Alterations in diaphragm contractility after nandrolone administration: an analysis of potential mechanisms. (1/470)

The aim of this study was to evaluate the potential mechanisms underlying the improved contractility of the diaphragm (Dia) in adult intact male hamsters after nandrolone (Nan) administration, given subcutaneously over 4 wk via a controlled-release capsule (initial dose: 4.5 mg. kg-1. day-1; with weight gain, final dose: 2.7 mg. kg-1. day-1). Control (Ctl) animals received blank capsules. Isometric contractile properties of the Dia were determined in vitro after 4 wk. The maximum velocity of unloaded shortening (Vo) was determined in vitro by means of the slack test. Dia fibers were classified histochemically on the basis of myofibrillar ATPase staining and fiber cross-sectional area (CSA), and the relative interstitial space was quantitated. Ca2+-activated myosin ATPase activity was determined by quantitative histochemistry in individual diaphragm fibers. Myosin heavy chain (MHC) isoforms were identified electrophoretically, and their proportions were determined by using scanning densitometry. Peak twitch and tetanic forces, as well as Vo, were significantly greater in Nan animals compared with Ctl. The proportion of type IIa Dia fibers was significantly increased in Nan animals. Nan increased the CSA of all fiber types (26-47%), whereas the relative interstitial space decreased. The relative contribution of fiber types to total costal Dia area was preserved between the groups. Proportions of MHC isoforms were similar between the groups. There was a tendency for increased expression of MHC2B with Nan. Ca2+-activated myosin ATPase activity was increased 35-39% in all fiber types in Nan animals. We conclude that, after Nan administration, the increase in Dia specific force results from the relatively greater Dia CSA occupied by hypertrophied muscle fibers, whereas the increased ATPase activity promotes a higher rate of cross-bridge turnover and thus increased Vo. We speculate that Nan in supraphysiological doses have the potential to offset or ameliorate conditions associated with enhanced proteolysis and disordered protein turnover.  (+info)

Effects of implants on daily gains of steers wintered on dormant native tallgrass prairie, subsequent performance, and carcass characteristics. (2/470)

Fall-weaned crossbred steer calves (n = 300; 184 +/- 2.9 kg) received either no implant (Control) or were implanted with Synovex-C (SC = 10 mg estradiol benzoate + 100 mg progesterone), Synovex-S (SS = 20 mg estradiol benzoate + 200 mg progesterone), or Revalor-G (RG = 8 mg estradiol-17beta + 40 mg trenbolone acetate) to determine the effects of implants on weight gain during winter grazing on dormant tallgrass prairie, subsequent grazing and finishing performance, and carcass characteristics. Steers grazed two dormant tallgrass prairie pastures from October 16, 1996, until March 29, 1997 (164 d), and received 1.36 kg/d of a 25% CP supplement that supplied 100 mg of monensin/steer. Following winter grazing, all steers were implanted with Ralgro (36 mg zeranol) and grazed a common tallgrass prairie pasture until July 17 (110 d). After summer grazing, all steers were implanted with Revalor-S (24 mg estradiol-17beta + 120 mg trenbolone acetate), and winter implant treatment groups were equally allotted to four feedlot pens. Steers were harvested November 17, 1997, after a 123-d finishing period. Daily gains during the winter grazing phase averaged .28, .32, .32, or .35 kg/d, respectively, for Control, SC, SS, or RG steers and were greater (P < .01) for implanted steers than for Controls. Summer daily gains were similar (1.05 +/- .016 kg/d; P > or = .61) for all treatment groups. Feedlot daily gains were also similar (1.67 +/- .034 kg/d; P > or = .21), with implanted steers weighing 14 kg more than Control steers (P = .05) at harvest, despite similar management during summer grazing and feedlot phases. Control steers tended (P = .06) to have lower yield grades. There were no differences (P = .99) in marbling between implanted and nonimplanted steers. Steers implanted during the wintering phase had increased skeletal and overall (P < .01) carcass maturities compared with nonimplanted steers, which resulted in more "B" and "C" maturity carcasses. Because carcass maturity score affects quality grade, the increased maturities of implanted steers resulted in a $9.04 decrease in carcass value/100 kg (P < .01) compared with Controls. The results of this study indicate that growth-promoting implants are efficacious for cattle wintered on dormant native range despite low daily gains. This increased weight is maintained through the summer grazing and feedlot phases; however, the benefit of the increased weight may be offset by decreased carcass quality grade and value due to increased carcass maturity.  (+info)

Increased dopaminergic and 5-hydroxytryptaminergic activities in male rat brain following long-term treatment with anabolic androgenic steroids. (3/470)

1. The effects of treating groups of rats with four different anabolic androgenic steroids (AAS) (testosterone, nandrolone, methandrostenolone, and oxymetholone) on 5-hydroxytryptamine (5-HT) and dopamine (DA) neurones in different brain regions were examined. The AAS was injected six times with 1 week's interval and the rats were sacrificed 2 days after the final injection. 5-HT and its metabolite 5-hydroxyindoleacetic acid (5-HIAA), DA and its metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) were measured. The effect on DA and 5-HT synthesis rate was analysed as the accumulation of 3,4-dihydroxyphenyl-alanine (DOPA) and 5-hydroxytryptophan (5-HTP), respectively, after inhibition of the amino acid decarboxylase with NSD-1015 (3-hydroxy-benzylhydrazine dihydrochloride). Additionally, the monoamine oxidase (MAO) activity was analysed in the hypothalamus. 2. The DOPAC + HVA/DA ratio was increased in the striatum in all treatment groups. However, the synthesis rate of DA was significantly increased only in the methandrostenolone treated group. 3. The 5-HIAA/5-HT ratio was increased in all treatment groups in the hippocampus, in the frontal cortex in the methandrostenolone-treated animals and in the hypothalamus in the testosterone- and oxymetholone-treated rats, while the 5-HT synthesis rate was not affected by the AAS-treatments. 4. The MAO-A activity was increased in the oxymetholone-treated rats while the other treatment groups were unaffected. The MAO-B activity was not changed. 5. The results indicate that relatively high doses of AAS increase dopaminergic and 5-hydroxytryptaminergic metabolism in male rat brain, probably due to enhanced turnover in these monaminergic systems.  (+info)

Reversal of weightlessness-induced musculoskeletal losses with androgens: quantification by MRI. (4/470)

Microgravity causes rapid decrement in musculoskeletal mass is associated with a marked decrease in circulatory testosterone levels, as we reported in hindlimb-suspended (HLS) rats. In this model which simulates microgravity, we hypothesized that testosterone supplementation should prevent these losses, and we tested this in two studies. Muscle volumes and bone masses were quantitated by using magnetic resonance imaging (MRI) on day 12. In the first study, 12-wk-old Sprague-Dawley rats that were HLS for 12 days lost 28.5% of muscle volume (53.3 +/- 4.8 vs. 74.5 +/- 3.6 cm3 in the ground control rats; P < 0.001) and had a 5% decrease in bone mineral density (BMD) (P < 0.05). In the second study, 30 male 12-wk-old Wistar rats were HLS and were administered either a vehicle (control), testosterone, or nandrolone decanoate (ND). An additional 20 rats were used as ground controls, one-half of which received testosterone. HLS rats had a significant reduction in muscle volume (42.9 +/- 3.0 vs. 56 +/- 1.8 cm3 in ground control rats; P < 0.01). Both testosterone and ND treatments prevented this muscle loss (51.5 +/- 2 and 51.6 +/- 1.2 cm3, respectively; a 63% improvement; P < 0. 05). There were no statistical differences between the two active treatment groups nor with the ground controls. Similarly, there was an 85% improvement in BMD in the testosterone group (1.15 +/- 0.04 vs. 1.04 +/- 0.04 density units in vehicle controls; P < 0.05) and a 76% improvement in the ND group (1.13 +/- 0.07 density units), whereas ground control rats had a BMD of 1.17 +/- 0.03 density units. Because serum testosterone levels are markedly reduced in this model of simulated microgravity, androgen replacement seems to be a rational countermeasure to prevent microgravity-induced musculoskeletal losses.  (+info)

Effects of anabolic-androgenic steroid use or gonadal testosterone suppression on serum leptin concentration in men. (5/470)

OBJECTIVE: Serum leptin concentration shows a sexual dimorphism that is not accounted for by gender differences in adiposity. A strong inverse association exists between serum leptin and testosterone concentrations in men, pointing to a likely influence of gonadal sex steroids on serum leptin concentration. The aim of this study was to investigate whether manipulation of sex steroid hormones in men would alter serum leptin concentration independently of changes in fat mass. DESIGN AND METHODS: The effects of sex steroid suppression on serum leptin concentration were investigated in nine healthy men in whom testosterone had been reversibly suppressed for 5 weeks after treatment with intramuscular triptorelin. The effects of sex steroid supplementation were investigated in nine male bodybuilders who self-administered anabolic--androgenic steroids (AAS) for a mean period of 6.5 weeks. A control group received no hormonal treatment. RESULTS: Testosterone concentration was significantly reduced by triptorelin administration (7.32+/- 1.92ng/ml at baseline compared with 1.15+/-0.57ng/ml at 5 weeks, P=0.002). High-dose AAS use was confirmed by urine analysis. Body fat percentage was unaffected by the AAS or triptorelin intervention (P>0.19). Leptin concentration was significantly reduced after one cycle of AAS use (2.40+/-0. 98ng/ml off cycle compared with 1.63+/-0.37ng/ml on cycle, P=0.012), and was significantly increased by triptorelin administration (2. 96+/-1.50ng/ml at baseline compared with 6.63+/-4.67ng/ml at five weeks, P=0.004). No significant change occurred in the control group. CONCLUSION: Androgenic sex hormone supplementation decreases serum leptin concentration, whereas suppression increases serum leptin concentration, independently of changes in body fat mass in healthy men. The sexual dimorphism evident in serum leptin concentration is likely to be due to a suppressive effect of testosterone on serum leptin concentration in males.  (+info)

Effects of anabolic steroids on diaphragm impairment induced by methylprednisolone in emphysematous hamsters. (6/470)

This study was designed to investigate whether the administration of the anabolic steroid nandrolone decanoate is able to antagonize the loss in diaphragm function induced by long-term administration of a low-dose of methylprednisolone in emphysematous hamsters. Normal and emphysematous male hamsters were randomized to receive either saline or methylprednisolone 0.2 mg x kg(-1) x day(-1) for 9 months, with or without nandrolone decanoate 1 mg x kg(-1) x week(-1) i.m. during the final 3 months. Diaphragm contractile properties and myosin heavy chain composition were determined. Compared to control hamsters, the force generating capacity of isolated diaphragm strips decreased by approximately 12% in the emphysema group and by approximately 22% in the emphysema plus methylprednisolone group. Addition of nandrolone decanoate to the emphysema plus methylprednisolone hamsters significantly improved force generation. The atrophy of type IIa and IIx diaphragm fibres in the emphysema plus methylprednisolone group was completely reversed to the level of control hamsters by the addition of nandrolone decanoate. In conclusion, nandrolone decanoate in part reversed the loss in diaphragm force-generating capacity in emphysematous hamsters treated with methylprednisolone, and reversed type IIa and IIx fibre atrophy completely.  (+info)

Effects of anabolic steroid (19-nortestosterone) on the secretion of testicular hormones in the stallion. (7/470)

The aim of this study was to clarify the effect of anabolic steroids on the testicular endocrine function of mature stallions. Mature thoroughbred stallions were treated with 800 mg nandrolone decanoate every 3 weeks for 3 months. After the first treatment, plasma concentrations of LH, immunoreactive inhibin and testosterone decreased rapidly to the nadir. These hormones were maintained at significantly lower concentrations compared with concentrations in intact stallions. Histology of the testicular tissue indicated the arrest of advanced spermatogenesis in the seminiferous tubules and a severe depletion of the number of Leydig cells in the interstitial compartment as a result of treatment. Most of the immunopositive cells for the inhibin alpha-subunit and steroidogenesis enzymes in the interstitial compartment decreased below detectable amounts, whereas immunopositive reactions of inhibin alpha-subunit in the seminiferous tubules were clearly observed. In conclusion, the treatment of mature stallions with nandrolone decanoate caused a decrease in the secretion of ir-inhibin and testosterone from the testis, the depletion of the number of Leydig cells and a decrease below detectable amounts of inhibin alpha-subunit and steroidogenesis enzymes. The concentration of ir-inhibin in the peripheral blood may be a useful marker for the examination of testicular activity in stallions being treated with anabolic steroids.  (+info)

Over-the-counter anabolic steroids 4-androsten-3,17-dione; 4-androsten-3beta,17beta-diol; and 19-nor-4-androsten-3,17-dione: excretion studies in men. (8/470)

Since the appearance of 4-androsten-3,17-dione (I) as a nutritional supplement in early 1997, we have frequently observed a characteristic deterioration of endogenous steroid profiles in athletes' urine in routine anabolic steroid testing in which concentrations of major endogenous urinary steroids and testosterone exceed normal. Human excretion studies are performed with I and newer, over-the-counter "supplements" 4-androsten-3beta,17beta-diol (II) and 19-nor-4-androsten-3,17-dione (III). Endogenous urinary steroids affected by I and II are androsterone, etiocholanolone, their hydroxylated derivatives 5alpha- and 5beta-androstan-3alpha,17beta-diols, testosterone, and epitestosterone. Their concentrations briefly increase by one to two orders of magnitude and return to normal 24 h after oral administration of I and II. The average male may test positive for testosterone because testosterone concentration rises faster than that of epitestosterone, causing the testosterone/epitestosterone (T/E) ratio to rise above the positive cutoff of 6:1. A remarkable distinction in excretion patterns was observed in eastern Asian men, for whom I and II did not affect urinary concentrations of testosterone and did not increase the T/E ratio. First-pass metabolism deactivates most of the orally administered drugs I and II, rapidly converting them into inactive androsterone and etiocholanolone. Drug II is a more effective testosterone booster because of its different metabolic pathway. After the use of III, a precursor of the potent anabolic nandrolone, high concentrations of norandrosterone and noretiocholanolone appear in urine, similar to nandrolone. These are detectable in urine for 7-10 days after a single oral dose of III (50 mg).  (+info)