A study of androgen-stimulated l-leucine transport by the intestine of rainbow trout (Salmo gairdneri Richardson) in vitro

Habibi, Hamid R.; Ince, Bernard W.

doi:10.1016/0300-9629(84)90722-9

Cited by 16 publications

References 38 publications

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Rapid stimulatory effects of testosterone upon myotubule metabolism and sugar transport, as assessed by silicon microphysiometry

Tsai

Sapolsky

1996

Aggr. Behav.

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A considerable number of studies have revealed behavioral circumstances that give rise to small or transient differences in circulating testosterone concentrations; however, careful consideration of androgen physiology leads to the disquieting conclusion that these differences are often unlikely to have much physiologic or behavioral significance. In the present report, we observe that small transients of testosterone secretion could have very rapid anabolic effects on a cultured muscle‐derived cell line. Specifically, we have examined the effects of testosterone on metabolism in cultured C2C12 myotubules, using a silicon microphysiometer. The instrument monitors cellular extrusion of protons and acidic metabolites, and such extrusion is directly linked to ATP hydrolysis, thus providing a real‐time measure of cellular metabolism. Testosterone caused a small but significant increase in metabolism. The most striking feature of this effect was its rapidity, in that it occurred within 3 hr. This rapid enhancement of metabolism suggested that testosterone might be enhancing substrate uptake even more rapidly. Indeed, we found that testosterone increased 2‐deoxyglucose uptake within 1 min. The rapidity of this effect seemed to preclude mediation by classical intracellular steroid receptors. In support of this, we were unable to detect specific intracellular binding of testosterone. These findings show that testosterone can exert rapid anabolic effects on substrate transport and metabolism in myotubules. Should this finding general to muscle in vivo, it suggests that relatively small individual differences in testosterone profiles, in response to various social interactions, may have very real consequence for subsequent muscle physiology. © 1996 Wiley‐Liss, Inc.

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Rapid stimulatory effects of testosterone upon myotubule metabolism and sugar transport, as assessed by silicon microphysiometry

Tsai

Sapolsky

1996

Aggr. Behav.

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Intestinal Calcium Absorption: The Calbindins, the Visualization of Transported Calcium and a New Rapid Action of 1,25-Dihydroxyvitamin D3

Wasserman

Fullmer

Chandra

et al. 1990

Calcium Transport and Intracellular Calcium Homeostasis

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Specific binding of 11-ketotestosterone in an androgen target organ, the kidney of the male three-spined stickleback,Gasterosteus aculeatus

Jakobsson

Mayer

Schulz

et al. 1996

Fish Physiol Biochem

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The kidney of male three-spined stickleback,Gasterosteus aculeatus, hypertrophies during the breeding season and produces a "glue" which is used in the building of the nest. This hypertrophy is androgen dependent, with 11-ketotestosterone (11KT) being more effective than other tested steroids in stimulating this secondary sexual character. In the present study kidneys were excised from stickleback males that had been castrated two days earlier. The purpose of this gonadectomy was to reduce the endogenous levels of androgens without allowing time for the kidney to regress. Tissue fragments were incubated with tritiated 11KT with and without unlabelled steroids at increasing concentrations. Displaceable specific 11KT binding was found in kidney tissue fragments whereas only non-specific binding was observed when liver and muscle were investigated in a similar way. Unlabelled 11KT displaced specifically bound, tritiated 11KT with an ED50-value (50% of displaceable binding) of 28 nM. Similar ED50 values were found for 17\-hydroxy-5α-androstane-3,11-dione (29 nM) and 5α-dihydrotestosterone (20 nM), whereas higher ED50 concentrations were estimated for testosterone (T; 203 nM) and progesterone (69 nM). No displacement of tritiated 11KT was found for the other investigated substances tested; estradiol, 17α,20β-dihydroxy-4-pregnen-3-one, flutamide or cyproterone acetate. No specific binding to kidney tissue fragments could be detected when labelled T was used instead of labelled 11KT. Specific binding of 11KT or T was not found either in the kidney cytosol or nuclear extracts. However, using the kidney membrane fraction a displacement of tritiated 11KT with unlabelled 11KT (10(-6)M) was observed. In conclusion there is a specific binding of 11KT in the stickleback kidney. The absence of binding in liver and muscle, the ED50 value observed and the displacement with some, but not all steroids are consistent with a receptor function. The presence of binding in membrane fractions, but not in cytosol or nuclear extracts suggests that the binding is not related to classic steroid receptors.

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A study of androgen-stimulated l-leucine transport by the intestine of rainbow trout (Salmo gairdneri Richardson) in vitro

Cited by 16 publications

References 38 publications

Rapid stimulatory effects of testosterone upon myotubule metabolism and sugar transport, as assessed by silicon microphysiometry

Rapid stimulatory effects of testosterone upon myotubule metabolism and sugar transport, as assessed by silicon microphysiometry

Intestinal Calcium Absorption: The Calbindins, the Visualization of Transported Calcium and a New Rapid Action of 1,25-Dihydroxyvitamin D3

Specific binding of 11-ketotestosterone in an androgen target organ, the kidney of the male three-spined stickleback,Gasterosteus aculeatus

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