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Ann S. Clark - One of the best experts on this subject based on the ideXlab platform.

  • Chronic administration of anabolic steroids disrupts pubertal onset and estrous cyclicity in rats.
    Biology of reproduction, 2003
    Co-Authors: Ann S. Clark, Megan C. Kelton, Andrew C. Whitney
    Abstract:

    Use of anabolic-androgenic steroids (AASs) is becoming increasingly popular among adolescent girls, yet the effects of AASs on female physiology and development are not well understood. The present study compared the effects of chronic exposure to three individual AASs, stanozolol (0.05‐5 mg/kg), 17a-methyltestosterone (0.5‐5 mg/kg), and Methandrostenolone (0.5‐5 mg/kg) on the onset of puberty and estrous cyclicity in the rat. Female rats received daily injections of AASs for 30 days (Postnatal Day [PN] 21‐51). Rats receiving the highest dose of each of the AASs (5 mg/kg) displayed vaginal opening at a younger age than rats receiving the oil vehicle. The day of first vaginal estrus was delayed in rats receiving stanozolol (5 mg/ kg) or 17a-methyltestosterone (0.5‐5 mg/kg) but not in rats receiving Methandrostenolone. At the highest dose (5 mg/kg), each of the AASs reduced the incidence of regular estrous cyclicity during the treatment period. Concurrent administration (on PN21‐51) of the androgen receptor antagonist, flutamide (10 mg/kg, twice daily), reversed the effects of 17a-methyltestosterone (5 mg/kg) on vaginal opening. Flutamide administration also eliminated the effects of stanozolol (5 mg/kg) and 17amethyltestosterone (5 mg/kg) on the day of first vaginal estrus. In contrast, rats receiving flutamide and Methandrostenolone (5 mg/kg) exhibited first vaginal estrus earlier than controls. The present results indicate that chronic exposure to AASs during development has deleterious effects on the female neuroendocrine axis and that these effects appear be mediated via multiple mechanisms. androgen receptor, mechanisms of hormone action, puberty, steroid-hormones, vagina,

  • The Effects of 17α-Methyltestosterone, Methandrostenolone, and Nandrolone Decanoate on the Rat Estrous Cycle
    Physiology & behavior, 1997
    Co-Authors: Meg E. Blasberg, Christopher J. Langan, Ann S. Clark
    Abstract:

    Abstract Blasberg, M. E., C. J. Langan and A. S. Clark. The effects of 17 α -methyltestosterone, Methandrostenolone, and nandrolone decanoate on the rat estrous cycle. Physiol Behav 61(2) 265–272, 1997.—In a series of four separate experiments, the effects of anabolic-androgenic steroid (AAS) compounds on the estrous cycle of adult Long-Evans rats were examined. Sexual receptivity, vaginal cytology, and body weight were monitored throughout a 2-week baseline, AAS treatment, and recovery periods. In Experiments 1–3, subjects were administered 17 α -methyltestosterone, Methandrostenolone, or nandrolone decanoate at doses selected to mimic the human abuse levels of each compound. In these studies, the highest doses of 17 α -methyltestosterone (7.5 mg/kg) and nandrolone decanoate (5.6 mg/kg) disrupted behavioral and vaginal cyclicity, whereas the highest dose of Methandrostenolone (3.75 mg/kg) appeared to have slightly less robust effects. To compare effects on estrous cyclicity across AAS compounds, subjects in Experiment 4 received a single high dose (7.5 mg/kg) of each compound for 2 weeks. At this dose, all AAS compounds interfered with vaginal cyclicity, although effects on behavioral cyclicity and uterine weight were not uniform. Across all 4 experiments, AAS effects on body weight were minimal. The short-term administration of AAS compounds at levels commonly used by humans disrupts female neuroendocrine function in a dose-dependent manner.

  • Anabolic-Androgenic Steroid Effects on Sexual Receptivity in Ovariectomized Rats
    Hormones and behavior, 1997
    Co-Authors: Meg E. Blasberg, Ann S. Clark
    Abstract:

    Abstract Anabolic-androgenic steroid (AAS) compounds are synthetic androgens taken by athletes to increase physical strength and endurance. Recent studies in our laboratory have demonstrated that AAS administration disrupts the estrous cycle of Long–Evans rats. The present experiments examined the effects of six commonly abused AAS compounds on sexual receptivity in ovariectomized rats. Adult female Long–Evans rats received estradiol benzoate (EB; 2.0 μg/day sc) for 6 consecutive days followed by 15 days of EB concurrent with daily sc injections of 7.5 mg/kg of one of the following AAS compounds: 17α-methyltestosterone, Methandrostenolone, nandrolone decanoate, stanozolol, oxymetholone, testosterone cypionate, or the oil vehicle. On Day 15, all female rats received progesterone (1.0 mg/rat) 4 h before testing. Tests for sexual receptivity were conducted on Days 3, 6, 14, and 15 of AAS treatment. Although the time course of AAS effects on sexual receptivity varied, some overall effects were clear. For example, 17α-methyltestosterone, Methandrostenolone, nandrolone decanoate, and stanozolol interfered with the display of sexual receptivity on Day 14, whereas oxymetholone and testosterone cypionate had no effect. Rats in all groups displayed high levels of sexual receptivity after receiving progesterone on Day 15. Our results show that AAS compounds vary in their degree of inhibition of female sexual behavior in ovariectomized rats.

  • Comparison of the effects of 17 alpha-methyltestosterone, Methandrostenolone, and nandrolone decanoate on the sexual behavior of castrated male rats.
    Behavioral neuroscience, 1996
    Co-Authors: Ann S. Clark, Alison S. Fast
    Abstract:

    In a series of 3 experiments, adult male Long-Evans rats were castrated and treated with 1 of 3 different anabolic-androgenic steroid (AAS) compounds (17 alpha-methyltestosterone, Methandrostenolone, or nandrolone decanoate) for 6 weeks. In each experiment, subjects received daily injections of a high, medium, or low dose of AAS or the oil vehicle. The AAS effects on body weight in gonadectomized male rats were modest, and no effects on locomotor activity were observed. The AAS compounds administered at doses comparable with human abuse levels were not equipotent in maintaining male sexual behavior patterns (nandrolone decanoate > Methandrostenolone > 17 alpha-methyltestosterone). In addition, the behavioral actions of AAS compounds did not parallel stimulation of sexual accessory glands. The authors reported that this study is the first to quantify the dose-response characteristics of individual AAS compounds with regard to these behavioral and endocrine measures.

  • Anabolic-androgenic steroid and adrenal steroid effects on hippocampal plasticity.
    Brain research, 1995
    Co-Authors: Ann S. Clark, Marcie C. Mitre, Truls Brinck-johnsen
    Abstract:

    Abstract Anabolic-androgenic steroids (AAS) are synthetic androgen-like compounds which are taken in high doses by athletes with the intention of enhancing muscular appearance, strength and/or athletic performance. Recent research indicates that high doses of AAS may influence the functions of the hippocampus. This evidence led us to explore the extent to which chronic AAS treatments influence spatial memory and the integrity of the hippocampus in the rat. Gonadally intact adult male Long-Evans rats were treated with either the AAS Methandrostenolone, a steroid ‘cocktail’ (TNB; testosterone cypionate, boldenone undecylenate and nandrolone decanoate), or the oil vehicle daily for 12 weeks. A group of male rats treated with corticosterone (CORT; 10 mg/day) was also examined. Spatial memory was assessed in the Morris water maze after 10 weeks of hormone treatment. At 12 weeks, the animals were sacrificed, blood collected and the brain sectioned to assess hippocampal cell number. There were no impairments in the acquisition or retention of the Morris water maze in any hormone treatment group. Although serum testosterone levels were elevated in rats treated with TNB relative to the oil controls, neither the TNB or Methandrostenolone treatments produced changes in hippocampal cell number. Serum CORT levels were significantly elevated in the rats treated with CORT and cell loss (15%) was detectable in the CA3b subfield in this group of animals. These results indicate that the AAS administered in the present study were not detrimental to hippocampal spatial memory or cell survival and that, while chronic CORT may produce mild hippocampal cell loss, this loss is not accompanied by deficits on a spatial memory task.

M L Marina - One of the best experts on this subject based on the ideXlab platform.

  • separation and online preconcentration by multistep stacking with large volume injection of anabolic steroids by capillary electrokinetic chromatography using charged cyclodextrins and uv absorption detection
    IEEE Journal of Solid-state Circuits, 2005
    Co-Authors: Pawel L Urban, Carmen Garciaruiz, M A Garcia, M L Marina
    Abstract:

    The separation of three common anabolic steroids (methyltestosterone, Methandrostenolone and testosterone) was performed for the first time by capillary EKC. Different charged CD derivatives and bile salts were tested as dispersed phases in order to achieve the separation. A mixture of 10 mmol/L succinylated-beta-CD with 1 mmol/L beta-CD in a 50 mmol/L borate buffer (pH 9) enabled the separation of the three anabolic steroids in less than 9 min. Concentration LODs, obtained for these compounds with low absorption of UV light, were approximately 5 x 10(-5) mol/L. The use of online reverse migrating sample stacking with large-volume injection (the effective length of the capillary) enabled to improve the detection sensitivity. Sensitivity enhancement factors (SEFs) ranging from 95 (for testosterone) to 149 (for methyltestosterone) were achieved by single stacking preconcentration. Then, the possibilities of multistep stacking to improve the sensitivity for these analytes were investigated. SEFs obtained by double stacking preconcentration ranged from 138 to 185, enabling concentration LODs of 2.79 x 10(-7) mol/L (for methyltestosterone), 3.47 x 10(-7) mol/L (for testosterone) and 3.56 x 10(-7) mol/L (for Methandrostenolone). Although online triple stacking preconcentration was achieved, its repeatability was very poor and SEFs for the studied analytes were not calculated.

A. V. Druzhinina - One of the best experts on this subject based on the ideXlab platform.

  • Conversion of 17α-methyltestosterone to Methandrostenolone by the bacterium pimelobacter simplex VKPM Ac-1632 with the presence of cyclodextrins
    Applied Biochemistry and Microbiology, 2008
    Co-Authors: A. V. Druzhinina, V. A. Andryushina, T. S. Stytsenko, N. E. Voishvillo
    Abstract:

    Conditions of conversion of 17α-methyltestosterone to Methandrostenolone with the presence of modified β-cyclodextrins (methylcyclodextrin, hydroxypropylcyclodextrin, and hydroxyethylcyclodextrin) in the steroid: cyclodextrin ratio 1: 1 were studied. The experimental solutions of modified β-cyclodextrins were prepared in deionized water with 5–7% methanol. Under the conditions found to be optimal, 1,2–dehydrogenation of 17α-methyltestosterone was carried out with 2–4 g/l Pimelobacter simplex VKPM Ac-1632 biomass. At the substrate concentration 5–20 g/l, the reaction occurred for 1–15 h without any by-products. The maximum rate of Methandrostenolone accumulation was observed with hydroxypropylcyclodextrin. The methylcyclodextrin solution can be reused for complete 17α-methyltestosterone conversion at the concentration 5 g/l.

  • Conversion of 17α-methyltestosterone to Methandrostenolone by the bacterium pimelobacter simplex VKPM Ac-1632 with the presence of cyclodextrins
    Applied Biochemistry and Microbiology, 2008
    Co-Authors: A. V. Druzhinina, V. A. Andryushina, T. S. Stytsenko, N. E. Voishvillo
    Abstract:

    Conditions of conversion of 17 alpha-methyltestosterone to Methandrostenolone with the presence of modified beta-cyclodextrins (methylcyclodextrin, hydroxypropylcyclodextrin, and hydroxyethylcyclodextrin) in the steroid:cyclodextrin ratio 1:1 were studied. The experimental solutions of modified beta-cyclodextrins were prepared in deionized water with 5-7% methanol. Under the conditions found to be optimal, 1,2-dehydrogenation of 17 alpha-methyltestosterone was carried out with 2-4 g/l Pimelobacter simplex VKPM Ac-1632 biomass. At the substrate concentration 5-20 g/l, the reaction occurred for 1-15 h without any by-products. The maximum rate of Methandrostenolone accumulation was observed with hydroxypropylcyclodextrin. The methylcyclodextrin solution can be reused for complete 17 alpha-methyltestosterone conversion at the concentration 5 g/l.

  • Conversion of 17 alpha-methyltestosterone to Methandrostenolone by the bacterium Pimelobacter simplex VKPM Ac-1632 with the presence of cyclodextrins
    Prikladnaia biokhimiia i mikrobiologiia, 2008
    Co-Authors: A. V. Druzhinina, T. S. Stytsenko, V A Andriushina, N E Voĭshvillo
    Abstract:

    Conditions of conversion of 17 alpha-methyltestosterone to Methandrostenolone with the presence of modified beta-cyclodextrins (methylcyclodextrin, hydroxypropylcyclodextrin, and hydroxyethylcyclodextrin) in the steroid:cyclodextrin ratio 1:1 were studied. The experimental solutions of modified beta-cyclodextrins were prepared in deionized water with 5-7% methanol. Under the conditions found to be optimal, 1,2-dehydrogenation of 17 alpha-methyltestosterone was carried out with 2-4 g/l Pimelobacter simplex VKPM Ac-1632 biomass. At the substrate concentration 5-20 g/l, the reaction occurred for 1-15 h without any by-products. The maximum rate of Methandrostenolone accumulation was observed with hydroxypropylcyclodextrin. The methylcyclodextrin solution can be reused for complete 17 alpha-methyltestosterone conversion at the concentration 5 g/l.

P R Hull - One of the best experts on this subject based on the ideXlab platform.

P R Lane - One of the best experts on this subject based on the ideXlab platform.