramuscularly in 5-week intervals are equally effective in terms of their long-term castration effect in previously untreated patients with prostatic carcinoma. However, Decapeptyl causes complete LH and subsequent testosterone down-regulation 1 week earlier than buserelin. Furthermore, this treatment is more convenient, and the compliance is better. Both LHRH analogues are equally well tolerated. Second, in groups of prostate cancer patients with far advanced disease treated with palliative intention, …
Inflammation and prostate cancer
2008
Prostate cancer remains a major health concern for the male population throughout the Western world. It is today widely accepted that inflammation has a role in many human cancers. In fact, inflammation is thought to incite carcinogenesis by causing cell and genome damage, promoting cellular turnover and creating a tissue microenvironment that can enhance cell replication, angiogenesis and tissue repair. Accordingly, there is a body of literature suggesting a link between chronic inflammation and prostate cancer, in which prostate inflammation may contribute to the promotion of prostate cancer development. On the other hand, high levels of endogenous gonadal steroids are considered as risk…
Concerted actions of insulin-like growth factor 1, testosterone, and estradiol on peripubertal bone growth: a 7-year longitudinal study.
2011
A better understanding of how bone growth is regulated during peripuberty is important for optimizing the attainment of peak bone mass and for the prevention of osteoporosis in later life. In this report we used hierarchical models to evaluate the associations of insulin-like growth factor 1 (IGF-1), estradiol (E(2) ), and testosterone (T) with peripubertal bone growth in a 7-year longitudinal study. Two-hundred and fifty-eight healthy girls were assessed at baseline (mean age 11.2 years) and at 1, 2, 3.5, and 7 years. Serum concentrations of IGF-1, E(2) , and T were determined. Musculoskeletal properties in the left lower leg were measured using peripheral quantitative computed tomography …
Effects of brofaremine (CGP 11 305A), a short-acting, reversible, and selective inhibitor of MAO-A on sleep, nocturnal penile tumescence and nocturna…
1987
The effects of brofaremine (CGP 11 305A), a short-acting, reversible and selective inhibitor of MAO-A, on sleep, nocturnal penile tumescence (NPT) and hormonal secretion during the night were studied during a long-term trial. Three healthy males underwent sleep-EEG and NPT recordings during consecutive nights (1) under placebo, (2) under stepwise increasing dosages of brofaremine and (3) under placebo after withdrawal. Hormone profiles were sampled during selected nights to analyze the plasma concentration of cortisol, HGH, prolactin, testosterone, LH and FSH. REM sleep was suppressed markedly under 150 mg brofaremine, while stages 1 and 2 increased. In comparison to the effect of irreversi…
Rewarding Properties of Testosterone in Intact Male Mice
2000
The present study examined the rewarding properties of 4-androsten-17β-ol-3-one testosterone in intact male mice using the conditioned place preference (CPP) technique. In Experiment 1, the pharmacokinetics of 0.8 and 1.2 mg/kg of testosterone were studied to determine the most appropriate temporal interval to test behavior. Additionally, the locomotor activity was recorded to control a possible interfering effect on CPP. The maximum testosterone concentration was registered at 45 min of administration, and no effects on activity were found. In Experiment 2, three groups of male OF-1 mice received four pairings of the least-preferred compartment with testosterone (0.8, 1, or 1.2 mg/kg, SC) …